#landing-modal-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: 99999;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: 'Inter', sans-serif;
    visibility: visible;
}

body.modal-open {
    overflow: hidden;
}

#landing-modal-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--modal-overlay-bg);
    backdrop-filter: blur(2px);
}

#landing-modal {
    position: relative;
    z-index: 100000;
    width: 60vw;
    max-width: 960px;
    max-height: 85vh;
    background: var(--modal-bg);
    border-radius: 12px;
    box-shadow: var(--modal-shadow);
    padding: 0;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    overflow: hidden;
    opacity: 0;
    transform: scale(0.95);
    animation: modalAppear 0.4s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

@keyframes modalAppear {
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.modal-body {
    display: flex;
    flex-direction: column;
    flex: 1;
    overflow: hidden;
    padding: 0;
}

.modal-body h1 {
    flex-shrink: 0;
    background-color: var(--modal-header-bg);
    color: var(--modal-header-text);
    font-size: 1.25rem;
    font-weight: 600;
    margin: 0;
    padding: 1.25rem 2rem;
    border-bottom: 1px solid var(--modal-header-border);
    letter-spacing: -0.01em;
    display: flex;
    align-items: center;
}

.modal-body h1::before {
    content: "\f0e7";
    font-family: "Font Awesome 6 Free";
    font-weight: 900;
    color: var(--modal-icon-accent);
    margin-right: 0.75rem;
    font-size: 1.1rem;
}

.modal-body .modal-content-scroll {
    flex: 1;
    overflow-y: auto;
    padding: 2rem 2.5rem;
}

.modal-body h2 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--modal-body-heading);
    margin-top: 2rem;
    margin-bottom: 1rem;
    letter-spacing: -0.015em;
}

.modal-body h3 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--modal-body-subheading);
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
}

.modal-body p {
    font-size: 1rem;
    line-height: 1.7;
    margin-bottom: 1.25rem;
    color: var(--modal-body-text);
}

.modal-body ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.modal-body>.modal-content-scroll>ul>li {
    position: relative;
    padding-left: 2rem;
    margin-bottom: 1.25rem;
    line-height: 1.6;
    color: var(--modal-list-text);
    font-size: 1rem;
}

.modal-body>.modal-content-scroll>ul>li::before {
    content: "\f058";
    font-family: "Font Awesome 6 Free";
    font-weight: 400;
    position: absolute;
    left: 0;
    top: -1px;
    color: var(--modal-list-icon);
    font-size: 1.1rem;
}


.modal-body ul ul {
    margin-top: 0.75rem;
    margin-bottom: 0.75rem;
    background: var(--modal-nested-bg);
    border-radius: 8px;
    padding: 1rem 1.5rem;
    border: 1px solid var(--modal-nested-border);
}

.modal-body ul ul li {
    margin-bottom: 0.5rem;
    font-size: 0.95rem;
    color: var(--modal-nested-text);
    display: flex;
    align-items: baseline;
}

.modal-body ul ul li:last-child {
    margin-bottom: 0;
}

.modal-body ul ul li strong {
    color: var(--modal-header-text);
    margin-right: 0.5rem;
}

.modal-body quote {
    display: block;
    border-left: 4px solid var(--color-accent-secondary);
    background: var(--modal-nested-bg);
    padding: 1rem 1.5rem;
    margin: 1.5rem 0;
    font-style: italic;
    color: var(--modal-body-heading);
    border-radius: 0 8px 8px 0;
}

.modal-body strong {
    font-weight: 600;
    color: var(--modal-header-text);
}

.modal-body .modal-content-scroll::-webkit-scrollbar {
    width: 8px;
}

.modal-body .modal-content-scroll::-webkit-scrollbar-track {
    background: transparent;
}

.modal-body .modal-content-scroll::-webkit-scrollbar-thumb {
    background-color: var(--scroll-thumb);
    border-radius: 4px;
}

.modal-body .modal-content-scroll::-webkit-scrollbar-thumb:hover {
    background-color: var(--scroll-thumb-hover);
}

.modal-footer {
    flex-shrink: 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.25rem 2rem;
    border-top: 1px solid var(--modal-footer-border);
    background: var(--modal-footer-bg);
    z-index: 10;
}

.modal-checkbox-label {
    display: flex;
    align-items: center;
    font-size: 0.9rem;
    color: var(--modal-checkbox-text);
    cursor: pointer;
    user-select: none;
    font-weight: 500;
}

.modal-checkbox-label:hover {
    color: var(--modal-header-text);
}

.modal-checkbox-label input {
    width: 16px;
    height: 16px;
    margin-right: 10px;
    cursor: pointer;
    accent-color: var(--color-accent-secondary);
}

.modal-ok-btn {
    background-color: var(--modal-btn-bg);
    color: white;
    border: none;
    padding: 10px 24px;
    border-radius: 6px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
    box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
}

.modal-ok-btn:hover {
    background-color: var(--modal-btn-hover-bg);
}

[data-theme="dark"] .accordion-header i.fa-chevron-down {
    background: var(--accordion-icon-bg);
    color: var(--accordion-icon-color);
}

[data-theme="dark"] .accordion-header:hover i.fa-chevron-down {
    background: var(--toolbar-btn-hover-bg);
    color: var(--toolbar-btn-hover-text);
}

[data-theme="dark"] #landing-modal-overlay {
    background-color: var(--modal-overlay-bg);
}

[data-theme="dark"] #landing-modal {
    background: var(--modal-bg);
    box-shadow: var(--modal-shadow);
}

[data-theme="dark"] .modal-body h1 {
    background-color: var(--modal-header-bg);
    color: var(--modal-header-text);
    border-bottom: 1px solid var(--modal-header-border);
}

[data-theme="dark"] .modal-body h1::before {
    color: var(--modal-icon-accent);
}

[data-theme="dark"] .modal-body h2 {
    color: var(--modal-body-heading);
}

[data-theme="dark"] .modal-body h3 {
    color: var(--modal-body-subheading);
}

[data-theme="dark"] .modal-body p {
    color: var(--modal-body-text);
}

[data-theme="dark"] .modal-body>.modal-content-scroll>ul>li {
    color: var(--modal-list-text);
}

[data-theme="dark"] .modal-body>.modal-content-scroll>ul>li::before {
    color: var(--modal-list-icon);
}

[data-theme="dark"] .modal-body ul ul {
    background: var(--modal-nested-bg);
    border: 1px solid var(--modal-nested-border);
}

[data-theme="dark"] .modal-body ul ul li {
    color: var(--modal-nested-text);
}

[data-theme="dark"] .modal-body ul ul li strong {
    color: var(--modal-header-text);
}

[data-theme="dark"] .modal-body strong {
    color: var(--modal-header-text);
}

[data-theme="dark"] .modal-body .modal-content-scroll::-webkit-scrollbar-thumb {
    background-color: var(--scroll-thumb);
}

[data-theme="dark"] .modal-body .modal-content-scroll::-webkit-scrollbar-thumb:hover {
    background-color: var(--scroll-thumb-hover);
}

[data-theme="dark"] .modal-footer {
    border-top: 1px solid var(--modal-footer-border);
    background: var(--modal-footer-bg);
}

[data-theme="dark"] .modal-checkbox-label {
    color: var(--modal-checkbox-text);
}

[data-theme="dark"] .modal-checkbox-label:hover {
    color: var(--modal-header-text);
}

[data-theme="dark"] .modal-checkbox-label input {
    accent-color: var(--color-accent-primary);
}

[data-theme="dark"] .modal-ok-btn {
    background-color: var(--modal-btn-bg);
    color: var(--modal-header-text);
}

[data-theme="dark"] .modal-ok-btn:hover {
    background-color: var(--modal-btn-hover-bg);
}

[data-theme="dark"] .problem-description {
    color: var(--problem-desc-text);
}

[data-theme="dark"] .example-card {
    background: var(--example-bg);
    border: 1px solid var(--example-border);
}

[data-theme="dark"] .example-header {
    background: var(--example-header-bg);
    color: var(--example-header-text);
    border-bottom: 1px solid var(--example-border);
}

[data-theme="dark"] .example-label {
    color: var(--example-label-text);
}

[data-theme="dark"] .example-explanation {
    border-top: 1px dashed var(--example-explanation-border);
    color: var(--example-explanation-text);
}

[data-theme="dark"] .edge-case-item {
    background: var(--edge-case-bg);
    border: 1px solid var(--edge-case-border);
}

[data-theme="dark"] .edge-icon {
    background: var(--edge-case-icon-bg);
    color: var(--edge-case-icon-color);
}

[data-theme="dark"] .edge-content {
    color: var(--edge-case-text);
}

[data-theme="dark"] .complexity-item {
    background: var(--complexity-bg);
    border: 1px solid var(--complexity-border);
}

[data-theme="dark"] .complexity-label {
    color: var(--complexity-label);
}

[data-theme="dark"] .complexity-value {
    color: var(--complexity-value);
}

[data-theme="dark"] .complexity-note {
    color: var(--complexity-note);
}

[data-theme="dark"] .code-inline {
    background: var(--code-inline-bg);
    color: var(--code-inline-text);
    border: 1px solid var(--code-inline-border);
}

[data-theme="dark"] .code-inline.method-name {
    color: var(--code-inline-method);
}

[data-theme="dark"] .code-inline.return-type {
    color: var(--code-inline-type);
}

[data-theme="dark"] .code-inline.params {
    color: var(--code-inline-params);
}

[data-theme="dark"] .code-inline.output-array {
    background: var(--example-output-bg);
    border-color: var(--example-border);
    color: var(--example-output-text);
}

[data-theme="dark"] .api-method {
    background: var(--code-block-bg);
    border: 1px solid var(--code-block-border);
    border-left: 3px solid var(--color-accent-primary);
}

[data-theme="dark"] .api-desc {
    color: var(--problem-desc-text);
}

[data-theme="dark"] .component-label {
    color: var(--example-label-text);
}

[data-theme="dark"] .highlight-good {
    background: var(--highlight-success-bg);
    color: var(--highlight-success-text);
    border: 1px solid var(--highlight-success-border);
}

[data-theme="dark"] .highlight-warn {
    background: var(--solution-verify-pass-bg);
    color: var(--solution-verify-fail-text);
    border: 1px solid var(--solution-verify-pass-border);
}

[data-theme="dark"] .output-value,
[data-theme="dark"] .solution-content code:not(.hljs),
[data-theme="dark"] .mono {
    background: var(--example-output-bg);
    color: var(--example-output-text);
}


[data-theme="dark"] .solution-content code:not(.hljs) {
    border: none;
}

[data-theme="dark"] .code-sm {
    background: var(--code-block-bg);
    color: var(--code-block-text);
}

[data-theme="dark"] .code-sm.null {
    color: var(--color-text-muted);
}

[data-theme="dark"] .code-sm.success {
    background: var(--solution-verify-pass-bg);
    color: var(--solution-verify-pass-text);
}

[data-theme="dark"] .code-sm.miss {
    background: var(--solution-verify-fail-bg);
    color: var(--solution-verify-fail-text);
}

[data-theme="dark"] .problem-id {
    background: var(--color-accent-primary);
    color: var(--color-bg-primary);
}

[data-theme="dark"] .solution-toggle-btn {
    color: var(--solution-toggle-btn-text);
    background: var(--solution-toggle-btn-bg);
    border: 1px solid var(--solution-toggle-btn-border);
}

[data-theme="dark"] .solution-toggle-btn:hover {
    background: var(--solution-toggle-hover-bg);
    color: var(--toolbar-btn-hover-text);
    border-color: var(--solution-toggle-border);
}

[data-theme="dark"] .solution-toggle-btn[aria-pressed="true"] {
    background: var(--solution-toggle-btn-active-bg);
    color: var(--solution-toggle-btn-active-text);
    border-color: var(--solution-toggle-btn-active-bg);
}

[data-theme="dark"] .solution-toggle-btn[aria-pressed="true"]:hover {
    background: var(--color-accent-secondary);
}

[data-theme="dark"] .visual-container {
    background: var(--visual-bg);
    border: 1px dashed var(--visual-border);
}

[data-theme="dark"] .visual-container.force-light-bg-in-dark {
    background: var(--force-light-bg-in-dark);
}

[data-theme="dark"] .example-explanation span.mono {
    background: var(--code-inline-bg);
    color: var(--code-inline-text);
}

[data-theme="dark"] .edge-case-item {
    background: var(--edge-case-bg);
    border: 1px solid var(--edge-case-border);
}

[data-theme="dark"] .problem-card.active::before {
    background: var(--card-active-gradient);
    background-size: 200% 200%;
    animation: gradientShift 3s ease-in-out infinite;
}

#landing-modal-overlay {
    background-color: var(--modal-overlay-bg);
}

#landing-modal {
    background: var(--modal-bg);
}

.modal-body h1 {
    background-color: var(--modal-header-bg);
    color: var(--text-header);
    border-bottom: 1px solid var(--border-color);
}

.modal-body h2 {
    color: var(--text-header);
}

.modal-body h3 {
    color: var(--text-main);
}

.modal-body p {
    color: var(--text-main);
}

.modal-body>.modal-content-scroll>ul>li {
    color: var(--text-main);
}

.modal-body ul ul {
    background: var(--code-block-bg);
    border: 1px solid var(--border-color);
}

.modal-body ul ul li {
    color: var(--text-main);
}

.modal-body ul ul li strong {
    color: var(--text-header);
}

.modal-body quote {
    background: var(--code-block-bg);
    color: var(--text-header);
}

.modal-body strong {
    color: var(--text-header);
}

.modal-body .modal-content-scroll::-webkit-scrollbar-thumb {
    background-color: var(--scroll-thumb);
}

.modal-body .modal-content-scroll::-webkit-scrollbar-thumb:hover {
    background-color: var(--scroll-thumb-hover);
}

.modal-footer {
    border-top: 1px solid var(--border-color);
    background: var(--modal-bg);
}

#main-toolbar {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 12px 16px;
    background: var(--toolbar-bg);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 50;
    box-shadow: var(--toolbar-shadow);
    backdrop-filter: blur(8px);
}

.toolbar-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    height: 32px;
    padding: 0 14px;
    font-size: 0.875rem;
    font-weight: 400;
    color: var(--btn-text);
    background: var(--btn-bg);
    border: 1px solid var(--btn-border);
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s ease;
}

.toolbar-btn:hover {
    background: var(--btn-hover-bg);
    color: var(--text-header);
    border-color: var(--sidebar-text);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font-sans);
    background-color: var(--main-bg);
    color: var(--text-main);
    display: flex;
    height: 100vh;
    overflow: hidden;
}

aside {
    width: 370px;
    background-color: var(--sidebar-bg);
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--sidebar-border);
    flex-shrink: 0;
    box-shadow: 2px 0 8px rgba(0, 0, 0, 0.04);
}

.brand {
    padding: 22px 24px;
    color: var(--text-header);
    font-size: 1.15rem;
    font-weight: 700;
    letter-spacing: -0.01em;
    border-bottom: 1px solid var(--sidebar-border);
    display: flex;
    align-items: center;
    gap: 10px;
    background: var(--sidebar-bg);
    box-shadow: var(--toolbar-shadow);
    z-index: 1;
    min-height: var(--toolbar-height);
}

.brand i {
    color: var(--accent);
    font-size: 1.2rem;
}

.search-box {
    padding: 16px 20px;
    background: var(--sidebar-bg);
    border-bottom: 1px solid var(--sidebar-border);
    z-index: 0;
}

.search-input-wrapper {
    position: relative;
    width: 100%;
}

.search-box input {
    width: 100%;
    padding: 12px 36px 12px 16px;
    /* Right padding 36px to accommodate button */
    border-radius: 10px;
    border: 1px solid var(--sidebar-border);
    background: var(--search-bg);
    color: var(--text-header);
    font-family: var(--font-sans);
    font-size: 0.9rem;
    outline: none;
    transition: all 0.2s ease;
}

.search-clear-btn {
    position: absolute;
    right: 12px;
    top: 50%;
    transform: translateY(-50%);
    background: var(--sidebar-search-clear-bg);
    border: none;
    color: var(--sidebar-search-clear-text);
    width: 20px;
    height: 20px;
    border-radius: 50%;
    display: none;
    align-items: center;
    justify-content: center;
    font-size: 0.7rem;
    cursor: pointer;
    padding: 0;
    transition: all 0.2s ease;
    z-index: 10;
}

.search-clear-btn:hover {
    background: var(--sidebar-search-clear-hover-bg);
    color: var(--sidebar-search-clear-hover-text);
}

.search-box input::placeholder {
    color: var(--sidebar-text);
}

.search-box input:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.nav-list {
    display: flex;
    flex-direction: column;
    flex: 1;
    min-height: 0;
    overflow: hidden;
}

.nav-item {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 13px 20px;
    margin: 1px 12px;
    color: var(--sidebar-text);
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    line-height: 1.5;
    border-radius: 8px;
    transition: all 0.15s ease;
    cursor: pointer;
    border: 1px solid transparent;
}

.nav-item:hover {
    background-color: var(--sidebar-hover);
    color: var(--text-header);
}

.nav-item.active {
    background-color: var(--sidebar-active-bg);
    color: var(--sidebar-active);
    font-weight: 600;
    border: 1px solid var(--accent);
}

.nav-item .id-badge {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--accent);
    background: var(--code-block-bg);
    padding: 3px 7px;
    border-radius: 5px;
    flex-shrink: 0;
    min-width: 26px;
    text-align: center;
}

.nav-item:hover .id-badge {
    background: var(--sidebar-hover);
    color: var(--text-main);
}

.nav-item.active .id-badge {
    background: rgba(37, 99, 235, 0.15);
    color: var(--sidebar-active);
}

main#problems {
    flex: 1;
    overflow-y: auto;
    padding: 48px 35vw 40px 60px;
    box-sizing: border-box;
    margin: 66px 0 0 0;
}

h1 {
    font-size: 2.5rem;
    color: var(--text-header);
    margin-bottom: 10px;
}

.problem-card {
    background: var(--card-bg);
    border-radius: 12px;
    border: 1px solid var(--border-color);
    padding: 32px;
    margin-bottom: 0;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    scroll-margin-top: 40px;
    position: relative;
}

.problem-divider {
    height: 0;
    width: 100%;
    margin: 48px 0;
    border-top: 2px solid var(--border-color);
}

.problem-card.active {
    border: none;
    background: var(--card-bg);
    z-index: 1;
}

.problem-card.active::before {
    content: '';
    position: absolute;
    inset: -4px;
    border-radius: 16px;
    background: var(--card-active-gradient);
    background-size: 200% 200%;
    animation: gradientShift 3s ease-in-out infinite;
    z-index: -1;
}

.problem-card.active::after {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: 12px;
    background: var(--card-bg);
    z-index: -1;
}

@keyframes gradientShift {

    0%,
    100% {
        background-position: 0% 50%;
    }

    50% {
        background-position: 100% 50%;
    }
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 20px;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 16px;
}

.problem-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-header);
    display: flex;
    align-items: center;
    gap: 12px;
}

.problem-id {
    background: var(--text-header);
    color: white;
    font-family: var(--font-mono);
    font-size: 0.9rem;
    padding: 4px 8px;
    border-radius: 4px;
}

.tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 8px;
}

.tag {
    background: var(--tag-bg);
    color: var(--tag-text);
    padding: 4px 10px;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
}

.section-title {
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--section-title-color);
    font-weight: 700;
    margin: 24px 0 12px 0;
    display: flex;
    align-items: center;
    gap: 8px;
}

p {
    line-height: 1.7;
    margin-bottom: 16px;
    color: var(--text-main);
}

.code-block {
    background: var(--code-block-bg);
    border-left: 4px solid var(--accent);
    padding: 16px;
    border-radius: 0 8px 8px 0;
    font-family: var(--font-mono);
    font-size: 1rem;
    margin-bottom: 16px;
    color: var(--text-main);
    line-height: 1.6rem;
}

.mono {
    font-family: var(--font-mono);
    background: var(--mono-bg);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.9em;
    color: var(--mono-color);
}

.highlight-word {
    background-color: var(--highlight-bg);
    padding: 0 4px;
    border-radius: 2px;
    font-weight: 600;
    color: var(--highlight-text);
}

.constraints-box {
    background: var(--constraints-bg);
    border: 1px solid var(--constraints-border);
    border-radius: 8px;
    padding: 16px;
}

.constraints-list {
    list-style: none;
}

.constraints-list li {
    position: relative;
    padding-left: 20px;
    margin-bottom: 8px;
    font-size: 1rem;
    color: var(--constraints-text);
}

.constraints-list li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--constraints-bullet);
    font-weight: bold;
}

.complexity {
    margin-top: 12px;
    font-family: var(--font-mono);
    font-size: 0.9rem;
    color: var(--complexity-color);
    background: var(--complexity-bg);
    padding: 8px;
    border-radius: 4px;
    display: inline-block;
}

.visual-container {
    background: var(--visual-container-bg);
    border: 1px dashed var(--visual-container-border);
    border-radius: 8px;
    padding: 20px;
    margin: 20px 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100px;
}

.node {
    width: 36px;
    height: 36px;
    border: 2px solid var(--accent);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    background: var(--visual-node-bg);
    z-index: 2;
}

.node {
    width: 40px;
    height: 40px;
    border-color: var(--visual-node-border);
}

.arrow {
    color: var(--visual-arrow);
    font-size: 20px;
}

.list-visual {
    display: flex;
    align-items: center;
    gap: 8px;
}

.word-search-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0;
    background: var(--ws-grid-bg);
    padding: 10px;
    border-radius: 8px;
    width: fit-content;
}

.word-search-cell {
    width: 36px;
    height: 36px;
    background: var(--ws-cell-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    color: var(--ws-cell-text);
    border: 1px solid var(--ws-cell-border);
    /* Overlap trick: negative margins */
    margin-right: -1px;
    margin-bottom: -1px;
    position: relative;
    font-family: var(--font-mono);
    font-size: 1rem;
    transition: all 0.2s ease;
}

.word-search-cell.active {
    background: var(--ws-cell-active-bg);
    color: var(--ws-cell-active-text);
    z-index: 10;
    border-color: var(--ws-cell-active-bg);
    box-shadow: 0 0 0 1px var(--ws-cell-active-bg);
}



.tree-visual {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.tree-row {
    display: flex;
    gap: 20px;
}

.rain-visual {
    display: flex;
    align-items: flex-end;
    gap: 4px;
    height: 100px;
}

.bar-col {
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    width: 20px;
}

.bar {
    background: var(--rain-bar-bg);
    width: 100%;
    transition: height 0.3s;
}

.water {
    background: var(--rain-water-bg);
    width: 100%;
    opacity: 0.7;
}

[data-theme="dark"] .water {
    background: var(--rain-water-bg);
}

.grid-visual {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 2px;
    background: var(--grid-visual-bg);
    border: 2px solid var(--grid-visual-border);
}

.cell {
    width: 30px;
    height: 30px;
    background: var(--grid-cell-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
}

.cell.land {
    background: var(--visual-land-bg);
    color: var(--visual-land-text);
}

.cell.water {
    background: var(--visual-water-bg);
}


.problem-description {
    font-size: 1.05rem;
    line-height: 1.7;
    color: var(--text-main);
}



.highlight-good {
    background: var(--highlight-success-bg);
    color: var(--highlight-success-text);
    padding: 2px 6px;
    border-radius: 4px;
    border: 1px solid var(--highlight-success-border);
}

.highlight-warn {
    background: var(--highlight-warning-bg);
    color: var(--highlight-warning-text);
    padding: 2px 6px;
    border-radius: 4px;
    border: 1px solid var(--highlight-warning-border);
}



.example-card {
    background: var(--example-bg);
    border: 1px solid var(--example-border);
    border-radius: 10px;
    margin-bottom: 16px;
    overflow: hidden;
}

.example-header {
    background: var(--example-header-bg);
    padding: 10px 16px;
    font-weight: 700;
    font-size: 0.8rem;
    color: var(--example-header-text);
    text-transform: uppercase;
    letter-spacing: 0.03em;
    border-bottom: 1px solid var(--example-border);
}

.example-body {
    padding: 16px;
}

.example-row {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 8px;
}

.example-label {
    font-weight: 600;
    color: var(--example-label-text);
    min-width: 60px;
    font-size: 0.85rem;
}

.output-value {
    background: var(--example-output-bg);
    color: var(--example-output-text);
    padding: 4px 10px;
    border-radius: 6px;
    font-weight: 700;
}

.example-explanation {
    margin-top: 12px;
    padding-top: 12px;
    border-top: 1px dashed var(--example-explanation-border);
    font-size: 0.9rem;
    color: var(--example-explanation-text);
    line-height: 1.6;
}

.edge-cases {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 12px;
}

.edge-case-item {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 14px;
    background: var(--edge-case-bg);
    border: 1px solid var(--edge-case-border);
    border-radius: 8px;
}

.edge-icon {
    width: 28px;
    height: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--edge-case-icon-bg);
    color: var(--edge-case-icon-color);
    border-radius: 6px;
    font-size: 0.75rem;
}

.edge-content {
    font-size: 0.9rem;
    color: var(--edge-case-text);
    line-height: 1.5;
}

.complexity-target {
    display: flex;
    gap: 24px;
    flex-wrap: wrap;
}

.complexity-item {
    flex: 1;
    min-width: 200px;
    background: var(--complexity-bg);
    border: 1px solid var(--complexity-border);
    border-radius: 10px;
    padding: 16px 20px;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.complexity-label {
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--complexity-value);
}

.complexity-value {
    font-family: var(--font-mono);
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--complexity-value);
}

.complexity-note {
    font-size: 0.8rem;
    color: var(--complexity-border);
    margin-top: 4px;
}

.code-inline {
    font-family: var(--font-mono);
    font-size: 0.875em;
    background: var(--code-inline-bg);
    color: var(--code-inline-text);
    padding: 2px 6px;
    border-radius: 4px;
    border: 1px solid var(--code-inline-border);
    white-space: nowrap;
}

.code-inline.method-name {
    color: var(--code-inline-method);
    font-weight: 600;
}

.code-inline.return-type {
    color: var(--code-inline-type);
}

.code-inline.params {
    color: var(--code-inline-params);
}

.code-inline.output-array {
    background: var(--highlight-success-bg);
    border-color: var(--highlight-success-border);
    color: var(--highlight-success-text);
}

.code-block-clean {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 1.7;
    background: var(--code-dark-bg);
    color: var(--code-dark-text);
    padding: 16px 20px;
    border-radius: 8px;
    overflow-x: auto;
}

.code-comment {
    color: var(--color-text-muted);
    font-style: italic;
}

.api-spec {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin-bottom: 20px;
}

.api-method {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-left: 3px solid var(--accent);
    border-radius: 6px;
    padding: 14px 18px;
}

.api-signature {
    margin-bottom: 8px;
}

.api-desc {
    font-size: 0.9rem;
    color: var(--color-text-tertiary);
    line-height: 1.5;
}

.lru-visual {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 24px;
    flex-wrap: wrap;
    margin-bottom: 20px;
}

.lru-component {
    text-align: center;
}

.component-label {
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-muted);
    margin-bottom: 10px;
}

.hashmap-box {
    background: var(--hashmap-bg);
    border: 2px solid var(--hashmap-border);
    border-radius: 8px;
    padding: 16px 20px;
}

.hashmap-entry {
    font-family: var(--font-mono);
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 8px;
}

.hm-key {
    color: var(--hashmap-key);
    font-weight: 600;
}

.hm-arrow {
    color: var(--hashmap-arrow);
}

.hm-value {
    color: var(--hashmap-value);
}

.lru-connector {
    color: var(--visual-arrow);
    font-size: 1.5rem;
}

.dll-visual {
    display: flex;
    align-items: center;
    gap: 6px;
}

.dll-sentinel {
    background: var(--code-block-bg);
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 0.7rem;
    font-weight: 700;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

.dll-arrow {
    color: var(--visual-arrow);
    font-size: 0.9rem;
}

.dll-node {
    width: 44px;
    height: 44px;
    border: 2px solid var(--dll-node-border);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--dll-node-bg);
}

.dll-node.mru {
    border-color: var(--dll-mru-border);
    background: var(--dll-mru-bg);
}

.dll-node.lru {
    border-color: var(--dll-lru-border);
    border-style: dashed;
    background: var(--dll-lru-bg);
}

.node-label {
    font-size: 0.65rem;
    font-weight: 700;
    color: inherit;
}

.dll-node.mru .node-label {
    color: var(--dll-mru-text);
}

.dll-node.lru .node-label {
    color: var(--dll-lru-text);
}

.node-dots {
    color: var(--visual-arrow);
    font-size: 1rem;
}

.visual-caption {
    display: flex;
    justify-content: center;
    gap: 24px;
    font-size: 0.8rem;
    color: var(--color-text-muted);
}

.caption-item {
    display: flex;
    align-items: center;
    gap: 6px;
}

.caption-dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    border: 2px solid;
}

.caption-dot.mru {
    border-color: var(--dll-mru-border);
    background: var(--dll-mru-bg);
}

.caption-dot.lru {
    border-color: var(--dll-lru-border);
    border-style: dashed;
    background: var(--dll-lru-bg);
}

.trace-table {
    border: 1px solid var(--trace-border);
    border-radius: 10px;
    overflow: hidden;
    margin: 16px 0 24px;
}

.trace-header {
    display: flex;
    background: var(--trace-header-bg);
    color: var(--trace-header-text);
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.trace-row {
    display: flex;
    border-bottom: 1px solid var(--trace-border);
    background: var(--trace-bg);
}

.trace-row:last-child {
    border-bottom: none;
}

.trace-row:nth-child(even) {
    background: var(--trace-row-stripe);
}

.trace-col {
    padding: 10px 14px;
    font-size: 0.85rem;
    display: flex;
    align-items: center;
}

.trace-col.op {
    width: 140px;
    flex-shrink: 0;
}

.trace-col.cache {
    flex: 1;
    gap: 6px;
    flex-wrap: wrap;
}

.trace-col.result {
    width: 80px;
    flex-shrink: 0;
    justify-content: center;
}

.code-sm {
    font-family: var(--font-mono);
    font-size: 0.95rem;
    background: var(--code-sm-bg);
    padding: 3px 6px;
    border-radius: 4px;
    color: var(--code-sm-text);
}

.code-sm.null {
    color: var(--code-sm-null);
}

.code-sm.success {
    background: var(--code-sm-success-bg);
    color: var(--code-sm-success-text);
    font-weight: 600;
}

.code-sm.miss {
    background: var(--code-sm-miss-bg);
    color: var(--code-sm-miss-text);
    font-weight: 600;
}

.cache-item {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    background: var(--cache-item-bg);
    color: var(--cache-item-text);
    padding: 3px 8px;
    border-radius: 4px;
    font-weight: 500;
}

.cache-item.active {
    background: var(--cache-item-active-bg);
    color: var(--cache-item-active-text);
    border: 1px solid var(--cache-item-active-border);
}

.evicted {
    font-size: 0.7rem;
    color: var(--cache-evicted-text);
    background: var(--cache-evicted-bg);
    padding: 2px 6px;
    border-radius: 4px;
    font-style: italic;
}

.empty-state {
    color: var(--color-text-subtle);
    font-style: italic;
}

.heap-visual {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
    padding: 10px 0;
}

.heap-structure {
    background: var(--heap-structure-bg);
    border: 2px dashed var(--heap-structure-border);
    border-radius: 12px;
    padding: 16px 30px;
    text-align: center;
    position: relative;
}

.heap-label {
    font-size: 0.7rem;
    font-weight: 700;
    text-transform: uppercase;
    color: var(--heap-label);
    margin-bottom: 12px;
    letter-spacing: 0.05em;
}

.heap-nodes {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
}

.heap-node {
    width: 44px;
    height: 44px;
    background: var(--heap-node-bg);
    border: 2px solid var(--heap-node-border);
    border-radius: 50%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    color: var(--heap-node-text);
    position: relative;
    box-shadow: 0 2px 4px var(--heap-node-shadow);
}

.heap-node.root {
    background: var(--heap-root-bg);
    border-color: var(--heap-root-border);
    z-index: 2;
}

.heap-node .h-val {
    font-size: 0.95rem;
    line-height: 1;
}

.heap-node .h-src {
    font-size: 0.6rem;
    color: var(--heap-src-text);
    margin-top: -2px;
}

.heap-children {
    display: flex;
    gap: 24px;
    position: relative;
}

.heap-children::before {
    content: '';
    position: absolute;
    top: -12px;
    left: 50%;
    width: 60%;
    height: 12px;
    border: 2px solid var(--heap-connector);
    border-top: none;
    border-bottom: none;
    transform: translateX(-50%) skewX(20deg);
    border-radius: 0 0 10px 10px;
    display: none;
}

.heap-caption {
    font-size: 0.7rem;
    color: var(--heap-caption);
    margin-top: 10px;
}

.merge-arrow {
    display: flex;
    flex-direction: column;
    align-items: center;
    color: var(--heap-action);
    gap: 4px;
}

.animate-pulse {
    animation: pulse 2s infinite;
}

@keyframes pulse {

    0%,
    100% {
        opacity: 1;
        transform: translateY(0);
    }

    50% {
        opacity: 0.6;
        transform: translateY(4px);
    }
}

.action-text {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--heap-action);
}

.result-list-visual {
    background: var(--result-list-bg);
    border: 1px solid var(--result-list-border);
    border-radius: 12px;
    padding: 16px 24px;
    width: 100%;
}

.list-chain {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}

.list-node {
    width: 36px;
    height: 36px;
    background: var(--dll-node-bg);
    border: 2px solid var(--dll-mru-border);
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    color: var(--dll-mru-text);
    font-family: var(--font-mono);
}

.list-node.ghost {
    border-style: dashed;
    background: transparent;
    border-color: var(--dll-mru-border);
    color: var(--dll-mru-border);
}

.list-link {
    color: var(--dll-mru-text);
    font-size: 1.1rem;
}

.h-item {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    padding: 2px 6px;
    border-radius: 4px;
    background: var(--code-inline-bg);
    color: var(--code-inline-text);
}



::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: var(--scrollbar-thumb-on-light);
    border-radius: 10px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--scrollbar-thumb-hover-on-light);
}

aside ::-webkit-scrollbar-thumb {
    background: var(--aside-scrollbar-thumb);
}

aside ::-webkit-scrollbar-thumb:hover {
    background: var(--aside-scrollbar-thumb-hover);
}


.accordion-section {
    display: flex;
    flex-direction: column;
    min-height: 0;
    flex: 1;
    border-bottom: 1px solid var(--sidebar-border);
    overflow: hidden;
}

.accordion-section:has(.accordion-content.collapsed) {
    flex: 0 0 auto;
}

.accordion-header {
    padding: 14px 20px;
    background: var(--accordion-bg);
    color: var(--accordion-text);
    font-weight: 600;
    font-size: 0.8rem;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    user-select: none;
    flex-shrink: 0;
    transition: all 0.15s ease;
    border-bottom: 1px solid var(--sidebar-border);
}

.accordion-header:hover {
    background: var(--accordion-bg-hover);
}

.accordion-header span {
    display: flex;
    align-items: center;
    gap: 10px;
}

.accordion-header span i:first-child {
    color: var(--accent);
    font-size: 0.9rem;
    opacity: 0.9;
}

.accordion-header i.fa-chevron-down {
    transition: transform 0.2s ease;
    font-size: 0.65rem;
    color: var(--accordion-icon-color-hover);
    padding: 5px;
    background: var(--accordion-icon-bg-hover);
    border-radius: 4px;
}

.accordion-header:hover i.fa-chevron-down {
    background: var(--accordion-icon-bg-hover);
    color: var(--accordion-header-text-hover);
}

.accordion-header.collapsed i.fa-chevron-down {
    transform: rotate(-90deg);
}

.accordion-content {
    flex: 1;
    min-height: 0;
    overflow-y: auto;
    padding: 6px 0 32px;
    background: var(--sidebar-bg);
    box-shadow: inset 0 -40px 30px -30px rgba(0, 0, 0, 0.10);
}

.accordion-content.collapsed {
    display: none;
}

.problem-set {
    display: block;
}

.problem-set.hidden {
    display: none;
}


.solution-toggle-btn {
    position: absolute;
    top: 28px;
    right: 32px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    min-width: 151px;
    padding: 8px 14px;
    font-size: 0.8rem;
    font-weight: 600;
    font-family: var(--font-sans);
    color: var(--solution-toggle-btn-text);
    background: var(--solution-toggle-btn-bg);
    border: 1px solid var(--solution-toggle-btn-border);
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s ease;
    z-index: 5;
}

.solution-toggle-btn:hover {
    background: var(--solution-toggle-btn-hover-bg);
    color: var(--solution-toggle-btn-hover-text);
    border-color: var(--solution-toggle-btn-hover-border);
}

.solution-toggle-btn[aria-pressed="true"] {
    background: var(--solution-toggle-btn-active-bg);
    color: var(--solution-toggle-btn-active-text);
    border-color: var(--solution-toggle-btn-active-bg);
}

.solution-toggle-btn[aria-pressed="true"]:hover {
    background: var(--solution-toggle-btn-active-hover-bg);
}

.solution-toggle-btn i {
    font-size: 0.9rem;
}

.card-content-wrapper {
    position: relative;
}

.problem-content,
.solution-content {
    transition: opacity 0.25s ease, transform 0.25s ease;
}

.problem-content {
    opacity: 1;
    transform: translateX(0);
}

.solution-content {
    display: none;
    opacity: 0;
    transform: translateX(10px);
}

.problem-card.show-solution .problem-content {
    display: none;
}

.problem-card.show-solution .solution-content {
    display: block;
    opacity: 1;
    transform: translateX(0);
}

.solution-tabs {
    display: flex;
    gap: 0;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 20px;
}

.solution-tab-btn {
    padding: 14px 22px;
    font-size: 0.95rem;
    font-weight: 600;
    font-family: var(--font-sans);
    color: var(--solution-toggle-btn-text);
    background: transparent;
    border: none;
    border-bottom: 2px solid transparent;
    cursor: pointer;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 10px;
}

.solution-tab-btn i {
    font-size: 1.2rem;
}

.solution-tab-btn:hover {
    color: var(--solution-toggle-btn-hover-text);
    background: var(--solution-toggle-btn-bg);
}

.solution-tab-btn.active {
    color: var(--accent);
    background: var(--solution-lang-active-bg);
    border-bottom-color: var(--accent);
}

.solution-tab-panel {
    display: none;
    animation: fadeIn 0.3s ease;
}

.solution-tab-panel.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(5px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.solution-content {
    line-height: 1.7;
}

.solution-content h1 {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--text);
    margin: 0 0 16px 0;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--accent);
}

.solution-content h2 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text);
    margin: 28px 0 12px 0;
}

.solution-content h3 {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--solution-h3-text);
    margin: 20px 0 10px 0;
}

.solution-content p {
    margin: 12px 0;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.solution-content ul,
.solution-content ol {
    margin: 12px 0;
    padding-left: 24px;
    color: var(--text-secondary);
}

.solution-content li {
    margin: 6px 0;
}

.solution-content strong {
    font-weight: 600;
    color: var(--text);
}

.solution-content em {
    font-style: italic;
}

.solution-content code {
    background: var(--code-inline-bg);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: var(--font-mono);
    font-size: 0.85em;
    color: var(--code-inline-text);
    border: 1px solid var(--code-inline-border);
}

.solution-content pre {
    background: var(--code-block-bg);
    border-radius: 8px;
    padding: 16px 20px;
    overflow-x: auto;
    margin: 16px 0;
    border: 1px solid var(--border-color);
}

[data-theme="dark"] .solution-content pre {
    background: var(--code-dark-bg);
    border: 1px solid var(--border-color);
}

.solution-content pre code {
    background: none;
    padding: 0;
    border: none;
    font-size: 0.875rem;
    line-height: 1.6;
    color: inherit;
}

.solution-content blockquote {
    border-left: 4px solid var(--accent);
    padding-left: 16px;
    margin: 16px 0;
    color: var(--color-text-tertiary);
    font-style: italic;
}

.solution-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 16px 0;
    font-size: 0.9rem;
}

.solution-content th,
.solution-content td {
    border: 1px solid var(--table-border);
    padding: 10px 12px;
    text-align: left;
}

.solution-content th {
    background: var(--table-th-bg);
    font-weight: 600;
    color: var(--text);
}

.solution-content tr:nth-child(even) {
    background: var(--table-stripe-bg);
}

.solution-content hr {
    border: none;
    border-top: 1px solid var(--table-border);
    margin: 24px 0;
}

.solution-loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 12px;
    padding: 60px;
    color: var(--solution-loading-text);
    font-size: 0.95rem;
}

.solution-loading i {
    font-size: 1.5rem;
    color: var(--accent);
}

.solution-error {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 16px;
    padding: 60px 40px;
    background: var(--solution-error-bg);
    border: 1px dashed var(--solution-error-border);
    border-radius: 12px;
    margin: 24px 0;
    text-align: center;
    color: var(--solution-error-text);
}

.solution-error>i {
    font-size: 1.5rem;
    color: var(--solution-error-icon-color);
    background: var(--solution-error-icon-bg);
    padding: 12px;
    border-radius: 50%;
    margin-bottom: 4px;
}

.solution-error span {
    font-size: 0.9rem;
    line-height: 1.5;
    color: var(--solution-error-subtext);
    margin-bottom: 12px;
}

.solution-retry-btn {
    padding: 10px 24px;
    font-size: 0.9rem;
    font-family: var(--font-sans);
    font-weight: 600;
    color: white;
    background: var(--accent);
    border: none;
    border-radius: 50px;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 4px 6px -1px rgba(37, 99, 235, 0.2);
}

.solution-retry-btn:hover {
    background: var(--solution-retry-btn-hover-bg);
    transform: translateY(-1px);
    box-shadow: 0 6px 12px -2px rgba(37, 99, 235, 0.3);
}

.solution-retry-btn:active {
    transform: translateY(0);
}

#main-toolbar {
    position: absolute;
    top: 0;
    left: 370px;
    width: calc(100% - 370px);
    height: var(--toolbar-height);
    z-index: 10;
    display: flex;
    justify-content: flex-end;
    align-items: center;
    gap: 8px;
    padding: 12px 16px;
    background: var(--toolbar-bg);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--border-color);
}

/* Spiral Matrix Visual */
.spiral-matrix-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    background: var(--sm-grid-bg);
    padding: 20px;
    border-radius: 16px;
    width: fit-content;
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.05);
}

.spiral-matrix-cell {
    width: 48px;
    height: 48px;
    background: var(--sm-cell-bg);
    border: 2px solid var(--sm-cell-border);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    color: var(--sm-cell-text);
    font-size: 1.1rem;
    position: relative;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    z-index: 1;
    font-family: var(--font-mono);
}

/* Directional Connectors (Lines) */
.spiral-matrix-cell::after {
    content: '';
    position: absolute;
    background: var(--sm-path-color);
    /* The line color */
    z-index: 10;
    pointer-events: none;
    transition: all 0.3s ease;
}

/* Arrow Heads */
.spiral-matrix-cell::before {
    content: '';
    position: absolute;
    width: 6px;
    height: 6px;
    border-right: 2px solid var(--sm-path-color);
    border-bottom: 2px solid var(--sm-path-color);
    z-index: 10;
    pointer-events: none;
}

/* Right Arrow */
.spiral-matrix-cell.dir-right::after {
    left: 50%;
    top: 50%;
    width: calc(100% + 12px);
    /* overlap gap */
    height: 3px;
    transform: translateY(-50%);
}

.spiral-matrix-cell.dir-right::before {
    left: calc(100% + 5px);
    /* In the gap */
    top: 50%;
    transform: translate(-50%, -50%) rotate(-45deg);
}

/* Down Arrow */
.spiral-matrix-cell.dir-down::after {
    top: 50%;
    left: 50%;
    height: calc(100% + 12px);
    width: 3px;
    transform: translateX(-50%);
}

.spiral-matrix-cell.dir-down::before {
    top: calc(100% + 5px);
    left: 50%;
    transform: translate(-50%, -50%) rotate(45deg);
}

/* Left Arrow */
.spiral-matrix-cell.dir-left::after {
    right: 50%;
    top: 50%;
    width: calc(100% + 12px);
    height: 3px;
    transform: translateY(-50%);
}

.spiral-matrix-cell.dir-left::before {
    right: calc(100% + 5px);
    top: 50%;
    transform: translate(50%, -50%) rotate(135deg);
}

/* Up Arrow */
.spiral-matrix-cell.dir-up::after {
    bottom: 50%;
    left: 50%;
    height: calc(100% + 12px);
    width: 3px;
    transform: translateX(-50%);
}

.spiral-matrix-cell.dir-up::before {
    bottom: calc(100% + 5px);
    left: 50%;
    transform: translate(-50%, 50%) rotate(-135deg);
}

/* =========================================
   Syntax Highlighting (Solution Content)
   Targeting .solution-content pre code.hljs
   ========================================= */

.solution-content pre code.hljs {
    background: var(--code-block-bg);
    color: var(--code-block-text);
    padding: 1.2em;
    border-radius: 8px;
    font-family: var(--font-mono);
    font-size: 0.9em;
    line-height: 1.6;
}

.solution-content pre code.hljs .hljs-comment,
.solution-content pre code.hljs .hljs-quote {
    color: var(--syntax-comment);
    font-style: italic;
}

.solution-content pre code.hljs .hljs-keyword,
.solution-content pre code.hljs .hljs-selector-tag,
.solution-content pre code.hljs .hljs-literal,
.solution-content pre code.hljs .hljs-name {
    color: var(--syntax-keyword);
}

.solution-content pre code.hljs .hljs-string,
.solution-content pre code.hljs .hljs-doctag,
.solution-content pre code.hljs .hljs-regexp {
    color: var(--syntax-string);
}

.solution-content pre code.hljs .hljs-title,
.solution-content pre code.hljs .hljs-section,
.solution-content pre code.hljs .hljs-selector-id {
    color: var(--syntax-function);
    font-weight: 600;
}

.solution-content pre code.hljs .hljs-class .hljs-title,
.solution-content pre code.hljs .hljs-type {
    color: var(--syntax-type);
}

.solution-content pre code.hljs .hljs-variable,
.solution-content pre code.hljs .hljs-template-variable,
.solution-content pre code.hljs .hljs-attr,
.solution-content pre code.hljs .hljs-attribute {
    color: var(--syntax-variable);
}

.solution-content pre code.hljs .hljs-number {
    color: var(--syntax-number);
}

.solution-content pre code.hljs .hljs-symbol,
.solution-content pre code.hljs .hljs-bullet,
.solution-content pre code.hljs .hljs-link {
    color: var(--syntax-operator);
}

.solution-content pre code.hljs .hljs-meta {
    color: var(--syntax-comment);
}

/* Rotting Oranges Visual */
.rotting-visual {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    justify-content: center;
    padding: 10px;
}

.rotting-step {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.step-label {
    font-size: 0.8rem;
    font-weight: 700;
    text-transform: uppercase;
    color: var(--visual-text);
}

.rotting-grid {
    display: grid;
    grid-template-columns: repeat(3, 30px);
    grid-template-rows: repeat(3, 30px);
    gap: 4px;
    padding: 6px;
    border: 2px solid var(--grid-visual-border);
    border-radius: 6px;
    background: var(--grid-visual-bg);
}

.r-cell {
    width: 30px;
    height: 30px;
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.9rem;
}

.r-cell.fresh {
    background: var(--orange-400, #fb923c);
    border: 1px solid #f97316;
}

.r-cell.rotten {
    background: var(--red-500, #ef4444);
    border: 1px solid #dc2626;
    color: white;
}

.r-cell.rotten i {
    font-size: 0.8rem;
    color: white;
}

.r-cell.empty {
    background: var(--grid-cell-bg);
}

[data-theme="dark"] .r-cell.fresh {
    background: var(--orange-600, #ea580c);
    border: 1px solid #c2410c;
}

[data-theme="dark"] .r-cell.rotten {
    background: var(--red-600, #dc2626);
    border: 1px solid #b91c1c;
}

/* ============================================
   PROBLEM NAVIGATION BUTTONS
============================================ */
.problem-nav-btns {
    position: absolute;
    top: 0px;
    right: -48px;
    display: flex;
    flex-direction: column;
    gap: 6px;
    z-index: 10;
}

.problem-nav-btn {
    width: 28px;
    height: 28px;
    border-radius: 4px;
    border: 1px solid var(--problem-nav-btn-border);
    background: var(--problem-nav-btn-bg);
    color: var(--problem-nav-btn-text);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 0.75rem;
    transition: all 0.2s ease;
}

.problem-nav-btn:hover {
    background: var(--problem-nav-btn-hover-bg);
    color: var(--problem-nav-btn-hover-text);
}

.problem-nav-btn:disabled,
.problem-nav-btn.disabled {
    opacity: var(--problem-nav-btn-disabled-opacity);
    cursor: not-allowed;
    pointer-events: none;
}

@media (max-width: 767px) {
    /* mobile */
}

@media (min-width: 768px) and (max-width: 1023px) {
    /* tablets, small screens */
}