:root {
    --bg: #fdfaf5;
    --fg: #000000;
    --muted: #000000;
    --accent: #a8481c;
    --accent-fg: #ffffff;
    --border: #e4dccb;
    --panel-bg: #ffffff;
    --code-bg: #f2ece0;
    --link: #8a3814;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #1c1a17;
        --fg: #ece6db;
        --muted: #a99d8c;
        --accent: #e08a4f;
        --accent-fg: #1c1a17;
        --border: #3a352d;
        --panel-bg: #24211c;
        --code-bg: #2a261f;
        --link: #e0a26a;
    }
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    background: var(--bg);
    color: var(--fg);
    font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans CJK JP", "Noto Sans Bengali",
        system-ui, sans-serif;
    line-height: 1.7;
}

.container {
    max-width: 860px;
    padding: 1.5rem 1.25rem 4rem;
}

a {
    color: var(--link);
}

h1, h2 {
    line-height: 1.3;
}

/* app layout: fixed sidebar + scrolling content */

.layout {
    display: flex;
    align-items: flex-start;
    min-height: 100vh;
}

.sidebar {
    flex: 0 0 240px;
    width: 240px;
    box-sizing: border-box;
    position: sticky;
    top: 0;
    height: 100vh;
    overflow-y: auto;
    padding: 1.25rem 1rem;
    border-right: 1px solid var(--border);
    background: var(--panel-bg);
}

.sidebar-title {
    font-weight: 700;
    margin-bottom: 1.25rem;
}

.sidebar-title a {
    text-decoration: none;
}

.sidebar-section {
    margin-bottom: 1.5rem;
}

.sidebar-section h2 {
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--muted);
    margin: 0 0 0.5rem;
}

.sidebar-list {
    list-style: none;
    margin: 0;
    padding: 0;
}

.sidebar-list li {
    margin: 0.3rem 0;
}

.sidebar-list a {
    text-decoration: none;
}

.sidebar-list a:hover {
    text-decoration: underline;
}

.content {
    flex: 1 1 auto;
    min-width: 0;
}

.doc-entry {
    margin-bottom: 0.75rem;
}

.doc-entry-label {
    margin: 0 0 0.3rem;
    font-size: 0.85rem;
}

@media (max-width: 800px) {
    .layout {
        flex-direction: column;
    }
    .sidebar {
        position: static;
        width: 100%;
        height: auto;
        border-right: none;
        border-bottom: 1px solid var(--border);
    }
}

/* index page */

.index-header {
    margin-bottom: 2rem;
}

.index-header h1 {
    font-size: 2rem;
    margin-bottom: 0.25rem;
}

.subtitle {
    color: var(--muted);
    margin: 0 0 0.75rem;
}

.repo-link {
    display: inline-block;
    font-size: 0.9rem;
}

.lead {
    color: var(--fg);
}

.content .container section {
    margin-top: 2rem;
}

.content .container section h2 {
    font-size: 1.15rem;
    margin-bottom: 0.5rem;
}

/* horizontal button grid (sidebar chapter list) */

ul.link-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
    list-style: none;
    margin: 0;
    padding: 0;
}

ul.link-row a {
    display: inline-block;
    border: 1px solid var(--border);
    background: var(--bg);
    border-radius: 6px;
    padding: 0.2rem 0.5rem;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.85rem;
}

ul.link-row a:hover {
    border-color: var(--accent);
}

ul.chapter-row a {
    min-width: 2.2em;
    text-align: center;
}

ul.chapter-row a.active {
    background: var(--accent);
    border-color: var(--accent);
    color: var(--accent-fg);
}

/* chapter / qa page header */

.page-header {
    margin-bottom: 1.5rem;
}

.page-header h1 {
    margin: 0;
}

/* chapter / index header image */

.header-image {
    display: block;
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    margin-bottom: 1.5rem;
}

/* language tabs */

.lang-tabs {
    display: flex;
    gap: 0.4rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.lang-tab {
    border: 1px solid var(--border);
    background: var(--panel-bg);
    color: var(--fg);
    padding: 0.4rem 0.9rem;
    border-radius: 999px;
    font-size: 0.95rem;
    cursor: pointer;
}

.lang-tab.active {
    background: var(--accent);
    border-color: var(--accent);
    color: var(--accent-fg);
}

.text-panel {
    display: none;
    background: var(--panel-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.25rem 1.5rem;
}

.text-panel.active {
    display: block;
}

.text-panel[lang="bn"] {
    font-family: "Noto Sans Bengali", "Siyam Rupali", "Vrinda", sans-serif;
}

.text-panel[lang="hi"] {
    font-family: "Noto Sans Devanagari", "Mangal", sans-serif;
}

.text-panel p {
    margin: 0 0 1em;
}

.text-panel p:last-child {
    margin-bottom: 0;
}

/* one section per segment, headed by that segment's caption in this language */

.segment + .segment {
    margin-top: 2rem;
}

.content .container .segment-caption {
    display: flex;
    align-items: baseline;
    gap: 0.6rem;
    margin: 0 0 0.75rem;
    padding-bottom: 0.4rem;
    border-bottom: 1px solid var(--border);
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--muted);
}

.segment-caption a {
    color: var(--muted);
    text-decoration: none;
}

/* chapter nav */

.chapter-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 2rem;
    font-size: 0.95rem;
}

.chapter-nav a {
    text-decoration: none;
}

/* QA table */

.qa-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.92rem;
}

.qa-table th, .qa-table td {
    border: 1px solid var(--border);
    padding: 0.6rem 0.7rem;
    text-align: left;
    vertical-align: top;
}

.qa-table th {
    background: var(--code-bg);
}

.qa-type {
    display: inline-block;
    padding: 0.1rem 0.5rem;
    border-radius: 999px;
    font-size: 0.8rem;
    background: var(--code-bg);
    color: var(--muted);
}

.qa-type-cross {
    background: var(--accent);
    color: var(--accent-fg);
}

.qa-question p {
    margin: 0 0 0.4rem;
}

.qa-answer-detail summary {
    cursor: pointer;
}

.qa-rationale {
    margin-top: 0.4rem;
    font-size: 0.85rem;
    color: var(--muted);
}

.qa-rationale summary {
    cursor: pointer;
}

.qa-chapters {
    white-space: nowrap;
}

/* responsive tables */

@media (max-width: 600px) {
    .qa-table, .qa-table thead, .qa-table tbody, .qa-table th, .qa-table td, .qa-table tr {
        display: block;
    }
    .qa-table thead {
        display: none;
    }
    .qa-table tr {
        border: 1px solid var(--border);
        border-radius: 8px;
        margin-bottom: 0.75rem;
        padding: 0.5rem;
    }
    .qa-table td {
        border: none;
        padding: 0.25rem 0;
    }
    .qa-table td::before {
        content: attr(data-label);
        display: block;
        font-size: 0.75rem;
        color: var(--muted);
    }
}

/* summary page */

.summary-chapter {
    background: var(--panel-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.25rem 1.5rem;
    margin-bottom: 1.5rem;
}

.summary-chapter h2 {
    margin-top: 0;
    font-size: 1.2rem;
}

.summary-chapter h2 a {
    text-decoration: none;
}

.summary-chapter[lang="bn"] {
    font-family: "Noto Sans Bengali", "Siyam Rupali", "Vrinda", sans-serif;
}

.summary-chapter[lang="hi"] {
    font-family: "Noto Sans Devanagari", "Mangal", sans-serif;
}

.summary-chapter p {
    margin: 0 0 0.5em;
}

.summary-chapter p:last-child {
    margin-bottom: 0;
}

/* doc pages */

.doc-lang-switch {
    margin: 0.25rem 0 0;
    font-size: 0.9rem;
}

.doc-content {
    background: var(--panel-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.25rem 1.5rem;
}

.doc-content h1, .doc-content h2, .doc-content h3 {
    margin-top: 1.5em;
}

.doc-content h1:first-child, .doc-content h2:first-child, .doc-content h3:first-child {
    margin-top: 0;
}

.doc-content p, .doc-content ul, .doc-content ol, .doc-content blockquote {
    margin: 0 0 1em;
}

.doc-content blockquote {
    border-left: 3px solid var(--accent);
    margin-left: 0;
    padding: 0.25rem 1rem;
    color: var(--muted);
}

.doc-content code {
    background: var(--code-bg);
    border-radius: 4px;
    padding: 0.1em 0.35em;
    font-size: 0.9em;
}

.doc-content pre {
    background: var(--code-bg);
    border-radius: 8px;
    padding: 0.75rem 1rem;
    overflow-x: auto;
}

.doc-content pre code {
    background: none;
    padding: 0;
}

.doc-content pre.mermaid {
    background: var(--panel-bg);
    text-align: center;
}

.doc-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 0 0 1em;
    overflow-x: auto;
    display: block;
}

.doc-content th, .doc-content td {
    border: 1px solid var(--border);
    padding: 0.4rem 0.6rem;
    text-align: left;
}

.doc-content th {
    background: var(--code-bg);
}