/* SSOT Guide — Visual Design v1 */

:root {
    --bg: #f0f2ff;
    --bg-card: #ffffff;
    --bg-secondary: #e8ebf8;
    --text: #1a1f3a;
    --text-secondary: #5a6080;
    --accent: #5b4cf5;
    --accent-2: #0ea5e9;
    --accent-3: #10b981;
    --accent-bg: #ede9ff;
    --accent-dark: #4338ca;
    --green: #10b981;
    --green-bg: #ecfdf5;
    --amber: #f59e0b;
    --amber-bg: #fffbeb;
    --red: #ef4444;
    --red-bg: #fef2f2;
    --blue: #3b82f6;
    --blue-bg: #eff6ff;
    --border: #c7cde8;
    --code-bg: #1c1f3a;
    --code-text: #e2e8f0;
    --radius: 18px;
    --radius-sm: 10px;
    --shadow: 0 2px 12px rgba(91,76,245,0.08);
    --shadow-lg: 0 8px 32px rgba(91,76,245,0.14);
    --shadow-card: 0 4px 20px rgba(91,76,245,0.10);
    --header-h: 64px;
    --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Noto Sans JP', 'Hiragino Sans', sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', ui-monospace, monospace;
    /* gradient colors */
    --grad-1: #5b4cf5;
    --grad-2: #0ea5e9;
    --grad-3: #10b981;
}

[data-theme="dark"] {
    --bg: #0d0f1e;
    --bg-card: #161929;
    --bg-secondary: #1e2240;
    --text: #e2e8f0;
    --text-secondary: #94a3b8;
    --accent: #7c6ffc;
    --accent-2: #38bdf8;
    --accent-3: #34d399;
    --accent-bg: #1e1b4b;
    --accent-dark: #a5b4fc;
    --green-bg: #064e3b;
    --amber-bg: #451a03;
    --red-bg: #450a0a;
    --blue-bg: #172554;
    --border: #2d3362;
    --code-bg: #0d0f1e;
    --code-text: #e2e8f0;
    --shadow: 0 2px 12px rgba(0,0,0,0.4);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.5);
    --shadow-card: 0 4px 20px rgba(0,0,0,0.35);
    --grad-1: #7c6ffc;
    --grad-2: #38bdf8;
    --grad-3: #34d399;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body { font-family: var(--font); color: var(--text); background: var(--bg); line-height: 1.8; min-height: 100vh; }
a { color: var(--accent-dark); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ===== HEADER ===== */
.site-header {
    position: fixed;
    top: 0; left: 0; right: 0;
    height: var(--header-h);
    background: linear-gradient(135deg, var(--grad-1) 0%, var(--grad-2) 100%);
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 20px;
    z-index: 100;
    box-shadow: 0 2px 20px rgba(91,76,245,0.35);
}

.site-title {
    font-size: 1.15rem;
    font-weight: 800;
    color: #fff;
    white-space: nowrap;
    letter-spacing: 0.04em;
    text-shadow: 0 1px 4px rgba(0,0,0,0.2);
}

/* Hamburger */
.menu-toggle {
    display: flex;
    flex-direction: column;
    gap: 5px;
    background: rgba(255,255,255,0.15);
    border: 1.5px solid rgba(255,255,255,0.3);
    cursor: pointer;
    padding: 8px 10px;
    border-radius: 8px;
}
.menu-toggle span {
    display: block;
    width: 20px;
    height: 2px;
    background: #fff;
    border-radius: 2px;
    transition: transform 0.3s, opacity 0.3s;
}
.menu-toggle.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.menu-toggle.active span:nth-child(2) { opacity: 0; }
.menu-toggle.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

.theme-toggle {
    background: rgba(255,255,255,0.2);
    border: 1.5px solid rgba(255,255,255,0.35);
    cursor: pointer;
    font-size: 1.15rem;
    padding: 6px 10px;
    border-radius: 10px;
    line-height: 1;
    transition: background 0.2s;
}
.theme-toggle:hover { background: rgba(255,255,255,0.35); }
[data-theme="light"] .icon-dark { display: none; }
[data-theme="dark"] .icon-light { display: none; }

/* ===== SIDEBAR ===== */
.sidebar {
    position: fixed;
    top: var(--header-h);
    left: 0; bottom: 0;
    width: 290px;
    background: var(--bg-card);
    border-right: 1px solid var(--border);
    transform: translateX(-100%);
    transition: transform 0.3s cubic-bezier(.4,0,.2,1);
    z-index: 90;
    overflow-y: auto;
    padding: 16px 0;
    box-shadow: 4px 0 24px rgba(91,76,245,0.08);
}
.sidebar.open { transform: translateX(0); }

.sidebar-header {
    padding: 4px 20px 16px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 8px;
}
.sidebar-header a { font-weight: 700; font-size: 1rem; color: var(--accent-dark); }

.sidebar-link {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 11px 24px;
    color: var(--text-secondary);
    font-size: 0.9rem;
    transition: background 0.15s, color 0.15s, padding-left 0.15s;
    border-left: 3px solid transparent;
}
.sidebar-link:hover {
    background: var(--accent-bg);
    color: var(--accent);
    text-decoration: none;
    padding-left: 28px;
    border-left-color: var(--accent);
}
.sidebar-link.active {
    color: var(--accent);
    font-weight: 700;
    background: var(--accent-bg);
    border-left: 3px solid var(--accent);
}
.sidebar-icon { font-size: 1.1rem; flex-shrink: 0; }

.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    top: var(--header-h);
    background: rgba(0,0,0,0.45);
    backdrop-filter: blur(2px);
    z-index: 80;
}
.sidebar-overlay.visible { display: block; }

/* ===== CONTENT ===== */
.content {
    max-width: 900px;
    margin: 0 auto;
    padding: calc(var(--header-h) + 24px) 18px 72px;
}

/* Chapter nav top */
.chapter-nav-top {
    display: flex;
    justify-content: space-between;
    gap: 8px;
    margin-bottom: 24px;
    font-size: 0.85rem;
}
.nav-prev, .nav-next {
    color: var(--accent);
    padding: 8px 16px;
    border: 1.5px solid var(--accent);
    border-radius: var(--radius-sm);
    font-weight: 700;
    transition: all 0.2s;
}
.nav-prev:hover, .nav-next:hover {
    background: var(--accent);
    color: #fff;
    text-decoration: none;
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

/* ===== CHAPTER BODY ===== */
.chapter-body h1 {
    font-size: 1.8rem;
    margin-bottom: 8px;
    color: var(--accent-dark);
    letter-spacing: 0.01em;
    line-height: 1.3;
}
.chapter-body h1 + p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 28px;
    padding-bottom: 20px;
    border-bottom: 2px solid var(--border);
}
.chapter-body h2 {
    font-size: 1.25rem;
    margin-top: 40px;
    margin-bottom: 16px;
    padding: 10px 16px;
    background: linear-gradient(90deg, var(--accent-bg) 0%, transparent 100%);
    border-left: 4px solid var(--accent);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    color: var(--accent-dark);
    font-weight: 800;
}
.chapter-body h3 {
    font-size: 1.05rem;
    margin-top: 28px;
    margin-bottom: 12px;
    color: var(--text);
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 8px;
}
.chapter-body h3::before {
    content: '';
    display: inline-block;
    width: 4px;
    height: 1em;
    background: linear-gradient(180deg, var(--grad-2), var(--grad-3));
    border-radius: 2px;
    flex-shrink: 0;
}
.chapter-body h4 {
    font-size: 0.95rem;
    margin-top: 18px;
    margin-bottom: 8px;
    font-weight: 700;
    color: var(--accent-dark);
}
.chapter-body p { margin-bottom: 14px; }
.chapter-body ul, .chapter-body ol { margin-bottom: 14px; padding-left: 22px; }
.chapter-body li { margin-bottom: 8px; padding-left: 4px; }
.chapter-body strong { color: var(--accent-dark); font-weight: 700; }
.chapter-body hr {
    border: none;
    height: 2px;
    background: linear-gradient(90deg, var(--accent), var(--accent-2), transparent);
    margin: 32px 0;
    border-radius: 1px;
}

/* ===== CODE BLOCKS ===== */
.code-block-wrapper { position: relative; margin-bottom: 18px; }
.chapter-body pre {
    background: var(--code-bg);
    color: var(--code-text);
    padding: 20px 18px;
    border-radius: var(--radius-sm);
    overflow-x: auto;
    font-size: 0.82rem;
    line-height: 1.75;
    border: 1px solid var(--border);
    box-shadow: var(--shadow-lg);
}
.chapter-body code { font-family: var(--font-mono); font-size: 0.9em; }
.chapter-body :not(pre) > code {
    background: var(--accent-bg);
    color: var(--accent-dark);
    padding: 2px 6px;
    border-radius: 5px;
    font-size: 0.88em;
    border: 1px solid rgba(91,76,245,0.2);
}
.copy-btn {
    position: absolute;
    top: 10px; right: 10px;
    background: rgba(91,76,245,0.2);
    color: var(--accent-dark);
    border: 1px solid rgba(91,76,245,0.3);
    padding: 4px 10px;
    border-radius: 6px;
    font-size: 0.75rem;
    cursor: pointer;
    font-family: var(--font);
    transition: all 0.2s;
}
.copy-btn:hover { background: var(--accent); color: #fff; }
.copy-btn.copied { background: var(--green); color: #fff; border-color: var(--green); }

/* ===== TABLES ===== */
.chapter-body table {
    width: 100%;
    border-collapse: collapse;
    margin: 20px 0;
    font-size: 0.88rem;
    border-radius: var(--radius-sm);
    overflow: hidden;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
}
.chapter-body th {
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-2) 100%);
    color: #fff;
    padding: 12px 14px;
    text-align: left;
    font-weight: 700;
    font-size: 0.83rem;
    letter-spacing: 0.03em;
}
.chapter-body td {
    padding: 11px 14px;
    border-bottom: 1px solid var(--border);
    background: var(--bg-card);
    vertical-align: top;
}
.chapter-body tr:last-child td { border-bottom: none; }
.chapter-body tr:hover td { background: var(--bg-secondary); }

/* ===== BLOCKQUOTE ===== */
.chapter-body blockquote {
    border-left: 4px solid var(--accent-2);
    background: linear-gradient(90deg, var(--blue-bg) 0%, transparent 100%);
    padding: 14px 18px;
    margin: 18px 0;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    color: var(--text-secondary);
    font-size: 0.93rem;
    font-style: italic;
}
[data-theme="dark"] .chapter-body blockquote {
    background: linear-gradient(90deg, rgba(56,189,248,0.1) 0%, transparent 100%);
}

/* ===== TOC ===== */
.toc {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px 20px;
    margin: 24px 0;
    box-shadow: var(--shadow);
}
.toc-title { font-weight: 800; margin-bottom: 12px; color: var(--accent-dark); font-size: 0.92rem; }
.toc-list { list-style: none; padding: 0; }
.toc-list li a {
    display: block;
    padding: 4px 0;
    color: var(--text-secondary);
    font-size: 0.88rem;
    border-radius: 4px;
    transition: color 0.15s, padding-left 0.15s;
}
.toc-list li a:hover { color: var(--accent); text-decoration: none; padding-left: 6px; }
.toc-h3 a { padding-left: 14px !important; }
.toc-h3 a::before { content: '└ '; color: var(--border); }

/* ===== SEARCH BAR ===== */
.search-bar {
    display: flex;
    align-items: center;
    gap: 6px;
    margin-bottom: 16px;
    padding: 10px 14px;
    background: var(--bg-card);
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow);
}
.search-bar input {
    flex: 1;
    border: none;
    outline: none;
    background: transparent;
    color: var(--text);
    font-size: 0.9rem;
    font-family: var(--font);
}
.search-count { font-size: 0.78rem; color: var(--text-secondary); white-space: nowrap; }
.search-prev, .search-next, .search-clear {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    padding: 4px 8px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.78rem;
    color: var(--text-secondary);
}
.search-prev:hover, .search-next:hover, .search-clear:hover {
    background: var(--accent);
    color: #fff;
    border-color: var(--accent);
}
.search-highlight { background: #fde047; color: #1a1f3a; border-radius: 2px; padding: 0 2px; }
.search-current { background: #f97316; color: #fff; }

/* ===== CHAPTER NAV BOTTOM ===== */
.chapter-nav-bottom {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
    margin-top: 48px;
    padding-top: 24px;
    border-top: 2px solid var(--border);
}
.nav-card {
    display: flex;
    flex-direction: column;
    padding: 16px 18px;
    background: var(--bg-card);
    border: 1.5px solid var(--border);
    border-radius: var(--radius);
    color: var(--text);
    transition: all 0.25s;
    box-shadow: var(--shadow);
}
.nav-card:hover {
    border-color: var(--accent);
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
    text-decoration: none;
}
.nav-card.prev { text-align: left; }
.nav-card.next { text-align: right; }
.nav-label { font-size: 0.78rem; color: var(--text-secondary); margin-bottom: 4px; }
.nav-title { font-size: 0.92rem; font-weight: 700; color: var(--accent); }

/* ===== INDEX PAGE ===== */
.index-page .content {
    max-width: 960px;
    padding-top: calc(var(--header-h) + 32px);
}

/* Hero section */
.hero {
    text-align: center;
    padding: 48px 24px 36px;
    margin-bottom: 12px;
    background: linear-gradient(135deg, rgba(91,76,245,0.07) 0%, rgba(14,165,233,0.05) 50%, rgba(16,185,129,0.04) 100%);
    border-radius: 24px;
    border: 1px solid rgba(91,76,245,0.12);
    position: relative;
    overflow: hidden;
}
.hero::before {
    content: '';
    position: absolute;
    top: -60px; right: -60px;
    width: 220px; height: 220px;
    background: radial-gradient(circle, rgba(91,76,245,0.1) 0%, transparent 70%);
    border-radius: 50%;
    pointer-events: none;
}
.hero::after {
    content: '';
    position: absolute;
    bottom: -40px; left: -40px;
    width: 160px; height: 160px;
    background: radial-gradient(circle, rgba(14,165,233,0.1) 0%, transparent 70%);
    border-radius: 50%;
    pointer-events: none;
}
.hero h1 {
    font-size: 2rem;
    font-weight: 900;
    background: linear-gradient(135deg, var(--grad-1) 0%, var(--grad-2) 50%, var(--grad-3) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 14px;
    letter-spacing: -0.01em;
    line-height: 1.2;
}
.hero p {
    font-size: 1rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* Chapter category */
.chapter-category {
    margin-bottom: 36px;
}
.chapter-category-heading {
    font-size: 1rem;
    font-weight: 700;
    color: var(--text-secondary);
    margin-bottom: 16px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--border);
}

/* Chapter grid */
.chapter-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 16px;
    margin: 28px 0;
}

.chapter-card {
    display: flex;
    flex-direction: column;
    padding: 22px 20px;
    background: var(--bg-card);
    border: 1.5px solid var(--border);
    border-radius: var(--radius);
    color: var(--text);
    transition: all 0.25s cubic-bezier(.4,0,.2,1);
    box-shadow: var(--shadow-card);
    position: relative;
    overflow: hidden;
}
.chapter-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--grad-1) 0%, var(--grad-2) 50%, var(--grad-3) 100%);
    opacity: 0;
    transition: opacity 0.25s;
}
.chapter-card:hover {
    border-color: var(--accent);
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
    text-decoration: none;
}
.chapter-card:hover::before { opacity: 1; }
.card-icon { font-size: 2.2rem; margin-bottom: 10px; line-height: 1; }
.card-number {
    font-size: 0.72rem;
    font-weight: 700;
    color: var(--accent);
    letter-spacing: 0.08em;
    text-transform: uppercase;
    margin-bottom: 4px;
    opacity: 0.7;
}
.card-title {
    font-size: 1.05rem;
    font-weight: 800;
    color: var(--text);
    margin-bottom: 8px;
    line-height: 1.3;
    transition: color 0.2s;
}
.chapter-card:hover .card-title { color: var(--accent); }
.card-desc {
    font-size: 0.82rem;
    color: var(--text-secondary);
    line-height: 1.55;
    flex: 1;
}

/* Features section */
.features {
    margin: 28px 0;
    padding: 28px 24px;
    background: var(--bg-card);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    box-shadow: var(--shadow);
}
.features h2 {
    font-size: 1.1rem;
    font-weight: 800;
    color: var(--text);
    margin-bottom: 20px;
}
.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 14px;
}
.feature-item {
    padding: 16px;
    background: var(--bg-secondary);
    border-radius: var(--radius-sm);
    text-align: center;
    border: 1px solid var(--border);
    transition: transform 0.2s, box-shadow 0.2s;
}
.feature-item:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.feature-icon { font-size: 1.8rem; margin-bottom: 8px; display: block; }
.feature-item h3 { font-size: 0.88rem; font-weight: 700; margin-bottom: 4px; color: var(--text); }
.feature-item p { font-size: 0.78rem; color: var(--text-secondary); line-height: 1.5; }

/* Footer */
.site-footer {
    text-align: center;
    padding: 24px;
    font-size: 0.82rem;
    color: var(--text-secondary);
    border-top: 1px solid var(--border);
    margin-top: 32px;
}
.site-footer a { color: var(--accent); }
.site-version {
    margin-top: 6px;
    font-size: 0.75rem;
    color: var(--text-secondary);
    opacity: 0.7;
    font-variant-numeric: tabular-nums;
}

/* ===== MOBILE ===== */
@media (max-width: 600px) {
    .hero { padding: 36px 16px 28px; }
    .hero h1 { font-size: 1.55rem; }
    .chapter-grid { grid-template-columns: 1fr; gap: 12px; }
    .chapter-nav-bottom { grid-template-columns: 1fr; }
    .feature-grid { grid-template-columns: repeat(2, 1fr); }
    .content { padding-left: 14px; padding-right: 14px; }
    .chapter-body h1 { font-size: 1.45rem; }
    .chapter-body h2 { font-size: 1.1rem; }
}

/* ===== TABLE WRAPPER ===== */
.table-wrapper { overflow-x: auto; margin-bottom: 20px; }

/* ===== CALLOUTS ===== */
.callout {
    padding: 14px 18px;
    border-radius: var(--radius-sm);
    margin: 18px 0;
    border-left: 4px solid;
    font-size: 0.9rem;
}
.callout-info { background: var(--blue-bg); border-color: var(--blue); }
.callout-tip { background: var(--green-bg); border-color: var(--green); }
.callout-warn { background: var(--amber-bg); border-color: var(--amber); }
.callout-danger { background: var(--red-bg); border-color: var(--red); }
[data-theme="dark"] .callout-info { background: rgba(59,130,246,0.1); }
[data-theme="dark"] .callout-tip { background: rgba(16,185,129,0.1); }
[data-theme="dark"] .callout-warn { background: rgba(245,158,11,0.1); }
[data-theme="dark"] .callout-danger { background: rgba(239,68,68,0.1); }

/* ===== MERMAID ===== */
.mermaid {
    margin: 20px 0;
    text-align: center;
    overflow-x: auto;
    background: var(--bg-secondary);
    border-radius: var(--radius-sm);
    padding: 16px;
    border: 1px solid var(--border);
}