:root {
    --bg: #0f172a;
    --sidebar-bg: #111c33;
    --content-bg: #f8fafc;
    --card-bg: #ffffff;
    --text: #1e293b;
    --muted: #64748b;
    --accent: #ff2d20;
    --border: #e2e8f0;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
    color: var(--text);
    background: var(--content-bg);
}

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

.sidebar {
    width: 280px;
    flex-shrink: 0;
    background: var(--sidebar-bg);
    color: #cbd5e1;
    padding: 20px 16px;
    position: sticky;
    top: 0;
    height: 100vh;
    overflow-y: auto;
}

.logo {
    display: block;
    color: #fff;
    font-size: 20px;
    font-weight: 700;
    text-decoration: none;
    margin-bottom: 16px;
}
.logo::first-letter { color: var(--accent); }

.search input {
    width: 100%;
    padding: 8px 12px;
    border-radius: 8px;
    border: 1px solid #334155;
    background: #1e293b;
    color: #e2e8f0;
    margin-bottom: 16px;
}

.nav-framework {
    text-transform: uppercase;
    font-size: 11px;
    letter-spacing: 0.08em;
    color: #94a3b8;
    margin: 18px 0 6px;
}

.nav-link {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 8px;
    padding: 7px 10px;
    border-radius: 8px;
    color: #cbd5e1;
    text-decoration: none;
    font-size: 14px;
}
.nav-link:hover { background: #1e293b; color: #fff; }
.nav-link.active { background: var(--accent); color: #fff; }
.nav-count { font-size: 12px; opacity: 0.7; }

.content {
    flex: 1;
    padding: 32px 40px 64px;
    max-width: 900px;
}

h1 { margin-top: 0; font-size: 28px; }
.lead { color: var(--muted); font-size: 16px; }

.framework-heading {
    margin-top: 32px;
    padding-bottom: 8px;
    border-bottom: 2px solid var(--border);
}

.topic-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 16px;
    margin-top: 16px;
}

.topic-card {
    display: flex;
    flex-direction: column;
    gap: 6px;
    padding: 16px;
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    text-decoration: none;
    color: var(--text);
    transition: box-shadow 0.15s ease, transform 0.15s ease;
}
.topic-card:hover { box-shadow: 0 4px 16px rgba(15, 23, 42, 0.12); transform: translateY(-2px); }
.topic-card-title { font-weight: 600; }
.topic-card-desc { font-size: 13px; color: var(--muted); }
.topic-card-count { font-size: 12px; color: var(--accent); font-weight: 600; }

.qa-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    margin-bottom: 12px;
    overflow: hidden;
}

.qa-card summary {
    display: flex;
    align-items: baseline;
    gap: 10px;
    padding: 14px 18px;
    cursor: pointer;
    font-weight: 600;
    list-style: none;
}
.qa-card summary::-webkit-details-marker { display: none; }
.qa-card summary::after {
    content: "+";
    margin-left: auto;
    color: var(--muted);
    font-size: 20px;
    line-height: 1;
}
.qa-card[open] summary::after { content: "−"; }
.qa-card summary:hover { background: #f1f5f9; }

.qa-question { flex: 1; }

.qa-answer {
    padding: 4px 18px 18px;
    border-top: 1px solid var(--border);
    font-size: 15px;
    line-height: 1.65;
}
.qa-answer pre {
    background: #0d1117;
    border-radius: 8px;
    padding: 14px 16px;
    overflow-x: auto;
}
.qa-answer pre code {
    color: #e6edf3;
}
.qa-answer code {
    font-family: "JetBrains Mono", "Fira Code", Consolas, monospace;
    font-size: 13.5px;
}
.qa-answer :not(pre) > code {
    background: #eef2f7;
    color: #b91c1c;
    padding: 1px 6px;
    border-radius: 5px;
}
.qa-topic { font-size: 13px; color: var(--muted); }

.badge {
    display: inline-block;
    padding: 2px 10px;
    border-radius: 999px;
    font-size: 11.5px;
    font-weight: 700;
    white-space: nowrap;
}
.badge-1 { background: #dcfce7; color: #15803d; }
.badge-2 { background: #fef9c3; color: #a16207; }
.badge-3 { background: #fee2e2; color: #b91c1c; }

@media (max-width: 860px) {
    .layout { flex-direction: column; }
    .sidebar { width: 100%; height: auto; position: static; }
    .content { padding: 20px; }
}