:root {
    --bg-dark: #121417;        
    --bg-panel: #1b1e23;       
    --text-main: #e2e8f0;      
    --text-muted: #94a3b8;     
    --accent-blue: #3b82f6;    
    --accent-cyan: #06b6d4;    
    --border-color: #2d3748;   
    --code-bg: #0f1115;        
    --warn-color: #eab308;     
    --font-mono: "Fira Code", Consolas, Monaco, monospace;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-main);
    line-height: 1.75;
    -webkit-font-smoothing: antialiased;
}
a { color: var(--accent-cyan); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--accent-blue); text-decoration: underline; }
.app-container { display: flex; min-height: 100vh; }
.sidebar {
    width: 260px;
    background-color: var(--bg-panel);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    position: sticky;
    top: 0;
    height: 100vh;
}
.sidebar-header { padding: 24px; border-bottom: 1px solid var(--border-color); }
.brand { font-size: 1.25rem; font-weight: 700; color: var(--text-main); letter-spacing: 0.5px; display: flex; align-items: center; }
.brand::before {
    content: "";
    display: inline-block;
    width: 12px;
    height: 12px;
    background-color: var(--accent-cyan);
    border-radius: 2px;
    margin-right: 10px;
    box-shadow: 0 0 8px rgba(6, 182, 212, 0.6);
}
.sidebar-nav { padding: 20px 0; overflow-y: auto; }
.sidebar-nav a {
    display: block;
    padding: 10px 24px;
    color: var(--text-muted);
    font-size: 0.95rem;
    font-weight: 500;
    border-left: 3px solid transparent;
}
.sidebar-nav a:hover {
    background-color: rgba(255, 255, 255, 0.03);
    color: var(--text-main);
    text-decoration: none;
    border-left-color: var(--accent-cyan);
}
.main-wrapper { flex: 1; display: flex; flex-direction: column; min-width: 0; }
.content-area { padding: 40px 60px; max-width: 900px; width: 100%; margin: 0 auto; flex: 1; }
@media (max-width: 800px) {
    .app-container { flex-direction: column; }
    .sidebar { width: 100%; height: auto; position: static; border-right: none; border-bottom: 1px solid var(--border-color); }
    .sidebar-nav { display: flex; overflow-x: auto; padding: 12px; white-space: nowrap; }
    .sidebar-nav a { display: inline-block; padding: 8px 16px; border-left: none; border-bottom: 2px solid transparent; }
    .sidebar-nav a:hover { border-left-color: transparent; border-bottom-color: var(--accent-cyan); }
    .content-area { padding: 24px 20px; }
}
h1, h2, h3, h4 { color: #ffffff; margin-top: 2.2em; margin-bottom: 1em; font-weight: 600; }
h1 { font-size: 2.2rem; margin-top: 0; border-bottom: 1px solid var(--border-color); padding-bottom: 16px; }
h2 { font-size: 1.5rem; border-bottom: 1px solid var(--border-color); padding-bottom: 10px; position: relative; padding-left: 14px; }
h2::before { content: ""; position: absolute; left: 0; top: 5px; bottom: 10px; width: 4px; background-color: var(--accent-blue); border-radius: 2px; }
h3 { font-size: 1.25rem; color: #e2e8f0; }
p { margin-bottom: 1.25em; }
ul, ol { margin-bottom: 1.5em; padding-left: 24px; color: var(--text-main); }
li { margin-bottom: 0.5em; }
blockquote {
    background-color: rgba(6, 182, 212, 0.05);
    border-left: 4px solid var(--accent-cyan);
    padding: 16px 20px;
    margin: 1.5em 0;
    border-radius: 0 4px 4px 0;
    color: var(--text-main);
}
blockquote p:last-child { margin-bottom: 0; }
code {
    background-color: var(--code-bg);
    color: var(--accent-cyan);
    padding: 3px 6px;
    border-radius: 4px;
    font-family: var(--font-mono);
    font-size: 0.9em;
    border: 1px solid var(--border-color);
    word-break: break-word;
}
pre {
    background-color: var(--code-bg);
    padding: 20px;
    border-radius: 6px;
    overflow-x: auto;
    margin-bottom: 1.5em;
    border: 1px solid var(--border-color);
}
pre code { background-color: transparent; color: #a0aec0; padding: 0; border: none; }
table { width: 100%; border-collapse: collapse; margin-bottom: 1.5em; display: block; overflow-x: auto; }
th, td { padding: 12px 16px; border: 1px solid var(--border-color); }
th { background-color: var(--bg-panel); font-weight: 600; color: #ffffff; text-align: left; }
td { background-color: rgba(255,255,255,0.01); }
img { max-width: 100%; height: auto; border-radius: 6px; margin: 1.5em 0; display: block; border: 1px solid var(--border-color); }

.module-grid { display: grid; grid-template-columns: 1fr; gap: 16px; margin-top: 24px; }
.module-card { display: flex; background-color: var(--bg-panel); border: 1px solid var(--border-color); border-radius: 6px; padding: 20px; transition: border-color 0.2s, background-color 0.2s; }
.module-card:hover { border-color: var(--accent-cyan); background-color: rgba(255, 255, 255, 0.02); }
.module-num { font-family: var(--font-mono); font-size: 1.5rem; font-weight: 700; color: var(--border-color); margin-right: 20px; width: 40px; }
.module-card:hover .module-num { color: var(--accent-cyan); }
.module-content h3 { margin: 0 0 8px 0; font-size: 1.1rem; border: none; padding: 0; }
.module-content h3 a { color: #ffffff; }
.module-content h3 a:hover { color: var(--accent-cyan); text-decoration: none; }
.module-content p { margin: 0; color: var(--text-muted); font-size: 0.95rem; }

.doc-nav { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 16px; margin-top: 60px; padding-top: 24px; border-top: 1px solid var(--border-color); }
.nav-btn { display: flex; flex-direction: column; padding: 12px 20px; border: 1px solid var(--border-color); border-radius: 4px; background-color: var(--bg-panel); transition: border-color 0.2s; min-width: 160px; flex: 1; }
.nav-btn.prev { text-align: left; }
.nav-btn.next { text-align: right; }
.nav-btn .label { font-size: 0.8rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 1px; margin-bottom: 4px; }
.nav-btn .title { color: var(--text-main); font-weight: 500; font-size: 0.95rem; }
.nav-btn:hover { border-color: var(--accent-cyan); text-decoration: none; }
.nav-btn:hover .title { color: var(--accent-cyan); }

.doc-footer { padding: 24px 60px; border-top: 1px solid var(--border-color); color: var(--text-muted); font-size: 0.85rem; font-family: var(--font-mono); text-align: right; }
@media (max-width: 800px) { .doc-footer { padding: 24px 20px; text-align: center; } }