:root {
    --bg-color: #f8fafc;
    --sidebar-bg: #ffffff;
    --topbar-bg: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --accent-color: #4f5d95;
    --accent-light: #eef2ff;
    --border-color: #e2e8f0;
    --sidebar-width: 280px;
    --topbar-height: 52px;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.7;
    overflow-x: hidden;
}

/* ======================== TOP BAR ======================== */
.topbar {
    position: fixed;
    top: 0; left: 0; right: 0;
    height: var(--topbar-height);
    background: var(--topbar-bg);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    padding: 0 16px;
    gap: 12px;
    z-index: 200;
}

.sidebar-toggle {
    background: none; border: none;
    cursor: pointer; padding: 6px;
    border-radius: 6px; color: var(--text-secondary);
    transition: all 0.15s;
}
.sidebar-toggle:hover { background: var(--accent-light); color: var(--accent-color); }

.topbar-logo {
    display: flex; align-items: center; gap: 8px;
    font-weight: 700; font-size: 15px;
    color: var(--accent-color);
    white-space: nowrap;
}
.logo-icon { font-size: 20px; }

.topbar-center { flex: 1; display: flex; justify-content: center; }

.search-trigger {
    display: flex; align-items: center; gap: 10px;
    padding: 7px 14px;
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    color: var(--text-secondary);
    font-size: 13px;
    min-width: 320px;
    transition: all 0.15s;
}
.search-trigger:hover { border-color: var(--accent-color); }
.search-trigger span { flex: 1; text-align: left; }
.search-trigger kbd {
    background: #fff; border: 1px solid var(--border-color);
    padding: 2px 6px; border-radius: 4px;
    font-size: 11px; font-family: inherit;
    color: var(--text-secondary);
}

.topbar-right {
    display: flex; align-items: center; gap: 12px;
}

.nav-arrows { display: flex; gap: 4px; }

.nav-btn {
    background: none; border: 1px solid var(--border-color);
    padding: 5px 8px; border-radius: 6px;
    cursor: pointer; color: var(--text-secondary);
    transition: all 0.15s;
}
.nav-btn:hover { border-color: var(--accent-color); color: var(--accent-color); }
.nav-btn:disabled { opacity: 0.3; cursor: default; }

.tutorial-counter {
    font-size: 12px; color: var(--text-secondary);
    white-space: nowrap;
}

/* ======================== MAIN LAYOUT ======================== */
.main-layout {
    display: flex;
    margin-top: var(--topbar-height);
    min-height: calc(100vh - var(--topbar-height));
}

/* ======================== SIDEBAR ======================== */
.sidebar {
    width: var(--sidebar-width);
    height: calc(100vh - var(--topbar-height));
    background: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    position: sticky;
    top: var(--topbar-height);
    transition: width 0.25s ease, opacity 0.25s ease;
    flex-shrink: 0;
    display: flex;
    flex-direction: column;
}
.sidebar.collapsed { width: 0; opacity: 0; overflow: hidden; }

.sidebar-nav { 
    padding: 12px 0; 
    flex: 1;
    overflow-y: auto;
}

#tutorial-list { list-style: none; }
#meta-list { list-style: none; }

.sidebar-footer {
    border-top: 1px solid var(--border-color);
    padding: 12px 0;
    background: var(--sidebar-bg);
}

.tutorial-item {
    padding: 8px 20px;
    font-size: 13px; font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.12s;
    border-left: 3px solid transparent;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}
.tutorial-item:hover { color: var(--accent-color); background: var(--accent-light); }
.tutorial-item.active {
    color: var(--accent-color);
    background: var(--accent-light);
    border-left-color: var(--accent-color);
    font-weight: 600;
}

/* ======================== CONTENT ======================== */
.content {
    flex: 1;
    padding: 48px 72px;
    max-width: 860px;
    margin: 0 auto;
    min-width: 0;
}

/* Welcome Screen */
.welcome-screen {
    height: calc(100vh - var(--topbar-height) - 120px);
    display: flex; align-items: center; justify-content: center;
    text-align: center;
}
.hero-icon { font-size: 56px; margin-bottom: 16px; }
.hero-content h1 {
    font-size: 36px; font-weight: 800;
    letter-spacing: -1px; margin-bottom: 12px;
}
.hero-content p {
    font-size: 16px; color: var(--text-secondary); margin-bottom: 36px;
}

.shortcut-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px; max-width: 420px; margin: 0 auto;
}
.shortcut-card {
    display: flex; align-items: center; gap: 10px;
    padding: 12px 16px;
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    font-size: 13px; color: var(--text-secondary);
}
.shortcut-card kbd {
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    padding: 3px 8px; border-radius: 5px;
    font-size: 11px; font-family: 'JetBrains Mono', monospace;
    color: var(--accent-color); font-weight: 600;
}

/* Tutorial Page */
.tutorial-page h1 {
    font-size: 34px; font-weight: 800;
    letter-spacing: -0.5px;
    color: var(--text-primary);
    margin-bottom: 16px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border-color);
}
.tutorial-meta {
    font-size: 13px; color: var(--text-secondary);
    margin-bottom: 32px;
}
.tutorial-meta a { color: var(--accent-color); text-decoration: none; }

.tutorial-body a {
    color: var(--accent-color);
    text-decoration: none;
    border-bottom: 1px solid rgba(79, 93, 149, 0.2);
    transition: all 0.15s;
}
.tutorial-body a:hover {
    border-bottom-color: var(--accent-color);
    background: var(--accent-light);
}

h2 { font-size: 22px; font-weight: 700; margin: 40px 0 14px; }
h3 { font-size: 18px; font-weight: 600; margin: 28px 0 10px; }
p  { margin-bottom: 18px; color: #334155; font-size: 15px; }
li { margin-bottom: 10px; margin-left: 22px; color: #334155; font-size: 15px; }

/* Code Blocks */
.code-wrapper { position: relative; margin: 20px 0; }

.copy-btn {
    position: absolute; top: 10px; right: 10px;
    padding: 5px 10px;
    background: #475569; border: none;
    color: #e2e8f0; border-radius: 5px;
    font-size: 11px; font-weight: 600;
    cursor: pointer; z-index: 10;
    transition: all 0.15s;
}
.copy-btn:hover { background: #334155; }
.copy-btn.copied { background: #10b981; color: #fff; }

pre {
    border-radius: 10px !important;
    margin: 0 !important;
    font-size: 13px !important;
}

/* Images */
.image-container { margin: 28px 0; text-align: center; }
.image-container img {
    max-width: 100%; height: auto;
    border-radius: 10px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.08);
}

/* ======================== COMMAND PALETTE ======================== */
.palette-overlay {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.5);
    backdrop-filter: blur(4px);
    z-index: 500;
    display: none;
    align-items: flex-start;
    justify-content: center;
    padding-top: 18vh;
}
.palette-overlay.open { display: flex; }

.palette {
    width: 540px;
    background: #fff;
    border-radius: 14px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.2);
    overflow: hidden;
    animation: paletteIn 0.15s ease;
}
@keyframes paletteIn {
    from { opacity: 0; transform: translateY(-12px) scale(0.97); }
    to   { opacity: 1; transform: translateY(0) scale(1); }
}

.palette-input-wrap {
    display: flex; align-items: center; gap: 10px;
    padding: 14px 16px;
    border-bottom: 1px solid var(--border-color);
}
.palette-input-wrap svg { color: var(--text-secondary); flex-shrink: 0; }
.palette-input-wrap kbd {
    background: var(--bg-color); border: 1px solid var(--border-color);
    padding: 2px 7px; border-radius: 4px;
    font-size: 11px; color: var(--text-secondary); font-family: inherit;
}

#palette-input {
    flex: 1; border: none; outline: none;
    font-size: 15px; font-family: inherit;
    background: transparent;
}

.palette-results {
    list-style: none;
    max-height: 360px;
    overflow-y: auto;
    padding: 6px;
}

.palette-item {
    padding: 10px 14px;
    font-size: 14px;
    color: var(--text-primary);
    border-radius: 8px;
    cursor: pointer;
    transition: background 0.1s;
}
.palette-item:hover, .palette-item.focused {
    background: var(--accent-light);
    color: var(--accent-color);
}
.palette-item .palette-hint {
    font-size: 12px;
    color: var(--text-secondary);
    margin-left: 8px;
}

.palette-empty {
    padding: 24px;
    text-align: center;
    color: var(--text-secondary);
    font-size: 14px;
}

/* ======================== SOURCES ======================== */
.tutorial-sources {
    margin-top: 64px;
    padding-top: 32px;
    border-top: 1px dashed var(--border-color);
}
.sources-title {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 12px;
}
.sources-title svg { color: var(--accent-color); }
.sources-list {
    list-style: none;
    margin: 0 !important;
}
.sources-list li {
    margin-bottom: 6px !important;
    font-size: 13px !important;
    margin-left: 0 !important;
}
.sources-list a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.15s;
    word-break: break-all;
}
.sources-list a:hover { color: var(--accent-color); }

/* ======================== RESPONSIVE ======================== */
@media (max-width: 1024px) {
    .content { padding: 36px; }
    .search-trigger { min-width: 240px; }
}
@media (max-width: 768px) {
    .sidebar { position: fixed; z-index: 150; top: var(--topbar-height); left: 0; bottom: 0; }
    .sidebar.collapsed { width: 0; }
    .content { padding: 24px 16px; }
    .search-trigger { min-width: auto; }
    .search-trigger span { display: none; }
    .topbar-logo .logo-text { display: none; }
}