/* ========================================
   学习辅助系统 - 样式表
   ======================================== */

:root {
    --primary: #4f46e5;
    --primary-hover: #4338ca;
    --danger: #ef4444;
    --success: #22c55e;
    --warning: #f59e0b;
    --bg: #f8fafc;
    --card-bg: #ffffff;
    --text: #1e293b;
    --text-muted: #94a3b8;
    --border: #e2e8f0;
    --radius: 12px;
    --shadow: 0 1px 3px rgba(0,0,0,0.08);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
}

/* Navigation */
.top-nav {
    background: var(--card-bg);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-inner {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    height: 56px;
    gap: 32px;
}

.nav-brand {
    font-weight: 700;
    font-size: 18px;
    text-decoration: none;
    color: var(--text);
    white-space: nowrap;
}

.nav-links {
    display: flex;
    gap: 8px;
    overflow-x: auto;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-muted);
    font-size: 14px;
    padding: 6px 12px;
    border-radius: 6px;
    transition: all 0.2s;
    white-space: nowrap;
}

.nav-links a:hover { color: var(--primary); background: #eef2ff; }

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 24px 20px;
}

/* Page Header */
.page-header { margin-bottom: 24px; }
.page-header h1 { font-size: 24px; font-weight: 700; }
.subtitle { color: var(--text-muted); font-size: 14px; margin-top: 4px; }

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 8px 20px;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 500;
    border: none;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
}

.btn-primary { background: var(--primary); color: white; }
.btn-primary:hover { background: var(--primary-hover); }

.btn-secondary { background: #f1f5f9; color: var(--text); }
.btn-secondary:hover { background: #e2e8f0; }

.btn-danger { background: var(--danger); color: white; }
.btn-danger:hover { background: #dc2626; }

.btn-lg { padding: 14px 36px; font-size: 18px; border-radius: 12px; }

/* Student Grid */
.student-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 16px;
    margin-bottom: 32px;
}

.student-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    text-align: center;
    transition: all 0.2s;
}

.student-card:hover { box-shadow: var(--shadow); border-color: var(--primary); }

.student-avatar {
    width: 64px;
    height: 64px;
    border-radius: 50%;
    background: linear-gradient(135deg, #6366f1, #8b5cf6);
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    font-weight: 700;
    margin: 0 auto 12px;
}

.student-name { font-size: 18px; font-weight: 600; margin-bottom: 4px; }
.student-grade { color: var(--text-muted); font-size: 13px; margin-bottom: 16px; }

/* Stats */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 16px;
    margin-top: 12px;
}

.stat-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
}

.stat-label { color: var(--text-muted); font-size: 13px; }
.stat-value { font-size: 28px; font-weight: 700; margin-top: 4px; }

/* Empty State */
.empty-state {
    text-align: center;
    padding: 64px 20px;
    color: var(--text-muted);
}

.empty-state p { margin-bottom: 16px; }

/* Monitor Layout (legacy - kept for sidebar) */

.camera-panel {
    background: #000;
    border-radius: var(--radius);
    overflow: hidden;
    aspect-ratio: 16/9;
    display: flex;
    flex-direction: column;
}

.camera-frame {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
}

.camera-placeholder { text-align: center; color: #666; }
.camera-placeholder span { font-size: 48px; }
.camera-placeholder p { margin-top: 8px; }

.camera-status {
    padding: 8px 16px;
    background: #111;
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    color: #999;
}

.status-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
}

.status-dot.online { background: var(--success); }
.status-dot.offline { background: var(--danger); }

/* Monitor Sidebar */
.monitor-sidebar { display: flex; flex-direction: column; gap: 16px; }

.session-timer, .focus-indicator, .event-log {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
}

.timer-label, .focus-label { color: var(--text-muted); font-size: 13px; }

.timer-value {
    font-size: 36px;
    font-weight: 700;
    font-variant-numeric: tabular-nums;
    margin: 8px 0;
}

.focus-value { font-size: 32px; font-weight: 700; color: var(--primary); margin-top: 4px; }

.timer-controls { display: flex; gap: 8px; margin-top: 12px; }
.timer-controls .btn { flex: 1; }

.event-log { flex: 1; }
.event-log h3 { font-size: 15px; margin-bottom: 12px; }

/* Photo Layout */
.photo-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.capture-frame {
    background: #000;
    border-radius: var(--radius);
    aspect-ratio: 4/3;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
}

.capture-frame video, .capture-frame canvas {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.capture-guide {
    position: absolute;
    inset: 10%;
    border: 2px dashed rgba(255,255,255,0.4);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.guide-text { color: rgba(255,255,255,0.6); font-size: 14px; }

.capture-controls, .upload-controls {
    display: flex;
    gap: 8px;
    margin-top: 12px;
}

/* Form Elements */
.form-input, .form-select {
    width: 100%;
    padding: 10px 14px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 14px;
    background: white;
    color: var(--text);
}

.form-input:focus, .form-select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(79,70,229,0.1);
}

.form-group { margin-bottom: 16px; }
.form-group label { display: block; font-size: 13px; font-weight: 500; margin-bottom: 6px; color: var(--text); }

/* Settings Layout */
.settings-layout { display: flex; flex-direction: column; gap: 24px; }

.settings-section h2 { font-size: 18px; margin-bottom: 12px; }

.settings-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
}

/* Toggle */
.toggle-label {
    display: flex;
    align-items: center;
    gap: 12px;
    cursor: pointer;
}

.toggle-label input[type="checkbox"] {
    width: 44px;
    height: 24px;
    border-radius: 12px;
    appearance: none;
    background: #cbd5e1;
    position: relative;
    transition: all 0.2s;
    cursor: pointer;
}

.toggle-label input[type="checkbox"]::before {
    content: '';
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: white;
    position: absolute;
    top: 2px;
    left: 2px;
    transition: all 0.2s;
}

.toggle-label input[type="checkbox"]:checked {
    background: var(--primary);
}

.toggle-label input[type="checkbox"]:checked::before {
    left: 22px;
}

/* Error Filters */
.error-filters {
    display: flex;
    gap: 12px;
    margin-bottom: 20px;
}

.error-filters .form-select { max-width: 200px; }

/* Report Grid */
.report-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-top: 20px;
}

.report-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
}

.report-card h3 { font-size: 15px; margin-bottom: 12px; }

.full-width { grid-column: 1 / -1; }

/* Practice Controls */
.practice-controls {
    display: flex;
    gap: 12px;
    margin-bottom: 20px;
}

.practice-controls .form-select { max-width: 200px; }

/* Responsive */
@media (max-width: 768px) {
    .photo-layout { grid-template-columns: 1fr; }
    .report-grid { grid-template-columns: 1fr; }
    .student-grid { grid-template-columns: repeat(2, 1fr); }
    .container { padding: 16px 12px; }
    .page-header h1 { font-size: 20px; }
    .stats-grid { grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); }
    .stat-value { font-size: 22px; }
    .student-select-bar { flex-wrap: wrap; }
    .student-select-bar .form-select { max-width: 100%; flex: 1; min-width: 120px; }
    .practice-controls { flex-direction: column; }
    .practice-controls .form-select { max-width: 100%; }
    .error-filters { flex-direction: column; }
    .error-filters .form-select { max-width: 100%; }
    .settings-card { padding: 16px; }
    .recording-indicator { font-size: 12px !important; padding: 10px 12px !important; }
    .timer-value { font-size: 28px; }
    .focus-value { font-size: 26px; }
    .monitor-sidebar { gap: 12px; }
    .session-timer, .focus-indicator, .event-log { padding: 14px; }
}

/* Utilities */
.text-muted { color: var(--text-muted); }
.loading { text-align: center; padding: 40px; color: var(--text-muted); }

/* Cards for results */
.result-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px;
    margin-bottom: 12px;
}

.result-correct { border-left: 4px solid var(--success); }
.result-wrong { border-left: 4px solid var(--danger); }

.result-question { font-weight: 600; margin-bottom: 8px; }

.result-answer { font-size: 14px; margin-bottom: 4px; }

.result-reason {
    font-size: 13px;
    color: var(--danger);
    margin-top: 4px;
}

/* Student list in settings */
.student-list { margin-top: 16px; }

.student-list-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 0;
    border-bottom: 1px solid var(--border);
}

/* Camera list items */
.camera-list-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 0;
    border-bottom: 1px solid var(--border);
    gap: 12px;
}
.camera-list-item:last-child { border-bottom: none; }

.camera-list-info {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

/* Multi-camera grid */
.camera-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    margin-bottom: 16px;
}

.camera-card {
    background: #000;
    border-radius: var(--radius);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    position: relative;
}

.camera-card-feed {
    aspect-ratio: 9/16;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #000;
    position: relative;
}

.camera-card-stream {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.camera-card-placeholder {
    text-align: center;
    color: #666;
    padding: 40px 20px;
}
.camera-card-placeholder span { font-size: 36px; display: block; margin-bottom: 8px; }
.camera-card-placeholder p { font-size: 13px; }

.camera-card-label {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 6px 12px;
    background: linear-gradient(to bottom, rgba(0,0,0,0.8), transparent);
    color: #fff;
    font-size: 11px;
    font-weight: 500;
    z-index: 2;
    pointer-events: none;
}

.camera-card-type {
    font-size: 11px;
    opacity: 0.7;
    font-weight: 400;
}

.camera-card-status {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 6px 12px;
    background: #111;
    font-size: 12px;
    color: #999;
}

.camera-grid-empty {
    grid-column: 1 / -1;
    text-align: center;
    padding: 60px 20px;
    color: var(--text-muted);
}
.camera-grid-empty p { margin-top: 8px; }

/* Monitor main area */
.monitor-main {
    flex: 1;
    min-width: 0;
}

.monitor-layout {
    display: grid;
    grid-template-columns: 1fr;
    gap: 20px;
    align-items: start;
}

/* Desktop: two-column layout */
@media (min-width: 769px) {
    .monitor-layout {
        grid-template-columns: 1fr 320px;
    }
}

/* Student select bar */
.student-select-bar {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 20px;
    padding: 16px;
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
}
.student-select-bar label {
    font-size: 14px;
    font-weight: 500;
    white-space: nowrap;
}
.student-select-bar .form-select {
    max-width: 200px;
}

@media (max-width: 768px) {
    .camera-grid { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
    .camera-grid { gap: 10px; }
    .camera-card-feed { aspect-ratio: 9/16; }
    .camera-card-status { font-size: 11px; padding: 4px 8px; }
}

/* History layout */
.history-layout {
    display: grid;
    grid-template-columns: 220px 1fr;
    gap: 20px;
    align-items: start;
}

.history-sidebar {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px;
    position: sticky;
    top: 80px;
    max-height: calc(100vh - 100px);
    overflow-y: auto;
}

.sidebar-section { margin-bottom: 20px; }
.sidebar-section:last-child { margin-bottom: 0; }
.sidebar-section h3 {
    font-size: 12px;
    text-transform: uppercase;
    color: var(--text-muted);
    margin-bottom: 8px;
    letter-spacing: 0.5px;
}

.sidebar-menu { display: flex; flex-direction: column; gap: 2px; }

.sidebar-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 7px 10px;
    border-radius: 6px;
    font-size: 13px;
    cursor: pointer;
    transition: all 0.15s;
    color: var(--text);
}
.sidebar-item:hover { background: #f1f5f9; }
.sidebar-item.active {
    background: #eef2ff;
    color: var(--primary);
    font-weight: 500;
}
.sidebar-count {
    font-size: 11px;
    color: var(--text-muted);
    background: #f1f5f9;
    padding: 1px 7px;
    border-radius: 10px;
    min-width: 20px;
    text-align: center;
}
.sidebar-item.active .sidebar-count {
    background: var(--primary);
    color: white;
}

@media (max-width: 768px) {
    .history-layout { grid-template-columns: 1fr; }
    .history-sidebar { position: static; max-height: none; }
}

/* History grid view */
.history-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 12px;
}

.history-grid-item {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    cursor: pointer;
    transition: box-shadow 0.2s;
    text-decoration: none;
    color: inherit;
    display: block;
}
.history-grid-item:hover { box-shadow: 0 2px 8px rgba(0,0,0,0.1); }

.history-grid-thumb {
    width: 100%;
    aspect-ratio: 4/3;
    background: #f1f5f9;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 32px;
    overflow: hidden;
}
.history-grid-thumb img { width: 100%; height: 100%; object-fit: cover; }

.history-grid-info {
    padding: 10px 12px;
}
.history-grid-info .subject { font-weight: 600; font-size: 14px; }
.history-grid-info .meta {
    font-size: 12px;
    color: var(--text-muted);
    margin-top: 2px;
}