/* ===== RESET & BASE ===== */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

:root {
    --bg: #f5f6f8;
    --bg-secondary: #edeef1;
    --surface: #ffffff;
    --surface-hover: #fafafa;
    --text: #111827;
    --text-secondary: #6b7280;
    --text-tertiary: #9ca3af;
    --accent: #7c3aed;
    --accent-hover: #6d28d9;
    --accent-light: #a78bfa;
    --accent-bg: #ede9fe;
    --accent-bg-hover: #ddd6fe;
    --danger: #ef4444;
    --danger-bg: #fef2f2;
    --success: #10b981;
    --success-bg: #ecfdf5;
    --warning: #f59e0b;
    --blue: #3b82f6;
    --blue-bg: #eff6ff;
    --green: #10b981;
    --green-bg: #ecfdf5;
    --orange: #f97316;
    --orange-bg: #fff7ed;
    --border: #e5e7eb;
    --border-hover: #d1d5db;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
    --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.04), 0 2px 4px rgba(0,0,0,0.04);
    --shadow-lg: 0 10px 25px rgba(0,0,0,0.08);
    --shadow-xl: 0 20px 50px rgba(0,0,0,0.12);
    --radius: 14px;
    --radius-sm: 10px;
    --radius-xs: 6px;
    --sidebar-width: 260px;
    --header-height: 68px;
    --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
    color-scheme: light;
}

[data-theme="dark"] {
    --bg: #0f0f14;
    --bg-secondary: #1a1a24;
    --surface: #1e1e2a;
    --surface-hover: #262636;
    --text: #f0f0f5;
    --text-secondary: #9898a8;
    --text-tertiary: #606070;
    --accent: #8b5cf6;
    --accent-hover: #7c3aed;
    --accent-light: #a78bfa;
    --accent-bg: rgba(139,92,246,0.12);
    --accent-bg-hover: rgba(139,92,246,0.2);
    --danger: #f87171;
    --danger-bg: rgba(248,113,113,0.1);
    --success: #34d399;
    --success-bg: rgba(52,211,153,0.1);
    --warning: #fbbf24;
    --blue: #60a5fa;
    --blue-bg: rgba(96,165,250,0.1);
    --green: #34d399;
    --green-bg: rgba(52,211,153,0.1);
    --orange: #fb923c;
    --orange-bg: rgba(251,146,60,0.1);
    --border: #2a2a3a;
    --border-hover: #3a3a4a;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.2);
    --shadow: 0 1px 3px rgba(0,0,0,0.3);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.3);
    --shadow-lg: 0 10px 25px rgba(0,0,0,0.4);
    --shadow-xl: 0 20px 50px rgba(0,0,0,0.5);
    color-scheme: dark;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    overflow: hidden;
    height: 100vh;
}

/* ===== LAYOUT ===== */
#app { display: flex; height: 100vh; }

/* ===== SIDEBAR ===== */
#sidebar {
    width: var(--sidebar-width);
    background: var(--surface);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    padding: 24px 14px;
    position: fixed;
    top: 0; left: 0;
    height: 100vh;
    z-index: 100;
    transition: transform var(--transition);
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 0 14px 28px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 20px;
}

.logo-icon {
    color: var(--accent);
    flex-shrink: 0;
}

.logo-text {
    font-size: 19px;
    font-weight: 800;
    color: var(--accent);
    letter-spacing: -0.5px;
}

nav {
    display: flex;
    flex-direction: column;
    gap: 4px;
    flex: 1;
}

.nav-btn {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 11px 14px;
    border: none;
    background: none;
    border-radius: var(--radius-sm);
    font-size: 14px;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition);
    font-family: inherit;
    position: relative;
}

.nav-btn:hover { background: var(--bg-secondary); color: var(--text); }
.nav-btn.active { background: var(--accent-bg); color: var(--accent); font-weight: 600; }
.nav-btn.active::before {
    content: '';
    position: absolute;
    left: 0; top: 50%;
    transform: translateY(-50%);
    width: 3px; height: 20px;
    background: var(--accent);
    border-radius: 0 3px 3px 0;
}
.nav-btn svg { flex-shrink: 0; }

.sidebar-footer {
    padding-top: 20px;
    border-top: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.theme-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 8px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    color: var(--text-secondary);
    transition: all var(--transition);
    font-family: inherit;
}
.theme-toggle:hover { color: var(--text); border-color: var(--border-hover); }

.icon-moon { display: none; }
[data-theme="dark"] .icon-sun { display: none; }
[data-theme="dark"] .icon-moon { display: block; }

.teacher-info {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 14px;
    font-size: 13px;
    font-weight: 500;
    color: var(--text-secondary);
    background: var(--bg-secondary);
    border-radius: var(--radius-sm);
}

.teacher-avatar {
    width: 32px; height: 32px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--accent), var(--accent-light));
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
    font-weight: 700;
    flex-shrink: 0;
}

/* ===== MAIN ===== */
#main {
    flex: 1;
    margin-left: var(--sidebar-width);
    display: flex;
    flex-direction: column;
    height: 100vh;
}

/* ===== HEADER ===== */
#header {
    height: var(--header-height);
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 32px;
    flex-shrink: 0;
}

.header-left { display: flex; align-items: center; gap: 16px; }

.header-left h1 {
    font-size: 22px;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.menu-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 6px;
    color: var(--text);
    border-radius: var(--radius-xs);
}
.menu-toggle:hover { background: var(--bg-secondary); }

.header-right { display: flex; align-items: center; gap: 16px; }

.class-selector select {
    padding: 9px 36px 9px 14px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-family: inherit;
    font-size: 14px;
    font-weight: 600;
    background: var(--surface);
    color: var(--text);
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%236b7280' stroke-width='2.5' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    transition: all var(--transition);
}
.class-selector select:hover { border-color: var(--border-hover); }
.class-selector select:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-bg); }

.live-badge {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 7px 16px;
    background: var(--accent-bg);
    border-radius: 24px;
    font-size: 13px;
    font-weight: 600;
    color: var(--accent);
    border: 1px solid transparent;
    transition: all var(--transition);
}
.live-badge.has-active {
    border-color: var(--accent-light);
    background: var(--accent-bg-hover);
}

.pulse {
    width: 8px; height: 8px;
    border-radius: 50%;
    background: var(--accent);
    position: relative;
}
.pulse::after {
    content: '';
    position: absolute;
    inset: -3px;
    border-radius: 50%;
    background: var(--accent);
    opacity: 0;
    animation: pulseAnim 2s infinite;
}
@keyframes pulseAnim {
    0% { opacity: 0.6; transform: scale(0.8); }
    100% { opacity: 0; transform: scale(2); }
}

/* ===== VIEWS ===== */
.view {
    display: none;
    overflow-y: auto;
    flex: 1;
    padding: 28px 32px;
    scroll-behavior: smooth;
}
.view.active { display: block; }

/* ===== DASHBOARD GRID ===== */
.students-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 14px;
}

.student-card {
    background: var(--surface);
    border: 1.5px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
    cursor: pointer;
    transition: all var(--transition);
    position: relative;
    user-select: none;
    display: flex;
    flex-direction: column;
    gap: 10px;
    overflow: hidden;
}

.student-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 3px;
    background: transparent;
    transition: background var(--transition);
}

.student-card:hover {
    border-color: var(--accent-light);
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.student-card:active {
    transform: translateY(0);
    box-shadow: var(--shadow-sm);
}

.student-card.away {
    border-color: var(--accent);
    background: var(--accent-bg);
}
.student-card.away::before {
    background: linear-gradient(90deg, var(--accent), var(--accent-light));
}

.student-card-top {
    display: flex;
    align-items: center;
    gap: 14px;
}

.student-avatar {
    width: 44px; height: 44px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 15px;
    font-weight: 700;
    color: white;
    flex-shrink: 0;
    transition: all var(--transition);
    position: relative;
}

.student-card.away .student-avatar::after {
    content: '';
    position: absolute;
    inset: -3px;
    border-radius: 14px;
    border: 2px solid var(--accent);
    animation: pulseAnim 2s infinite;
}

.student-info { flex: 1; min-width: 0; }

.student-name {
    font-size: 15px;
    font-weight: 600;
    line-height: 1.3;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.student-status {
    font-size: 12px;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 6px;
    margin-top: 2px;
}

.student-status svg { flex-shrink: 0; }

.student-card.away .student-status { color: var(--accent); font-weight: 500; }

.student-bottom {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 8px;
}

.student-timer {
    font-variant-numeric: tabular-nums;
    font-weight: 700;
    font-size: 24px;
    color: var(--accent);
    display: none;
    letter-spacing: -0.5px;
}
.student-card.away .student-timer { display: block; }

.visit-badge {
    display: inline-flex;
    align-items: center;
    gap: 5px;
    font-size: 12px;
    font-weight: 600;
    color: var(--text-tertiary);
    background: var(--bg-secondary);
    padding: 4px 10px;
    border-radius: 20px;
    transition: all var(--transition);
}

.visit-badge svg { opacity: 0.6; }

.student-card.away .visit-badge {
    background: rgba(124,58,237,0.15);
    color: var(--accent);
}

.visit-badge.has-visits {
    color: var(--text-secondary);
}

.visit-badge.top-visitor {
    background: linear-gradient(135deg, #fbbf24, #f59e0b);
    color: #78350f;
}

[data-theme="dark"] .visit-badge.top-visitor {
    background: linear-gradient(135deg, rgba(251,191,36,0.2), rgba(245,158,11,0.2));
    color: #fbbf24;
}

.visit-badge.frequent-visitor {
    background: var(--accent-bg);
    color: var(--accent);
}

/* ===== PANEL HEADER ===== */
.panel-header {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 18px;
    color: var(--text);
}
.panel-header svg { color: var(--accent); flex-shrink: 0; }
.panel-header h3 { font-size: 16px; font-weight: 600; }

/* ===== STATS ===== */
.stats-container {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.stats-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 14px;
}

.stat-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    position: relative;
    overflow: hidden;
    transition: all var(--transition);
}
.stat-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }

.stat-icon-wrap {
    width: 44px; height: 44px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 14px;
}

.stat-card--purple .stat-icon-wrap { background: var(--accent-bg); color: var(--accent); }
.stat-card--blue .stat-icon-wrap { background: var(--blue-bg); color: var(--blue); }
.stat-card--green .stat-icon-wrap { background: var(--green-bg); color: var(--green); }
.stat-card--orange .stat-icon-wrap { background: var(--orange-bg); color: var(--orange); }

.stat-value {
    font-size: 36px;
    font-weight: 800;
    color: var(--text);
    letter-spacing: -1.5px;
    line-height: 1;
}

.stat-label {
    font-size: 13px;
    color: var(--text-secondary);
    margin-top: 6px;
    font-weight: 500;
}

.stats-panels {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
    gap: 16px;
}

.stats-panel {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
}
.stats-panel.full-width { grid-column: 1 / -1; }

/* ===== LEADERBOARD ===== */
.leaderboard { display: flex; flex-direction: column; gap: 6px; }

.leaderboard-item {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 10px 14px;
    border-radius: var(--radius-sm);
    background: var(--bg-secondary);
    transition: all var(--transition);
}
.leaderboard-item:hover { background: var(--border); }

.leaderboard-item:nth-child(1) { background: linear-gradient(135deg, #fef9c3, #fef08a); }
.leaderboard-item:nth-child(2) { background: linear-gradient(135deg, #f1f5f9, #e2e8f0); }
.leaderboard-item:nth-child(3) { background: linear-gradient(135deg, #fef3e2, #fed7aa); }

[data-theme="dark"] .leaderboard-item:nth-child(1) { background: linear-gradient(135deg, rgba(250,204,21,0.12), rgba(234,179,8,0.12)); }
[data-theme="dark"] .leaderboard-item:nth-child(2) { background: linear-gradient(135deg, rgba(148,163,184,0.1), rgba(100,116,139,0.1)); }
[data-theme="dark"] .leaderboard-item:nth-child(3) { background: linear-gradient(135deg, rgba(251,146,60,0.12), rgba(234,88,12,0.12)); }

.leaderboard-rank {
    font-size: 15px;
    font-weight: 800;
    width: 28px;
    text-align: center;
    color: var(--text-tertiary);
}
.leaderboard-item:nth-child(1) .leaderboard-rank { color: #ca8a04; }
.leaderboard-item:nth-child(2) .leaderboard-rank { color: #64748b; }
.leaderboard-item:nth-child(3) .leaderboard-rank { color: #c2410c; }

.leaderboard-name { flex: 1; font-size: 14px; font-weight: 500; }

.leaderboard-value {
    font-size: 14px;
    font-weight: 700;
    color: var(--accent);
    font-variant-numeric: tabular-nums;
}

.leaderboard-bar-wrap {
    flex: 1;
    display: flex;
    align-items: center;
    gap: 8px;
}

.leaderboard-bar {
    flex: 1;
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    overflow: hidden;
}

.leaderboard-bar-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent), var(--accent-light));
    border-radius: 3px;
    transition: width 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ===== HISTORY ===== */
.history-list { max-height: 420px; overflow-y: auto; }

.history-item {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 12px 0;
    border-bottom: 1px solid var(--border);
    font-size: 13px;
    transition: background var(--transition);
}
.history-item:last-child { border-bottom: none; }

.history-dot {
    width: 8px; height: 8px;
    border-radius: 50%;
    background: var(--accent);
    flex-shrink: 0;
}

.history-name { font-weight: 600; min-width: 160px; }
.history-time { color: var(--text-secondary); flex: 1; }
.history-duration { font-weight: 700; color: var(--accent); font-variant-numeric: tabular-nums; }
.history-date { color: var(--text-tertiary); font-size: 12px; }

/* ===== PREDICTIONS ===== */
.predictions-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
    gap: 16px;
}

.prediction-subtitle {
    font-size: 12px;
    color: var(--text-tertiary);
    margin: -14px 0 18px;
}

.predictions-list { display: flex; flex-direction: column; gap: 6px; }

.prediction-item {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 10px 14px;
    border-radius: var(--radius-sm);
    background: var(--bg-secondary);
    transition: all var(--transition);
}
.prediction-item:hover { background: var(--border); transform: translateX(4px); }

.prediction-prob {
    font-size: 18px;
    font-weight: 800;
    color: var(--accent);
    min-width: 56px;
    text-align: right;
    font-variant-numeric: tabular-nums;
}

.prediction-name { flex: 1; font-size: 14px; font-weight: 500; }
.prediction-detail { font-size: 12px; color: var(--text-tertiary); }

.hourly-chart {
    display: flex;
    align-items: flex-end;
    gap: 6px;
    height: 150px;
    padding-top: 10px;
}

.hourly-bar-wrap {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    height: 100%;
    justify-content: flex-end;
}

.hourly-bar {
    width: 100%;
    max-width: 40px;
    background: var(--accent-bg);
    border-radius: 6px 6px 0 0;
    transition: height 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    min-height: 3px;
    position: relative;
}
.hourly-bar.highlight {
    background: linear-gradient(180deg, var(--accent), var(--accent-light));
}

.hourly-label { font-size: 11px; color: var(--text-tertiary); font-weight: 500; }
.hourly-value { font-size: 11px; font-weight: 700; color: var(--accent); }

.daily-forecast {
    display: flex;
    flex-direction: column;
    gap: 14px;
    align-items: center;
    padding: 24px 0;
}

.forecast-number {
    font-size: 64px;
    font-weight: 800;
    color: var(--accent);
    line-height: 1;
    letter-spacing: -3px;
}

.forecast-label { font-size: 14px; color: var(--text-secondary); font-weight: 500; }

.forecast-row {
    display: flex;
    gap: 32px;
    margin-top: 8px;
}

.forecast-item { text-align: center; }
.forecast-item-value { font-size: 28px; font-weight: 800; color: var(--accent); letter-spacing: -1px; }
.forecast-item-label { font-size: 12px; color: var(--text-tertiary); margin-top: 2px; }

.forecast-confidence {
    font-size: 12px;
    color: var(--text-tertiary);
    background: var(--bg-secondary);
    padding: 5px 14px;
    border-radius: 14px;
    font-weight: 500;
    margin-top: 4px;
}

/* ===== SETTINGS ===== */
.settings-container {
    display: flex;
    flex-direction: column;
    gap: 20px;
    max-width: 680px;
}

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

.add-class-form, .add-student-form {
    display: flex;
    gap: 10px;
    margin-bottom: 16px;
}

.add-class-form input, .add-student-form input {
    flex: 1;
    padding: 10px 16px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    font-family: inherit;
    font-size: 14px;
    background: var(--bg-secondary);
    color: var(--text);
    transition: all var(--transition);
}
.add-class-form input:focus, .add-student-form input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-bg);
    background: var(--surface);
}

.btn-primary {
    padding: 10px 20px;
    background: linear-gradient(135deg, var(--accent), var(--accent-hover));
    color: white;
    border: none;
    border-radius: var(--radius-sm);
    font-family: inherit;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    white-space: nowrap;
}
.btn-primary:hover { box-shadow: 0 4px 12px rgba(124,58,237,0.3); transform: translateY(-1px); }
.btn-primary:active { transform: translateY(0); }

.btn-secondary {
    padding: 10px 20px;
    background: var(--bg-secondary);
    color: var(--text);
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    font-family: inherit;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 8px;
}
.btn-secondary:hover { border-color: var(--border-hover); background: var(--border); }

.btn-danger {
    padding: 10px 20px;
    background: var(--danger-bg);
    color: var(--danger);
    border: 1.5px solid transparent;
    border-radius: var(--radius-sm);
    font-family: inherit;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 8px;
}
.btn-danger:hover { border-color: var(--danger); }

.btn-icon {
    width: 34px; height: 34px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: none;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    color: var(--text-secondary);
    transition: all var(--transition);
    flex-shrink: 0;
}
.btn-icon:hover {
    background: var(--danger-bg);
    color: var(--danger);
    border-color: var(--danger);
}

.classes-list, .students-list-settings {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.class-item, .student-item-settings {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 10px 14px;
    border-radius: var(--radius-sm);
    background: var(--bg-secondary);
    transition: all var(--transition);
}
.class-item:hover, .student-item-settings:hover { background: var(--border); }

.class-item-name, .student-item-name { flex: 1; font-size: 14px; font-weight: 500; }
.class-item-count { font-size: 12px; color: var(--text-secondary); font-weight: 500; }

.data-actions { display: flex; gap: 12px; flex-wrap: wrap; }

/* ===== MODAL ===== */
.modal-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.4);
    backdrop-filter: blur(8px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}
.modal-overlay.active { display: flex; }

.modal {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-xl);
    width: 100%;
    max-width: 440px;
    margin: 20px;
    animation: modalIn 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes modalIn {
    from { opacity: 0; transform: scale(0.9) translateY(20px); }
    to { opacity: 1; transform: scale(1) translateY(0); }
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 18px 24px;
    border-bottom: 1px solid var(--border);
}
.modal-header h3 { font-size: 16px; font-weight: 600; }

.modal-close {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-secondary);
    padding: 4px;
    border-radius: var(--radius-xs);
    display: flex;
    transition: all var(--transition);
}
.modal-close:hover { background: var(--bg-secondary); color: var(--text); }

.modal-body { padding: 24px; }

/* ===== EMPTY STATE ===== */
.empty-state {
    text-align: center;
    padding: 48px 20px;
    color: var(--text-tertiary);
}
.empty-state svg { margin-bottom: 12px; opacity: 0.4; }
.empty-state-text { font-size: 14px; font-weight: 500; }

/* ===== TOAST ===== */
.toast {
    position: fixed;
    bottom: 28px; right: 28px;
    background: var(--text);
    color: var(--bg);
    padding: 14px 24px;
    border-radius: var(--radius);
    font-size: 14px;
    font-weight: 500;
    box-shadow: var(--shadow-lg);
    z-index: 2000;
    display: flex;
    align-items: center;
    gap: 10px;
    animation: toastIn 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
}
@keyframes toastIn {
    from { opacity: 0; transform: translateY(16px) scale(0.95); }
    to { opacity: 1; transform: translateY(0) scale(1); }
}

/* ===== SCROLLBAR ===== */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--border-hover); }

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
    #sidebar { transform: translateX(-100%); }
    #sidebar.open { transform: translateX(0); box-shadow: var(--shadow-xl); }
    #main { margin-left: 0; }
    .menu-toggle { display: flex; }
    .students-grid { grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); gap: 10px; }
    #header { padding: 0 20px; }
    .view { padding: 20px; }
    .stats-panels, .predictions-container { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
    .students-grid { grid-template-columns: 1fr 1fr; gap: 8px; }
    .student-card { padding: 14px; }
    .student-avatar { width: 36px; height: 36px; font-size: 13px; border-radius: 10px; }
    .header-right { gap: 8px; }
    .stats-cards { grid-template-columns: 1fr 1fr; }
    .stat-card { padding: 18px; }
    .stat-value { font-size: 28px; }
}