:root {
    --bg: #0d1117;
    --bg-elevated: #161b22;
    --surface: #1c2433;
    --surface-hover: #243040;
    --border: #30404d;
    --border-light: #4a6070;
    --text: #f0f6fc;
    --text-secondary: #b0c4d8;
    --text-muted: #7d95a8;
    --primary: #58a6ff;
    --primary-hover: #79c0ff;
    --primary-bg: rgba(88, 166, 255, 0.15);
    --success: #3fb950;
    --success-bg: rgba(63, 185, 80, 0.15);
    --warning: #d29922;
    --danger: #f85149;
    --radius-sm: 8px;
    --radius: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.25);
    --shadow: 0 4px 16px rgba(0,0,0,0.35);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.45);
    --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-spring: 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

[data-theme="light"] {
    --bg: #f5f7fa;
    --bg-elevated: #ffffff;
    --surface: #ffffff;
    --surface-hover: #f0f4f8;
    --border: #e2e8f0;
    --border-light: #edf2f7;
    --text: #1a202c;
    --text-secondary: #4a5568;
    --text-muted: #a0aec0;
    --primary: #3182ce;
    --primary-hover: #2b6cb0;
    --primary-bg: rgba(49, 130, 206, 0.08);
    --shadow-sm: 0 1px 4px rgba(0,0,0,0.06);
    --shadow: 0 4px 12px rgba(0,0,0,0.08);
    --shadow-lg: 0 8px 24px rgba(0,0,0,0.12);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

.app { max-width: 1200px; margin: 0 auto; padding: 0 20px; }
.hidden { display: none !important; }

/* Header */
.header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px 0;
    border-bottom: 1px solid var(--border);
    margin-bottom: 32px;
    position: sticky;
    top: 0;
    background: var(--bg);
    z-index: 100;
    backdrop-filter: blur(12px);
}

.header-brand {
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo-icon {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--primary-bg);
    border-radius: var(--radius-sm);
    color: var(--primary);
}

.brand-text {
    font-size: 1.1rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.header-steps {
    display: flex;
    align-items: center;
    gap: 8px;
}

.step-pill {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 16px;
    border-radius: 999px;
    border: 1px solid var(--border);
    background: transparent;
    color: var(--text-muted);
    cursor: pointer;
    transition: all var(--transition);
    font-size: 0.875rem;
}

.step-pill:hover { border-color: var(--primary); color: var(--text-secondary); }

.step-pill.active {
    background: var(--primary);
    border-color: var(--primary);
    color: white;
}

.step-pill.completed {
    background: var(--success-bg);
    border-color: var(--success);
    color: var(--success);
}

.step-num {
    width: 20px;
    height: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    background: rgba(255,255,255,0.15);
    font-size: 0.75rem;
    font-weight: 600;
}

.step-connector {
    width: 24px;
    height: 2px;
    background: var(--border);
    border-radius: 1px;
}

.header-actions { display: flex; gap: 8px; }

.icon-btn {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border);
    background: transparent;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition);
}

.icon-btn:hover {
    background: var(--surface-hover);
    color: var(--text);
    border-color: var(--border-light);
}

/* Screens */
.screen { display: none; opacity: 0; transform: translateY(16px) scale(0.98); }
.screen.active { display: block; animation: screenIn 0.5s cubic-bezier(0.22, 1, 0.36, 1) forwards; }
.screen-inner { max-width: 720px; margin: 0 auto; padding: 20px 0 40px; }

.section-header { margin-bottom: 28px; text-align: center; }
.section-header h2 { font-size: 1.75rem; font-weight: 700; margin-bottom: 8px; }
.subtitle { color: var(--text-secondary); font-size: 0.95rem; }

/* Upload Zone */
.upload-zone {
    border: 2px dashed var(--border-light);
    border-radius: var(--radius-xl);
    padding: 64px 24px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.22, 1, 0.36, 1);
    background: linear-gradient(145deg, var(--surface), var(--bg-elevated));
    position: relative;
    overflow: hidden;
}

.upload-zone::before {
    content: "";
    position: absolute;
    inset: 0;
    background: radial-gradient(circle at 50% 50%, var(--primary-bg), transparent 70%);
    opacity: 0;
    transition: opacity 0.3s ease;
}

.upload-zone:hover::before, .upload-zone.drag-over::before { opacity: 1; }

.upload-zone:hover, .upload-zone.drag-over {
    border-color: var(--primary);
    transform: translateY(-4px);
    box-shadow: 0 12px 40px rgba(88, 166, 255, 0.15);
}

.upload-icon {
    color: var(--primary);
    margin-bottom: 20px;
    opacity: 0.9;
    animation: floatUpDown 3s ease-in-out infinite;
}

.upload-zone h3 { font-size: 1.15rem; margin-bottom: 8px; font-weight: 600; position: relative; }
.upload-zone p { color: var(--text-muted); font-size: 0.875rem; position: relative; }

/* Import Progress */
.import-progress {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 20px;
    margin-top: 16px;
    background: var(--surface);
    border-radius: var(--radius);
    border: 1px solid var(--border);
}

.progress-ring {
    width: 32px;
    height: 32px;
    border: 3px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

.import-status { flex: 1; }
.import-status span { font-size: 0.875rem; color: var(--text-secondary); display: block; margin-bottom: 8px; }

/* Progress Bar */
.progress-bar {
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    overflow: hidden;
}

.progress-bar.big { height: 10px; }

.progress-bar-fill {
    height: 100%;
    width: 0;
    background: linear-gradient(90deg, var(--primary), var(--success));
    border-radius: 3px;
    transition: width 0.3s ease;
}

/* Import Summary */
.import-summary {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px 20px;
    margin-top: 16px;
    background: var(--success-bg);
    border: 1px solid rgba(54, 211, 153, 0.3);
    border-radius: var(--radius);
    color: var(--success);
    font-weight: 500;
}

.summary-icon { font-size: 1.2rem; }

/* Cards */
.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    margin-bottom: 16px;
    overflow: hidden;
    transition: box-shadow var(--transition);
}

.card:hover { box-shadow: var(--shadow-sm); }

.card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px 20px;
}

.card-header h3 { font-size: 0.95rem; font-weight: 600; }
.card-header p { color: var(--text-muted); font-size: 0.8rem; margin-top: 2px; }

.card-body { padding: 0 20px 20px; }

.collapsible .card-header { cursor: pointer; user-select: none; }
.collapsible .card-header .chevron { transition: transform var(--transition); }
.collapsible[open] .card-header .chevron { transform: rotate(180deg); }

/* Mode Cards */
.mode-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 12px;
    margin-bottom: 24px;
}

.mode-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    padding: 20px 12px;
    border-radius: var(--radius);
    border: 2px solid var(--border);
    background: var(--surface);
    cursor: pointer;
    transition: all var(--transition);
    text-align: center;
}

.mode-card:hover {
    border-color: var(--primary);
    background: var(--primary-bg);
    transform: translateY(-2px);
}

.mode-card.active {
    border-color: var(--primary);
    background: var(--primary-bg);
    box-shadow: 0 0 0 3px rgba(76, 154, 255, 0.2);
}

.mode-card-icon { font-size: 1.5rem; }
.mode-card-title { font-size: 0.875rem; font-weight: 600; color: var(--text); }
.mode-card-desc { font-size: 0.75rem; color: var(--text-secondary); }

/* Form Elements */
.config-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 16px;
    padding: 0 20px 20px;
}

.field { display: flex; flex-direction: column; gap: 6px; }
.field-full { grid-column: 1 / -1; }
.field label { font-size: 0.85rem; color: var(--text); font-weight: 500; }
.field-desc { color: var(--text-muted); font-size: 0.8rem; margin-bottom: 12px; }

input, select {
    background: var(--bg-elevated);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 10px 14px;
    font-size: 0.9rem;
    transition: border-color var(--transition), box-shadow var(--transition);
    outline: none;
}

input:focus, select:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-bg);
}

input[type="range"] {
    -webkit-appearance: none;
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    border: none;
    padding: 0;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--primary);
    cursor: pointer;
    box-shadow: 0 2px 6px rgba(76, 154, 255, 0.4);
    transition: transform var(--transition);
}

input[type="range"]::-webkit-slider-thumb:hover { transform: scale(1.2); }

select[multiple] { min-height: 140px; padding: 8px; }

.range-value { color: var(--primary); font-weight: 600; margin-left: 4px; }

.hint { font-size: 0.8rem; color: var(--text-muted); }

/* Stepper */
.stepper {
    display: flex;
    align-items: center;
    gap: 0;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    overflow: hidden;
}

.stepper input {
    border: none;
    border-radius: 0;
    text-align: center;
    width: 60px;
    padding: 8px 4px;
}

.stepper-btn {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: none;
    background: var(--surface-hover);
    color: var(--text);
    cursor: pointer;
    font-size: 1.1rem;
    transition: background var(--transition);
}

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

/* Toggle Switch */
.toggle-switch { position: relative; display: inline-block; width: 40px; height: 22px; }
.toggle-switch input { opacity: 0; width: 0; height: 0; }
.toggle-slider {
    position: absolute;
    inset: 0;
    background: var(--border);
    border-radius: 11px;
    cursor: pointer;
    transition: background var(--transition);
}
.toggle-slider::before {
    content: "";
    position: absolute;
    width: 16px;
    height: 16px;
    left: 3px;
    bottom: 3px;
    background: white;
    border-radius: 50%;
    transition: transform var(--transition);
}
.toggle-switch input:checked + .toggle-slider { background: var(--primary); }
.toggle-switch input:checked + .toggle-slider::before { transform: translateX(18px); }

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    border-radius: var(--radius-sm);
    border: none;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    text-decoration: none;
    line-height: 1;
}

.btn-primary {
    background: var(--primary);
    color: white;
}
.btn-primary:hover { background: var(--primary-hover); transform: translateY(-1px); box-shadow: var(--shadow); }

.btn-secondary {
    background: var(--surface-hover);
    color: var(--text);
    border: 1px solid var(--border);
}
.btn-secondary:hover { border-color: var(--primary); color: var(--primary); }

.btn-ghost {
    background: transparent;
    color: var(--text-secondary);
}
.btn-ghost:hover { color: var(--text); background: var(--surface-hover); }

.btn-sm { padding: 6px 12px; font-size: 0.8rem; }
.btn-lg { padding: 14px 28px; font-size: 1rem; }

.btn:disabled { opacity: 0.5; cursor: not-allowed; transform: none !important; }

/* Screen Actions */
.screen-actions {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 32px;
    padding-top: 20px;
    border-top: 1px solid var(--border);
}

/* Mapping */
.mapping-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    padding: 0 20px 20px;
}

.mapping-card .btn { margin: 0 20px 20px; }

.row-inline { display: flex; gap: 12px; align-items: center; padding: 0 20px 20px; }

/* Data Preview */
.data-preview {
    margin-top: 16px;
    max-height: 300px;
    overflow: auto;
    border: 1px solid var(--border);
    border-radius: var(--radius);
}

.data-preview table { border-collapse: collapse; width: 100%; font-size: 0.85rem; }
.data-preview th, .data-preview td { padding: 8px 12px; border-bottom: 1px solid var(--border); text-align: left; }
.data-preview th { background: var(--surface-hover); font-weight: 600; position: sticky; top: 0; }
.data-preview tr:hover td { background: var(--primary-bg); }

/* Constraints */
.constraint-form {
    display: flex;
    gap: 8px;
    align-items: center;
    flex-wrap: wrap;
    margin-bottom: 12px;
}

.constraint-select { flex: 1; min-width: 120px; }
.constraint-type { width: 120px; }

.constraints-list {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.chip {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 6px 12px;
    border-radius: 999px;
    background: var(--primary-bg);
    border: 1px solid rgba(76, 154, 255, 0.3);
    font-size: 0.8rem;
    color: var(--text);
}

.chip button {
    border: none;
    background: transparent;
    color: var(--danger);
    cursor: pointer;
    font-size: 1rem;
    line-height: 1;
    padding: 0;
}

/* Progress Overlay */
.progress-overlay {
    position: fixed;
    inset: 0;
    background: rgba(15, 20, 25, 0.85);
    backdrop-filter: blur(8px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.progress-modal {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 40px;
    width: min(500px, 90vw);
    text-align: center;
}

.progress-modal h3 { margin-bottom: 24px; font-size: 1.1rem; }

.progress-modal-icon { margin-bottom: 20px; }

.progress-meta {
    display: flex;
    justify-content: space-between;
    margin-top: 12px;
    font-size: 0.8rem;
    color: var(--text-muted);
}

.live-chart-wrap {
    margin-top: 24px;
    height: 180px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 8px;
}

.live-chart-wrap canvas { width: 100% !important; height: 100% !important; }

/* Results */
.results-toolbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 20px;
    padding: 12px 16px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
}

.toolbar-left, .toolbar-right { display: flex; gap: 8px; flex-wrap: wrap; }

/* Tabs */
.tabs-bar {
    display: flex;
    gap: 4px;
    margin-bottom: 20px;
    padding: 4px;
    background: var(--bg-elevated);
    border-radius: var(--radius-sm);
    border: 1px solid var(--border);
}

.tab-btn {
    padding: 8px 16px;
    border-radius: 6px;
    border: none;
    background: transparent;
    color: var(--text-muted);
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
}

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

.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* Quality Cards */
.quality-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    gap: 12px;
    margin-bottom: 20px;
}

.quality-item {
    padding: 16px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    text-align: center;
}

.quality-item > div:first-child { font-size: 0.8rem; color: var(--text-muted); margin-bottom: 6px; }
.qv { font-size: 1.4rem; font-weight: 700; color: var(--primary); }

/* Groups Grid */
.groups-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 16px;
}

.group-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    transition: all var(--transition);
}

.group-card:hover { box-shadow: var(--shadow); transform: translateY(-2px); }
.group-card.order-mode { cursor: grab; }
.group-card.drag-over { outline: 2px dashed var(--primary); outline-offset: -2px; }

.group-header {
    padding: 14px 16px;
    background: linear-gradient(135deg, var(--primary), #6366f1);
    color: white;
    font-weight: 600;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.group-stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 8px;
    padding: 12px 16px;
    font-size: 0.8rem;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--border);
}

.group-members { padding: 8px 16px 16px; }

.student-item {
    display: grid;
    grid-template-columns: 20px 1fr auto;
    gap: 10px;
    align-items: center;
    padding: 8px 0;
    border-bottom: 1px solid var(--border-light);
    font-size: 0.85rem;
}

.student-item:last-child { border-bottom: none; }
.student-item.dragging { opacity: 0.3; background: var(--primary-bg); }

.drag-handle { opacity: 0.5; cursor: grab; user-select: none; font-size: 0.75rem; }
.drag-handle:hover { opacity: 1; color: var(--primary); }

/* Dashboard */
.insight-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 12px;
    margin-bottom: 20px;
}

.insight-card {
    padding: 16px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
}

.insight-label { font-size: 0.75rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.05em; }
.insight-value { font-size: 1.3rem; font-weight: 700; margin-top: 4px; }

.charts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 16px;
    margin-top: 20px;
}

.charts-grid.single { grid-template-columns: 1fr; }

.chart-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px;
    min-height: 280px;
}

.chart-card.wide { min-height: 360px; }
.chart-card canvas { width: 100% !important; height: 100% !important; }

/* Tables */
.table-scroll { max-height: 400px; overflow: auto; border-radius: var(--radius-sm); }

table { border-collapse: collapse; width: 100%; font-size: 0.85rem; }
th, td { padding: 10px 14px; text-align: left; border-bottom: 1px solid var(--border); }
th { background: var(--surface-hover); font-weight: 600; position: sticky; top: 0; z-index: 1; }
tr:hover td { background: var(--primary-bg); }

.group-folds { margin-top: 16px; }

details.mini-fold {
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    margin-bottom: 8px;
    overflow: hidden;
}

details.mini-fold summary {
    padding: 10px 14px;
    cursor: pointer;
    font-size: 0.85rem;
    font-weight: 500;
    background: var(--surface-hover);
    list-style: none;
}

details.mini-fold summary::-webkit-details-marker { display: none; }

.mini-stats {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    padding: 10px 14px;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.mini-stats span {
    padding: 3px 10px;
    background: var(--primary-bg);
    border-radius: 999px;
}

/* Toast */
.toast-container {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 9999;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.toast {
    padding: 12px 20px;
    border-radius: var(--radius-sm);
    background: var(--surface);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-lg);
    font-size: 0.875rem;
    animation: slideInRight 0.3s var(--transition-spring);
}

.toast.success { border-left: 3px solid var(--success); }
.toast.error { border-left: 3px solid var(--danger); }
.toast.info { border-left: 3px solid var(--primary); }

/* Responsive */
@media (max-width: 768px) {
    .header-steps { display: none; }
    .mode-cards { grid-template-columns: repeat(2, 1fr); }
    .config-grid { grid-template-columns: 1fr; }
    .groups-grid { grid-template-columns: 1fr; }
    .results-toolbar { flex-direction: column; }
    .charts-grid { grid-template-columns: 1fr; }
    .mapping-grid { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
    .app { padding: 0 12px; }
    .mode-cards { grid-template-columns: 1fr; }
    .screen-actions { flex-direction: column; gap: 12px; }
}

/* Footer */
.app-footer {
    margin-top: 60px;
    padding: 24px 0;
    border-top: 1px solid var(--border);
}

.footer-section {
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    margin-bottom: 8px;
    overflow: hidden;
}

.footer-section summary {
    padding: 12px 16px;
    cursor: pointer;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
    background: var(--surface);
    list-style: none;
    transition: color var(--transition);
}

.footer-section summary:hover { color: var(--text); }
.footer-section summary::-webkit-details-marker { display: none; }

.footer-content {
    padding: 16px;
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.footer-content p { margin-bottom: 8px; }
.footer-content ul { margin: 8px 0 8px 20px; }
.footer-content li { margin-bottom: 4px; }
.footer-content strong { color: var(--text); }

.footer-copyright {
    text-align: center;
    padding: 16px;
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* Disclaimer Overlay */
.disclaimer-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 10000;
    animation: fadeIn 0.5s ease;
    cursor: pointer;
}

.disclaimer-overlay.hidden { display: none; }

.disclaimer-modal {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 40px;
    max-width: 420px;
    text-align: center;
    animation: modalBounceIn 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.disclaimer-icon { font-size: 2.5rem; margin-bottom: 16px; }
.disclaimer-modal h3 { font-size: 1.2rem; margin-bottom: 12px; }
.disclaimer-modal p { color: var(--text-secondary); font-size: 0.9rem; line-height: 1.7; margin-bottom: 16px; }
.disclaimer-hint { font-size: 0.75rem; color: var(--text-muted); }

/* Toolbar tip */
.toolbar-tip {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-style: italic;
}

/* Always-on drag handles */
.group-card .drag-handle {
    opacity: 0.5;
    cursor: grab;
    transition: opacity var(--transition), color var(--transition);
}

.group-card .drag-handle:hover {
    opacity: 1;
    color: var(--primary);
}

.group-header {
    cursor: grab;
}

.group-header:active {
    cursor: grabbing;
}

/* Pulse dots animation */
.pulse-dots {
    display: flex;
    gap: 8px;
    justify-content: center;
    padding: 12px 0;
}

.pulse-dots span {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--primary);
    animation: pulseDot 1.4s ease-in-out infinite;
}

.pulse-dots span:nth-child(2) { animation-delay: 0.2s; }
.pulse-dots span:nth-child(3) { animation-delay: 0.4s; }

@keyframes pulseDot {
    0%, 80%, 100% { transform: scale(0.6); opacity: 0.4; }
    40% { transform: scale(1.2); opacity: 1; }
}

/* Stepper readonly style */
.stepper input[readonly] {
    cursor: default;
    user-select: none;
}

/* Background Canvas */
.bg-canvas {
    position: fixed;
    inset: 0;
    z-index: -1;
    pointer-events: none;
    opacity: 0.4;
}

/* Drop target highlight */
.group-card.drop-target {
    outline: 3px solid var(--primary);
    outline-offset: -3px;
    background: var(--primary-bg);
    box-shadow: 0 0 20px rgba(88, 166, 255, 0.3);
    transform: scale(1.01);
    transition: all 0.15s ease;
}

.student-item.dragging {
    opacity: 0.3;
    transform: scale(0.95);
}

/* Insert position indicator */
.student-item.insert-above {
    border-top: 3px solid var(--primary);
    margin-top: -1px;
    padding-top: 7px;
}

/* Group header draggable */
.group-header {
    cursor: grab;
    user-select: none;
}

.group-header:active {
    cursor: grabbing;
}

.group-card.dragging {
    opacity: 0.5;
    transform: scale(0.97) rotate(1deg);
}