:root {
    /* Modern Flat Color Palette (Indigo/Slate) */
    --bg-body: #f8fafc;
    /* Slate 50 */
    --bg-card: #ffffff;
    /* White */

    --primary: #4f46e5;
    /* Indigo 600 */
    --primary-hover: #4338ca;
    /* Indigo 700 */
    --primary-light: #e0e7ff;
    /* Indigo 100 */

    --text-main: #0f172a;
    /* Slate 900 */
    --text-muted: #64748b;
    /* Slate 500 */
    --text-light: #94a3b8;
    /* Slate 400 */

    --success: #10b981;
    /* Emerald 500 */
    --success-bg: #d1fae5;
    /* Emerald 100 */
    --success-text: #065f46;
    /* Emerald 800 */

    --danger: #ef4444;
    /* Red 500 */
    --danger-bg: #fee2e2;
    /* Red 100 */
    --danger-text: #991b1b;
    /* Red 800 */

    --warning: #f59e0b;
    /* Amber 500 */
    --warning-bg: #fef3c7;
    /* Amber 100 */
    --warning-text: #92400e;
    /* Amber 800 */

    --info: #3b82f6;
    /* Blue 500 */
    --info-bg: #dbeafe;
    /* Blue 100 */
    --info-text: #1e40af;
    /* Blue 800 */

    /* Borders & Shadows */
    --border-color: #e2e8f0;
    /* Slate 200 */

    /* Modern Shadows (Tailwind-like) */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

    /* Spacing */
    --radius-sm: 0.375rem;
    /* 6px */
    --radius-md: 0.5rem;
    /* 8px */
    --radius-lg: 0.75rem;
    /* 12px */
    --radius-xl: 1rem;
    /* 16px */
    --radius-pill: 9999px;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-body);
    color: var(--text-main);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
}

/* Layout */
.app-wrapper {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    background-color: var(--bg-body);
}

.container {
    width: 100%;
    max-width: 1280px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
    flex: 1;
}

/* Header */
.main-header {
    background-color: var(--bg-card);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 50;
    box-shadow: var(--shadow-sm);
    border-bottom: 1px solid var(--border-color);
}

.header-content {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo-section {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.logo-icon {
    width: 40px;
    height: 40px;
    background: var(--primary-light);
    color: var(--primary);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
}

.main-header h1 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-main);
    letter-spacing: -0.025em;
}

.header-actions {
    display: flex;
    gap: 0.75rem;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.625rem 1.25rem;
    border-radius: var(--radius-md);
    font-weight: 500;
    font-size: 0.875rem;
    cursor: pointer;
    transition: all 0.2s ease;
    border: 1px solid transparent;
    text-decoration: none;
}

.btn-primary {
    background-color: var(--primary);
    color: white;
    box-shadow: var(--shadow-sm);
}

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

.btn-secondary {
    background-color: white;
    color: var(--text-main);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
    background-color: var(--bg-body);
    border-color: var(--text-muted);
}

.btn-ghost {
    background: transparent;
    color: var(--text-muted);
}

.btn-ghost:hover {
    background: var(--bg-body);
    color: var(--text-main);
}

.btn-outline-danger {
    background: white;
    color: var(--danger);
    border: 1px solid var(--danger-bg);
}

.btn-outline-danger:hover {
    background: var(--danger-bg);
    border-color: var(--danger);
}

.btn-sm {
    padding: 0.375rem 0.75rem;
    font-size: 0.75rem;
}

.btn-icon-only {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    border-radius: var(--radius-md);
    transition: all 0.2s;
}

.btn-icon-only:hover {
    background-color: var(--bg-body);
    color: var(--danger);
}

/* Control Panel */
.control-panel {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1.5rem;
    background: var(--bg-card);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

.import-section {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.file-controls {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.file-info {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.file-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.25rem 0.75rem;
    background-color: var(--success-bg);
    color: var(--success-text);
    border-radius: var(--radius-pill);
    font-size: 0.75rem;
    font-weight: 600;
    border: 1px solid var(--success);
}

/* Toggle Switch */
.prediction-toggle-wrapper {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.toggle-switch {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    cursor: pointer;
}

.toggle-switch input {
    display: none;
}

.toggle-slider {
    width: 44px;
    height: 24px;
    background-color: var(--text-light);
    border-radius: 9999px;
    position: relative;
    transition: all 0.3s;
}

.toggle-slider::after {
    content: '';
    position: absolute;
    top: 2px;
    left: 2px;
    width: 20px;
    height: 20px;
    background-color: white;
    border-radius: 50%;
    transition: transform 0.3s;
    box-shadow: var(--shadow-sm);
}

.toggle-switch input:checked+.toggle-slider {
    background-color: var(--primary);
}

.toggle-switch input:checked+.toggle-slider::after {
    transform: translateX(20px);
}

.toggle-label {
    font-weight: 500;
    color: var(--text-main);
    font-size: 0.875rem;
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: var(--bg-card);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 1.25rem;
    transition: transform 0.2s, box-shadow 0.2s;
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.stat-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

.stat-card.primary .stat-icon {
    background-color: var(--primary-light);
    color: var(--primary);
}

.stat-card.success .stat-icon {
    background-color: var(--success-bg);
    color: var(--success-text);
}

.stat-card.info .stat-icon {
    background-color: var(--info-bg);
    color: var(--info-text);
}

.stat-content h3 {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-weight: 600;
    margin-bottom: 0.25rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.stat-content strong {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-main);
}

/* Alert */
.prediction-help-alert {
    background-color: var(--warning-bg);
    color: var(--warning-text);
    padding: 1rem 1.5rem;
    border-radius: var(--radius-md);
    margin-bottom: 2rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    border: 1px solid var(--warning);
    animation: slideDown 0.3s ease-out;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Tabs */
.semester-tabs {
    margin-bottom: 1.5rem;
    overflow-x: auto;
    padding-bottom: 0.5rem;
}

#semester-buttons {
    display: flex;
    gap: 0.75rem;
}

.semester-btn {
    background: white;
    border: 1px solid var(--border-color);
    padding: 0.5rem 1rem;
    border-radius: var(--radius-pill);
    color: var(--text-muted);
    font-weight: 500;
    cursor: pointer;
    white-space: nowrap;
    transition: all 0.2s;
    font-size: 0.875rem;
}

.semester-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.semester-btn.active {
    background-color: var(--primary);
    color: white;
    border-color: var(--primary);
    box-shadow: var(--shadow-sm);
}

.view-mode-tabs {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 2rem;
}

.view-mode-btn {
    background: transparent;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-pill);
    color: var(--text-muted);
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.view-mode-btn:hover {
    background-color: var(--bg-body);
    color: var(--text-main);
}

.view-mode-btn.active {
    background-color: white;
    color: var(--primary);
    box-shadow: var(--shadow-sm);
}

/* Table */
.table-container {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    overflow: hidden;
    margin-bottom: 2rem;
}

table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.875rem;
}

th {
    background-color: var(--bg-body);
    color: var(--text-muted);
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.75rem;
    letter-spacing: 0.05em;
    padding: 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

td {
    padding: 1rem;
    color: var(--text-main);
    border-bottom: 1px solid var(--border-color);
    vertical-align: middle;
}

tbody tr:last-child td {
    border-bottom: none;
}

tbody tr:hover {
    background-color: var(--bg-body);
}

.predicted-score {
    color: var(--primary) !important;
    font-weight: 700;
    background-color: var(--primary-light);
    padding: 0.25rem 0.5rem;
    border-radius: var(--radius-sm);
}

/* Semester Summary */
.semester-summary {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

.summary-card h3 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: var(--text-main);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.summary-card h3::before {
    content: '';
    display: block;
    width: 4px;
    height: 24px;
    background-color: var(--primary);
    border-radius: 2px;
}

#semester-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
}

#semester-stats .stat-item {
    background-color: var(--bg-body);
    padding: 1rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}

#semester-stats .stat-label {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-bottom: 0.25rem;
    font-weight: 600;
}

#semester-stats .stat-value {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--text-main);
}

/* Modals */
.modal {
    display: none;
    position: fixed;
    z-index: 100;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(15, 23, 42, 0.4);
    /* Slate 900 with opacity */
    backdrop-filter: blur(4px);
    animation: fadeIn 0.2s ease-out;
}

.modal-content {
    background-color: var(--bg-card);
    margin: 5% auto;
    padding: 2rem;
    border-radius: var(--radius-xl);
    width: 90%;
    max-width: 480px;
    box-shadow: var(--shadow-xl);
    position: relative;
    border: 1px solid var(--border-color);
    animation: scaleIn 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

.close {
    position: absolute;
    right: 1.5rem;
    top: 1.5rem;
    font-size: 1.25rem;
    color: var(--text-muted);
    cursor: pointer;
    transition: color 0.2s;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
}

.close:hover {
    background-color: var(--bg-body);
    color: var(--danger);
}

.modal h3 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: var(--text-main);
}

/* Prediction Form */
.prediction-form {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.prediction-form input {
    flex: 1;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 1rem;
    background: white;
    color: var(--text-main);
    transition: all 0.2s;
}

.prediction-form input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-light);
}

.prediction-form button {
    background-color: var(--primary);
    color: white;
    border: none;
    padding: 0 1.5rem;
    border-radius: var(--radius-md);
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.prediction-form button:hover {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
}

.prediction-note {
    background-color: var(--bg-body);
    padding: 1rem;
    border-radius: var(--radius-md);
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-bottom: 1.5rem;
    border: 1px solid var(--border-color);
}

/* Grade Scale Table */
.grade-scale details {
    background-color: white;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.grade-scale summary {
    padding: 1rem;
    cursor: pointer;
    font-weight: 600;
    background-color: var(--bg-body);
    color: var(--text-main);
    list-style: none;
}

.grade-scale summary:hover {
    color: var(--primary);
}

.scale-table {
    width: 100%;
}

.scale-table th,
.scale-table td {
    padding: 0.75rem;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}

.scale-table tr:last-child td {
    border-bottom: none;
}

/* Toast Messages */
.message-toast {
    position: fixed;
    top: 2rem;
    right: 2rem;
    padding: 1rem 1.5rem;
    border-radius: var(--radius-md);
    font-weight: 500;
    z-index: 1000;
    box-shadow: var(--shadow-lg);
    animation: slideIn 0.3s ease-out;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    background: white;
    color: var(--text-main);
    border: 1px solid var(--border-color);
}

.message-toast.success {
    border-left: 4px solid var(--success);
}

.message-toast.error {
    border-left: 4px solid var(--danger);
}

.message-toast.info {
    border-left: 4px solid var(--info);
}

/* Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

@keyframes scaleIn {
    from {
        transform: scale(0.95);
        opacity: 0;
    }

    to {
        transform: scale(1);
        opacity: 1;
    }
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }

    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* Responsive */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }

    .control-panel {
        flex-direction: column;
        align-items: stretch;
        padding: 1.25rem;
    }

    .import-section {
        width: 100%;
    }

    .file-controls {
        flex-direction: column;
    }

    .file-controls button {
        width: 100%;
        justify-content: center;
    }

    .prediction-toggle-wrapper {
        justify-content: space-between;
        width: 100%;
        padding-top: 1rem;
        border-top: 1px solid var(--border-color);
    }

    .stats-grid {
        grid-template-columns: 1fr;
    }

    /* Mobile Table Optimization */
    .table-container {
        padding: 0;
        border-radius: 0;
        border-left: none;
        border-right: none;
    }

    table {
        font-size: 0.85rem;
    }

    th,
    td {
        padding: 0.75rem 0.5rem;
    }

    /* Hide unwanted columns on mobile */
    th:nth-child(1),
    td:nth-child(1),
    /* STT */
    th:nth-child(2),
    td:nth-child(2),
    /* Mã MH */
    th:nth-child(4),
    td:nth-child(4),
    /* Số tín chỉ */
    th:nth-child(5),
    td:nth-child(5),
    /* Điểm thi */
    th:nth-child(7),
    td:nth-child(7),
    /* Điểm TK (4) */
    th:nth-child(8),
    td:nth-child(8),
    /* Điểm TK (C) */
    th:nth-child(10),
    td:nth-child(10)

    /* Chi tiết */
        {
        display: none;
    }

    /* Adjust remaining columns */
    th:nth-child(3),
    td:nth-child(3) {
        width: 40%;
    }

    /* Tên môn */
    th:nth-child(6),
    td:nth-child(6) {
        width: 30%;
        text-align: center;
    }

    /* Điểm TK (10) */
    th:nth-child(9),
    td:nth-child(9) {
        width: 30%;
        text-align: center;
    }

    /* Kết quả */
}