/* CSS Variables & Tokens */
:root {
    /* Colors - Light Theme */
    --bg-main: #f8fafc;
    --bg-sidebar: #ffffff;
    --bg-card: rgba(255, 255, 255, 0.7);
    --text-primary: #0f172a;
    --text-secondary: #64748b;
    --border-color: rgba(226, 232, 240, 0.8);
    --accent-color: #3b82f6;
    --accent-hover: #2563eb;
    --glass-border: rgba(255, 255, 255, 0.5);
    
    /* Chart Colors */
    --chart-math: #ef4444;
    --chart-lang: #3b82f6;
    --chart-sci: #10b981;
    --chart-eng: #f59e0b;

    /* Shadows */
    --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);
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
}

[data-theme="dark"] {
    /* Colors - Dark Theme */
    --bg-main: #0b0f19;
    --bg-sidebar: #111827;
    --bg-card: rgba(31, 41, 55, 0.6);
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --border-color: rgba(51, 65, 85, 0.5);
    --accent-color: #3b82f6;
    --accent-hover: #60a5fa;
    --glass-border: rgba(255, 255, 255, 0.05);
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.4), 0 2px 4px -2px rgb(0 0 0 / 0.4);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.5), 0 4px 6px -4px rgb(0 0 0 / 0.5);
}

/* Reset & Base */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

body {
    background-color: var(--bg-main);
    color: var(--text-primary);
    transition: background-color var(--transition-normal), color var(--transition-normal);
    overflow-x: hidden;
}

/* Layout */
.app-container {
    display: flex;
    min-height: 100vh;
}

/* Sidebar */
.sidebar {
    width: 280px;
    background-color: var(--bg-sidebar);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
    transition: all var(--transition-normal);
    z-index: 10;
}

.sidebar-header {
    margin-bottom: 2rem;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--accent-color);
}

.logo i {
    font-size: 1.5rem;
    background: linear-gradient(135deg, #3b82f6, #8b5cf6);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.sidebar-nav {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    flex-grow: 1;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.875rem 1rem;
    text-decoration: none;
    color: var(--text-secondary);
    border-radius: 0.75rem;
    font-weight: 500;
    transition: all var(--transition-fast);
}

.nav-item:hover {
    background-color: rgba(59, 130, 246, 0.1);
    color: var(--accent-color);
    transform: translateX(4px);
}

.nav-item.active {
    background-color: var(--accent-color);
    color: white;
}

.sidebar-footer {
    margin-top: auto;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.theme-toggle {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.875rem 1rem;
    cursor: pointer;
    color: var(--text-secondary);
    border-radius: 0.75rem;
    transition: all var(--transition-fast);
    font-weight: 500;
}

.theme-toggle:hover {
    background-color: rgba(59, 130, 246, 0.1);
    color: var(--accent-color);
}

/* Main Content */
.main-content {
    flex-grow: 1;
    padding: 2rem;
    overflow-y: auto;
    height: 100vh;
}

/* Header */
.top-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 2rem;
    animation: slideDown 0.5s ease;
}

.header-titles h1 {
    font-size: 1.875rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
    background: linear-gradient(to right, var(--text-primary), var(--text-secondary));
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.stat-badge {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    background-color: var(--bg-card);
    padding: 0.75rem 1.25rem;
    border-radius: 1rem;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}

.stat-badge i {
    color: var(--accent-color);
    font-size: 1.25rem;
}

.stat-badge span:not(.stat-label) {
    font-weight: 700;
    font-size: 1.125rem;
}

.stat-label {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

/* Dashboard Grid */
.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
}

/* Glass Effect */
.glass {
    background: var(--bg-card);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-radius: 1.25rem;
    box-shadow: var(--shadow-md);
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.glass:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

/* KPI Cards */
.kpi-card {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1.5rem;
    animation: fadeIn 0.5s ease backwards;
}

.kpi-card:nth-child(1) { animation-delay: 0.1s; }
.kpi-card:nth-child(2) { animation-delay: 0.2s; }
.kpi-card:nth-child(3) { animation-delay: 0.3s; }
.kpi-card:nth-child(4) { animation-delay: 0.4s; }

.kpi-icon {
    width: 3.5rem;
    height: 3.5rem;
    border-radius: 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    flex-shrink: 0;
}

.kpi-icon.math { background: rgba(239, 68, 68, 0.1); color: var(--chart-math); }
.kpi-icon.language { background: rgba(59, 130, 246, 0.1); color: var(--chart-lang); }
.kpi-icon.science { background: rgba(16, 185, 129, 0.1); color: var(--chart-sci); }
.kpi-icon.english { background: rgba(245, 158, 11, 0.1); color: var(--chart-eng); }

.kpi-info {
    display: flex;
    flex-direction: column;
}

.kpi-title {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.kpi-value {
    font-size: 1.5rem;
    font-weight: 700;
    margin-top: 0.25rem;
}

.kpi-trend {
    font-size: 0.75rem;
    margin-top: 0.25rem;
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.kpi-trend.positive { color: #10b981; }
.kpi-trend.negative { color: #ef4444; }

/* Charts */
.chart-card {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    animation: fadeIn 0.6s ease backwards;
}

.main-chart {
    grid-column: span 4;
    animation-delay: 0.5s;
}

.secondary-chart {
    grid-column: span 2;
    animation-delay: 0.6s;
}

.chart-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.chart-header h3 {
    font-size: 1.125rem;
    font-weight: 600;
}

.glass-select {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    outline: none;
    font-family: inherit;
    cursor: pointer;
}

.chart-container {
    position: relative;
    height: 300px;
    width: 100%;
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes slideDown {
    from { opacity: 0; transform: translateY(-20px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Responsive */
@media (max-width: 1200px) {
    .dashboard-grid { grid-template-columns: repeat(2, 1fr); }
    .top10-grid { grid-template-columns: repeat(2, 1fr); }
    .secondary-chart { grid-column: span 2; }
}

@media (max-width: 768px) {
    .app-container { flex-direction: column; }
    .sidebar { width: 100%; height: auto; border-right: none; border-bottom: 1px solid var(--border-color); flex-direction: row; flex-wrap: wrap; justify-content: space-between; align-items: center; padding: 1rem; }
    .sidebar-header { margin-bottom: 0; }
    .sidebar-nav { flex-direction: row; gap: 1rem; overflow-x: auto; padding-bottom: 0.5rem; margin-top: 1rem; width: 100%; }
    .sidebar-footer { padding-top: 0; border-top: none; }
    .main-content { padding: 1rem; height: auto; overflow: visible; }
    .dashboard-grid { grid-template-columns: 1fr; }
    .top10-grid { grid-template-columns: 1fr; }
    .main-chart, .secondary-chart { grid-column: span 1; }
    .top-header { flex-direction: column; gap: 1rem; }
}

/* Custom Grid for Top 10 */
.top10-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
}

/* Chart Expansion Modal */
.chart-modal {
    position: fixed;
    z-index: 9999;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    background-color: rgba(15, 23, 42, 0.9);
    backdrop-filter: blur(8px);
    display: flex;
    justify-content: center;
    align-items: center;
    animation: fadeIn 0.3s ease;
}

.modal-content {
    margin: auto;
    display: block;
    max-width: 90%;
    max-height: 90%;
    border-radius: 10px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.5);
    background: var(--bg-card);
    padding: 20px;
}

.close-modal {
    position: absolute;
    top: 20px;
    right: 35px;
    color: #f1f1f1;
    font-size: 40px;
    font-weight: bold;
    transition: 0.3s;
    cursor: pointer;
    z-index: 10000;
}

.close-modal:hover,
.close-modal:focus {
    color: var(--accent-color);
    text-decoration: none;
    cursor: pointer;
}

.clickable-chart {
    cursor: pointer;
    transition: opacity 0.2s;
}

.clickable-chart:hover {
    opacity: 0.8;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}