/**
 * ExamHub Pro - Main Stylesheet
 * Modern, responsive design for the exam management system
 */

/* ============================================
   CSS Variables & Theme
   ============================================ */
:root {
    /* Primary Colors */
    --primary-blue: #4A90E2;
    --primary-purple: #7B68EE;
    --primary-green: #4CAF50;

    /* Subject-specific Colors */
    --biology-green: #66BB6A;
    --maths-blue: #5C6BC0;
    --physics-orange: #FF7043;
    --chemistry-purple: #AB47BC;

    /* UI Colors */
    --success: #4CAF50;
    --warning: #FFC107;
    --danger: #F44336;
    --info: #2196F3;

    /* Neutral Colors */
    --dark: #2C3E50;
    --gray: #95A5A6;
    --light: #ECF0F1;
    --white: #FFFFFF;

    /* Sidebar */
    --sidebar-width: 260px;
    --sidebar-bg: #2C3E50;
    --sidebar-text: #ECF0F1;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;

    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;

    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px rgba(0,0,0,0.1);

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

/* ============================================
   Reset & Base Styles
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--dark);
    background-color: #f8f9fa;
}

a {
    text-decoration: none;
    color: var(--primary-blue);
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--primary-purple);
}

img {
    max-width: 100%;
    height: auto;
}

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

/* Sidebar */
.sidebar {
    width: var(--sidebar-width);
    background: var(--sidebar-bg);
    color: var(--sidebar-text);
    position: fixed;
    height: 100vh;
    overflow-y: auto;
    box-shadow: var(--shadow-lg);
    z-index: 1000;
}

.logo-section {
    padding: var(--spacing-lg);
    text-align: center;
    border-bottom: 1px solid rgba(255,255,255,0.1);
}

.logo-section img {
    max-width: 60px;
    margin-bottom: var(--spacing-sm);
}

.logo-section h3 {
    color: var(--white);
    font-size: 1.5rem;
    font-weight: 600;
}

/* Navigation Menu */
.nav-menu {
    padding: var(--spacing-md) 0;
}

.nav-item {
    display: flex;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-lg);
    color: var(--sidebar-text);
    transition: all var(--transition-fast);
    position: relative;
}

.nav-item:hover {
    background: rgba(255,255,255,0.1);
    color: var(--white);
}

.nav-item.active {
    background: rgba(74, 144, 226, 0.2);
    color: var(--white);
    border-left: 4px solid var(--primary-blue);
}

.nav-item i {
    margin-right: var(--spacing-sm);
    font-size: 1.2rem;
}

.nav-item .badge {
    margin-left: auto;
    background: var(--danger);
    color: var(--white);
    padding: 0.2rem 0.5rem;
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 600;
}

/* Main Content Area */
.main-content {
    margin-left: var(--sidebar-width);
    flex: 1;
    display: flex;
    flex-direction: column;
}

/* Top Bar */
.top-bar {
    background: var(--white);
    padding: var(--spacing-md) var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 999;
}

.search-bar {
    display: flex;
    align-items: center;
    background: #f8f9fa;
    border-radius: var(--radius-lg);
    padding: var(--spacing-sm) var(--spacing-md);
    width: 400px;
}

.search-bar i {
    color: var(--gray);
    margin-right: var(--spacing-sm);
}

.search-bar input {
    border: none;
    background: transparent;
    outline: none;
    width: 100%;
    font-size: 0.95rem;
}

.user-menu {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.notification-btn {
    background: none;
    border: none;
    position: relative;
    cursor: pointer;
    font-size: 1.3rem;
    color: var(--dark);
}

.notification-badge {
    position: absolute;
    top: -5px;
    right: -5px;
    background: var(--danger);
    color: var(--white);
    border-radius: 50%;
    width: 18px;
    height: 18px;
    font-size: 0.7rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

.user-profile {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    cursor: pointer;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    transition: background var(--transition-fast);
}

.user-profile:hover {
    background: #f8f9fa;
}

.user-profile img {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    object-fit: cover;
}

/* Page Content */
.page-content {
    padding: var(--spacing-lg);
    flex: 1;
}

/* ============================================
   Cards & Components
   ============================================ */
.card {
    background: var(--white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
}

.card-header {
    border-bottom: 1px solid #e9ecef;
    padding-bottom: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.card-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--dark);
}

/* Stats Cards */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.stat-card {
    background: var(--white);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: transform var(--transition-fast);
}

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

.stat-content h3 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 0.25rem;
}

.stat-content p {
    color: var(--gray);
    font-size: 0.9rem;
}

.stat-icon {
    width: 60px;
    height: 60px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
}

.stat-icon.blue {
    background: rgba(74, 144, 226, 0.1);
    color: var(--primary-blue);
}

.stat-icon.green {
    background: rgba(76, 175, 80, 0.1);
    color: var(--success);
}

.stat-icon.orange {
    background: rgba(255, 112, 67, 0.1);
    color: var(--physics-orange);
}

.stat-icon.purple {
    background: rgba(123, 104, 238, 0.1);
    color: var(--primary-purple);
}

/* ============================================
   Buttons
   ============================================ */
.btn {
    display: inline-block;
    padding: 0.6rem 1.5rem;
    border: none;
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
    text-align: center;
}

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

.btn-primary:hover {
    background: #3a7bc8;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

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

.btn-success:hover {
    background: #45a049;
}

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

.btn-danger:hover {
    background: #da190b;
}

.btn-secondary {
    background: var(--gray);
    color: var(--white);
}

.btn-secondary:hover {
    background: #7f8c8d;
}

/* ============================================
   Forms
   ============================================ */
.form-group {
    margin-bottom: var(--spacing-md);
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 500;
    color: var(--dark);
}

.form-control {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid #ddd;
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    transition: border-color var(--transition-fast);
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-blue);
    box-shadow: 0 0 0 3px rgba(74, 144, 226, 0.1);
}

/* ============================================
   Tables
   ============================================ */
.table {
    width: 100%;
    border-collapse: collapse;
}

.table th,
.table td {
    padding: var(--spacing-sm) var(--spacing-md);
    text-align: left;
    border-bottom: 1px solid #e9ecef;
}

.table th {
    background: #f8f9fa;
    font-weight: 600;
    color: var(--dark);
}

.table tbody tr:hover {
    background: #f8f9fa;
}

/* ============================================
   Utilities
   ============================================ */
.text-center {
    text-align: center;
}

.text-right {
    text-align: right;
}

.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }

.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }

.p-1 { padding: var(--spacing-sm); }
.p-2 { padding: var(--spacing-md); }
.p-3 { padding: var(--spacing-lg); }

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 768px) {
    .sidebar {
        transform: translateX(-100%);
        transition: transform var(--transition-normal);
    }

    .sidebar.active {
        transform: translateX(0);
    }

    .main-content {
        margin-left: 0;
    }

    .search-bar {
        width: 100%;
    }

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