/* ========================================
   MCQ Exam Management System - Custom CSS
   Modern, Customizable Design System
   ======================================== */

/* CSS Custom Properties (Variables) */
:root {
    /* Primary Colors */
    --color-primary: #10b981;
    --color-primary-dark: #059669;
    --color-primary-light: #34d399;
    --color-primary-lighter: #d1fae5;
    
    /* Secondary Colors */
    --color-secondary: #3b82f6;
    --color-secondary-dark: #2563eb;
    --color-secondary-light: #60a5fa;
    
    /* Neutral Colors */
    --color-white: #ffffff;
    --color-gray-50: #f9fafb;
    --color-gray-100: #f3f4f6;
    --color-gray-200: #e5e7eb;
    --color-gray-300: #d1d5db;
    --color-gray-400: #9ca3af;
    --color-gray-500: #6b7280;
    --color-gray-600: #4b5563;
    --color-gray-700: #374151;
    --color-gray-800: #1f2937;
    --color-gray-900: #111827;
    
    /* Status Colors */
    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-danger: #ef4444;
    --color-info: #3b82f6;
    
    /* Dark Mode Colors */
    --color-dark-bg: #0f172a;
    --color-dark-surface: #1e293b;
    --color-dark-border: #334155;
    --color-dark-text: #e2e8f0;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    
    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* ========================================
   Reset & Base Styles
   ======================================== */

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-gray-800);
    background-color: var(--color-gray-50);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ========================================
   Container & Layout
   ======================================== */

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.container-wide {
    max-width: 1400px;
}

.container-narrow {
    max-width: 800px;
}

/* ========================================
   Navigation
   ======================================== */

.navbar {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    box-shadow: var(--shadow-md);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: var(--spacing-md) 0;
}

.navbar-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.navbar-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    text-decoration: none;
    color: var(--color-white);
}

.navbar-logo {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-full);
    background: rgba(255, 255, 255, 0.2);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-xl);
    font-weight: 700;
}

.navbar-title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    margin: 0;
}

.navbar-subtitle {
    font-size: var(--font-size-xs);
    opacity: 0.9;
    margin: 0;
}

.navbar-nav {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    list-style: none;
}

.nav-btn {
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-lg);
    background: transparent;
    border: none;
    color: var(--color-white);
    font-size: var(--font-size-sm);
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-base);
    text-decoration: none;
    display: inline-block;
}

.nav-btn:hover {
    background: rgba(255, 255, 255, 0.15);
}

.nav-btn.active {
    background: rgba(255, 255, 255, 0.2);
    font-weight: 600;
}

/* ========================================
   Cards
   ======================================== */

.card {
    background: var(--color-white);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
}

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

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
}

.card-title {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    color: var(--color-gray-800);
    margin: 0 0 var(--spacing-sm) 0;
}

.card-subtitle {
    font-size: var(--font-size-base);
    color: var(--color-gray-600);
    margin: 0;
}

.card-icon {
    font-size: 4rem;
}

.card-body {
    margin-bottom: var(--spacing-lg);
}

.card-footer {
    border-top: 1px solid var(--color-gray-200);
    padding-top: var(--spacing-lg);
}

/* ========================================
   Buttons
   ======================================== */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    border-radius: var(--radius-xl);
    font-size: var(--font-size-base);
    font-weight: 600;
    text-decoration: none;
    border: none;
    cursor: pointer;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn:active {
    transform: translateY(0);
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: var(--color-white);
}

.btn-secondary {
    background: linear-gradient(135deg, var(--color-secondary) 0%, var(--color-secondary-dark) 100%);
    color: var(--color-white);
}

.btn-success {
    background: linear-gradient(135deg, var(--color-success) 0%, #059669 100%);
    color: var(--color-white);
}

.btn-danger {
    background: linear-gradient(135deg, var(--color-danger) 0%, #dc2626 100%);
    color: var(--color-white);
}

.btn-warning {
    background: linear-gradient(135deg, var(--color-warning) 0%, #d97706 100%);
    color: var(--color-white);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--color-primary);
    color: var(--color-primary);
}

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

.btn-lg {
    padding: var(--spacing-lg) var(--spacing-2xl);
    font-size: var(--font-size-lg);
}

.btn-sm {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-sm);
}

.btn-block {
    width: 100%;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn:disabled:hover {
    transform: none;
    box-shadow: var(--shadow-md);
}

/* ========================================
   Form Elements
   ======================================== */

.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-label {
    display: block;
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-gray-700);
    margin-bottom: var(--spacing-sm);
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: var(--spacing-md);
    border: 2px solid var(--color-gray-200);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-base);
    font-family: var(--font-sans);
    transition: all var(--transition-base);
    background: var(--color-white);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.1);
}

.form-textarea {
    min-height: 120px;
    resize: vertical;
}

.form-checkbox,
.form-radio {
    width: 18px;
    height: 18px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    accent-color: var(--color-primary);
}

.form-radio {
    border-radius: var(--radius-full);
}

/* ========================================
   Grid System
   ======================================== */

.grid {
    display: grid;
    gap: var(--spacing-lg);
}

.grid-cols-1 { grid-template-columns: repeat(1, 1fr); }
.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 768px) {
    .grid-cols-2,
    .grid-cols-3,
    .grid-cols-4 {
        grid-template-columns: 1fr;
    }
}

/* ========================================
   Badges
   ======================================== */

.badge {
    display: inline-flex;
    align-items: center;
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-full);
    font-size: var(--font-size-xs);
    font-weight: 600;
    white-space: nowrap;
}

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

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

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

.badge-warning {
    background: var(--color-warning);
    color: var(--color-white);
}

.badge-info {
    background: var(--color-info);
    color: var(--color-white);
}

/* ========================================
   Utilities
   ======================================== */

.hidden { display: none !important; }
.visible { display: block !important; }

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

.flex { display: flex; }
.flex-col { flex-direction: column; }
.flex-row { flex-direction: row; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-sm { gap: var(--spacing-sm); }
.gap-md { gap: var(--spacing-md); }
.gap-lg { gap: var(--spacing-lg); }

.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }

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

/* ========================================
   Animations
   ======================================== */

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

.fade-in {
    animation: fadeIn var(--transition-slow) ease-out;
}

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

.slide-in {
    animation: slideIn var(--transition-base) ease-out;
}

/* ========================================
   Course & Semester Cards
   ======================================== */

.course-card {
    background: var(--color-white);
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
    cursor: pointer;
    border: 2px solid transparent;
}

.course-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-xl);
    border-color: var(--color-primary);
}

.course-icon {
    width: 80px;
    height: 80px;
    border-radius: var(--radius-2xl);
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    margin-bottom: var(--spacing-lg);
}

.course-title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-gray-800);
    margin-bottom: var(--spacing-sm);
}

.course-meta {
    color: var(--color-gray-600);
    font-size: var(--font-size-sm);
}

.semester-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.semester-card {
    background: var(--color-white);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
    cursor: pointer;
    text-align: center;
}

.semester-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    background: linear-gradient(135deg, var(--color-primary-lighter) 0%, var(--color-white) 100%);
}

.semester-number {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
}

.semester-info {
    font-size: var(--font-size-sm);
    color: var(--color-gray-600);
}

/* ========================================
   Test History
   ======================================== */

.history-item {
    background: var(--color-white);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    border-left: 4px solid var(--color-primary);
    margin-bottom: var(--spacing-md);
    transition: all var(--transition-base);
}

.history-item:hover {
    box-shadow: var(--shadow-md);
    transform: translateX(4px);
}

.history-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-sm);
}

.history-score {
    font-size: var(--font-size-2xl);
    font-weight: 700;
}

.score-excellent { color: var(--color-success); }
.score-good { color: var(--color-secondary); }
.score-fair { color: var(--color-warning); }
.score-poor { color: var(--color-danger); }

/* ========================================
   Dark Mode
   ======================================== */

body.dark-mode {
    background: var(--color-dark-bg);
    color: var(--color-dark-text);
}

.dark-mode .navbar {
    background: linear-gradient(135deg, var(--color-dark-surface) 0%, var(--color-dark-border) 100%);
}

/* Cards and Surfaces */
.dark-mode .card,
.dark-mode .course-card,
.dark-mode .semester-card,
.dark-mode .history-item {
    background: var(--color-dark-surface);
    border-color: var(--color-dark-border);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
}

.dark-mode .card-footer {
    border-top-color: var(--color-dark-border);
}

/* Text Colors */
.dark-mode .card-title,
.dark-mode .course-title,
.dark-mode .semester-card h3,
.dark-mode h1,
.dark-mode h2,
.dark-mode h3,
.dark-mode h4,
.dark-mode h5,
.dark-mode h6 {
    color: var(--color-dark-text);
}

.dark-mode .card-subtitle,
.dark-mode .course-meta,
.dark-mode .semester-info,
.dark-mode p,
.dark-mode span,
.dark-mode div {
    color: var(--color-gray-400);
}

/* Form Elements */
.dark-mode .form-input,
.dark-mode .form-select,
.dark-mode .form-textarea {
    background: var(--color-dark-bg);
    border-color: var(--color-dark-border);
    color: var(--color-dark-text);
}

.dark-mode .form-label {
    color: var(--color-gray-300);
}

.dark-mode .form-input::placeholder,
.dark-mode .form-textarea::placeholder {
    color: var(--color-gray-500);
}

/* Buttons - maintain gradients in dark mode */
.dark-mode .btn-outline {
    border-color: var(--color-primary-light);
    color: var(--color-primary-light);
}

.dark-mode .btn-outline:hover {
    background: var(--color-primary-light);
    color: var(--color-dark-bg);
}

/* Semester & Course Cards Hover */
.dark-mode .semester-card:hover {
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.2) 0%, var(--color-dark-surface) 100%);
}

.dark-mode .course-card:hover {
    border-color: var(--color-primary-light);
    background: var(--color-dark-surface);
}

/* Question Cards and Options */
.dark-mode .question-card {
    background: var(--color-dark-surface);
    border-left-color: var(--color-gray-600);
    color: var(--color-dark-text);
}

.dark-mode .question-card.answered {
    border-left-color: var(--color-primary);
}

.dark-mode .option-label {
    background: var(--color-dark-bg);
    border-color: var(--color-dark-border);
    color: var(--color-dark-text);
}

.dark-mode .option-label:hover {
    border-color: var(--color-primary);
    background: rgba(16, 185, 129, 0.15);
}

.dark-mode .option-label.selected {
    border-color: var(--color-primary);
    background: rgba(16, 185, 129, 0.2);
}

.dark-mode .option-text {
    color: var(--color-dark-text);
}

/* Correct/Incorrect Answers */
.dark-mode .option-label.correct {
    background: rgba(16, 185, 129, 0.2);
    border-color: var(--color-success);
}

.dark-mode .option-label.incorrect {
    background: rgba(239, 68, 68, 0.2);
    border-color: var(--color-danger);
}

/* Tables */
.dark-mode table {
    color: var(--color-dark-text);
}

.dark-mode th {
    background: var(--color-dark-border);
    color: var(--color-dark-text);
    border-color: var(--color-dark-border);
}

.dark-mode td {
    background: var(--color-dark-surface);
    color: var(--color-gray-300);
    border-color: var(--color-dark-border);
}

.dark-mode tr:hover td {
    background: rgba(16, 185, 129, 0.1);
}

/* Badges in dark mode - keep visible */
.dark-mode .badge {
    color: var(--color-white);
}

/* History Items */
.dark-mode .history-header {
    color: var(--color-dark-text);
}

.dark-mode .history-score {
    color: var(--color-dark-text);
}

/* Stats Cards */
.dark-mode .card > div[style*="text-align: center"] {
    background: rgba(16, 185, 129, 0.1) !important;
}

/* Links */
.dark-mode a:not(.btn):not(.nav-btn):not(.navbar-brand) {
    color: var(--color-primary-light);
}

.dark-mode a:not(.btn):not(.nav-btn):not(.navbar-brand):hover {
    color: var(--color-primary);
}

/* Inline text colors that need fixing */
.dark-mode [style*="color: var(--color-gray-800)"],
.dark-mode [style*="color: var(--color-gray-700)"],
.dark-mode [style*="color: var(--color-gray-600)"] {
    color: var(--color-gray-300) !important;
}

/* Empty states */
.dark-mode [style*="color: var(--color-gray-500)"] {
    color: var(--color-gray-400) !important;
}

/* Book cards checkbox area */
.dark-mode .book-checkbox + label {
    color: var(--color-dark-text);
}

.dark-mode .book-checkbox + label > div {
    color: var(--color-gray-300);
}

/* Score display sticky sidebar */
.dark-mode .score-display {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: var(--color-white);
}

/* Print preview */
.dark-mode #paperPreview {
    background: var(--color-dark-surface);
    color: var(--color-dark-text);
}

.dark-mode .answer-sheet {
    background: var(--color-dark-bg);
}

.dark-mode .answer-item {
    background: var(--color-dark-surface);
    color: var(--color-dark-text);
    border-color: var(--color-dark-border);
}

/* ========================================
   Scrollbar
   ======================================== */

::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--color-gray-100);
    border-radius: var(--radius-sm);
}

::-webkit-scrollbar-thumb {
    background: var(--color-gray-400);
    border-radius: var(--radius-sm);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-gray-500);
}

.dark-mode ::-webkit-scrollbar-track {
    background: var(--color-dark-bg);
}

.dark-mode ::-webkit-scrollbar-thumb {
    background: var(--color-dark-border);
}

/* ========================================
   Responsive Design
   ======================================== */

@media (max-width: 768px) {
    .navbar-nav {
        gap: 0;
    }
    
    .nav-btn {
        font-size: var(--font-size-xs);
        padding: var(--spacing-sm);
    }
    
    .container {
        padding: 0 var(--spacing-md);
    }
    
    .card {
        padding: var(--spacing-lg);
    }
    
    .card-title {
        font-size: var(--font-size-2xl);
    }
}

/* ========================================
   Print Styles
   ======================================== */

@media print {
    .no-print {
        display: none !important;
    }
    
    body {
        background: var(--color-white);
        color: #000;
    }
    
    .card {
        box-shadow: none;
        border: 1px solid var(--color-gray-300);
    }
}