/* Ultra-Secure MCQ Quiz Platform - Mobile-First Responsive Design */

:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --secondary-color: #64748b;
    --success-color: #10b981;
    --error-color: #ef4444;
    --warning-color: #f59e0b;
    --bg-color: #f8fafc;
    --text-color: #1e293b;
    --text-light: #64748b;
    --border-color: #e2e8f0;
    --card-bg: #ffffff;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 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);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Navigation */
.navbar {
    background: var(--card-bg);
    box-shadow: var(--shadow);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand a {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.nav-brand img {
    height: 40px;
    width: auto;
    max-width: 150px;
    object-fit: contain;
}

.nav-menu {
    list-style: none;
    display: flex;
    gap: 1.5rem;
    align-items: center;
}

.nav-menu a {
    color: var(--text-color);
    text-decoration: none;
    transition: color 0.3s;
}

.nav-menu a:hover {
    color: var(--primary-color);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-color);
    transition: 0.3s;
}

/* Main Content */
.main-content {
    flex: 1;
    padding: 2rem 0;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* Hero Section */
.hero-section {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 4rem 0;
    text-align: center;
}

.hero-content h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 3rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.1rem;
}

.hero-actions {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 0.5rem;
    font-size: 1rem;
    font-weight: 500;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.3s;
    text-align: center;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
}

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

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

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

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

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

.btn-block {
    display: block;
    width: 100%;
}

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.1rem;
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

/* Cards */
.exam-card, .category-card {
    background: var(--card-bg);
    border-radius: 0.75rem;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    transition: transform 0.3s, box-shadow 0.3s;
}

.exam-card:hover, .category-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.exam-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.exam-category {
    font-size: 0.875rem;
    color: var(--text-light);
}

.exam-badge {
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 600;
}

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

.exam-meta {
    display: flex;
    gap: 1rem;
    margin: 1rem 0;
    flex-wrap: wrap;
    font-size: 0.875rem;
    color: var(--text-light);
}

.exam-meta i {
    margin-right: 0.25rem;
}

/* Grids */
.exams-grid, .categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

/* Forms */
.auth-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 60vh;
    padding: 2rem 0;
}

.auth-card {
    background: var(--card-bg);
    border-radius: 0.75rem;
    padding: 2rem;
    box-shadow: var(--shadow-lg);
    width: 100%;
    max-width: 450px;
}

.auth-card h2 {
    margin-bottom: 1.5rem;
    text-align: center;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 1rem;
    transition: border-color 0.3s;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.auth-link {
    text-align: center;
    margin-top: 1.5rem;
}

.auth-link a {
    color: var(--primary-color);
    text-decoration: none;
}

/* Alerts */
.alert {
    padding: 1rem;
    border-radius: 0.5rem;
    margin-bottom: 1.5rem;
}

.alert-success {
    background: #d1fae5;
    color: #065f46;
    border: 1px solid #10b981;
}

.alert-error {
    background: #fee2e2;
    color: #991b1b;
    border: 1px solid #ef4444;
}

/* Dashboard */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: var(--card-bg);
    border-radius: 0.75rem;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 1rem;
}

.stat-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
}

.stat-content h3 {
    font-size: 2rem;
    margin-bottom: 0.25rem;
}

.dashboard-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
}

.dashboard-section {
    background: var(--card-bg);
    border-radius: 0.75rem;
    padding: 1.5rem;
    box-shadow: var(--shadow);
}

.dashboard-section h2 {
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Tables */
table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1rem;
}

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

table th {
    background: var(--bg-color);
    font-weight: 600;
}

/* Exam Interface */
.exam-container {
    max-width: 900px;
    margin: 0 auto;
}

.exam-header-bar {
    background: var(--card-bg);
    border-radius: 0.75rem;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.exam-timer {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--error-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.exam-progress {
    margin-bottom: 2rem;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--border-color);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 0.5rem;
}

.progress-fill {
    height: 100%;
    background: var(--primary-color);
    transition: width 0.3s;
}

.progress-text {
    text-align: center;
    color: var(--text-light);
}

.question-card {
    background: var(--card-bg);
    border-radius: 0.75rem;
    padding: 2rem;
    box-shadow: var(--shadow-lg);
    display: none;
}

.question-card.active {
    display: block;
}

.question-header h3 {
    margin-bottom: 1.5rem;
    color: var(--primary-color);
}

.question-text {
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
    line-height: 1.8;
}

.options-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.option-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    padding: 1rem;
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.3s;
}

.option-item:hover {
    border-color: var(--primary-color);
    background: #f0f7ff;
}

.option-item input[type="radio"] {
    margin-top: 0.25rem;
    cursor: pointer;
}

.option-item input[type="radio"]:checked + .option-label {
    color: var(--primary-color);
    font-weight: 600;
}

.option-label {
    font-weight: 600;
    min-width: 30px;
}

.option-text {
    flex: 1;
}

.exam-navigation {
    display: flex;
    justify-content: space-between;
    margin-top: 2rem;
    gap: 1rem;
}

/* Result Page */
.result-header {
    text-align: center;
    margin-bottom: 2rem;
}

.result-summary {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 2rem;
    margin-bottom: 2rem;
}

.score-circle {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    background: conic-gradient(var(--primary-color) 0deg, var(--primary-color) var(--percentage), var(--border-color) var(--percentage), var(--border-color) 360deg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto;
}

.score-inner {
    width: 160px;
    height: 160px;
    border-radius: 50%;
    background: var(--card-bg);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.score-value {
    font-size: 2.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

.result-stats {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
}

.stat-box {
    background: var(--bg-color);
    padding: 1rem;
    border-radius: 0.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.stat-box i {
    font-size: 2rem;
}

.text-success { color: var(--success-color); }
.text-error { color: var(--error-color); }
.text-warning { color: var(--warning-color); }

/* Review Questions */
.review-question {
    background: var(--card-bg);
    border-radius: 0.75rem;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
    border-left: 4px solid var(--border-color);
}

.review-question.correct {
    border-left-color: var(--success-color);
}

.review-question.incorrect {
    border-left-color: var(--error-color);
}

.review-question-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.option-review {
    padding: 0.75rem;
    margin: 0.5rem 0;
    border-radius: 0.5rem;
    border: 2px solid var(--border-color);
}

.option-review.correct-answer {
    background: #d1fae5;
    border-color: var(--success-color);
}

.option-review.user-wrong {
    background: #fee2e2;
    border-color: var(--error-color);
}

.explanation-section {
    margin-top: 1rem;
    padding: 1rem;
    background: var(--bg-color);
    border-radius: 0.5rem;
}

/* Leaderboard */
.leaderboard-table {
    background: var(--card-bg);
    border-radius: 0.75rem;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    overflow-x: auto;
}

.top-rank {
    background: var(--bg-color);
}

.rank-cell {
    font-weight: bold;
}

.gold { color: #fbbf24; }
.silver { color: #9ca3af; }
.bronze { color: #cd7f32; }

/* Footer */
.footer {
    background: var(--text-color);
    color: white;
    padding: 3rem 0 1rem;
    margin-top: 4rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3,
.footer-section h4 {
    margin-bottom: 1rem;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.3s;
}

.footer-section a:hover {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

/* Admin Styles */
.admin-stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.admin-stat-card {
    background: var(--card-bg);
    border-radius: 0.75rem;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 1rem;
}

.quick-links-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
}

.quick-link-card {
    background: var(--card-bg);
    border-radius: 0.75rem;
    padding: 2rem;
    box-shadow: var(--shadow);
    text-decoration: none;
    color: var(--text-color);
    transition: transform 0.3s, box-shadow 0.3s;
    text-align: center;
}

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

.quick-link-card i {
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.admin-table-container {
    background: var(--card-bg);
    border-radius: 0.75rem;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    overflow-x: auto;
}

.admin-table {
    width: 100%;
    border-collapse: collapse;
}

.badge {
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 600;
    display: inline-block;
}

.badge-success {
    background: #d1fae5;
    color: #065f46;
}

.badge-error {
    background: #fee2e2;
    color: #991b1b;
}

.badge-warning {
    background: #fef3c7;
    color: #92400e;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: var(--card-bg);
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--shadow-lg);
        padding: 2rem 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-toggle {
        display: flex;
    }

    .hero-content h1 {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .hero-stats {
        gap: 1.5rem;
    }

    .exams-grid,
    .categories-grid {
        grid-template-columns: 1fr;
    }

    .form-row {
        grid-template-columns: 1fr;
    }

    .result-summary {
        grid-template-columns: 1fr;
    }

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

    .exam-header-bar {
        flex-direction: column;
        align-items: flex-start;
    }

    .exam-navigation {
        flex-direction: column;
    }

    .exam-navigation .btn {
        width: 100%;
    }

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

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

@media (max-width: 480px) {
    .container {
        padding: 0 0.75rem;
    }

    .auth-card {
        padding: 1.5rem;
    }

    .question-card {
        padding: 1rem;
    }

    .score-circle {
        width: 150px;
        height: 150px;
    }

    .score-inner {
        width: 120px;
        height: 120px;
    }

    .score-value {
        font-size: 2rem;
    }
}

/* PWA Install Button */
.btn-install {
    background: var(--primary-color) !important;
    color: white !important;
    border: none !important;
    padding: 0.5rem 1rem !important;
    border-radius: 0.5rem !important;
    cursor: pointer !important;
    font-size: 0.9rem !important;
    font-family: inherit !important;
    transition: background 0.3s !important;
    display: inline-flex !important;
    align-items: center !important;
    gap: 0.5rem !important;
    text-decoration: none !important;
    white-space: nowrap !important;
}

.btn-install:hover {
    background: var(--primary-dark) !important;
}

.btn-install:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.nav-menu li .btn-install {
    margin: 0;
    padding: 0.5rem 1rem;
}

/* Utility Classes */
.text-center {
    text-align: center;
}

.text-muted {
    color: var(--text-light);
}

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }

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

.page-header h1 {
    margin-bottom: 0.5rem;
}

.section-title {
    margin-bottom: 1.5rem;
    text-align: center;
}

.empty-state {
    text-align: center;
    padding: 3rem;
    color: var(--text-light);
}

.empty-state i {
    font-size: 4rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}