:root {
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --success-gradient: linear-gradient(135deg, #43e97b 0%, #38f9d7 100%);
    --warning-gradient: linear-gradient(135deg, #f6d365 0%, #fda085 100%);
    --danger-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --info-gradient: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
}

body {
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
}

.navbar.bg-gradient {
    background: var(--primary-gradient) !important;
    box-shadow: 0 4px 20px rgba(102, 126, 234, 0.4);
}

.navbar-brand {
    font-size: 1.3rem;
    letter-spacing: 0.5px;
}

.main-content {
    min-height: calc(100vh - 180px);
}

.card {
    border: none;
    border-radius: 16px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.08);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.12);
}

.card-header {
    border-radius: 16px 16px 0 0 !important;
}

.btn {
    border-radius: 10px;
    padding: 8px 20px;
    font-weight: 500;
    transition: all 0.2s ease;
}

.btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.btn-primary {
    background: var(--primary-gradient);
    border: none;
}

.btn-success {
    background: var(--success-gradient);
    border: none;
    color: #1a1a2e;
}

.btn-danger {
    background: var(--danger-gradient);
    border: none;
}

.btn-warning {
    background: var(--warning-gradient);
    border: none;
}

.btn-info {
    background: var(--info-gradient);
    border: none;
}

.btn-outline-light:hover {
    background: rgba(255, 255, 255, 0.2);
    border-color: rgba(255, 255, 255, 0.5);
}

.form-control {
    border-radius: 10px;
    border: 2px solid #e8ecf1;
    padding: 10px 16px;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.form-control:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.15);
}

.form-check-input:checked {
    background-color: #667eea;
    border-color: #667eea;
}

.login-container {
    min-height: 85vh;
}

.login-card {
    border-radius: 20px;
    overflow: hidden;
}

.login-card .card-header {
    background: var(--primary-gradient);
    padding: 2rem 1.5rem;
}

.stat-card {
    border-radius: 16px;
    overflow: hidden;
    position: relative;
}

.stat-card .stat-icon {
    font-size: 2.5rem;
    opacity: 0.2;
    position: absolute;
    right: 15px;
    bottom: 15px;
}

.stat-card .stat-value {
    font-size: 2rem;
    font-weight: 700;
}

.stat-card .stat-label {
    font-size: 0.85rem;
    opacity: 0.85;
}

.quiz-card {
    border-left: 4px solid #667eea;
    border-radius: 12px;
}

.quiz-card .card-title {
    color: #2d3748;
    font-weight: 600;
}

.option-card {
    border: 2px solid #e8ecf1;
    border-radius: 12px;
    padding: 12px 16px;
    cursor: pointer;
    transition: all 0.2s ease;
}

.option-card:hover {
    border-color: #667eea;
    background: rgba(102, 126, 234, 0.05);
}

.option-card.selected {
    border-color: #667eea;
    background: rgba(102, 126, 234, 0.1);
}

.rank-badge {
    width: 40px;
    height: 40px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    font-weight: 700;
    font-size: 1.1rem;
}

.rank-1 {
    background: linear-gradient(135deg, #ffd700, #ffed4e);
    color: #7a6200;
    box-shadow: 0 2px 8px rgba(255, 215, 0, 0.4);
}

.rank-2 {
    background: linear-gradient(135deg, #c0c0c0, #e8e8e8);
    color: #555;
    box-shadow: 0 2px 8px rgba(192, 192, 192, 0.4);
}

.rank-3 {
    background: linear-gradient(135deg, #cd7f32, #e8a65a);
    color: #5a3500;
    box-shadow: 0 2px 8px rgba(205, 127, 50, 0.4);
}

.answer-score-badge {
    display: inline-block;
    padding: 4px 12px;
    border-radius: 20px;
    font-weight: 600;
    font-size: 0.85rem;
}

.score-high {
    background: #d1e7dd;
    color: #0f5132;
}

.score-low {
    background: #f8d7da;
    color: #842029;
}

.score-zero {
    background: #e2e3e5;
    color: #41464b;
}

.leaderboard-row {
    transition: all 0.2s ease;
}

.leaderboard-row:hover {
    background: rgba(102, 126, 234, 0.05) !important;
}

.leaderboard-row.current-user {
    background: rgba(102, 126, 234, 0.08) !important;
    border-left: 3px solid #667eea;
}

.progress-thin {
    height: 6px;
    border-radius: 3px;
}

.table > :not(caption) > * > * {
    padding: 12px 16px;
}

.trophy-icon {
    font-size: 1.3rem;
}

.detail-table td, .detail-table th {
    vertical-align: middle;
}

.question-list-item {
    border-radius: 10px;
    border: 1px solid #e8ecf1;
    padding: 12px 16px;
    margin-bottom: 8px;
    transition: all 0.2s ease;
}

.question-list-item:hover {
    background: rgba(102, 126, 234, 0.03);
    border-color: #667eea;
}

.footer {
    background: rgba(255, 255, 255, 0.5);
    backdrop-filter: blur(10px);
}

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

.animate-in {
    animation: fadeInUp 0.4s ease forwards;
}

.animate-in-delay-1 { animation-delay: 0.1s; }
.animate-in-delay-2 { animation-delay: 0.2s; }
.animate-in-delay-3 { animation-delay: 0.3s; }