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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: #333;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

.card {
    background: white;
    border-radius: 16px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.1);
    padding: 30px;
    margin-bottom: 20px;
}

.header {
    background: white;
    border-radius: 16px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.08);
    padding: 20px 30px;
    margin-bottom: 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header h1 {
    color: #667eea;
    font-size: 28px;
    font-weight: 700;
}

.nav-links a {
    color: #667eea;
    text-decoration: none;
    margin-left: 20px;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: #764ba2;
}

.btn {
    padding: 12px 30px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    transition: all 0.3s;
    text-decoration: none;
    display: inline-block;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 20px rgba(102, 126, 234, 0.4);
}

.btn-success {
    background: linear-gradient(135deg, #11998e 0%, #38ef7d 100%);
    color: white;
}

.btn-danger {
    background: linear-gradient(135deg, #eb3349 0%, #f45c43 100%);
    color: white;
}

.btn-secondary {
    background: #e0e0e0;
    color: #333;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: #555;
}

.form-control {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 16px;
    transition: border-color 0.3s;
}

.form-control:focus {
    outline: none;
    border-color: #667eea;
}

textarea.form-control {
    min-height: 100px;
    resize: vertical;
}

.question-card {
    background: #f8f9fa;
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 20px;
    border-left: 4px solid #667eea;
}

.question-type {
    display: inline-block;
    background: #667eea;
    color: white;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 12px;
    margin-bottom: 10px;
}

.question-text {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 15px;
    color: #333;
}

.options-list {
    list-style: none;
}

.options-list li {
    padding: 12px 16px;
    background: white;
    border-radius: 8px;
    margin-bottom: 10px;
    cursor: pointer;
    transition: all 0.3s;
    border: 2px solid transparent;
}

.options-list li:hover {
    background: #f0f0f0;
}

.options-list li.selected {
    border-color: #667eea;
    background: #e8eaf6;
}

.options-list li.correct {
    border-color: #38ef7d;
    background: #e8f5e9;
}

.options-list li.wrong {
    border-color: #f45c43;
    background: #ffebee;
}

.explanation {
    background: #fff3cd;
    border-left: 4px solid #ffc107;
    padding: 15px;
    border-radius: 8px;
    margin-top: 15px;
    display: none;
}

.explanation.show {
    display: block;
}

.explanation h4 {
    color: #856404;
    margin-bottom: 8px;
}

.timer {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: white;
    padding: 15px 25px;
    border-radius: 10px;
    font-size: 24px;
    font-weight: 700;
    text-align: center;
    margin-bottom: 20px;
}

.timer.warning {
    background: linear-gradient(135deg, #ff6b6b 0%, #ee5a24 100%);
    animation: pulse 1s infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.7; }
}

.progress-bar {
    background: #e0e0e0;
    border-radius: 10px;
    height: 8px;
    overflow: hidden;
    margin-bottom: 20px;
}

.progress-fill {
    background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
    height: 100%;
    transition: width 0.3s;
}

.rank-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 20px;
}

.rank-table th,
.rank-table td {
    padding: 15px;
    text-align: left;
    border-bottom: 1px solid #e0e0e0;
}

.rank-table th {
    background: #f8f9fa;
    font-weight: 600;
    color: #667eea;
}

.rank-table tr:hover {
    background: #f8f9fa;
}

.rank-badge {
    display: inline-block;
    width: 30px;
    height: 30px;
    line-height: 30px;
    text-align: center;
    border-radius: 50%;
    font-weight: 700;
}

.rank-1 {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: white;
}

.rank-2 {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    color: white;
}

.rank-3 {
    background: linear-gradient(135deg, #43e97b 0%, #38f9d7 100%);
    color: white;
}

.score-display {
    font-size: 48px;
    font-weight: 700;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-align: center;
    margin: 20px 0;
}

.alert {
    padding: 15px 20px;
    border-radius: 8px;
    margin-bottom: 20px;
}

.alert-success {
    background: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.alert-danger {
    background: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.alert-warning {
    background: #fff3cd;
    color: #856404;
    border: 1px solid #ffeaa7;
}

.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.5);
    z-index: 1000;
    justify-content: center;
    align-items: center;
}

.modal.show {
    display: flex;
}

.modal-content {
    background: white;
    border-radius: 16px;
    padding: 30px;
    max-width: 500px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.modal-header h3 {
    color: #667eea;
}

.modal-close {
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: #999;
}

.modal-close:hover {
    color: #333;
}

.pagination {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-top: 20px;
}

.pagination button {
    padding: 8px 16px;
    border: 1px solid #e0e0e0;
    background: white;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s;
}

.pagination button:hover {
    background: #f0f0f0;
}

.pagination button.active {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border-color: transparent;
}

.file-upload {
    border: 2px dashed #667eea;
    border-radius: 12px;
    padding: 40px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s;
}

.file-upload:hover {
    background: #f8f9fa;
}

.file-upload input[type="file"] {
    display: none;
}

.file-upload-icon {
    font-size: 48px;
    color: #667eea;
    margin-bottom: 10px;
}

@media (max-width: 768px) {
    .container {
        padding: 10px;
    }

    .card {
        padding: 20px;
    }

    .header {
        flex-direction: column;
        gap: 15px;
        text-align: center;
    }

    .header h1 {
        font-size: 22px;
    }

    .nav-links a {
        margin: 0 10px;
    }

    .btn {
        padding: 10px 20px;
        font-size: 14px;
    }

    .question-text {
        font-size: 16px;
    }

    .timer {
        font-size: 20px;
        padding: 12px 20px;
    }

    .rank-table {
        font-size: 14px;
    }

    .rank-table th,
    .rank-table td {
        padding: 10px;
    }

    .modal-content {
        padding: 20px;
    }

    .score-display {
        font-size: 36px;
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 18px;
    }

    .nav-links {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        gap: 10px;
    }

    .nav-links a {
        margin: 0;
        font-size: 14px;
    }

    .question-card {
        padding: 15px;
    }

    .options-list li {
        padding: 10px 12px;
        font-size: 14px;
    }
}