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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    background: white;
    border-radius: 10px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.2);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 30px;
}

header h1 {
    margin-bottom: 20px;
    font-size: 28px;
}

nav {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

nav button {
    padding: 10px 20px;
    border: 2px solid white;
    background: transparent;
    color: white;
    border-radius: 5px;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.3s;
}

nav button:hover {
    background: white;
    color: #667eea;
}

main {
    padding: 30px;
}

.section {
    display: none;
}

.section.active {
    display: block;
}

.card {
    background: #f8f9fa;
    padding: 25px;
    border-radius: 8px;
    margin-top: 20px;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    padding: 15px 30px;
    font-size: 16px;
    border-radius: 5px;
    cursor: pointer;
    transition: transform 0.2s;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

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

select {
    width: 100%;
    padding: 12px;
    margin: 10px 0 20px 0;
    border: 2px solid #e0e0e0;
    border-radius: 5px;
    font-size: 14px;
}

.status-message {
    margin-top: 20px;
    padding: 15px;
    border-radius: 5px;
    display: none;
}

.status-message.success {
    background: #d4edda;
    border: 1px solid #c3e6cb;
    color: #155724;
    display: block;
}

.status-message.error {
    background: #f8d7da;
    border: 1px solid #f5c6cb;
    color: #721c24;
    display: block;
}

.conflict-report {
    margin-top: 20px;
}

.conflict-item {
    background: #fff3cd;
    border: 1px solid #ffeaa7;
    padding: 10px;
    margin-bottom: 10px;
    border-radius: 5px;
}

.timetable-grid {
    margin-top: 20px;
    overflow-x: auto;
}

.timetable-table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.timetable-table th {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 15px;
    text-align: left;
    font-weight: 600;
}

.timetable-table td {
    padding: 12px 15px;
    border-bottom: 1px solid #e0e0e0;
}

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

.lecture-card {
    background: white;
    border-left: 4px solid #667eea;
    padding: 10px;
    margin-bottom: 8px;
    border-radius: 4px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.lecture-card .subject {
    font-weight: 600;
    color: #333;
    margin-bottom: 5px;
}

.lecture-card .details {
    font-size: 13px;
    color: #666;
}

.time-badge {
    display: inline-block;
    background: #667eea;
    color: white;
    padding: 3px 8px;
    border-radius: 3px;
    font-size: 12px;
    margin-right: 5px;
}

.loader {
    border: 4px solid #f3f3f3;
    border-top: 4px solid #667eea;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
    margin: 20px auto;
    display: none;
}

.loader.active {
    display: block;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

@media (max-width: 768px) {
    header h1 {
        font-size: 22px;
    }
    
    nav {
        flex-direction: column;
    }
    
    nav button {
        width: 100%;
    }
}