:root {
    --primary-color: #3498db;
    --secondary-color: #2ecc71;
    --danger-color: #e74c3c;
    --dark-color: #2c3e50;
    --light-color: #ecf0f1;
    --border-color: #bdc3c7;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: #f5f6fa;
    color: var(--dark-color);
    line-height: 1.6;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
}

header {
    text-align: center;
    margin-bottom: 40px;
}

header h1 {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 10px;
}

header p {
    color: #7f8c8d;
    font-size: 1.1rem;
}

.upload-section {
    background: white;
    border-radius: 10px;
    padding: 40px;
    box-shadow: var(--shadow);
    margin-bottom: 30px;
}

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 10px;
    padding: 60px 40px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
}

.upload-area:hover,
.upload-area.drag-over {
    border-color: var(--primary-color);
    background-color: rgba(52, 152, 219, 0.05);
}

.upload-icon {
    width: 60px;
    height: 60px;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.upload-button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 12px 30px;
    border-radius: 5px;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s ease;
    margin-top: 15px;
}

.upload-button:hover {
    background-color: #2980b9;
}

.data-section {
    background: white;
    border-radius: 10px;
    padding: 30px;
    box-shadow: var(--shadow);
}

.controls {
    display: flex;
    justify-content: flex-end;
    gap: 10px;
    margin-bottom: 20px;
}

.reset-btn,
.export-btn {
    padding: 8px 20px;
    border: none;
    border-radius: 5px;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

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

.reset-btn:hover {
    background-color: #c0392b;
}

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

.export-btn:hover {
    background-color: #27ae60;
}

.tabs {
    display: flex;
    border-bottom: 2px solid var(--light-color);
    margin-bottom: 30px;
}

.tab-btn {
    background: none;
    border: none;
    padding: 15px 30px;
    font-size: 1rem;
    cursor: pointer;
    color: #7f8c8d;
    transition: all 0.3s ease;
    position: relative;
}

.tab-btn:hover {
    color: var(--dark-color);
}

.tab-btn.active {
    color: var(--primary-color);
}

.tab-btn.active::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    right: 0;
    height: 2px;
    background-color: var(--primary-color);
}

.tab-content {
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.filter-controls {
    display: flex;
    gap: 15px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.search-input,
.sort-select,
.chart-select {
    padding: 10px 15px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    font-size: 0.95rem;
    transition: border-color 0.3s ease;
}

.search-input:focus,
.sort-select:focus,
.chart-select:focus {
    outline: none;
    border-color: var(--primary-color);
}

.search-input {
    flex: 1;
    min-width: 250px;
}

.sort-btn {
    padding: 10px 15px;
    border: 1px solid var(--border-color);
    background-color: white;
    border-radius: 5px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.sort-btn:hover {
    background-color: var(--light-color);
}

.table-wrapper {
    overflow-x: auto;
    margin-bottom: 20px;
}

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

th,
td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid var(--light-color);
}

th {
    background-color: #f8f9fa;
    font-weight: 600;
    color: var(--dark-color);
    position: sticky;
    top: 0;
    z-index: 10;
}

tr:hover {
    background-color: #f8f9fa;
}

.pagination {
    display: flex;
    justify-content: center;
    gap: 5px;
    margin-top: 20px;
}

.pagination button {
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    background-color: white;
    border-radius: 3px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.pagination button:hover {
    background-color: var(--light-color);
}

.pagination button.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.stat-card {
    background-color: #f8f9fa;
    padding: 20px;
    border-radius: 8px;
    border: 1px solid var(--light-color);
}

.stat-card h3 {
    color: var(--primary-color);
    margin-bottom: 15px;
    font-size: 1.1rem;
}

.stat-item {
    display: flex;
    justify-content: space-between;
    padding: 8px 0;
    border-bottom: 1px solid var(--light-color);
}

.stat-item:last-child {
    border-bottom: none;
}

.stat-label {
    color: #7f8c8d;
}

.stat-value {
    font-weight: 600;
    color: var(--dark-color);
}

.chart-controls {
    display: flex;
    gap: 15px;
    margin-bottom: 30px;
    flex-wrap: wrap;
}

.chart-container {
    position: relative;
    height: 400px;
    max-width: 800px;
    margin: 0 auto;
}

@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    
    header h1 {
        font-size: 2rem;
    }
    
    .tabs {
        overflow-x: auto;
    }
    
    .tab-btn {
        padding: 12px 20px;
        white-space: nowrap;
    }
    
    .filter-controls {
        flex-direction: column;
    }
    
    .search-input {
        min-width: 100%;
    }
    
    .table-wrapper {
        font-size: 0.9rem;
    }
    
    th, td {
        padding: 8px;
    }
}