:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --light-bg: #f8f9fa;
}

body {
    background-color: var(--light-bg);
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
}

.navbar-brand {
    font-weight: 600;
    color: var(--primary-color) !important;
}

.page-header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 2rem 0;
    margin-bottom: 2rem;
    border-radius: 0 0 1rem 1rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.card {
    border: none;
    border-radius: 1rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    transition: transform 0.2s;
    margin-bottom: 2rem;
}

.card:hover {
    transform: translateY(-5px);
}

.card-header {
    background: white;
    border-bottom: 2px solid var(--secondary-color);
    border-radius: 1rem 1rem 0 0 !important;
    padding: 1rem 1.5rem;
}

.card-title {
    color: var(--primary-color);
    font-weight: 600;
    margin: 0;
    font-size: 1.25rem;
}

.upload-area {
    border: 2px dashed var(--secondary-color);
    border-radius: 1rem;
    padding: 2rem;
    text-align: center;
    background-color: rgba(52, 152, 219, 0.05);
    cursor: pointer;
    transition: all 0.3s ease;
}

.upload-area:hover {
    border-color: var(--accent-color);
    background-color: rgba(231, 76, 60, 0.05);
}

.btn-primary {
    background-color: var(--secondary-color);
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 500;
}

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

.table-responsive {
    border-radius: 0.5rem;
    background: white;
}

.form-select {
    border-radius: 0.5rem;
    padding: 0.75rem;
    border-color: #dee2e6;
}

.chart-container {
    background: white;
    border-radius: 1rem;
    padding: 1rem;
    box-shadow: inset 0 0 10px rgba(0, 0, 0, 0.05);
}

footer {
    background-color: var(--primary-color);
    color: white;
    padding: 1rem 0;
    text-align: center;
    margin-top: 2rem;
}

.spinner-border {
    color: var(--secondary-color);
    width: 3rem;
    height: 3rem;
}

.alert {
    border-radius: 0.5rem;
}