* {
    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: 1200px;
    margin: 0 auto;
    background: white;
    border-radius: 15px;
    padding: 30px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.2);
}

h1 {
    color: #333;
    text-align: center;
    margin-bottom: 30px;
    font-size: 28px;
}

.upload-section {
    text-align: center;
    margin: 40px 0;
}

.file-label {
    display: inline-block;
    padding: 15px 30px;
    background: #667eea;
    color: white;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
    font-size: 16px;
}

.file-label:hover {
    background: #5568d3;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

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

#fileName {
    margin-top: 15px;
    color: #666;
    font-style: italic;
}

.loading {
    text-align: center;
    padding: 40px;
}

.spinner {
    border: 4px solid #f3f3f3;
    border-top: 4px solid #667eea;
    border-radius: 50%;
    width: 50px;
    height: 50px;
    animation: spin 1s linear infinite;
    margin: 0 auto 20px;
}

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

.hidden {
    display: none;
}

.results {
    margin: 30px 0;
    padding: 20px;
    background: #f8f9fa;
    border-radius: 8px;
}

#stats {
    margin: 20px 0;
    padding: 15px;
    background: white;
    border-radius: 5px;
    border-left: 4px solid #667eea;
}

.download-btn {
    display: block;
    margin: 20px auto;
    padding: 12px 30px;
    background: #28a745;
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.3s;
}

.download-btn:hover {
    background: #218838;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(40, 167, 69, 0.4);
}

.preview {
    margin-top: 30px;
    overflow-x: auto;
}

#previewTable {
    margin-top: 15px;
}

table {
    width: 100%;
    border-collapse: collapse;
    font-size: 14px;
}

th, td {
    padding: 10px;
    text-align: right;
    border: 1px solid #ddd;
}

th {
    background: #667eea;
    color: white;
    font-weight: 600;
}

tr:nth-child(even) {
    background: #f8f9fa;
}

.original-row {
    background: white;
}

.inserted-row-1 {
    background: #fff3cd !important;
}

.inserted-row-2 {
    background: #d1ecf1 !important;
}

.inserted-row-3 {
    background: #d4edda !important;
}

.original-treated-row {
    background: #FFE6E6 !important;
}