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

:root {
    --primary: #007bff;
    --secondary: #6c757d;
    --success: #28a745;
    --warning: #ffc107;
    --danger: #dc3545;
    --light: #f8f9fa;
    --dark: #343a40;
    --border: #dee2e6;
    --shadow: 0 2px 8px rgba(0,0,0,0.1);
    --transition: all 0.3s ease;
}

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;
    padding: 20px;
    color: var(--dark);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background: white;
    border-radius: 12px;
    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: 40px 20px;
    text-align: center;
}

.header h1 {
    font-size: 2.5em;
    margin-bottom: 10px;
}

.header p {
    font-size: 1.1em;
    opacity: 0.9;
}

.content {
    padding: 40px;
}

.section {
    margin-bottom: 40px;
    animation: slideIn 0.3s ease;
}

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

.section-header {
    border-bottom: 3px solid var(--primary);
    margin-bottom: 20px;
    padding-bottom: 15px;
}

.section-header h2 {
    color: var(--primary);
    font-size: 1.8em;
}

/* Upload Area */
.upload-area {
    border: 3px dashed var(--primary);
    border-radius: 8px;
    padding: 40px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    background: var(--light);
}

.upload-area:hover {
    border-color: var(--secondary);
    background: #f1f3f5;
}

.upload-area.dragover {
    border-color: var(--success);
    background: #e8f5e9;
}

.upload-icon {
    width: 60px;
    height: 60px;
    color: var(--primary);
    margin-bottom: 15px;
}

.upload-text {
    font-size: 1.1em;
    color: var(--dark);
}

/* File Info */
.file-info {
    background: var(--light);
    padding: 15px;
    border-radius: 8px;
    margin-top: 15px;
    border-left: 4px solid var(--success);
}

/* CSV Config */
.csv-config {
    background: var(--light);
    padding: 20px;
    border-radius: 8px;
    margin-top: 20px;
    border: 1px solid var(--border);
}

.csv-config h3 {
    margin-bottom: 15px;
    color: var(--dark);
}

.csv-config label {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 15px;
}

.csv-config select {
    flex: 1;
    padding: 8px 12px;
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 0.95em;
}

/* Sheet Selector */
.sheet-selector {
    background: var(--light);
    padding: 15px;
    border-radius: 8px;
    margin-top: 15px;
}

.sheet-selector label {
    display: flex;
    align-items: center;
    gap: 10px;
}

.sheet-selector select {
    flex: 1;
    padding: 8px 12px;
    border: 1px solid var(--border);
    border-radius: 4px;
}

/* Loading */
.loading {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 15px;
    padding: 30px;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Messages */
.error {
    background: #ffebee;
    color: var(--danger);
    padding: 15px;
    border-radius: 8px;
    border-left: 4px solid var(--danger);
    margin-top: 15px;
}

.success {
    background: #e8f5e9;
    color: var(--success);
    padding: 15px;
    border-radius: 8px;
    border-left: 4px solid var(--success);
    margin-top: 15px;
}

/* Tools */
.tools {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
    margin-bottom: 25px;
    background: var(--light);
    padding: 20px;
    border-radius: 8px;
}

.tool-group {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.tool-group label {
    font-weight: 500;
    color: var(--dark);
    font-size: 0.95em;
}

.tool-group input,
.tool-group select {
    padding: 10px;
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 0.95em;
}

.tool-group input:focus,
.tool-group select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.1);
}

/* Buttons */
.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 4px;
    font-size: 0.95em;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    display: inline-block;
}

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

.btn-primary:hover {
    background: #0056b3;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

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

.btn-secondary:hover {
    background: #545b62;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

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

.btn-success:hover {
    background: #218838;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.btn-warning {
    background: var(--warning);
    color: #000;
}

.btn-warning:hover {
    background: #e0a800;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

/* Table */
.table-wrapper {
    overflow-x: auto;
    border-radius: 8px;
    border: 1px solid var(--border);
    margin-bottom: 20px;
}

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

.data-table thead {
    background: var(--primary);
    color: white;
}

.data-table th {
    padding: 12px;
    text-align: left;
    font-weight: 600;
    cursor: pointer;
    user-select: none;
}

.data-table td {
    padding: 10px 12px;
    border-bottom: 1px solid var(--border);
}

.data-table tr:hover {
    background: var(--light);
}

.data-table tbody tr:nth-child(even) {
    background: #fafbfc;
}

.data-table input {
    width: 100%;
    padding: 6px 8px;
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 0.9em;
}

.data-table input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 2px rgba(0, 123, 255, 0.1);
}

/* Actions */
.actions {
    display: flex;
    gap: 10px;
    justify-content: center;
    flex-wrap: wrap;
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        border-radius: 0;
    }

    .header {
        padding: 30px 15px;
    }

    .header h1 {
        font-size: 1.8em;
    }

    .content {
        padding: 20px;
    }

    .tools {
        grid-template-columns: 1fr;
    }

    .upload-area {
        padding: 30px 20px;
    }

    .data-table {
        font-size: 0.9em;
    }

    .data-table th,
    .data-table td {
        padding: 8px;
    }

    .actions {
        flex-direction: column;
    }

    .btn {
        width: 100%;
        text-align: center;
    }
}