body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: #f4f7f6;
    color: #333;
    margin: 0;
    padding: 20px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background-color: #fff;
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.05);
}

h1 {
    color: #0056b3;
    border-bottom: 2px solid #e9ecef;
    padding-bottom: 10px;
    margin-bottom: 20px;
}

h2 {
    color: #17a2b8;
    margin-top: 40px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    font-weight: bold;
    margin-bottom: 8px;
}

.form-group input[type="file"] {
    width: 100%;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 4px;
}

button {
    background-color: #007bff;
    color: white;
    padding: 12px 20px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 16px;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #0056b3;
}

button:disabled {
    background-color: #aaa;
    cursor: not-allowed;
}

.table-container {
    overflow-x: auto;
    margin-top: 20px;
    max-height: 500px;
}

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

th, td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid #ddd;
}

th {
    background-color: #f8f9fa;
    font-weight: bold;
}

tbody tr:nth-child(even) {
    background-color: #f2f2f2;
}

.download-btn, .back-link {
    display: inline-block;
    margin-top: 10px;
    margin-bottom: 10px;
    background-color: #28a745;
    color: white;
    padding: 10px 15px;
    text-decoration: none;
    border-radius: 4px;
    transition: background-color 0.3s;
}

.back-link {
    background-color: #6c757d;
}

.download-btn:hover {
    background-color: #218838;
}

.back-link:hover {
    background-color: #5a6268;
}

.error-box {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
    padding: 15px;
    border-radius: 4px;
    margin-top: 20px;
}

.flash-messages {
    padding: 15px;
    margin-bottom: 20px;
    border: 1px solid transparent;
    border-radius: 4px;
}

.flash-error {
    color: #721c24;
    background-color: #f8d7da;
    border-color: #f5c6cb;
    padding: 10px;
}

/* Loading Spinner */
#loading {
    text-align: center;
    margin-top: 30px;
}
.spinner {
    border: 8px solid #f3f3f3;
    border-top: 8px solid #3498db;
    border-radius: 50%;
    width: 60px;
    height: 60px;
    animation: spin 2s linear infinite;
    margin: 0 auto 10px auto;
}
.hidden {
    display: none;
}
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}