:root {
    --primary-color: #007bff;
    --secondary-color: #f8f9fa;
    --border-color: #dee2e6;
    --text-color: #333;
    --success-color: #28a745;
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

body {
    font-family: var(--font-family);
    background-color: var(--secondary-color);
    color: var(--text-color);
    margin: 0;
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    box-sizing: border-box;
}

.container {
    width: 100%;
    max-width: 800px;
    background-color: #fff;
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    text-align: center;
}

header h1 {
    margin-top: 0;
    color: var(--primary-color);
}

#drop-zone {
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 40px;
    margin: 20px 0;
    cursor: pointer;
    transition: background-color 0.2s, border-color 0.2s;
    position: relative;
}

#drop-zone p {
    margin: 0;
    font-size: 1.1em;
    color: #6c757d;
}

#drop-zone.dragover {
    background-color: #e9ecef;
    border-color: var(--primary-color);
}

#file-input {
    display: none;
}

#status-container {
    margin: 20px 0;
    min-height: 50px;
}

.hidden {
    display: none !important;
}

#loader {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
}

.spinner {
    border: 4px solid rgba(0, 0, 0, 0.1);
    width: 36px;
    height: 36px;
    border-radius: 50%;
    border-left-color: var(--primary-color);
    animation: spin 1s ease infinite;
    margin-bottom: 10px;
}

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

#success-message {
    color: var(--success-color);
    font-weight: bold;
}

#download-area {
    margin-top: 20px;
    display: flex;
    flex-direction: column;
    gap: 10px;
    align-items: center;
}

.download-btn {
    display: inline-block;
    background-color: var(--success-color);
    color: #fff;
    padding: 12px 24px;
    border: none;
    border-radius: 5px;
    text-decoration: none;
    font-size: 1em;
    cursor: pointer;
    transition: background-color 0.2s;
    width: 80%;
    max-width: 300px;
}

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

footer {
    margin-top: 30px;
    font-size: 0.9em;
    color: #6c757d;
}