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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, #19753c 0%, #016101 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.container {
    background: white;
    border-radius: 20px;
    padding: 40px;
    max-width: 600px;
    width: 100%;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

h1 {
    color: #333;
    font-size: 32px;
    margin-bottom: 10px;
    text-align: center;
}

.subtitle {
    color: #666;
    text-align: center;
    margin-bottom: 30px;
    font-size: 14px;
}

.upload-area {
    border: 3px dashed #667eea;
    border-radius: 15px;
    padding: 50px 20px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    background: #f8f9ff;
}

.upload-area:hover {
    background: #f0f2ff;
    border-color: #764ba2;
}

.upload-area.dragover {
    background: #e8ebff;
    border-color: #764ba2;
    transform: scale(1.02);
}

.upload-icon {
    width: 60px;
    height: 60px;
    color: #667eea;
    margin: 0 auto 20px;
}

.upload-text {
    color: #667eea;
    font-size: 16px;
    font-weight: 500;
}

.file-list {
    margin: 30px 0;
    display: none;
}

.file-list.active {
    display: block;
}

.file-item {
    background: #f8f9ff;
    padding: 15px 20px;
    border-radius: 10px;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    cursor: move;
    transition: all 0.2s ease;
}

.file-item:hover {
    background: #f0f2ff;
}

.file-item.dragging {
    opacity: 0.5;
}

.file-info {
    display: flex;
    align-items: center;
    gap: 15px;
    flex: 1;
}

.file-number {
    background: #667eea;
    color: white;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    font-size: 14px;
}

.file-name {
    color: #333;
    font-size: 14px;
    flex: 1;
    text-overflow: ellipsis;
    overflow: hidden;
    white-space: nowrap;
}

.file-actions {
    display: flex;
    align-items: center;
    gap: 5px;
}

.file-move {
    background: #667eea;
    border: none;
    color: white;
    cursor: pointer;
    font-size: 16px;
    width: 30px;
    height: 30px;
    border-radius: 5px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
}

.file-move:hover:not(:disabled) {
    background: #764ba2;
    transform: scale(1.1);
}

.file-move:disabled {
    background: #ccc;
    cursor: not-allowed;
    opacity: 0.5;
}

.file-remove {
    background: none;
    border: none;
    color: #dc3545;
    cursor: pointer;
    font-size: 20px;
    padding: 5px 10px;
    transition: all 0.2s ease;
}

.file-remove:hover {
    color: #c82333;
    transform: scale(1.2);
}

.merge-btn {
    width: 100%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    padding: 18px;
    border-radius: 10px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.merge-btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(102, 126, 234, 0.4);
}

.merge-btn:disabled {
    background: #ccc;
    cursor: not-allowed;
}

.progress {
    margin-top: 20px;
    background: #f0f0f0;
    border-radius: 10px;
    overflow: hidden;
    height: 8px;
}

.progress-bar {
    height: 100%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    width: 0%;
    transition: width 0.3s ease;
}

@media (max-width: 600px) {
    .container {
        padding: 25px;
    }

    h1 {
        font-size: 24px;
    }

    .upload-area {
        padding: 35px 15px;
    }
}