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

body {
font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
min-height: 100vh;
color: #333;
}

.header {
background: rgba(255, 255, 255, 0.1);
backdrop-filter: blur(10px);
padding: 1rem 2rem;
display: flex;
justify-content: space-between;
align-items: center;
border-bottom: 1px solid rgba(255, 255, 255, 0.2);
}

.logo {
color: white;
text-decoration: none;
font-size: 1.2rem;
font-weight: 600;
}

.back-btn {
color: white;
text-decoration: none;
padding: 0.5rem 1rem;
background: rgba(255, 255, 255, 0.2);
border-radius: 8px;
transition: all 0.3s ease;
}

.back-btn:hover {
background: rgba(255, 255, 255, 0.3);
}

.container {
max-width: 1200px;
margin: 0 auto;
padding: 2rem;
}

.hero {
text-align: center;
color: white;
margin-bottom: 3rem;
}

.hero h1 {
font-size: 3rem;
margin-bottom: 1rem;
font-weight: 700;
}

.hero p {
font-size: 1.2rem;
opacity: 0.9;
max-width: 600px;
margin: 0 auto;
}

.main-card {
background: white;
border-radius: 20px;
padding: 2rem;
box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
margin-bottom: 2rem;
}

.upload-area {
border: 3px dashed #ddd;
border-radius: 15px;
padding: 3rem;
text-align: center;
transition: all 0.3s ease;
cursor: pointer;
margin-bottom: 2rem;
}

.upload-area:hover {
border-color: #667eea;
background: #f8f9ff;
}

.upload-area.dragover {
border-color: #667eea;
background: #f0f4ff;
}

.upload-icon {
font-size: 4rem;
color: #87ceeb;
margin-bottom: 1rem;
}

.upload-text {
font-size: 1.2rem;
color: #666;
margin-bottom: 0.5rem;
}

.upload-subtext {
color: #999;
font-size: 0.9rem;
}

.file-input {
display: none;
}

.upload-btn {
background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
color: white;
border: none;
padding: 1rem 2rem;
border-radius: 10px;
font-size: 1rem;
cursor: pointer;
transition: all 0.3s ease;
margin-top: 1rem;
}

.upload-btn:hover {
transform: translateY(-2px);
box-shadow: 0 10px 20px rgba(102, 126, 234, 0.3);
}

.files-list {
display: none;
margin: 2rem 0;
}

.files-list.show {
display: block;
}

.files-list h3 {
color: #333;
margin-bottom: 1rem;
display: flex;
align-items: center;
gap: 0.5rem;
}

.file-item {
background: #f8f9fa;
border-radius: 10px;
padding: 1rem;
margin-bottom: 1rem;
display: flex;
align-items: center;
justify-content: space-between;
border: 2px solid transparent;
transition: all 0.3s ease;
}

.file-item:hover {
border-color: #667eea;
}

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

.file-icon {
font-size: 2rem;
color: #dc3545;
}

.file-details {
display: flex;
flex-direction: column;
}

.file-name {
font-weight: 600;
color: #333;
margin-bottom: 0.25rem;
}

.file-size {
color: #666;
font-size: 0.9rem;
}

.file-actions {
display: flex;
gap: 0.5rem;
}

.move-btn {
background: #6c757d;
color: white;
border: none;
padding: 0.5rem;
border-radius: 5px;
cursor: pointer;
font-size: 0.8rem;
transition: all 0.3s ease;
}

.move-btn:hover {
background: #5a6268;
}

.remove-btn {
background: #dc3545;
color: white;
border: none;
padding: 0.5rem;
border-radius: 5px;
cursor: pointer;
font-size: 0.8rem;
transition: all 0.3s ease;
}

.remove-btn:hover {
background: #c82333;
}

.merge-controls {
display: none;
text-align: center;
margin: 2rem 0;
}

.merge-controls.show {
display: block;
}

.merge-btn {
background: linear-gradient(135deg, #28a745 0%, #20c997 100%);
color: white;
border: none;
padding: 1rem 3rem;
border-radius: 10px;
font-size: 1.1rem;
cursor: pointer;
transition: all 0.3s ease;
margin: 0 0.5rem;
}

.merge-btn:hover {
transform: translateY(-2px);
box-shadow: 0 10px 20px rgba(40, 167, 69, 0.3);
}

.merge-btn:disabled {
background: #6c757d;
cursor: not-allowed;
transform: none;
box-shadow: none;
}

.clear-btn {
background: linear-gradient(135deg, #6c757d 0%, #495057 100%);
color: white;
border: none;
padding: 1rem 2rem;
border-radius: 10px;
font-size: 1rem;
cursor: pointer;
transition: all 0.3s ease;
margin: 0 0.5rem;
}

.clear-btn:hover {
transform: translateY(-2px);
box-shadow: 0 10px 20px rgba(108, 117, 125, 0.3);
}

.progress-area {
display: none;
text-align: center;
margin: 2rem 0;
}

.progress-area.show {
display: block;
}

.progress-bar {
width: 100%;
height: 10px;
background: #e9ecef;
border-radius: 5px;
overflow: hidden;
margin: 1rem 0;
}

.progress-fill {
height: 100%;
background: linear-gradient(90deg, #28a745, #20c997);
width: 0%;
transition: width 0.3s ease;
}

.result-area {
display: none;
text-align: center;
background: #d4edda;
border: 1px solid #c3e6cb;
border-radius: 10px;
padding: 2rem;
margin: 2rem 0;
}

.result-area.show {
display: block;
}

.success-icon {
font-size: 3rem;
color: #28a745;
margin-bottom: 1rem;
}

.download-btn {
background: linear-gradient(135deg, #007bff 0%, #0056b3 100%);
color: white;
border: none;
padding: 1rem 2rem;
border-radius: 10px;
font-size: 1rem;
cursor: pointer;
transition: all 0.3s ease;
margin: 0 0.5rem;
}

.download-btn:hover {
transform: translateY(-2px);
box-shadow: 0 10px 20px rgba(0, 123, 255, 0.3);
}

.reset-btn {
background: linear-gradient(135deg, #6c757d 0%, #495057 100%);
color: white;
border: none;
padding: 1rem 2rem;
border-radius: 10px;
font-size: 1rem;
cursor: pointer;
transition: all 0.3s ease;
margin: 0 0.5rem;
}

.reset-btn:hover {
transform: translateY(-2px);
box-shadow: 0 10px 20px rgba(108, 117, 125, 0.3);
}

.features {
display: grid;
grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
gap: 2rem;
margin-top: 3rem;
}

.feature {
background: white;
padding: 2rem;
border-radius: 15px;
text-align: center;
box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.feature-icon {
font-size: 3rem;
margin-bottom: 1rem;
}

.feature h3 {
margin-bottom: 1rem;
color: #333;
}

.feature p {
color: #666;
line-height: 1.6;
}

@media (max-width: 768px) {
.container {
padding: 1rem;
}

.hero h1 {
font-size: 2rem;
}

.main-card {
padding: 1rem;
}

.file-item {
flex-direction: column;
align-items: flex-start;
gap: 1rem;
}

.file-actions {
align-self: stretch;
justify-content: space-between;
}
}