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

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

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    text-align: center;
    margin-bottom: 30px;
    color: white;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    font-weight: 700;
}

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

main {
    flex: 1;
    background: white;
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    margin-bottom: 30px;
}

.upload-section {
    margin-bottom: 30px;
}

.upload-area {
    border: 3px dashed #ddd;
    border-radius: 15px;
    padding: 60px 40px;
    text-align: center;
    transition: all 0.3s ease;
    cursor: pointer;
    background: #fafafa;
}

.upload-area:hover {
    border-color: #667eea;
    background: #f8f9ff;
    transform: translateY(-2px);
}

.upload-area.dragover {
    border-color: #667eea;
    background: #f0f4ff;
    transform: scale(1.02);
}

.upload-icon {
    font-size: 4rem;
    margin-bottom: 20px;
}

.upload-area h3 {
    font-size: 1.5rem;
    margin-bottom: 10px;
    color: #333;
}

.upload-area p {
    color: #666;
    margin-bottom: 25px;
    font-size: 1rem;
}

.upload-btn {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 50px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.upload-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(102, 126, 234, 0.4);
}

.file-info {
    background: #f8f9fa;
    border-radius: 15px;
    padding: 20px;
    margin-bottom: 20px;
    border: 1px solid #e9ecef;
}

.file-details {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.file-icon {
    font-size: 2.5rem;
    margin-right: 15px;
}

.file-data {
    flex: 1;
}

.file-data h4 {
    color: #333;
    font-size: 1.2rem;
    margin-bottom: 5px;
}

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

.remove-btn {
    background: #dc3545;
    color: white;
    border: none;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.remove-btn:hover {
    background: #c82333;
    transform: scale(1.1);
}

.convert-section {
    text-align: center;
    margin: 30px 0;
}

.convert-btn {
    background: linear-gradient(135deg, #28a745 0%, #20c997 100%);
    color: white;
    border: none;
    padding: 18px 40px;
    border-radius: 50px;
    font-size: 1.2rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    position: relative;
    overflow: hidden;
}

.convert-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(40, 167, 69, 0.4);
}

.convert-btn:disabled {
    opacity: 0.7;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.loading-spinner {
    display: inline-block;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.progress-bar {
    width: 100%;
    height: 6px;
    background: #e9ecef;
    border-radius: 3px;
    margin-top: 20px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(135deg, #28a745 0%, #20c997 100%);
    width: 0%;
    transition: width 0.3s ease;
    border-radius: 3px;
}

.download-section {
    text-align: center;
    padding: 30px;
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    border-radius: 15px;
}

.success-message {
    margin-bottom: 25px;
}

.success-icon {
    font-size: 3rem;
    margin-bottom: 15px;
}

.success-message h3 {
    color: #28a745;
    font-size: 1.5rem;
    margin-bottom: 10px;
}

.success-message p {
    color: #666;
    font-size: 1rem;
}

.download-btn {
    background: linear-gradient(135deg, #007bff 0%, #0056b3 100%);
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 50px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-right: 15px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.download-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(0, 123, 255, 0.4);
}

.new-conversion-btn {
    background: linear-gradient(135deg, #6c757d 0%, #495057 100%);
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 50px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.new-conversion-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(108, 117, 125, 0.4);
}

.error-message {
    background: #f8d7da;
    color: #721c24;
    padding: 20px;
    border-radius: 15px;
    text-align: center;
    border: 1px solid #f5c6cb;
    margin: 20px 0;
}

.error-icon {
    font-size: 2rem;
    margin-bottom: 10px;
}

footer {
    color: white;
    text-align: center;
}

.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 30px;
    margin-bottom: 30px;
}

.feature {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: 15px;
    padding: 25px 20px;
    text-align: center;
    transition: all 0.3s ease;
}

.feature:hover {
    transform: translateY(-5px);
    background: rgba(255, 255, 255, 0.15);
}

.feature-icon {
    font-size: 2.5rem;
    margin-bottom: 15px;
}

.feature h4 {
    font-size: 1.2rem;
    margin-bottom: 10px;
    color: white;
}

.feature p {
    font-size: 0.9rem;
    opacity: 0.9;
    line-height: 1.4;
}

footer p {
    opacity: 0.8;
    font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 15px;
    }
    
    header h1 {
        font-size: 2rem;
    }
    
    main {
        padding: 25px 20px;
    }
    
    .upload-area {
        padding: 40px 20px;
    }
    
    .upload-area h3 {
        font-size: 1.3rem;
    }
    
    .file-details {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .remove-btn {
        align-self: flex-end;
        margin-top: 10px;
    }
    
    .features {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .download-btn, .new-conversion-btn {
        display: block;
        width: 100%;
        margin: 10px 0;
    }
}

@media (max-width: 480px) {
    header h1 {
        font-size: 1.8rem;
    }
    
    .upload-area {
        padding: 30px 15px;
    }
    
    .upload-icon {
        font-size: 3rem;
    }
    
    .convert-btn, .download-btn, .new-conversion-btn {
        padding: 15px 25px;
        font-size: 1rem;
    }
}