* {
    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;
}

header {
    text-align: center;
    margin-bottom: 40px;
    color: white;
}

header h1 {
    font-size: 3rem;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}

header p {
    font-size: 1.2rem;
    opacity: 0.9;
}

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

.input-group {
    margin-bottom: 30px;
}

.input-group label {
    display: block;
    margin-bottom: 10px;
    font-weight: 600;
    color: #555;
}

.input-group input {
    width: 100%;
    padding: 15px;
    border: 2px solid #e1e5e9;
    border-radius: 10px;
    font-size: 16px;
    transition: border-color 0.3s ease;
}

.input-group input:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.convert-btn {
    width: 100%;
    padding: 18px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 18px;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    position: relative;
    overflow: hidden;
}

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

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

.btn-loader {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

.spinner {
    width: 20px;
    height: 20px;
    border: 2px solid rgba(255,255,255,0.3);
    border-top: 2px solid white;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

.status-message {
    padding: 15px;
    border-radius: 10px;
    margin-top: 20px;
    text-align: center;
}

.status-message.error {
    background-color: #fee;
    color: #c33;
    border: 1px solid #fcc;
}

.status-message.success {
    background-color: #efe;
    color: #363;
    border: 1px solid #cfc;
}

.download-section {
    text-align: center;
    padding: 30px;
    background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
    border-radius: 15px;
    margin-top: 20px;
}

.download-section h3 {
    margin-bottom: 10px;
    color: #333;
}

.download-section p {
    margin-bottom: 20px;
    color: #666;
}

.download-btn {
    display: inline-block;
    padding: 15px 30px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-decoration: none;
    border-radius: 10px;
    font-weight: 600;
    transition: transform 0.2s ease;
}

.download-btn:hover {
    transform: translateY(-2px);
}

.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 30px;
    margin-bottom: 40px;
}

.feature {
    background: white;
    padding: 30px;
    border-radius: 15px;
    text-align: center;
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
}

.feature:hover {
    transform: translateY(-5px);
}

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

.feature h3 {
    margin-bottom: 10px;
    color: #333;
}

.feature p {
    color: #666;
}

footer {
    text-align: center;
    color: white;
    opacity: 0.8;
    margin-top: 40px;
}

@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    
    header h1 {
        font-size: 2rem;
    }
    
    .converter-card {
        padding: 20px;
    }
    
    .features {
        grid-template-columns: 1fr;
    }
}