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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

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

header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}

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

main {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
}

.form-section, .preview-section {
    background: white;
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

.input-group {
    margin-bottom: 25px;
}

.input-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: #555;
}

.input-group input, 
.input-group select, 
.input-group textarea {
    width: 100%;
    padding: 12px;
    border: 2px solid #e1e5e9;
    border-radius: 8px;
    font-size: 16px;
    transition: border-color 0.3s ease;
}

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

.color-group {
    display: grid;
    grid-template-columns: auto 1fr auto 1fr;
    gap: 10px;
    align-items: center;
}

.color-group input[type="color"] {
    width: 50px;
    height: 40px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
}

.logo-section {
    border: 2px dashed #e1e5e9;
    padding: 20px;
    border-radius: 10px;
    background: #f8f9fa;
}

.logo-toggle {
    display: flex;
    align-items: center;
    gap: 15px;
    margin-bottom: 20px;
}

.switch {
    position: relative;
    display: inline-block;
    width: 60px;
    height: 34px;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: .4s;
    border-radius: 34px;
}

.slider:before {
    position: absolute;
    content: "";
    height: 26px;
    width: 26px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
}

input:checked + .slider {
    background-color: #667eea;
}

input:checked + .slider:before {
    transform: translateX(26px);
}

.logo-options {
    animation: slideDown 0.3s ease;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.file-info {
    font-size: 0.9rem;
    color: #666;
    margin-top: 5px;
}

.input-group input[type="range"] {
    width: calc(100% - 60px);
    margin-right: 10px;
}

.sample-logo {
    text-align: center;
    margin-top: 15px;
}

.sample-logo button {
    background: #28a745;
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    transition: background 0.3s ease;
}

.sample-logo button:hover {
    background: #218838;
}

.action-buttons {
    display: flex;
    gap: 15px;
    margin-top: 30px;
}

.btn-primary, .btn-secondary {
    flex: 1;
    padding: 15px;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
    background: #6c757d;
    color: white;
}

.btn-secondary:hover:not(:disabled) {
    background: #5a6268;
    transform: translateY(-2px);
}

.btn-secondary:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.preview-container {
    text-align: center;
    margin-bottom: 20px;
}

#qr-preview {
    min-height: 350px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px dashed #e1e5e9;
    border-radius: 10px;
    background: #f8f9fa;
}

.placeholder {
    text-align: center;
    color: #666;
}

.placeholder-icon {
    font-size: 4rem;
    margin-bottom: 10px;
    opacity: 0.5;
}

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

footer {
    text-align: center;
    color: white;
    opacity: 0.8;
    padding: 20px 0;
}

/* Responsive Design */
@media (max-width: 768px) {
    main {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .container {
        padding: 15px;
    }
    
    header h1 {
        font-size: 2rem;
    }
    
    .form-section, .preview-section {
        padding: 20px;
    }
    
    .color-group {
        grid-template-columns: 1fr;
        gap: 15px;
    }
    
    .action-buttons {
        flex-direction: column;
    }
}

/* Loading Animation */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255,255,255,.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 1s ease-in-out infinite;
}

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

/* Success Animation */
.success-animation {
    animation: pulse 0.6s ease-in-out;
}

@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.05); }
    100% { transform: scale(1); }
}