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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.container {
    background: #ffffff;
    border-radius: 24px;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    max-width: 900px;
    width: 100%;
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    color: #ffffff;
    padding: 40px;
    text-align: center;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 8px;
    letter-spacing: -0.5px;
}

.subtitle {
    color: rgba(255, 255, 255, 0.7);
    font-size: 1.1rem;
}

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

@media (max-width: 768px) {
    main {
        grid-template-columns: 1fr;
    }
}

.form-section {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.input-group label {
    font-weight: 600;
    color: #1a1a2e;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.input-group input[type="url"] {
    padding: 16px;
    border: 2px solid #e2e8f0;
    border-radius: 12px;
    font-size: 1rem;
    transition: all 0.2s ease;
}

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

.color-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.color-picker-wrapper {
    display: flex;
    align-items: center;
    gap: 12px;
}

.color-picker-wrapper span {
    font-family: 'Monaco', 'Menlo', monospace;
    font-size: 0.85rem;
    color: #64748b;
    background: #f1f5f9;
    padding: 6px 10px;
    border-radius: 6px;
}

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 8px;
    border-radius: 4px;
    background: #e2e8f0;
    outline: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    cursor: pointer;
    box-shadow: 0 2px 6px rgba(102, 126, 234, 0.4);
}

input[type="range"]::-moz-range-thumb {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    cursor: pointer;
    border: none;
}

#marginValue {
    display: inline-block;
    background: #f1f5f9;
    padding: 4px 12px;
    border-radius: 6px;
    font-weight: 600;
    color: #1a1a2e;
    margin-top: 8px;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: #ffffff;
    border: none;
    padding: 18px 32px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 1px;
}

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

.btn-primary:active {
    transform: translateY(0);
}

.preview-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 24px;
}

.preview-container {
    background: #f8fafc;
    border: 2px dashed #e2e8f0;
    border-radius: 16px;
    width: 100%;
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    transition: all 0.3s ease;
}

.preview-container.has-qr {
    border-style: solid;
    border-color: #667eea;
}

.placeholder {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
    color: #94a3b8;
}

.placeholder svg {
    opacity: 0.5;
}

.placeholder p {
    font-size: 0.95rem;
}

#qrPreview {
    max-width: 100%;
    max-height: 100%;
    border-radius: 8px;
}

.btn-secondary {
    background: #1a1a2e;
    color: #ffffff;
    border: none;
    padding: 16px 40px;
    font-size: 0.95rem;
    font-weight: 600;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.btn-secondary:hover:not(:disabled) {
    background: #16213e;
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(26, 26, 46, 0.2);
}

.btn-secondary:disabled {
    background: #cbd5e1;
    cursor: not-allowed;
}

.loading {
    position: relative;
    pointer-events: none;
}

.loading::after {
    content: '';
    position: absolute;
    width: 20px;
    height: 20px;
    border: 2px solid transparent;
    border-top-color: #ffffff;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
}

@keyframes spin {
    to {
        transform: translateY(-50%) rotate(360deg);
    }
}