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

:root {
    --primary-color: #8b5cf6;
    --primary-hover: #7c3aed;
    --background: #0f172a;
    --surface: #1e293b;
    --surface-light: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --border-color: #334155;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -2px rgba(0, 0, 0, 0.4);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
}

header {
    text-align: center;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.subtitle {
    font-size: 1rem;
    color: var(--text-secondary);
}

.main-content {
    display: grid;
    grid-template-columns: 1fr 500px;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.controls-panel,
.preview-panel {
    background: var(--surface);
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
}

.controls-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

.control-section {
    margin-bottom: 1rem;
}

.control-section:last-of-type {
    margin-bottom: 0;
}

.control-section h2 {
    font-size: 0.9375rem;
    font-weight: 600;
    margin-bottom: 0.625rem;
    color: var(--text-primary);
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.375rem;
}

.input-group {
    margin-bottom: 0.625rem;
}

.input-group:last-child {
    margin-bottom: 0;
}

.control-section.full-width {
    grid-column: 1 / -1;
}

label {
    display: block;
    font-size: 0.75rem;
    font-weight: 500;
    margin-bottom: 0.25rem;
    color: var(--text-secondary);
}

input[type="text"],
textarea,
select {
    width: 100%;
    padding: 0.4rem 0.625rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 0.8125rem;
    transition: border-color 0.2s, box-shadow 0.2s;
    font-family: inherit;
    background: var(--surface-light);
    color: var(--text-primary);
}

textarea {
    resize: vertical;
}

input[type="text"]:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.2);
}

input[type="range"] {
    width: calc(100% - 50px);
    height: 5px;
    border-radius: 3px;
    background: var(--border-color);
    outline: none;
    -webkit-appearance: none;
    margin-right: 0.75rem;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    transition: transform 0.2s;
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

input[type="range"]::-moz-range-thumb {
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
    transition: transform 0.2s;
}

input[type="range"]::-moz-range-thumb:hover {
    transform: scale(1.2);
}

.range-value {
    display: inline-block;
    min-width: 40px;
    text-align: right;
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--text-secondary);
}

input[type="color"] {
    width: 100%;
    height: 36px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    cursor: pointer;
    background: var(--surface-light);
}

input[type="file"] {
    width: 100%;
    padding: 0.5rem;
    border: 2px dashed var(--border-color);
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.8125rem;
    transition: border-color 0.2s;
    background: var(--surface-light);
    color: var(--text-primary);
}

input[type="file"]:hover {
    border-color: var(--primary-color);
}

.logo-preview {
    margin-top: 0.5rem;
    min-height: 60px;
    display: none;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 0.5rem;
    background: var(--surface-light);
}

.logo-preview.active {
    display: flex;
}

.logo-preview img {
    max-width: 100%;
    max-height: 60px;
    object-fit: contain;
}

.generate-btn,
.download-btn {
    padding: 0.625rem 1.25rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 0.9375rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s, transform 0.1s;
    box-shadow: var(--shadow-sm);
}

.generate-btn {
    width: 100%;
}

.generate-btn:hover,
.download-btn:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
}

.generate-btn:active,
.download-btn:active {
    transform: translateY(0);
}

.download-btn:disabled {
    background: var(--border-color);
    color: var(--text-secondary);
    cursor: not-allowed;
    transform: none;
}

.download-btn:disabled:hover {
    background: var(--border-color);
    transform: none;
}

.preview-panel {
    display: flex;
    flex-direction: column;
}

.preview-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.preview-header h2 {
    font-size: 1rem;
    font-weight: 600;
}

.qr-container {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    background: var(--background);
    padding: 2rem;
    margin-bottom: 1rem;
}

.qr-container canvas {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    box-shadow: var(--shadow-lg);
}

.placeholder {
    text-align: center;
    color: var(--text-secondary);
}

.placeholder svg {
    margin-bottom: 1rem;
    opacity: 0.3;
}

.placeholder p {
    font-size: 0.875rem;
}

.auto-update-container {
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 0.75rem;
}

.toggle-label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    user-select: none;
}

.toggle-label input[type="checkbox"] {
    width: 40px;
    height: 20px;
    appearance: none;
    background: var(--border-color);
    border-radius: 10px;
    position: relative;
    cursor: pointer;
    transition: background-color 0.3s;
}

.toggle-label input[type="checkbox"]:checked {
    background: var(--primary-color);
}

.toggle-label input[type="checkbox"]::before {
    content: '';
    position: absolute;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: white;
    top: 2px;
    left: 2px;
    transition: transform 0.3s;
}

.toggle-label input[type="checkbox"]:checked::before {
    transform: translateX(20px);
}

.toggle-text {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.button-group {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.75rem;
}

footer {
    text-align: center;
    padding: 1.5rem 0;
    color: var(--text-secondary);
    font-size: 0.8125rem;
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
}

footer a:hover {
    text-decoration: underline;
}

@media (max-width: 1200px) {
    .controls-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 1024px) {
    .main-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 640px) {
    .container {
        padding: 1rem;
    }

    header h1 {
        font-size: 1.75rem;
    }

    .controls-panel,
    .preview-panel {
        padding: 1rem;
    }

    .button-group {
        grid-template-columns: 1fr;
    }
}