/* CSS Variables */
:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --secondary-color: #818cf8;
    --background-color: #0f172a;
    --surface-color: #1e293b;
    --surface-light: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --border-color: #475569;
    --success-color: #22c55e;
    --preview-gradient: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #d946ef 100%);
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -2px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.3), 0 4px 6px -4px rgba(0, 0, 0, 0.2);
    --radius: 12px;
    --transition: all 0.2s ease;
}

/* Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

/* App Container */
.app-container {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 2.5rem;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    background: var(--preview-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.5rem;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Main Content */
main {
    flex: 1;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    align-items: start;
}

/* Preview Section */
.preview-section {
    background: var(--surface-color);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow-lg);
    position: sticky;
    top: 2rem;
}

.preview-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 300px;
    background: var(--surface-light);
    border-radius: var(--radius);
    padding: 2rem;
    margin-bottom: 1.5rem;
}

.preview-box {
    width: 200px;
    height: 200px;
    background: var(--preview-gradient);
    box-shadow: var(--shadow-lg);
    transition: border-radius 0.15s ease, width 0.2s ease, height 0.2s ease;
}

.preview-size-control {
    display: flex;
    align-items: center;
    gap: 1rem;
    justify-content: center;
}

.preview-size-control label {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.preview-size-control input[type="range"] {
    width: 150px;
}

#previewSizeValue {
    color: var(--text-secondary);
    font-size: 0.9rem;
    min-width: 50px;
}

/* Controls Section */
.controls-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.control-group {
    background: var(--surface-color);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
}

.control-group h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Unit Toggle */
.unit-toggle {
    display: flex;
    gap: 0.5rem;
}

.unit-btn {
    flex: 1;
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-color);
    background: transparent;
    color: var(--text-secondary);
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    transition: var(--transition);
}

.unit-btn:hover {
    border-color: var(--primary-color);
    color: var(--text-primary);
}

.unit-btn.active {
    background: var(--primary-color);
    border-color: var(--primary-color);
    color: white;
}

/* Link Toggle */
.link-toggle {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.toggle-switch {
    position: relative;
    display: inline-block;
    width: 52px;
    height: 28px;
}

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

.toggle-slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--surface-light);
    border-radius: 28px;
    transition: var(--transition);
}

.toggle-slider::before {
    position: absolute;
    content: "";
    height: 20px;
    width: 20px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    border-radius: 50%;
    transition: var(--transition);
}

.toggle-switch input:checked + .toggle-slider {
    background-color: var(--primary-color);
}

.toggle-switch input:checked + .toggle-slider::before {
    transform: translateX(24px);
}

.toggle-label {
    color: var(--text-secondary);
}

/* Corners Grid */
.corners-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.corner-input label {
    display: block;
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.input-wrapper {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.input-wrapper input[type="range"] {
    width: 100%;
}

.input-wrapper input[type="number"] {
    width: 100%;
    padding: 0.6rem 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    background: var(--surface-light);
    color: var(--text-primary);
    font-size: 1rem;
    transition: var(--transition);
}

.input-wrapper input[type="number"]:focus {
    outline: none;
    border-color: var(--primary-color);
}

.unit-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-align: right;
}

/* Range Input Styling */
input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    height: 6px;
    background: var(--surface-light);
    border-radius: 3px;
    cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 18px;
    height: 18px;
    background: var(--primary-color);
    border-radius: 50%;
    cursor: pointer;
    transition: var(--transition);
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.1);
    background: var(--primary-hover);
}

input[type="range"]::-moz-range-thumb {
    width: 18px;
    height: 18px;
    background: var(--primary-color);
    border-radius: 50%;
    cursor: pointer;
    border: none;
    transition: var(--transition);
}

input[type="range"]::-moz-range-thumb:hover {
    transform: scale(1.1);
    background: var(--primary-hover);
}

/* Presets Grid */
.presets-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.75rem;
}

.preset-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    background: transparent;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
}

.preset-btn:hover {
    border-color: var(--primary-color);
    background: var(--surface-light);
}

.preset-btn.active {
    border-color: var(--primary-color);
    background: rgba(99, 102, 241, 0.2);
}

.preset-preview {
    width: 40px;
    height: 40px;
    background: var(--preview-gradient);
}

.preset-btn span {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

/* CSS Output */
.css-output {
    position: relative;
}

.code-container {
    display: flex;
    align-items: stretch;
    background: var(--background-color);
    border-radius: 8px;
    overflow: hidden;
    border: 2px solid var(--border-color);
}

.code-container pre {
    flex: 1;
    padding: 1rem;
    font-family: 'Fira Code', 'Monaco', 'Consolas', monospace;
    font-size: 0.9rem;
    color: var(--secondary-color);
    white-space: pre-wrap;
    word-break: break-all;
    margin: 0;
}

.copy-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1rem;
    background: var(--primary-color);
    color: white;
    border: none;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    transition: var(--transition);
}

.copy-btn:hover {
    background: var(--primary-hover);
}

.copy-btn svg {
    width: 18px;
    height: 18px;
}

.copy-feedback {
    position: absolute;
    bottom: -30px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--success-color);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 6px;
    font-size: 0.85rem;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
}

.copy-feedback.show {
    opacity: 1;
    visibility: visible;
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 0 1rem;
    margin-top: 2rem;
    border-top: 1px solid var(--border-color);
}

footer p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

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

footer a:hover {
    color: var(--secondary-color);
    text-decoration: underline;
}

/* Responsive Design */
@media (max-width: 900px) {
    main {
        grid-template-columns: 1fr;
    }

    .preview-section {
        position: static;
    }

    .presets-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

@media (max-width: 600px) {
    .app-container {
        padding: 1rem;
    }

    header h1 {
        font-size: 1.75rem;
    }

    .subtitle {
        font-size: 0.95rem;
    }

    .preview-container {
        min-height: 200px;
        padding: 1rem;
    }

    .preview-box {
        width: 150px;
        height: 150px;
    }

    .control-group {
        padding: 1rem;
    }

    .corners-grid {
        grid-template-columns: 1fr;
    }

    .presets-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .unit-toggle {
        flex-direction: column;
    }

    .code-container {
        flex-direction: column;
    }

    .copy-btn {
        justify-content: center;
        padding: 1rem;
    }

    .preview-size-control {
        flex-wrap: wrap;
    }
}

/* Animations */
@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.7;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        transition: none !important;
        animation: none !important;
    }
}

/* Focus styles for accessibility */
button:focus-visible,
input:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}