:root {
    --color-bg: #111827; /* gray-900 */
    --color-card: #1f2937; /* gray-800 */
    --color-input: #374151; /* gray-700 */
    --color-border: #4b5563; /* gray-600 */
    --color-text-primary: #f9fafb; /* gray-50 */
    --color-text-secondary: #9ca3af; /* gray-400 */
    --color-text-placeholder: #6b7280; /* gray-500 */
    --color-accent: #6366f1; /* indigo-500 */
    --color-red: #ef4444;
    --color-green: #22c55e;
    --color-blue: #3b82f6;
    --font-sans: 'Inter', sans-serif;
}

*, *::before, *::after {
    box-sizing: border-box;
}

body {
    font-family: var(--font-sans);
    background-color: var(--color-bg);
    color: var(--color-text-primary);
    margin: 0;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

#app {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 1rem;
}

.card {
    width: 100%;
    max-width: 28rem; /* max-w-md */
    background-color: var(--color-card);
    border-radius: 1rem; /* rounded-2xl */
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25), 0 0 15px rgba(99, 102, 241, 0.1);
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.title {
    font-size: 1.5rem;
    font-weight: 700;
    text-align: center;
    color: #fff;
    margin: 0;
}

.color-preview {
    position: relative;
    width: 100%;
    padding-top: 100%; /* 1:1 Aspect Ratio */
    border-radius: 0.5rem;
    overflow: hidden;
    transition: background-color 0.3s ease;
}

.color-preview-overlay {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
}

.color-preview-text {
    font-family: monospace;
    font-size: 1.5rem;
    font-weight: 600;
    color: #fff;
    background-color: rgba(0, 0, 0, 0.3);
    padding: 0.5rem 1rem;
    border-radius: 0.375rem;
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.group-title {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-text-secondary);
    margin: 0;
}

.slider-container {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.slider-label {
    width: 1.5rem;
    font-size: 0.875rem;
    font-weight: 600;
    color: #d1d5db; /* gray-300 */
}

.slider {
    width: 100%;
    -webkit-appearance: none;
    appearance: none;
    height: 0.5rem;
    background-color: var(--color-input);
    border-radius: 9999px;
    outline: none;
    cursor: pointer;
}
.slider.slider-r { accent-color: var(--color-red); }
.slider.slider-g { accent-color: var(--color-green); }
.slider.slider-b { accent-color: var(--color-blue); }

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 1.25rem;
    height: 1.25rem;
    border-radius: 50%;
    background-color: var(--color-text-primary);
    border: 3px solid var(--color-bg);
    transition: transform 0.2s ease;
}
.slider:active::-webkit-slider-thumb {
    transform: scale(1.2);
}

.slider::-moz-range-thumb {
    width: 1.25rem;
    height: 1.25rem;
    border-radius: 50%;
    background-color: var(--color-text-primary);
    border: 3px solid var(--color-bg);
    transition: transform 0.2s ease;
}
.slider:active::-moz-range-thumb {
    transform: scale(1.2);
}

.slider-value {
    width: 2.5rem;
    text-align: right;
    font-family: monospace;
    color: #d1d5db; /* gray-300 */
}

.input-wrapper {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.input-label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text-secondary);
}

.input-container {
    position: relative;
}

.input-field {
    width: 100%;
    background-color: var(--color-input);
    border: 1px solid var(--color-border);
    border-radius: 0.375rem;
    padding: 0.5rem 2.5rem 0.5rem 0.75rem;
    color: #fff;
    outline: none;
    transition: border-color 0.2s, box-shadow 0.2s;
}
.input-field::placeholder {
    color: var(--color-text-placeholder);
}
.input-field:focus {
    border-color: var(--color-accent);
    box-shadow: 0 0 0 2px var(--color-accent);
}
.input-field[readonly] {
    cursor: default;
}


.copy-button {
    position: absolute;
    inset-block: 0;
    right: 0;
    display: flex;
    align-items: center;
    padding-inline: 0.75rem;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--color-text-secondary);
    transition: color 0.2s ease;
}
.copy-button:hover {
    color: #fff;
}

.icon {
    width: 1.25rem;
    height: 1.25rem;
}

.icon-check {
    color: var(--color-green);
}

.hidden {
    display: none !important;
}

.group-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.eyedropper-container {
    display: flex;
}

.eyedropper-button {
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--color-input);
    border: 1px solid var(--color-border);
    border-radius: 0.375rem;
    padding: 0.25rem;
    color: var(--color-text-primary);
    cursor: pointer;
    transition: all 0.2s ease;
}

.eyedropper-button:hover {
    background-color: var(--color-border);
    border-color: var(--color-text-secondary);
    color: var(--color-accent);
}

.eyedropper-button:active {
    transform: scale(0.9);
}

.eyedropper-button .icon {
    width: 1.25rem;
    height: 1.25rem;
}