:root {
    /* Base Colors - Light Theme */
    --bg-color: #f8f9fa;
    --surface-color: #ffffff;
    --text-color: #212529;
    --text-muted: #6c757d;
    --border-color: #dee2e6;
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    
    /* Spacing & Layout */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    
    --border-radius-sm: 4px;
    --border-radius-md: 8px;
    --border-radius-lg: 12px;
    --border-radius-full: 9999px;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #0f172a;
        --surface-color: #1e293b;
        --text-color: #f8fafc;
        --text-muted: #94a3b8;
        --border-color: #334155;
        --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.5);
        --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.5), 0 2px 4px -2px rgb(0 0 0 / 0.5);
    }
}

/* Override for explicit theme toggling */
[data-theme="light"] {
    --bg-color: #f8f9fa;
    --surface-color: #ffffff;
    --text-color: #212529;
    --text-muted: #6c757d;
    --border-color: #dee2e6;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
}

[data-theme="dark"] {
    --bg-color: #0f172a;
    --surface-color: #1e293b;
    --text-color: #f8fafc;
    --text-muted: #94a3b8;
    --border-color: #334155;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.5);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.5), 0 2px 4px -2px rgb(0 0 0 / 0.5);
}

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

body {
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

header {
    width: 100%;
    max-width: 600px;
    padding: var(--spacing-xl) var(--spacing-md) var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

h1 {
    font-size: 1.75rem;
    font-weight: 700;
    letter-spacing: -0.025em;
}

button {
    background: none;
    border: none;
    cursor: pointer;
    color: inherit;
    font-family: inherit;
    transition: all var(--transition-fast);
}

#theme-toggle {
    padding: var(--spacing-sm);
    border-radius: var(--border-radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

#theme-toggle:hover {
    background-color: var(--border-color);
}

main {
    width: 100%;
    max-width: 600px;
    padding: var(--spacing-md);
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
}

/* Hide labels visually but keep them for screen readers */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.picker-section {
    background-color: var(--surface-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xl);
    transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

/* Customizing the color input to be a large clickable area */
.color-preview {
    width: 160px;
    height: 160px;
    border-radius: 50%;
    overflow: hidden;
    position: relative;
    box-shadow: var(--shadow-md);
    border: 4px solid var(--surface-color);
    transition: transform var(--transition-fast);
}

.color-preview:hover {
    transform: scale(1.05);
}

.color-preview:focus-within {
    outline: 2px solid var(--primary-color);
    outline-offset: 4px;
}

input[type="color"] {
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    cursor: pointer;
    border: none;
    padding: 0;
    background: none;
}

/* Hide default color picker styling */
input[type="color"]::-webkit-color-swatch-wrapper {
    padding: 0;
}
input[type="color"]::-webkit-color-swatch {
    border: none;
}

.values-container {
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.value-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.value-group label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.input-wrapper input {
    width: 100%;
    padding: var(--spacing-md);
    padding-right: 3rem;
    font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
    font-size: 1rem;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    color: var(--text-color);
    transition: all var(--transition-fast);
}

.input-wrapper input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.copy-btn {
    position: absolute;
    right: 0.5rem;
    width: 2rem;
    height: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--border-radius-sm);
    color: var(--text-muted);
}

.copy-btn:hover, .copy-btn:focus-visible {
    background-color: var(--border-color);
    color: var(--text-color);
    outline: none;
}

/* History Section */
.history-section {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.history-section h2 {
    font-size: 1.25rem;
    font-weight: 600;
}

.color-history {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    gap: var(--spacing-sm);
}

.history-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm);
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    box-shadow: var(--shadow-sm);
}

.history-item:hover {
    border-color: var(--text-muted);
    transform: translateY(-1px);
}

.history-color-swatch {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    border: 1px solid rgba(0, 0, 0, 0.1);
}

.history-color-value {
    font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
    font-size: 0.875rem;
    text-transform: uppercase;
}

.secondary-btn {
    align-self: flex-start;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.875rem;
    color: var(--text-muted);
    border-radius: var(--border-radius-md);
    border: 1px solid transparent;
}

.secondary-btn:hover {
    background-color: var(--surface-color);
    border-color: var(--border-color);
    color: var(--text-color);
}

/* Native Dialog for Toasts */
.toast {
    margin: auto auto 2rem auto;
    padding: var(--spacing-md) var(--spacing-lg);
    background-color: var(--text-color);
    color: var(--bg-color);
    border: none;
    border-radius: var(--border-radius-full);
    box-shadow: var(--shadow-md);
    font-weight: 500;
    opacity: 0;
    transform: translateY(1rem);
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.toast[open] {
    opacity: 1;
    transform: translateY(0);
}

/* Responsive adjustments */
@media (max-width: 480px) {
    .picker-section {
        padding: var(--spacing-md);
    }
    
    .color-preview {
        width: 120px;
        height: 120px;
    }
}