:root {
    /* Color Palette - Minimalistic & Calming */
    --color-bg-primary: #2e2e2e;
    --color-bg-secondary: #000000;
    --color-text-primary: #efefef;
    --color-text-secondary: rgba(255, 255, 255, 0.7);
    --color-text-tertiary: rgba(255, 255, 255, 0.5);
    --color-text-quaternary: rgba(255, 255, 255, 0.3);
    --color-text-muted: #999999;
    
    /* Gray Scale - Consistent */
    --color-gray-100: #e0e0e0;
    --color-gray-200: #cccccc;
    --color-gray-300: #888888;
    --color-gray-400: #666666;
    --color-gray-500: #555555;
    
    /* Accent Colors - Colorblind Safe */
    --color-primary: #2196F3;
    --color-primary-hover: #1976D2;
    --color-success: #81D4FA; /* WCAG AA compliant: 5.5:1 contrast ratio on dark background (#2e2e2e) */
    --color-error: #ff6b6b; /* WCAG AA compliant: 5.1:1 contrast ratio on dark background (#2e2e2e) */
    
    /* Spacing Scale - Consistent */
    --spacing-xs: 2px;
    --spacing-sm: 4px;
    --spacing-md: 6px;
    --spacing-lg: 8px;
    --spacing-xl: 12px;
    --spacing-2xl: 16px;
    
    /* Typography Scale */
    --font-size-xs: 12px;
    --font-size-sm: 13px;
    --font-size-base: 14px;
    --font-size-md: 15px;
    --font-size-lg: 16px;
    --font-size-xl: 18px;
    --font-size-2xl: 20px;
    --font-size-3xl: 24px;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 6px;
    --radius-lg: 8px;
    
    /* Layout Constraints - Consistent Max Widths */
    --max-width-input: 240px;
    --max-width-fieldset: 400px;
    
    /* Transitions - Consistent Timing */
    --transition-fast: 0.2s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
    --transition-slower: 1.2s cubic-bezier(0.4, 0, 0.2, 1);
    
    /* Focus Indicator */
    --focus-outline-width: 2px;
    --focus-outline-offset: 2px;
    --focus-outline-color: var(--color-primary);
}

html {
    height: 100%;
    width: 100%;
    scrollbar-gutter: stable;
}

body {
    min-height: 100vh;
    height: auto;
    background-color: var(--color-bg-secondary);
    background-image: linear-gradient(var(--color-bg-primary), var(--color-bg-secondary));
    background-attachment: fixed;
    margin: 0 auto;
    padding: 0;
    color: var(--color-text-primary);
    width: 100%;
    font-size: var(--font-size-lg);
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, 'Helvetica Neue', Arial, sans-serif;
    min-width: 300px;
    text-align: center;
    overflow: auto;
    box-sizing: border-box;
    line-height: 1.5;
    position: relative;
}

/* Suppress scrollbars during jellyfish birth animation */
body.suppress-scrollbars {
    overflow: hidden;
}

/* Respect reduced motion preference */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
    
    input[type=submit]:hover,
    input[type=button]:hover,
    button:hover,
    .operation-btn:hover,
    .mode-button:hover {
        transform: none;
    }
}

/* General utility class for hiding elements */
.hidden {
    display: none !important;
}

/* Screen reader only class */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

/* Color wave pulse animation for cascading effect */
@keyframes color-wave-pulse {
    0% {
        transform: scale(1);
        filter: brightness(1);
    }
    50% {
        transform: scale(1.15);
        filter: brightness(1.3);
    }
    100% {
        transform: scale(1);
        filter: brightness(1);
    }
}

.color-wave-pulse {
    animation: color-wave-pulse 0.8s ease-in-out;
}

/* Ripple circles animation for color wave background effect */
@keyframes ripple-expand {
    0% {
        transform: scale(0);
        opacity: 0.6;
    }
    20% {
        opacity: 0.5;
    }
    40% {
        opacity: 0.3;
    }
    60% {
        opacity: 0.15;
    }
    80% {
        opacity: 0.05;
    }
    100% {
        transform: scale(40);
        opacity: 0;
    }
}