/* ==========================================================================
   BASE — CSS Custom Properties, Reset, Typography
   ========================================================================== */

/* --------------------------------------------------------------------------
   Design Tokens — Light Mode (default)
   -------------------------------------------------------------------------- */
:root {
    /* Colors */
    --color-bg-rgb:      242, 244, 243;
    --color-bg:          #F2F4F3;
    --color-bg-card:     #FFFFFF;
    --color-bg-subtle:   #E8EBE9;
    --color-bg-elevated: #FFFFFF;
    --color-text:        #1E2D2A;
    --color-text-muted:  #4A5C57;
    --color-text-faint:  #7A928C;
    --color-heading:     #0F1F1C;
    --color-accent:      #2D7A5F;
    --color-accent-hover:#1F5A44;
    --color-accent-rgb:  45, 122, 95;
    --color-accent-light:rgba(45, 122, 95, 0.10);
    --color-accent-glow: rgba(45, 122, 95, 0.25);
    --color-border:      #CDD4D1;
    --color-border-light:#E0E5E3;
    --color-shadow:      rgba(15, 31, 28, 0.08);
    --color-shadow-md:   rgba(15, 31, 28, 0.14);
    --color-overlay:     rgba(15, 31, 28, 0.55);

    /* Section colors */
    --color-science:     #2D7A5F;
    --color-belief:      #5B6D9E;
    --color-humanities:  #8B5E3C;
    --color-dialogue:    #7A5C8C;

    /* Typography */
    --font-serif:     'Playfair Display', Georgia, 'Times New Roman', serif;
    --font-body:      'Merriweather', Georgia, serif;
    --font-ui:        'DM Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono:      'JetBrains Mono', 'Fira Code', monospace;

    /* Spacing */
    --space-xs:   0.25rem;
    --space-sm:   0.5rem;
    --space-md:   1rem;
    --space-lg:   1.5rem;
    --space-xl:   2.5rem;
    --space-2xl:  4rem;
    --space-3xl:  6rem;

    /* Layout */
    --container-max:    1400px;
    --container-narrow: 720px;
    --container-mid:    960px;
    --header-height:    72px;

    /* Radius */
    --radius-sm:  4px;
    --radius-md:  8px;
    --radius-lg:  16px;
    --radius-xl:  24px;
    --radius-pill:9999px;

    /* Transitions */
    --transition-fast:   150ms ease;
    --transition-base:   250ms ease;
    --transition-slow:   400ms ease;
    --transition-colors: background-color 300ms ease, color 300ms ease, border-color 300ms ease, box-shadow 300ms ease;
}

/* --------------------------------------------------------------------------
   Dark Mode — via OS preference
   -------------------------------------------------------------------------- */
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        --color-bg-rgb:      26, 31, 46;
        --color-bg:          #1A1F2E;
        --color-bg-card:     #222840;
        --color-bg-subtle:   #1E2535;
        --color-bg-elevated: #2A3250;
        --color-text:        #E8EEF4;
        --color-text-muted:  #8DA3B5;
        --color-text-faint:  #566880;
        --color-heading:     #F0F6FF;
        --color-accent:      #3ECFCF;
        --color-accent-hover:#2BA8A8;
        --color-accent-rgb:  62, 207, 207;
        --color-accent-light:rgba(62, 207, 207, 0.10);
        --color-accent-glow: rgba(62, 207, 207, 0.20);
        --color-border:      #2E3650;
        --color-border-light:#242B40;
        --color-shadow:      rgba(0, 0, 0, 0.30);
        --color-shadow-md:   rgba(0, 0, 0, 0.45);
        --color-overlay:     rgba(0, 0, 0, 0.65);
    }
}

/* Dark mode via manual toggle */
[data-theme="dark"] {
    --color-bg-rgb:      26, 31, 46;
    --color-bg:          #1A1F2E;
    --color-bg-card:     #222840;
    --color-bg-subtle:   #1E2535;
    --color-bg-elevated: #2A3250;
    --color-text:        #E8EEF4;
    --color-text-muted:  #8DA3B5;
    --color-text-faint:  #566880;
    --color-heading:     #F0F6FF;
    --color-accent:      #3ECFCF;
    --color-accent-hover:#2BA8A8;
    --color-accent-rgb:  62, 207, 207;
    --color-accent-light:rgba(62, 207, 207, 0.10);
    --color-accent-glow: rgba(62, 207, 207, 0.20);
    --color-border:      #2E3650;
    --color-border-light:#242B40;
    --color-shadow:      rgba(0, 0, 0, 0.30);
    --color-shadow-md:   rgba(0, 0, 0, 0.45);
    --color-overlay:     rgba(0, 0, 0, 0.65);
}

/* Light mode via manual toggle */
[data-theme="light"] {
    --color-bg-rgb:      242, 244, 243;
    --color-bg:          #F2F4F3;
    --color-bg-card:     #FFFFFF;
    --color-bg-subtle:   #E8EBE9;
    --color-bg-elevated: #FFFFFF;
    --color-text:        #1E2D2A;
    --color-text-muted:  #4A5C57;
    --color-text-faint:  #7A928C;
    --color-heading:     #0F1F1C;
    --color-accent:      #2D7A5F;
    --color-accent-hover:#1F5A44;
    --color-accent-rgb:  45, 122, 95;
    --color-accent-light:rgba(45, 122, 95, 0.10);
    --color-accent-glow: rgba(45, 122, 95, 0.25);
    --color-border:      #CDD4D1;
    --color-border-light:#E0E5E3;
    --color-shadow:      rgba(15, 31, 28, 0.08);
    --color-shadow-md:   rgba(15, 31, 28, 0.14);
    --color-overlay:     rgba(15, 31, 28, 0.55);
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    margin: 0;
    background-color: var(--color-bg);
    color: var(--color-text);
    font-family: var(--font-ui);
    font-size: 1rem;
    line-height: 1.6;
    transition: var(--transition-colors);
    overflow-x: hidden;
}

img, video, svg {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover { color: var(--color-accent-hover); }
a:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 3px;
    border-radius: var(--radius-sm);
}

ul, ol { margin: 0; padding: 0; list-style: none; }
p { margin: 0 0 1.4em; }
h1, h2, h3, h4, h5, h6 {
    margin: 0 0 0.6em;
    font-family: var(--font-serif);
    font-weight: 700;
    color: var(--color-heading);
    line-height: 1.2;
    letter-spacing: -0.01em;
}

h1 { font-size: clamp(2rem, 4vw, 3.25rem); }
h2 { font-size: clamp(1.6rem, 3vw, 2.25rem); }
h3 { font-size: clamp(1.25rem, 2.5vw, 1.6rem); }
h4 { font-size: 1.2rem; }
h5 { font-size: 1rem; font-family: var(--font-ui); font-weight: 600; }
h6 { font-size: 0.875rem; font-family: var(--font-ui); font-weight: 600; }

blockquote {
    margin: 2rem 0;
    padding: 1.5rem 2rem;
    border-left: 4px solid var(--color-accent);
    background: var(--color-accent-light);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    font-family: var(--font-body);
    font-style: italic;
    font-size: 1.1rem;
    color: var(--color-text);
}

blockquote cite {
    display: block;
    margin-top: 0.75rem;
    font-size: 0.85rem;
    font-style: normal;
    color: var(--color-text-muted);
}

figure { margin: 0; }
figcaption {
    font-size: 0.825rem;
    color: var(--color-text-muted);
    font-family: var(--font-ui);
    margin-top: 0.5rem;
}

hr {
    border: none;
    border-top: 1px solid var(--color-border);
    margin: var(--space-xl) 0;
}

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

.skip-link {
    position: absolute;
    top: -100%;
    left: 1rem;
    padding: 0.75rem 1.5rem;
    background: var(--color-accent);
    color: #fff;
    font-family: var(--font-ui);
    font-weight: 600;
    border-radius: var(--radius-md);
    z-index: 9999;
    transition: top var(--transition-fast);
}
.skip-link:focus { top: 1rem; color: #fff; }

/* Reduced motion */
@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;
    }
}