/* ============================================================
   BASE.CSS — Design Tokens, Reset, Foundation
   Sathya Elumalai Personal Site
   ============================================================ */

/* ---------- Type Scale (Fluid) ---------- */
:root {
  --text-xs:   clamp(0.75rem,  0.7rem  + 0.25vw, 0.875rem);
  --text-sm:   clamp(0.875rem, 0.8rem  + 0.35vw, 1rem);
  --text-base: clamp(1rem,     0.95rem + 0.25vw, 1.125rem);
  --text-lg:   clamp(1.125rem, 1rem    + 0.75vw, 1.5rem);
  --text-xl:   clamp(1.5rem,   1.2rem  + 1.25vw, 2.25rem);
  --text-2xl:  clamp(2rem,     1.2rem  + 2.5vw,  3.5rem);
  --text-3xl:  clamp(2.5rem,   1rem    + 4vw,    5rem);
  --text-hero: clamp(3rem,     0.5rem  + 7vw,    8rem);

  /* ---------- 4px Spacing System ---------- */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-5:  1.25rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  --space-32: 8rem;

  /* ---------- Font Families ---------- */
  --font-display: 'Instrument Serif', Georgia, serif;
  --font-body: 'Satoshi', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-system: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Segoe UI', sans-serif;

  /* ---------- Radius ---------- */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-full: 9999px;

  /* ---------- Transitions ---------- */
  --transition-interactive: 180ms cubic-bezier(0.16, 1, 0.3, 1);
  --transition-slow: 400ms cubic-bezier(0.16, 1, 0.3, 1);

  /* ---------- Content Widths ---------- */
  --content-narrow: 640px;
  --content-default: 960px;
  --content-wide: 1200px;
  --content-full: 100%;
}

/* ---------- Light Mode (Default) ---------- */
:root, [data-theme="light"] {
  --color-bg:             #FAFAF8;
  --color-surface:        #F5F5F2;
  --color-surface-2:      #EEEEEB;
  --color-surface-offset: #F0F0ED;
  --color-divider:        #E0E0DC;
  --color-border:         #D4D4D0;

  --color-text:           #1A1A1A;
  --color-text-muted:     #6B6B66;
  --color-text-faint:     #A0A09A;
  --color-text-inverse:   #FAFAF8;

  --color-accent:         #2A6F6F;
  --color-accent-hover:   #1E5555;
  --color-accent-light:   rgba(42, 111, 111, 0.08);
  --color-accent-highlight: #D4E6E6;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.06);
  --shadow-lg: 0 12px 32px rgba(0,0,0,0.08);
}

/* ---------- Dark Mode ---------- */
[data-theme="dark"] {
  --color-bg:             #141414;
  --color-surface:        #1C1C1C;
  --color-surface-2:      #242424;
  --color-surface-offset: #1E1E1E;
  --color-divider:        #2A2A2A;
  --color-border:         #333333;

  --color-text:           #E8E6E2;
  --color-text-muted:     #9A9894;
  --color-text-faint:     #5E5E5A;
  --color-text-inverse:   #141414;

  --color-accent:         #3D8B8B;
  --color-accent-hover:   #4DA3A3;
  --color-accent-light:   rgba(61, 139, 139, 0.12);
  --color-accent-highlight: #1E3535;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.2);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.3);
  --shadow-lg: 0 12px 32px rgba(0,0,0,0.4);
}

/* System preference fallback */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --color-bg:             #141414;
    --color-surface:        #1C1C1C;
    --color-surface-2:      #242424;
    --color-surface-offset: #1E1E1E;
    --color-divider:        #2A2A2A;
    --color-border:         #333333;
    --color-text:           #E8E6E2;
    --color-text-muted:     #9A9894;
    --color-text-faint:     #5E5E5A;
    --color-text-inverse:   #141414;
    --color-accent:         #3D8B8B;
    --color-accent-hover:   #4DA3A3;
    --color-accent-light:   rgba(61, 139, 139, 0.12);
    --color-accent-highlight: #1E3535;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.3);
    --shadow-lg: 0 12px 32px rgba(0,0,0,0.4);
  }
}

/* ============================================================
   RESET & BASE
   ============================================================ */

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

html {
  -moz-text-size-adjust: none;
  -webkit-text-size-adjust: none;
  text-size-adjust: none;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  hanging-punctuation: first last;
  scroll-padding-top: 5rem;
}

body {
  min-height: 100dvh;
  line-height: 1.6;
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  overflow-x: hidden;
}

img, picture, video, canvas, svg { display: block; max-width: 100%; height: auto; }
ul[role="list"], ol[role="list"] { list-style: none; }
input, button, textarea, select { font: inherit; color: inherit; }

h1, h2, h3, h4, h5, h6 { text-wrap: balance; line-height: 1.15; }
p, li, figcaption { text-wrap: pretty; max-width: 72ch; }

::selection {
  background: var(--color-accent-light);
  color: var(--color-text);
}

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

@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;
  }
}

button { cursor: pointer; background: none; border: none; }
table { border-collapse: collapse; width: 100%; }

a, button, [role="button"], [role="link"], input, textarea, select {
  transition: color var(--transition-interactive),
              background var(--transition-interactive),
              border-color var(--transition-interactive),
              box-shadow var(--transition-interactive),
              opacity var(--transition-interactive);
}

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

a:hover {
  color: var(--color-accent-hover);
}

.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;
}