/* ==========================================================================
   Benjamin Yi — personal site
   Hand-written CSS. Two families: Archivo (variable, wdth+wght) / JetBrains Mono.
   Dark-first with a paper light theme. Texture over gloss. No frameworks.
   ========================================================================== */

/* ---------- tokens ---------- */

:root {
  --font-sans: "Archivo", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  --w: min(1100px, calc(100vw - 2 * var(--gutter)));
  --gutter: clamp(1.25rem, 5vw, 4rem);

  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0c0c0b;
  --surface: #131311;
  --ink: #ece9e2;
  --muted: #8d8a80;
  --accent: #ff4d00;
  --accent-ink: #0c0c0b;
  --line: #262520;
  --line-strong: #3a3830;
  --glow: rgba(255, 77, 0, 0.07);
  --noise-opacity: 0.05;
}

:root[data-theme="light"] {
  color-scheme: light;
  --bg: #f2efe7;
  --surface: #faf8f1;
  --ink: #181712;
  --muted: #6f6b5e;
  --accent: #bf3300; /* 4.9:1 on the paper background — WCAG AA for small text */
  --accent-ink: #f2efe7;
  --line: #dcd6c6;
  --line-strong: #c4bda9;
  --glow: rgba(214, 58, 0, 0.06);
  --noise-opacity: 0.07;
}

/* ---------- base ---------- */

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: 6rem;
}

body {
  margin: 0;
  overflow-x: clip; /* the hero particle canvas bleeds past the content column */
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: clamp(1rem, 0.95rem + 0.3vw, 1.125rem);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  transition: background-color 0.35s ease, color 0.35s ease;
}

.mono {
  font-family: var(--font-mono);
  font-size: 0.78em;
  letter-spacing: 0.06em;
}

a { color: var(--ink); text-decoration-color: var(--accent); text-decoration-thickness: 1.5px; text-underline-offset: 0.2em; }
a:hover { color: var(--accent); }

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

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

h1, h2, h3 { margin: 0; font-weight: 700; line-height: 1.05; letter-spacing: -0.02em; text-wrap: balance; }
p { margin: 0; }

/* ---------- chrome: skip link, grain, svg defs ---------- */

.skip {
  position: fixed;
  top: 0.75rem;
  left: 50%;
  translate: -50% -300%;
  z-index: 100;
  background: var(--accent);
  color: var(--accent-ink);
  padding: 0.5rem 1rem;
  border-radius: 999px;
  text-decoration: none;
  transition: translate 0.25s var(--ease-out);
}
.skip:focus-visible { translate: -50% 0; color: var(--accent-ink); }

.noise {
  position: fixed;
  inset: -50%;
  z-index: 90;
  pointer-events: none;
  opacity: var(--noise-opacity);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='240' height='240'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

.svg-defs { position: absolute; width: 0; height: 0; overflow: hidden; }

/* ---------- header ---------- */

.site-head {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 80;
  display: flex;
  align-items: center;
  gap: 1.5rem;
  padding: 0.9rem var(--gutter);
  background: color-mix(in srgb, var(--bg) 78%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}

.mark {
  font-weight: 500;
  text-decoration: none;
  color: var(--accent);
}

.site-nav { display: flex; gap: 1.4rem; margin-left: auto; }
.site-nav a { text-decoration: none; color: var(--muted); text-transform: uppercase; }
.site-nav a:hover { color: var(--accent); }

.theme-toggle {
  border: 1px solid var(--line-strong);
  background: transparent;
  color: var(--muted);
  border-radius: 999px;
  padding: 0.3rem 0.85rem;
  cursor: pointer;
  font-size: 0.68rem;
  letter-spacing: 0.08em;
}
.theme-toggle:hover { color: var(--accent); border-color: var(--accent); }
:root[data-theme="dark"]  .theme-toggle__dark  { display: none; }
:root[data-theme="light"] .theme-toggle__light { display: none; }

/* ---------- hero ---------- */

.hero {
  width: var(--w);
  margin-inline: auto;
  min-height: 86svh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding-top: 6rem;
  padding-bottom: clamp(3rem, 5vh, 4.5rem);
  position: relative;
  /* Indent intro copy to the ASCII art's left edge: the art is 73 columns
     of mono (0.6em advance) centered in the column. JS refines this with
     the measured value once the canvas is live. */
  --ascii-fs: clamp(7px, calc((100vw - 2 * var(--gutter)) / 44), 25px);
  --hero-indent: max(0px, calc((var(--w) - var(--ascii-fs) * 43.8) / 2));
}

.hero > .eyebrow,
.hero > .lede,
.hero > .hero__cta {
  margin-left: var(--hero-indent, 0px);
}

/* faint structural grid behind the hero */
.hero::before {
  content: "";
  position: absolute;
  inset: 0 calc(-1 * var(--gutter));
  background-image:
    linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 72px 72px;
  mask-image: radial-gradient(ellipse 75% 60% at 30% 45%, black 0%, transparent 70%);
  opacity: 0.5;
  pointer-events: none;
}

.eyebrow {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.25rem 0.6rem;
  color: var(--muted);
  margin-bottom: 1.2rem;
}

.pulse {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 0 var(--accent);
  animation: pulse 2.4s infinite;
}
@keyframes pulse {
  0%   { box-shadow: 0 0 0 0 color-mix(in srgb, var(--accent) 60%, transparent); }
  70%  { box-shadow: 0 0 0 12px transparent; }
  100% { box-shadow: 0 0 0 0 transparent; }
}

.hero__name {
  position: relative;
  z-index: 1;
  margin: 0;
}

/* The name is ASCII art in a <pre>; the h1 carries the real text via
   aria-label. 73 columns of JetBrains Mono (0.6em advance) sized to fill
   the content width: (100vw - gutters) / (73 * 0.6) ≈ / 44. */
.hero__ascii {
  margin: 0;
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: clamp(7px, calc((100vw - 2 * var(--gutter)) / 44), 25px);
  line-height: 1.06;
  letter-spacing: 0;
  color: var(--ink);
  user-select: none;
  text-align: center; /* each art line centers itself in the column */
}

/* When the particle canvas takes over, the <pre> keeps its layout box
   but stops painting. */
.hero__ascii.ghost { visibility: hidden; }

.hero__canvas {
  position: absolute;
  pointer-events: none;
}

.hero__name { cursor: crosshair; }

.hero__tag {
  font-size: clamp(1.35rem, 3vw, 2.2rem);
  font-weight: 300;
  margin-top: 1.6rem;
  letter-spacing: -0.01em;
  max-width: 26em;
  text-wrap: balance;
}

.lede {
  max-width: 38em;
  color: var(--muted);
  margin-top: 1.6rem;
}
.lede a { color: var(--ink); }
.lede a:hover { color: var(--accent); }

.hero__cta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1.4rem;
  margin-top: 2.6rem;
}

.hero__flag {
  width: 21px;
  height: 14px;
  border-radius: 2px;
  outline: 1px solid var(--line-strong);
  flex-shrink: 0;
}

/* ---------- buttons ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.8rem 1.5rem;
  border-radius: 999px;
  border: 1px solid var(--accent);
  background: var(--accent);
  color: var(--accent-ink);
  font: inherit;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: transform 0.25s var(--ease-out), background-color 0.25s ease, color 0.25s ease;
}
.btn:hover { transform: translateY(-2px); color: var(--accent-ink); }

.btn--ghost {
  background: transparent;
  color: var(--ink);
  border-color: var(--line-strong);
}
.btn--ghost:hover { border-color: var(--accent); color: var(--accent); }

/* ---------- stats ---------- */

.stats {
  border-block: 1px solid var(--line);
  background: var(--surface);
}

.stats__grid {
  width: var(--w);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
}

.stat {
  padding: 2rem 1.5rem 2rem 0;
  border-left: 1px solid var(--line);
  padding-left: 1.5rem;
}
.stat:first-child { border-left: none; padding-left: 0; }

.stat dt { color: var(--muted); font-size: 0.68rem; }
.stat dd {
  margin: 0.4rem 0 0;
  font-size: clamp(1.8rem, 3.4vw, 2.6rem);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.02em;
}

/* ---------- sections ---------- */

.section {
  width: var(--w);
  margin-inline: auto;
  padding-block: clamp(4.5rem, 9vh, 7rem);
  border-top: 1px solid var(--line);
}
.section:first-of-type { border-top: none; }

.section__no {
  color: var(--accent);
  margin-bottom: 1.4rem;
}

.section h2 {
  font-size: clamp(2rem, 5.4vw, 3.6rem);
  max-width: 16em;
}

.section__intro {
  max-width: 38em;
  color: var(--muted);
  margin-top: 1.4rem;
}

.section__link {
  display: inline-block;
  margin-top: 2.6rem;
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--accent);
  padding-bottom: 0.3rem;
}
.section__link:hover { color: var(--accent); }

/* rows (work + building) */

.rows {
  list-style: none;
  margin: 3rem 0 0;
  padding: 0;
}

.row {
  display: grid;
  grid-template-columns: minmax(0, 16rem) 1fr;
  gap: 1rem 3rem;
  padding-block: 1.8rem;
  border-top: 1px solid var(--line);
  transition: border-color 0.3s ease;
}
.row:hover { border-top-color: var(--accent); }

.row h3 { font-size: 1.25rem; }
.row p { color: var(--muted); max-width: 42em; }

.rows--tagged .row { grid-template-columns: minmax(0, 16rem) 1fr; align-items: baseline; }
.row__tag { color: var(--accent); }

/* paper cards (research section) */

.paper-link {
  display: grid;
  grid-template-columns: minmax(0, 16rem) 1fr;
  gap: 1rem 3rem;
  text-decoration: none;
  color: inherit;
}
.row--paper { display: block; padding-block: 0; }
.row--paper .paper-link { padding-block: 1.8rem; }
.row--paper h3 { font-size: 1.25rem; transition: color 0.25s ease; }
.paper-link:hover h3 { color: var(--accent); }
.paper-link:hover { color: inherit; }
.paper-link__body { display: block; }
.paper-link__body p { margin-top: 0.5rem; }
.paper-link__cta {
  display: inline-block;
  margin-top: 1rem;
  color: var(--accent);
}

@media (max-width: 720px) {
  .paper-link { grid-template-columns: 1fr; }
}

/* the two-company split */

.split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  margin-top: 3rem;
}

.split__panel {
  background: var(--bg);
  padding: 2.2rem 2rem 2rem;
  transition: background-color 0.3s ease;
}
.split__panel:hover { background: var(--surface); }

.split__label { color: var(--accent); font-size: 0.65rem; }

.split__brand {
  display: flex;
  align-items: center;
  height: 40px;
  margin-bottom: 1.1rem;
}
.rf-logo { max-height: 32px; max-width: 200px; width: auto; }
:root[data-theme="dark"]  .rf-logo--onlight { display: none; }
:root[data-theme="light"] .rf-logo--ondark  { display: none; }

/* If the brand image can't load, fall back to a text wordmark. */
.split__wordmark { display: none; font-size: 1.05rem; font-weight: 700; letter-spacing: 0.14em; }
.split__brand.noimg .rf-logo { display: none; }
.split__brand.noimg .split__wordmark { display: inline; }

.split__panel h3 { font-size: 1.35rem; margin-top: 0.9rem; }
.split__sub { color: var(--muted); margin-top: 0.3rem; }

.split__list {
  list-style: none;
  margin: 1.5rem 0 0;
  padding: 0;
}
.split__list li {
  padding: 0.6rem 0;
  border-top: 1px solid var(--line);
  color: var(--muted);
}
.split__list li::before {
  content: "—";
  color: var(--accent);
  margin-right: 0.7rem;
}

.split__foot {
  margin-top: 1.6rem;
  padding-top: 1rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.62rem;
  line-height: 1.8;
}

@media (max-width: 820px) {
  .split { grid-template-columns: 1fr; }
}

/* interests */

.interests {
  list-style: none;
  margin: 3rem 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(290px, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.icard {
  background: var(--bg);
  padding: 1.8rem 1.6rem;
  transition: background-color 0.3s ease;
}
.icard:hover { background: var(--surface); }

.icard__art {
  display: block;
  width: 100%;
  max-width: 230px;
  height: auto;
  color: var(--muted);
  margin-bottom: 1.3rem;
  transition: color 0.3s ease;
}
.icard:hover .icard__art { color: var(--ink); }
.icard__art .acc { stroke: var(--accent); }
.icard__art circle.acc[fill="currentColor"],
.icard__art .acc[fill="currentColor"] { fill: var(--accent); stroke: none; }

.icard__tag { color: var(--accent); font-size: 0.65rem; }
.icard h3 { font-size: 1.15rem; margin-top: 0.5rem; }
.icard p { color: var(--muted); margin-top: 0.4rem; font-size: 0.95rem; }

/* contact */

.section--contact { padding-bottom: clamp(6rem, 16vh, 11rem); }

.cform {
  margin-top: 1.6rem;
  max-width: 44rem;
}

.cform__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
}
@media (max-width: 720px) {
  .cform__grid { grid-template-columns: 1fr; }
}

.cform__field {
  display: block;
  margin-bottom: 1.2rem;
}
.cform__field > span {
  display: block;
  color: var(--muted);
  font-size: 0.65rem;
  margin-bottom: 0.45rem;
}

.cform input,
.cform textarea {
  width: 100%;
  background: var(--surface);
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  color: var(--ink);
  font: inherit;
  padding: 0.75rem 0.9rem;
  transition: border-color 0.25s ease;
}
.cform textarea { resize: vertical; min-height: 7.5rem; }
.cform input:focus-visible,
.cform textarea:focus-visible {
  outline: none;
  border-color: var(--accent);
}

.cform__actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1.2rem;
  margin-top: 0.4rem;
}
.cform__hint { color: var(--muted); font-size: 0.62rem; }

.contact__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
  margin-top: 2.6rem;
  padding-top: 2rem;
  border-top: 1px solid var(--line);
}

/* ---------- footer ---------- */

.site-foot {
  border-top: 1px solid var(--line);
  background: var(--surface);
  padding: 2rem var(--gutter) 2.6rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.8rem 2.5rem;
  color: var(--muted);
}
.site-foot p { font-size: 0.68rem; }

.break {
  margin-left: auto;
  border: 1px dashed var(--line-strong);
  background: transparent;
  color: var(--muted);
  border-radius: 999px;
  padding: 0.45rem 1rem;
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  cursor: pointer;
  transition: color 0.25s ease, border-color 0.25s ease;
}
.break:hover { color: var(--accent); border-color: var(--accent); }

/* black-hole easter egg overlay */
.bh-canvas {
  position: fixed;
  inset: 0;
  z-index: 95;
  pointer-events: none;
}
html.bh-lock,
html.bh-lock body { overflow: hidden; }

/* ---------- toast ---------- */

.toast {
  position: fixed;
  bottom: 1.4rem;
  left: 50%;
  translate: -50% 200%;
  z-index: 100;
  background: var(--ink);
  color: var(--bg);
  padding: 0.7rem 1.3rem;
  border-radius: 999px;
  font-size: 0.72rem;
  letter-spacing: 0.05em;
  transition: translate 0.4s var(--ease-out);
  pointer-events: none;
  max-width: calc(100vw - 2rem);
  text-align: center;
}
.toast.show { translate: -50% 0; }

/* ---------- reveal on scroll ---------- */

/* Hidden-until-scrolled only when JS is running — without JS, all content
   is visible immediately. */
.js .reveal {
  opacity: 0;
  transform: translateY(22px);
  transition: opacity 0.7s var(--ease-out), transform 0.7s var(--ease-out);
}
.js .reveal.in {
  opacity: 1;
  transform: none;
}

/* ---------- responsive ---------- */

@media (max-width: 720px) {
  .site-nav { display: none; }
  .theme-toggle { margin-left: auto; }
  .row, .rows--tagged .row { grid-template-columns: 1fr; }
  .stat { border-left: none; padding-left: 0; border-top: 1px solid var(--line); }
  .stat:first-child { border-top: none; }
}

/* ---------- reduced motion: everything lands instantly ---------- */

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .js .reveal { opacity: 1; transform: none; transition: none; }
  .pulse { animation: none; }
  .btn, .row { transition: none; }
}