/* ===== Tokens ===== */
:root {
  color-scheme: dark;
  --ink: #0b0c10;
  --ink-2: #12141b;
  --ink-3: #1a1d26;
  --line: #262a35;
  --bone: #ece9e1;
  --mute: #a0a3ae;
  --signal: #ff5a36;
  --signal-deep: #e8431f;
  --on-signal: #170602;
  --ok: #8fd694;

  --font-display: "Bricolage Grotesque", "Segoe UI", system-ui, sans-serif;
  --font-body: "Be Vietnam Pro", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, Consolas, monospace;

  --gutter: clamp(16px, 4vw, 48px);
  --maxw: 1240px;
  --radius: 10px;
  --ease: cubic-bezier(0.16, 1, 0.3, 1);
  --nav-h: 64px;
}

/* ===== Base ===== */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: calc(var(--nav-h) + 16px); }
body {
  margin: 0;
  background: var(--ink);
  color: var(--bone);
  font: 400 1.0625rem/1.6 var(--font-body);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
h1, h2, h3 { font-family: var(--font-display); line-height: 1.02; margin: 0; text-wrap: balance; }
p { margin: 0; text-wrap: pretty; }
a { color: inherit; }
ul, ol, dl, dd { margin: 0; padding: 0; }
li { list-style: none; }
code { font-family: var(--font-mono); font-size: 0.88em; background: var(--ink-3); padding: 0.1em 0.4em; border-radius: 4px; }
:focus-visible { outline: 2px solid var(--signal); outline-offset: 3px; border-radius: 4px; }
::selection { background: var(--signal); color: var(--on-signal); }

.wrap { width: 100%; max-width: var(--maxw); margin-inline: auto; padding-inline: var(--gutter); }
.skip { position: absolute; left: -999px; top: 8px; background: var(--bone); color: var(--ink); padding: 8px 14px; border-radius: 6px; z-index: 100; }
.skip:focus { left: 8px; }

/* ===== Buttons ===== */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--signal); color: var(--on-signal);
  font: 600 1rem/1 var(--font-body);
  padding: 16px 24px; border-radius: 999px; text-decoration: none;
  border: 1.5px solid var(--signal);
  transition: transform 0.35s var(--ease), background 0.2s, color 0.2s;
}
.btn:hover { transform: translateY(-2px); background: var(--bone); border-color: var(--bone); }
.btn--ghost { background: transparent; color: var(--bone); border-color: var(--line); }
.btn--ghost:hover { background: var(--bone); color: var(--ink); }
.btn--small { padding: 10px 18px; font-size: 0.9375rem; }

/* ===== Nav ===== */
.nav {
  position: fixed; inset: 0 0 auto 0; z-index: 50; height: var(--nav-h);
  display: flex; align-items: center; justify-content: space-between; gap: 24px;
  padding-inline: var(--gutter);
  background: color-mix(in srgb, var(--ink) 78%, transparent);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid color-mix(in srgb, var(--line) 70%, transparent);
}
.nav__logo { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; font: 800 1.125rem var(--font-display); }
.nav__links { display: flex; gap: 28px; margin-left: auto; }
.nav__links a { text-decoration: none; color: var(--mute); font-size: 0.9375rem; transition: color 0.2s; }
.nav__links a:hover { color: var(--bone); }

.nav__end { display: flex; align-items: center; gap: 12px; }
.lang {
  display: inline-flex; gap: 2px; padding: 4px; cursor: pointer;
  background: transparent; border: 1px solid var(--line); border-radius: 999px;
  font: 500 0.75rem var(--font-mono); color: var(--mute);
}
.lang span { padding: 5px 9px; border-radius: 999px; transition: background 0.2s, color 0.2s; }
html[lang="en"] .lang [data-l="en"], html[lang="vi"] .lang [data-l="vi"] { background: var(--bone); color: var(--ink); }
.lang:hover { border-color: var(--mute); }

/* ===== Hero ===== */
.hero {
  position: relative; isolation: isolate; overflow: hidden;
  min-height: 100svh; padding-top: calc(var(--nav-h) + 40px);
  display: flex; flex-direction: column; justify-content: space-between; gap: 40px;
  border-bottom: 1px solid var(--line);
}
.hero__graph { position: absolute; inset: 0; width: 100%; height: 100%; z-index: -1; }
.hero::after { /* soft vignette keeps copy legible over the graph */
  content: ""; position: absolute; inset: 0; z-index: -1; pointer-events: none;
  background: linear-gradient(90deg, var(--ink) 0%, color-mix(in srgb, var(--ink) 85%, transparent) 34%, transparent 62%);
}
.hero__copy { display: grid; gap: 24px; max-width: calc(var(--maxw)); align-content: center; flex: 1; }
.hero__copy > * { max-width: 36rem; }
.hero__copy > .hero__role { max-width: 44rem; font: 500 0.875rem var(--font-mono); color: var(--signal); letter-spacing: 0.02em; }
.hero h1 { font-size: clamp(3.25rem, 10vw, 6rem); font-weight: 800; letter-spacing: -0.035em; max-width: none; }
.hero__lede { font-size: clamp(1.125rem, 1.6vw, 1.3125rem); color: var(--bone); line-height: 1.5; }
.hero__cta { display: flex; flex-wrap: wrap; gap: 12px; }

.hero__log { padding-bottom: 28px; }
.hero__logtitle { font: 400 0.75rem var(--font-mono); color: var(--mute); margin-bottom: 10px; }
.runlog { display: grid; gap: 4px; font: 400 0.8125rem/1.5 var(--font-mono); color: var(--mute); min-height: 6.2em; align-content: end; }
.runlog b { color: var(--bone); font-weight: 500; }
.runlog .ok { color: var(--ok); }
.runlog li { animation: logIn 0.5s var(--ease) both; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
@keyframes logIn { from { opacity: 0; transform: translateY(8px); } }

/* ===== Facts ===== */
.facts {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0; padding-block: 0;
}
.facts p {
  padding: 36px 28px 36px 0; color: var(--mute); font-size: 1rem; border-bottom: 1px solid var(--line);
}
.facts strong { display: block; font: 800 clamp(1.5rem, 2.6vw, 2rem)/1.1 var(--font-display); color: var(--bone); margin-bottom: 4px; letter-spacing: -0.02em; }

/* ===== Section head ===== */
section { padding-block: clamp(72px, 11vw, 140px); }
.hero, .facts { padding-block: 0; }
.hero { padding-top: calc(var(--nav-h) + 40px); }
.section-head { display: grid; gap: 16px; margin-bottom: clamp(32px, 5vw, 64px); max-width: 46rem; }
.section-head h2 { font-size: clamp(2.25rem, 5.5vw, 4rem); font-weight: 800; letter-spacing: -0.03em; }
.section-head p { color: var(--mute); font-size: 1.125rem; }

/* ===== Systems (tabs) ===== */
.systems__body { display: grid; grid-template-columns: minmax(260px, 340px) 1fr; gap: clamp(24px, 4vw, 64px); align-items: start; }
.tabs { display: grid; gap: 6px; position: sticky; top: calc(var(--nav-h) + 24px); }
.tab {
  text-align: left; cursor: pointer; font: inherit; color: var(--mute);
  background: transparent; border: 1px solid transparent; border-radius: var(--radius);
  padding: 16px 18px; display: grid; gap: 4px;
  transition: background 0.25s, border-color 0.25s, color 0.25s, transform 0.4s var(--ease);
}
.tab:hover { background: var(--ink-2); color: var(--bone); }
.tab[aria-selected="true"] { background: var(--ink-2); border-color: var(--line); color: var(--bone); transform: translateX(6px); box-shadow: inset 0 0 0 0 var(--signal), 0 12px 32px -12px #000; }
.tab__name { font: 600 1.0625rem var(--font-display); }
.tab[aria-selected="true"] .tab__name { color: var(--signal); }
.tab__meta { font: 400 0.8125rem var(--font-mono); }

.panel { display: grid; gap: 28px; animation: panelIn 0.6s var(--ease) both; }
.panel[hidden] { display: none; }
@keyframes panelIn { from { opacity: 0; transform: translateY(14px); } }
.panel h3 { font-size: clamp(1.75rem, 3.6vw, 2.75rem); font-weight: 800; letter-spacing: -0.03em; }
.panel__lede { color: var(--mute); font-size: 1.125rem; max-width: 42rem; }

/* flow: steps light up in sequence, like a pulse travelling the pipeline */
.flow { display: flex; flex-wrap: wrap; gap: 10px 0; counter-reset: step; }
.flow li {
  position: relative; font: 500 0.8125rem var(--font-mono);
  padding: 10px 14px; margin-right: 22px;
  border: 1px solid var(--line); border-radius: 8px; background: var(--ink-2); color: var(--mute);
  animation: step calc(var(--n) * 0.7s) calc(var(--i) * 0.7s) infinite;
}
.flow li:not(:last-child)::after {
  content: ""; position: absolute; left: 100%; top: 50%; width: 22px; height: 1px; background: var(--line);
}
@keyframes step {
  0%, 10% { border-color: var(--signal); color: var(--bone); background: color-mix(in srgb, var(--signal) 16%, var(--ink-2)); }
  18%, 100% { border-color: var(--line); color: var(--mute); background: var(--ink-2); }
}

.story { display: grid; gap: 0; border-top: 1px solid var(--line); }
.story > div { display: grid; grid-template-columns: 7rem 1fr; gap: 24px; padding: 20px 0; border-bottom: 1px solid var(--line); }
.story dt { font: 500 0.8125rem var(--font-mono); color: var(--signal); padding-top: 4px; }
.story dd { color: var(--bone); max-width: 46rem; }
.tags { display: flex; flex-wrap: wrap; gap: 8px; }
.tags li { font: 400 0.75rem var(--font-mono); color: var(--mute); border: 1px solid var(--line); border-radius: 999px; padding: 5px 12px; }

/* ===== Tools rows ===== */
.rows { display: grid; border-top: 1px solid var(--line); }
.rows li {
  display: grid; grid-template-columns: minmax(180px, 0.9fr) 2.2fr minmax(180px, 1fr); gap: 16px 32px;
  padding: 28px 0; border-bottom: 1px solid var(--line); align-items: baseline;
  transition: background 0.3s;
}
.rows li:hover { background: var(--ink-2); }
.rows h3 { transition: transform 0.4s var(--ease); }
.rows li:hover h3 { transform: translateX(14px); }
.rows h3 { font-size: 1.375rem; font-weight: 800; letter-spacing: -0.02em; }
.rows p { color: var(--mute); }
.rows span { font: 400 0.8125rem var(--font-mono); color: var(--signal); text-align: right; }

/* ===== Repos ===== */
.repolist { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.repolist a {
  display: grid; gap: 8px; height: 100%; padding: 24px; text-decoration: none; background: var(--ink);
  transition: background 0.25s;
}
.repolist a:hover { background: var(--ink-2); }
.repolist b { font: 600 1.0625rem var(--font-mono); color: var(--bone); }
.repolist a:hover b { color: var(--signal); }
.repolist span { color: var(--mute); font-size: 0.9375rem; }
.repolist i { font: normal 400 0.75rem var(--font-mono); color: var(--mute); margin-top: auto; }
.repos__more { margin-top: 24px; }
.repos__more a { color: var(--signal); text-decoration: none; font-weight: 500; }
.repos__more a:hover { text-decoration: underline; text-underline-offset: 4px; }

/* ===== Experience ===== */
.timeline { display: grid; border-top: 1px solid var(--line); }
.timeline li { display: grid; grid-template-columns: 13rem 1fr; gap: 24px 40px; padding: 36px 0; border-bottom: 1px solid var(--line); }
.timeline time { font: 400 0.875rem var(--font-mono); color: var(--signal); padding-top: 6px; }
.timeline h3 { font-size: 1.75rem; font-weight: 800; letter-spacing: -0.02em; }
.role { color: var(--mute); margin: 4px 0 14px; }
.timeline p:last-child { max-width: 46rem; }

/* ===== Stack ===== */
.stackgrid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 40px 48px; }
.stackgrid dt { font: 500 0.8125rem var(--font-mono); color: var(--signal); margin-bottom: 10px; }
.stackgrid dd { color: var(--bone); line-height: 1.8; }

/* ===== Contact (drenched) ===== */
.contact { background: var(--signal); color: var(--on-signal); padding-block: clamp(96px, 16vw, 200px); }
.contact h2 { font-size: clamp(2.5rem, 7vw, 6rem); font-weight: 800; letter-spacing: -0.035em; max-width: 14ch; }
.contact__mail {
  display: inline-block; margin-top: clamp(32px, 5vw, 56px);
  font: 800 clamp(1.5rem, 4.4vw, 3.25rem)/1.1 var(--font-display); letter-spacing: -0.02em; word-break: break-word;
  text-decoration: underline; text-decoration-thickness: 3px; text-underline-offset: 8px;
  transition: text-underline-offset 0.4s var(--ease);
}
.contact__mail:hover { text-underline-offset: 14px; }
.contact__links { display: flex; flex-wrap: wrap; gap: 8px 28px; margin-top: 32px; font-weight: 600; }
.contact__links a { text-underline-offset: 4px; }
.contact__links span { opacity: 0.8; }

.foot { display: flex; justify-content: space-between; gap: 16px; padding-block: 28px; color: var(--mute); font-size: 0.875rem; }
.foot a { text-decoration: none; }
.foot a:hover { color: var(--bone); }

/* ===== Scroll reveal (content stays visible without JS) ===== */
.js .reveal { opacity: 0; transform: translateY(22px); transition: opacity 0.8s var(--ease), transform 0.8s var(--ease); }
.js .reveal.in { opacity: 1; transform: none; }

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .systems__body { grid-template-columns: 1fr; }
  .tabs { position: static; grid-auto-flow: column; grid-auto-columns: minmax(220px, 1fr); overflow-x: auto; padding-bottom: 8px; scroll-snap-type: x proximity; }
  .tab { scroll-snap-align: start; }
  .tab[aria-selected="true"] { transform: none; }
  .rows li { grid-template-columns: 1fr; gap: 8px; }
  .rows span { text-align: left; }
  .rows li:hover { background: none; }
  .rows li:hover h3 { transform: none; }
  .timeline li { grid-template-columns: 1fr; gap: 8px; }
}
@media (max-width: 760px) {
  .nav__links { display: none; }
  .nav__end { margin-left: auto; }
  .hero { padding-top: calc(var(--nav-h) + 72vw); gap: 24px; }
  .hero::after { background: linear-gradient(180deg, transparent 18%, var(--ink) 52%); }
  .story > div { grid-template-columns: 1fr; gap: 6px; }
  .flow li { margin-right: 18px; }
  .flow li:not(:last-child)::after { width: 18px; }
  .runlog li:nth-child(n+3) { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .js .reveal { opacity: 1; transform: none; }
}