/* ==========================================================================
   Yi Shen — Senior Full-Stack & AI Solutions Developer
   Hand-written CSS. No framework, no CDN: one cached request, fast CWV.
   ========================================================================== */

/* ---------- Tokens ---------- */
:root {
  --bg: #f7f9fc;
  --bg-deep: #eef1f6;
  --surface: rgba(15, 23, 42, 0.035);
  --surface-2: rgba(15, 23, 42, 0.06);
  --border: rgba(15, 23, 42, 0.10);
  --border-strong: rgba(15, 23, 42, 0.18);

  --text: #0f172a;
  --text-dim: #45536b;
  --text-faint: #5b6b84;

  /* Text/icon-safe "ink" shades — what var(--accent)/(--cyan)/(--amber) resolve
     to almost everywhere, since almost every use is a foreground color that
     needs AA contrast against the light background. */
  --accent: #047857;        /* emerald-700 */
  --cyan: #0e7490;          /* cyan-700 */
  --amber: #b45309;         /* amber-700 */

  /* Original saturated hues, kept only for solid fills where vividness
     matters more than text contrast: buttons, badges, dots, brand mark. */
  --accent-bright: #34d399; /* electric emerald */
  --accent-deep: #10b981;
  --cyan-bright: #22d3ee;
  --amber-bright: #fbbf24;

  --font-sans: "Inter", "Plus Jakarta Sans", system-ui, -apple-system,
    "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-cjk: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
    "Noto Sans SC", sans-serif;
  --font-mono: "JetBrains Mono", "Fira Code", ui-monospace, SFMono-Regular,
    "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;

  --wrap: 1200px;
  --radius: 16px;
  --radius-sm: 10px;
  --tap: 48px;               /* minimum touch target */

  --section-y: clamp(4rem, 9vw, 7.5rem);
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 5.5rem;   /* clears the sticky header on anchor jumps */
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: clamp(1rem, 0.97rem + 0.15vw, 1.075rem);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;          /* belt-and-braces against horizontal scroll */
}

/* Chinese pages get a CJK-first stack (system fonts — no megabyte webfont). */
html[lang^="zh"] body { font-family: var(--font-cjk); }
html[lang^="zh"] h1, html[lang^="zh"] h2, html[lang^="zh"] h3 {
  letter-spacing: 0;
}

/* Ambient glow. Fixed + pointer-events:none so it never traps taps. */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background:
    radial-gradient(58rem 34rem at 12% -8%, rgba(16, 185, 129, 0.14), transparent 60%),
    radial-gradient(46rem 30rem at 92% 4%, rgba(34, 211, 238, 0.10), transparent 62%),
    linear-gradient(180deg, var(--bg) 0%, var(--bg-deep) 100%);
}

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

a { color: inherit; text-decoration: none; }

h1, h2, h3 {
  margin: 0;
  line-height: 1.15;
  letter-spacing: -0.02em;
  font-weight: 700;
}

p { margin: 0; }

ul { margin: 0; padding: 0; list-style: none; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

::selection { background: rgba(16, 185, 129, 0.28); color: var(--text); }

/* ---------- Utilities ---------- */
.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: clamp(1.15rem, 4vw, 2.5rem);
}

.mono {
  font-family: var(--font-mono);
  font-size: 0.8em;
  letter-spacing: 0.02em;
}

.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;
}

/* Spam-trap field: hidden from sighted users AND assistive tech (unlike
   .sr-only, which stays announced) — bots that auto-fill every input walk
   into it, real visitors and screen readers never see it. */
.hp {
  position: absolute;
  left: -9999px;
  width: 1px;
  height: 1px;
  overflow: hidden;
}

.skip-link {
  position: absolute;
  top: 0; left: 50%;
  transform: translate(-50%, -110%);
  z-index: 200;
  padding: 0.75rem 1.25rem;
  background: var(--accent-bright);
  color: #06281c;
  font-weight: 600;
  border-radius: 0 0 var(--radius-sm) var(--radius-sm);
  transition: transform 0.2s var(--ease);
}
.skip-link:focus { transform: translate(-50%, 0); }

/* ---------- Section furniture ---------- */
.section { padding-block: var(--section-y); }

.section-head { max-width: 46rem; margin-bottom: clamp(2.25rem, 5vw, 3.5rem); }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 500;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
}
.eyebrow::before {
  content: "";
  width: 1.75rem; height: 1px;
  background: currentColor;
  opacity: 0.55;
}

.section-title { font-size: clamp(1.85rem, 1.2rem + 2.6vw, 2.9rem); }

.section-sub {
  margin-top: 1.05rem;
  color: var(--text-dim);
  font-size: clamp(1rem, 0.96rem + 0.2vw, 1.125rem);
}

/* ---------- Header ---------- */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(247, 249, 252, 0.72);
  backdrop-filter: blur(14px) saturate(160%);
  -webkit-backdrop-filter: blur(14px) saturate(160%);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s var(--ease), background 0.3s var(--ease);
}
.header.is-stuck {
  border-bottom-color: var(--border);
  background: rgba(250, 251, 253, 0.92);
}

.header-inner {
  display: flex;
  align-items: center;
  gap: 1rem;
  min-height: 4.5rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  margin-right: auto;
  min-height: var(--tap);
  font-weight: 700;
  letter-spacing: -0.015em;
}
.brand-mark {
  display: grid;
  place-items: center;
  width: 2.15rem; height: 2.15rem;
  flex: 0 0 auto;
  border-radius: 9px;
  background: linear-gradient(135deg, var(--accent-bright), var(--cyan-bright));
  color: #05231a;
  font-family: var(--font-mono);
  font-size: 0.92rem;
  font-weight: 700;
}
.brand-text { display: flex; flex-direction: column; line-height: 1.2; }
.brand-name { font-size: 1rem; }
.brand-role {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 400;
  letter-spacing: 0.06em;
  color: var(--text-faint);
  text-transform: uppercase;
}

/* Hubs badge — desktop only (it lives in the drawer on mobile). */
.hubs-badge {
  display: none;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 0.8rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.05em;
  color: var(--text-dim);
  white-space: nowrap;
}
.dot {
  width: 6px; height: 6px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--accent-bright);
  box-shadow: 0 0 0 0 rgba(52, 211, 153, 0.6);
  animation: pulse 2.6s infinite;
}
@keyframes pulse {
  0%   { box-shadow: 0 0 0 0 rgba(52, 211, 153, 0.55); }
  70%  { box-shadow: 0 0 0 8px rgba(52, 211, 153, 0); }
  100% { box-shadow: 0 0 0 0 rgba(52, 211, 153, 0); }
}

.nav-desktop { display: none; }
.nav-desktop ul { display: flex; align-items: center; gap: 0.35rem; }
.nav-desktop a {
  display: inline-flex;
  align-items: center;
  padding: 0.6rem 0.85rem;
  border-radius: var(--radius-sm);
  color: var(--text-dim);
  font-size: 0.94rem;
  font-weight: 500;
  transition: color 0.2s var(--ease), background 0.2s var(--ease);
}
.nav-desktop a:hover { color: var(--text); background: var(--surface-2); }

/* ---------- Language switcher ---------- */
.lang {
  position: relative;
  flex: 0 0 auto;
}
.lang-toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  min-height: var(--tap);
  padding: 0.5rem 0.8rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 500;
  cursor: pointer;
  transition: border-color 0.2s var(--ease), background 0.2s var(--ease);
}
.lang-toggle:hover { border-color: var(--border-strong); background: var(--surface-2); }
.lang-caret { transition: transform 0.2s var(--ease); }
.lang-toggle[aria-expanded="true"] .lang-caret { transform: rotate(180deg); }

.lang-menu {
  position: absolute;
  top: calc(100% + 0.5rem);
  right: 0;
  min-width: 11.5rem;
  padding: 0.4rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.97);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  box-shadow: 0 18px 44px rgba(15, 23, 42, 0.16);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-6px);
  transition: opacity 0.18s var(--ease), transform 0.18s var(--ease),
    visibility 0.18s;
}
.lang.is-open .lang-menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.lang-menu a {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  min-height: 2.75rem;
  padding: 0.5rem 0.7rem;
  border-radius: 8px;
  color: var(--text-dim);
  font-size: 0.92rem;
  transition: background 0.16s var(--ease), color 0.16s var(--ease);
}
.lang-menu a:hover { background: var(--surface-2); color: var(--text); }
.lang-menu a[aria-current="true"] { color: var(--accent); background: rgba(52, 211, 153, 0.08); }
.lang-menu a[aria-current="true"]::after {
  content: "✓";
  margin-left: auto;
  font-size: 0.8rem;
}

/* ---------- Mobile drawer ---------- */
.burger {
  display: inline-grid;
  place-items: center;
  width: var(--tap); height: var(--tap);
  flex: 0 0 auto;
  padding: 0;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  cursor: pointer;
}
.burger-box { display: block; width: 20px; height: 14px; position: relative; }
.burger-box span {
  position: absolute;
  left: 0;
  width: 100%; height: 2px;
  border-radius: 2px;
  background: var(--text);
  transition: transform 0.28s var(--ease), opacity 0.2s var(--ease), top 0.28s var(--ease);
}
.burger-box span:nth-child(1) { top: 0; }
.burger-box span:nth-child(2) { top: 6px; }
.burger-box span:nth-child(3) { top: 12px; }
.burger[aria-expanded="true"] .burger-box span:nth-child(1) { top: 6px; transform: rotate(45deg); }
.burger[aria-expanded="true"] .burger-box span:nth-child(2) { opacity: 0; }
.burger[aria-expanded="true"] .burger-box span:nth-child(3) { top: 6px; transform: rotate(-45deg); }

.drawer {
  position: fixed;
  inset: 0;
  z-index: 150;
  display: flex;
  flex-direction: column;
  padding: 1.15rem;
  background: rgba(255, 255, 255, 0.985);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.26s var(--ease), visibility 0.26s;
}
.drawer.is-open { opacity: 1; visibility: visible; }

.drawer-top { display: flex; align-items: center; justify-content: flex-end; }
.drawer-close {
  display: grid;
  place-items: center;
  width: var(--tap); height: var(--tap);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--text);
  font-size: 1.35rem;
  line-height: 1;
  cursor: pointer;
}

.drawer nav { margin-top: 1.5rem; }
.drawer nav ul { display: flex; flex-direction: column; gap: 0.35rem; }
.drawer nav a {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  min-height: 3.65rem;
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-sm);
  font-size: 1.35rem;
  font-weight: 600;
  letter-spacing: -0.015em;
  transition: background 0.18s var(--ease);
}
.drawer nav a:hover, .drawer nav a:active { background: var(--surface-2); }
.drawer nav a i {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-style: normal;
  font-weight: 400;
  color: var(--accent);
  opacity: 0.75;
}

.drawer-foot {
  margin-top: auto;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  display: grid;
  gap: 0.9rem;
}
.drawer-hubs {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-dim);
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.55rem;
  min-height: var(--tap);
  padding: 0.85rem 1.5rem;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  text-align: center;
  transition: transform 0.18s var(--ease), box-shadow 0.22s var(--ease),
    background 0.2s var(--ease), border-color 0.2s var(--ease);
}
.btn-primary {
  background: linear-gradient(135deg, var(--accent-bright) 0%, var(--accent-deep) 100%);
  color: #052b1e;
  box-shadow: 0 8px 26px rgba(16, 185, 129, 0.28);
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 14px 34px rgba(16, 185, 129, 0.38);
}
.btn-ghost {
  background: var(--surface);
  border-color: var(--border-strong);
  color: var(--text);
}
.btn-ghost:hover { background: var(--surface-2); transform: translateY(-2px); }
.btn-block { width: 100%; }

/* ---------- Hero ---------- */
.hero { padding-block: clamp(3rem, 7vw, 6rem) var(--section-y); }
.hero-grid { display: grid; gap: clamp(2.5rem, 6vw, 4rem); align-items: center; }

.hero-intro {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  margin-bottom: 1.5rem;
}

/* Source photo is 140x162 with its own oval alpha cutout — displayed at
   exactly half that (70x81) so it's pixel-perfect on 2x/retina screens
   instead of upscaled and soft. The ring/overflow-hidden double-clips
   harmlessly since the container matches the source's own aspect ratio. */
.hero-avatar {
  width: 70px; height: 81px;
  flex: 0 0 auto;
  border-radius: 50%;
  overflow: hidden;
  border: 2px solid var(--accent-bright);
  box-shadow: 0 6px 16px rgba(16, 185, 129, 0.22);
  background: var(--surface);
}
.hero-avatar img { width: 100%; height: 100%; object-fit: cover; display: block; }

.hero-availability {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  margin-bottom: 0;
  padding: 0.45rem 0.9rem;
  border: 1px solid rgba(52, 211, 153, 0.3);
  border-radius: 999px;
  background: rgba(52, 211, 153, 0.07);
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.05em;
  color: var(--accent);
}

.hero h1 {
  font-size: clamp(2.15rem, 1.15rem + 4.4vw, 4rem);
  letter-spacing: -0.035em;
}
.hero h1 .grad {
  background: linear-gradient(105deg, var(--accent) 0%, var(--cyan) 92%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: transparent;
}
.hero h1 small {
  display: block;
  margin-top: 0.6rem;
  font-size: 0.44em;
  font-weight: 500;
  letter-spacing: -0.01em;
  color: var(--text-dim);
}

.hero-sub {
  margin-top: 1.6rem;
  max-width: 34rem;
  color: var(--text-dim);
  font-size: clamp(1.05rem, 1rem + 0.32vw, 1.22rem);
}
.hero-sub strong { color: var(--text); font-weight: 600; }

.hero-geo {
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
  margin-top: 1.5rem;
  font-size: 0.94rem;
  color: var(--text-faint);
}
.hero-geo svg { flex: 0 0 auto; margin-top: 0.22rem; color: var(--accent); }

.hero-cta {
  display: grid;
  gap: 0.85rem;
  margin-top: 2.25rem;
}

.hero-proof {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.5rem;
  margin-top: 2.75rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
}
.hero-proof dt {
  font-family: var(--font-mono);
  font-size: clamp(1.25rem, 1rem + 1vw, 1.75rem);
  font-weight: 600;
  color: var(--accent);
  letter-spacing: -0.02em;
}
.hero-proof dd {
  margin: 0.3rem 0 0;
  font-size: 0.8rem;
  line-height: 1.4;
  color: var(--text-faint);
}

/* ---------- Terminal ----------
   Deliberately stays a dark console regardless of page theme — like a code
   block in a light-mode doc site. Fully self-contained: local custom
   properties, not the page's light-theme text/accent tokens. */
.terminal {
  --t-text: #e8eefa;
  --t-dim: #93a4bf;
  --t-faint: #6b7d99;
  --t-accent: #34d399;
  --t-cyan: #22d3ee;
  --t-amber: #fbbf24;

  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  background: linear-gradient(180deg, rgba(19, 29, 51, 0.95), rgba(12, 20, 37, 0.95));
  box-shadow: 0 30px 70px -20px rgba(15, 23, 42, 0.35);
  overflow: hidden;
}
.terminal-bar {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.7rem 0.9rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.09);
  background: rgba(255, 255, 255, 0.025);
}
.terminal-bar i {
  width: 11px; height: 11px;
  border-radius: 50%;
  background: #3d4a63;
}
.terminal-bar i:nth-child(1) { background: #ff5f57; }
.terminal-bar i:nth-child(2) { background: #febc2e; }
.terminal-bar i:nth-child(3) { background: #28c840; }
.terminal-bar span {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--t-faint);
}

.terminal-body {
  margin: 0;
  padding: 1.15rem clamp(0.95rem, 3vw, 1.4rem) 1.5rem;
  font-family: var(--font-mono);
  font-size: clamp(0.72rem, 0.63rem + 0.42vw, 0.86rem);
  line-height: 1.9;
  white-space: pre-wrap;
  word-break: break-word;
  color: var(--t-dim);
  overflow-x: auto;
}
.terminal-body .row { display: block; }
.t-prompt { color: var(--t-accent); }
.t-cmd { color: var(--t-text); }
.t-key { color: var(--t-cyan); }
.t-val { color: var(--t-text); }
.t-num { color: var(--t-amber); }
.t-ok { color: var(--t-accent); }
.t-dim { color: var(--t-faint); }

/* JS staggers the reveal; without JS every line is simply visible. */
.js .terminal-body .row { opacity: 0; }
.js .terminal-body .row.is-in { animation: lineIn 0.34s var(--ease) forwards; }
@keyframes lineIn {
  from { opacity: 0; transform: translateY(4px); }
  to   { opacity: 1; transform: none; }
}
.caret {
  display: inline-block;
  width: 0.6em; height: 1.05em;
  translate: 0 0.18em;
  background: var(--t-accent, var(--accent-bright));
  animation: blink 1.15s steps(2, start) infinite;
}
@keyframes blink { 0%, 100% { opacity: 1; } 50% { opacity: 0; } }

/* ---------- Cards ---------- */
.grid { display: grid; gap: 1.15rem; }

.card {
  position: relative;
  display: flex;
  flex-direction: column;
  padding: clamp(1.4rem, 3.5vw, 1.9rem);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: transform 0.28s var(--ease), border-color 0.28s var(--ease),
    background 0.28s var(--ease), box-shadow 0.28s var(--ease);
}
.card:hover {
  transform: translateY(-4px);
  border-color: rgba(16, 185, 129, 0.34);
  background: var(--surface-2);
  box-shadow: 0 22px 48px -22px rgba(15, 23, 42, 0.18);
}
.card-featured {
  border-color: rgba(251, 191, 36, 0.34);
  background: linear-gradient(180deg, rgba(251, 191, 36, 0.055), var(--surface));
}
.card-featured:hover { border-color: rgba(251, 191, 36, 0.5); }

.card-flag {
  position: absolute;
  top: -0.7rem;
  left: clamp(1.4rem, 3.5vw, 1.9rem);
  padding: 0.2rem 0.65rem;
  border-radius: 999px;
  background: var(--amber-bright);
  color: #3a2708;
  font-family: var(--font-mono);
  font-size: 0.66rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.card-icon {
  display: grid;
  place-items: center;
  width: 2.85rem; height: 2.85rem;
  margin-bottom: 1.15rem;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: rgba(52, 211, 153, 0.09);
  color: var(--accent);
}
.card-featured .card-icon {
  background: rgba(251, 191, 36, 0.1);
  color: var(--amber);
}

.card h3 { font-size: clamp(1.12rem, 1.05rem + 0.35vw, 1.3rem); }

.card-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 0.85rem;
  margin-top: 0.9rem;
  padding-block: 0.85rem;
  border-block: 1px solid var(--border);
}
.card-price {
  font-family: var(--font-mono);
  font-size: 1.02rem;
  font-weight: 600;
  color: var(--accent);
}
.card-featured .card-price { color: var(--amber); }
.card-eta {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  color: var(--text-faint);
}
.card-eta svg { flex: 0 0 auto; }

.card-focus { margin-top: 1rem; color: var(--text-dim); font-size: 0.95rem; }

.tags { display: flex; flex-wrap: wrap; gap: 0.4rem; margin-top: 1.15rem; }
.tag {
  padding: 0.3rem 0.62rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.028);
  font-family: var(--font-mono);
  font-size: 0.71rem;
  color: var(--text-dim);
  white-space: nowrap;
}

/* Portfolio-specific */
.card-index {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  color: var(--text-faint);
  margin-bottom: 0.7rem;
}
.metric {
  display: flex;
  gap: 0.7rem;
  margin-top: 1.15rem;
  padding: 0.9rem 1rem;
  border: 1px solid rgba(52, 211, 153, 0.2);
  border-radius: var(--radius-sm);
  background: rgba(52, 211, 153, 0.055);
}
.metric svg { flex: 0 0 auto; margin-top: 0.2rem; color: var(--accent); }
.metric p { font-size: 0.88rem; line-height: 1.55; color: var(--text); }
.metric b { color: var(--accent); font-weight: 600; }

.card-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-top: 1.15rem;
  min-height: var(--tap);
  font-size: 0.86rem;
  font-weight: 600;
  color: var(--accent);
  transition: gap 0.2s var(--ease);
}
.card-link:hover { gap: 0.6rem; }
.card-link svg { flex: 0 0 auto; }

/* ---------- Video embed ---------- */
.video-embed {
  position: relative;
  aspect-ratio: 16 / 9;
  margin-block: 1.15rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--surface);
}
.video-embed iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

/* ---------- AI Engineering Lab ---------- */
.ai-lab-grid {
  display: grid;
  gap: 1.15rem;
}
.ai-lab-card {
  overflow: hidden;
}
.ai-lab-card-media {
  aspect-ratio: 1;
  margin: calc(clamp(1.4rem, 3.5vw, 1.9rem) * -1);
  margin-bottom: clamp(1.4rem, 3.5vw, 1.9rem);
  border-bottom: 1px solid var(--border);
  background: var(--bg-deep);
}
.ai-lab-card-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.ai-lab-status {
  display: inline-flex;
  align-items: center;
  min-height: 1.7rem;
  margin-bottom: 0.85rem;
  padding: 0.25rem 0.6rem;
  border: 1px solid rgba(14, 116, 144, 0.22);
  border-radius: 999px;
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.ai-lab-status.is-future {
  border-color: rgba(180, 83, 9, 0.28);
  color: var(--amber);
}
.ai-lab-course-art {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  width: 100%;
  height: 100%;
  background:
    radial-gradient(circle at 28% 24%, rgba(251, 191, 36, 0.28), transparent 28%),
    linear-gradient(135deg, rgba(52, 211, 153, 0.12), rgba(14, 116, 144, 0.14));
  color: var(--accent);
  font-family: var(--font-mono);
}
.ai-lab-course-art span {
  font-size: clamp(4.5rem, 11vw, 7rem);
  font-weight: 600;
  letter-spacing: -0.08em;
  line-height: 0.8;
}
.ai-lab-course-art small {
  color: var(--amber);
  font-size: clamp(0.75rem, 1.8vw, 1rem);
  font-weight: 600;
  letter-spacing: 0.12em;
  line-height: 1.35;
}
.ai-lab-card h3 { font-size: clamp(1.12rem, 1.05rem + 0.35vw, 1.3rem); }
.ai-lab-card .card-focus { min-height: 5.4rem; }
.ai-lab-method {
  display: grid;
  gap: 0.7rem;
  margin-top: 2rem;
}
.ai-lab-method-step {
  display: flex;
  align-items: baseline;
  gap: 0.65rem;
  padding: 0.85rem 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
}
.ai-lab-method-step strong {
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.1em;
}
.ai-lab-method-step span { color: var(--text-dim); }
.ai-lab-page .hero { padding-bottom: 3rem; }
.ai-lab-hero-note {
  max-width: 48rem;
  margin-top: 1.2rem;
  color: var(--text-dim);
  font-size: clamp(1.05rem, 1rem + 0.32vw, 1.22rem);
}
.ai-lab-page .card-focus { line-height: 1.65; }
.ai-lab-page .card h3 { margin-bottom: 0.85rem; }
.ai-lab-skill-image {
  width: 100%;
  max-width: 42rem;
  margin-inline: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}
.ai-lab-phase-grid {
  display: grid;
  gap: 1.15rem;
  counter-reset: phase;
}
.ai-lab-phase {
  counter-increment: phase;
}
.ai-lab-phase::before {
  content: "0" counter(phase);
  display: block;
  margin-bottom: 0.85rem;
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.1em;
}
.ai-lab-syllabus-top,
.ai-lab-syllabus-grid,
.ai-lab-syllabus-phase-grid {
  display: grid;
  gap: 1.15rem;
}
.ai-lab-syllabus-meta {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.85rem 1.15rem;
  margin: 0;
  padding: 1.4rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}
.ai-lab-syllabus-meta > div {
  min-width: 0;
}
.ai-lab-syllabus-meta dt {
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.ai-lab-syllabus-meta dd {
  margin: 0.35rem 0 0;
  color: var(--text-dim);
  line-height: 1.55;
}
.ai-lab-syllabus-mission {
  height: 100%;
}
.ai-lab-syllabus-steps,
.ai-lab-syllabus-list {
  margin: 1rem 0 0;
  padding-left: 1.3rem;
  color: var(--text-dim);
  line-height: 1.7;
}
.ai-lab-syllabus-steps li + li,
.ai-lab-syllabus-list li + li {
  margin-top: 0.45rem;
}
.ai-lab-syllabus-phase-grid {
  margin-top: 1.15rem;
}
.ai-lab-syllabus-phase h3 {
  margin-bottom: 0.65rem;
  font-size: 1.05rem;
}
.ai-lab-syllabus-phase p {
  margin: 0;
  color: var(--text-dim);
  line-height: 1.65;
}
.ai-lab-syllabus-completion {
  margin-top: 1.15rem;
}
.lesson-content {
  max-width: 58rem;
}
.lesson-content > section + section {
  margin-top: clamp(2.5rem, 5vw, 4.25rem);
}
.lesson-content h2 {
  margin-bottom: 1rem;
  font-size: clamp(1.45rem, 1.25rem + 0.75vw, 2rem);
}
.lesson-content h3 {
  margin-bottom: 0.65rem;
  font-size: clamp(1.1rem, 1rem + 0.35vw, 1.35rem);
}
.lesson-content p,
.lesson-content li {
  line-height: 1.75;
}
.lesson-content p + p,
.lesson-content ul + p,
.lesson-content ol + p,
.lesson-content pre + p {
  margin-top: 1rem;
}
.lesson-content .zh {
  color: var(--text-dim);
}
.lesson-content .zh-label {
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.lesson-content pre {
  overflow-x: auto;
  margin: 1.25rem 0;
  padding: 1rem 1.15rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  color: var(--text);
  font-size: 0.86rem;
  line-height: 1.65;
}
.lesson-content code {
  font-family: var(--font-mono);
}
.lesson-table-scroll {
  overflow-x: auto;
  margin: 1.25rem 0;
}
.lesson-diagram-scroll {
  overflow-x: auto;
  margin: 1.25rem 0;
}
.lesson-diagram-scroll svg {
  display: block;
  min-width: 62rem;
  width: 100%;
  height: auto;
}
.lesson-diagram-scroll figcaption {
  margin-top: 0.6rem;
  color: var(--text-dim);
  font-size: 0.85rem;
}
.lesson-content table {
  width: 100%;
  min-width: 42rem;
  border-collapse: collapse;
  font-size: 0.92rem;
}
.lesson-content th,
.lesson-content td {
  padding: 0.8rem 0.9rem;
  border: 1px solid var(--border);
  text-align: left;
  vertical-align: top;
}
.lesson-content th {
  background: var(--surface-2);
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.lesson-callout {
  margin: 1.25rem 0;
  padding: 0.9rem 1rem;
  border-left: 3px solid var(--accent);
  background: rgba(52, 211, 153, 0.06);
  color: var(--text-dim);
}
.lesson-quiz {
  margin: 1.25rem 0;
  padding: clamp(1rem, 2vw, 1.35rem);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}
.lesson-quiz-options {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-top: 1rem;
}
.lesson-quiz button {
  padding: 0.65rem 0.85rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  color: var(--text);
  cursor: pointer;
  font: 500 0.8rem/1.25 var(--font-mono);
  transition: border-color 0.2s var(--ease), background 0.2s var(--ease), color 0.2s var(--ease);
}
.lesson-quiz button:hover:not(:disabled),
.lesson-quiz button:focus-visible {
  border-color: var(--accent);
}
.lesson-quiz button:disabled {
  cursor: default;
  opacity: 0.72;
}
.lesson-quiz button.is-correct {
  border-color: var(--accent);
  background: rgba(52, 211, 153, 0.13);
  color: var(--accent-bright);
}
.lesson-quiz button.is-incorrect {
  border-color: var(--amber);
  background: rgba(251, 191, 36, 0.1);
  color: var(--amber-bright);
}
.lesson-feedback {
  min-height: 1.5em;
  margin: 1rem 0 0;
  color: var(--text-dim);
}
.lesson-feedback.is-correct {
  color: var(--accent-bright);
}
.lesson-feedback.is-incorrect {
  color: var(--amber-bright);
}
.lesson-worksheet {
  display: grid;
  gap: 0.85rem;
  margin-top: 1.25rem;
}
.lesson-worksheet label {
  display: grid;
  gap: 0.4rem;
  color: var(--text-dim);
  font-size: 0.92rem;
}
.lesson-worksheet textarea,
.lesson-worksheet input {
  width: 100%;
  padding: 0.75rem 0.85rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  color: var(--text);
  font: inherit;
}
.lesson-worksheet textarea {
  min-height: 7rem;
  resize: vertical;
}
.lesson-reference-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.25rem;
  margin-top: 2rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--border);
  font-family: var(--font-mono);
  font-size: 0.78rem;
}
.ai-lab-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.6rem;
}

/* Source-lesson structures retained when the full content is embedded. */
.lesson-content .table-scroll,
.lesson-content .lesson-table-scroll {
  overflow-x: auto;
  margin: 1rem 0;
}
.lesson-content .comparison-table,
.lesson-content .lesson-comparison-table {
  min-width: 42rem;
}
.lesson-content .diagram-scroll,
.lesson-content .lesson-diagram-scroll {
  overflow-x: auto;
  margin: 1rem 0;
}
.lesson-content .diagram-scroll svg,
.lesson-content .lesson-diagram-scroll svg {
  display: block;
  min-width: 62rem;
  width: 100%;
  height: auto;
}
.lesson-content .callout,
.lesson-content .lesson-callout {
  border-left: 3px solid var(--amber);
  padding: 0.9rem 1rem;
  background: rgba(251, 191, 36, 0.08);
}

/* ---------- Global hubs banner ---------- */
.globe {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background:
    radial-gradient(34rem 20rem at 88% 12%, rgba(34, 211, 238, 0.09), transparent 65%),
    linear-gradient(135deg, rgba(52, 211, 153, 0.07), var(--surface));
  padding: clamp(1.75rem, 5vw, 3.25rem);
}
.globe-grid { display: grid; gap: clamp(2rem, 5vw, 3.5rem); }

.globe h3 {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 500;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--accent);
}
.globe-list { display: grid; gap: 0.85rem; margin-top: 1.4rem; }
.globe-item {
  display: flex;
  align-items: baseline;
  gap: 0.85rem;
  padding-bottom: 0.85rem;
  border-bottom: 1px solid var(--border);
}
.globe-item:last-child { border-bottom: 0; padding-bottom: 0; }
.globe-item .flag { font-size: 1.35rem; line-height: 1; flex: 0 0 auto; }
.globe-item b { display: block; font-size: 1.05rem; font-weight: 600; }
.globe-item span { font-size: 0.86rem; color: var(--text-faint); }

/* ---------- Tech stack ---------- */
.stack-grid { display: grid; gap: 1.15rem; }
.stack-group {
  padding: clamp(1.25rem, 3vw, 1.6rem);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}
.stack-group h3 {
  margin-bottom: 1.05rem;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  font-weight: 500;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--cyan);
}
.stack-group .tags { margin-top: 0; }
.stack-group .tag {
  min-height: 2.1rem;
  display: inline-flex;
  align-items: center;
  font-size: 0.76rem;
  color: var(--text);
  transition: border-color 0.2s var(--ease), background 0.2s var(--ease);
}
.stack-group .tag:hover {
  border-color: rgba(52, 211, 153, 0.4);
  background: rgba(52, 211, 153, 0.08);
}

/* ---------- Contact ---------- */
.contact-grid { display: grid; gap: clamp(2rem, 5vw, 3.25rem); align-items: start; }

.form {
  display: grid;
  gap: 1.1rem;
  padding: clamp(1.4rem, 4vw, 2.15rem);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}
.field { display: grid; gap: 0.45rem; }
.field-row { display: grid; gap: 1.1rem; }
.field label {
  font-size: 0.83rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--text-dim);
}
.field label .req { color: var(--accent); }

.field input,
.field select,
.field textarea {
  width: 100%;
  min-height: var(--tap);
  padding: 0.8rem 0.95rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  background: #ffffff;
  color: var(--text);
  font-family: inherit;
  font-size: 1rem;   /* 16px+ stops iOS zoom-on-focus */
  transition: border-color 0.2s var(--ease), box-shadow 0.2s var(--ease);
}
.field textarea { min-height: 7.5rem; resize: vertical; line-height: 1.6; }
.field select {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='14' height='14' viewBox='0 0 24 24' fill='none' stroke='%235b6b84' stroke-width='2.5' stroke-linecap='round'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 1rem center;
  padding-right: 2.6rem;
  cursor: pointer;
}
.field input::placeholder, .field textarea::placeholder { color: var(--text-faint); }
.field input:focus, .field select:focus, .field textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(52, 211, 153, 0.16);
}
.form-note { font-size: 0.8rem; color: var(--text-faint); }

.direct { display: grid; gap: 0.85rem; }
.direct-link {
  display: flex;
  align-items: center;
  gap: 1rem;
  min-height: var(--tap);
  padding: 1rem 1.15rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  transition: transform 0.2s var(--ease), border-color 0.2s var(--ease),
    background 0.2s var(--ease);
}
.direct-link:hover {
  transform: translateX(3px);
  border-color: rgba(52, 211, 153, 0.34);
  background: var(--surface-2);
}
.direct-link svg { flex: 0 0 auto; color: var(--accent); }
.direct-link b { display: block; font-size: 0.94rem; font-weight: 600; }
.direct-link span {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-faint);
  word-break: break-all;
}
.direct-link .arrow { margin-left: auto; color: var(--text-faint); }

/* ---------- Footer ---------- */
.footer {
  padding-block: 2.75rem;
  border-top: 1px solid var(--border);
  background: rgba(15, 23, 42, 0.025);
}
.footer-inner { display: grid; gap: 1.5rem; }
.footer-meta { display: grid; gap: 0.45rem; }
.footer-meta p { font-size: 0.86rem; color: var(--text-faint); }
.footer-meta .mono { font-size: 0.76rem; }
.footer-links { display: flex; flex-wrap: wrap; gap: 0.65rem; }
.footer-links a {
  display: grid;
  place-items: center;
  width: var(--tap); height: var(--tap);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--text-dim);
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease),
    transform 0.2s var(--ease);
}
.footer-links a:hover {
  color: var(--accent);
  border-color: rgba(52, 211, 153, 0.4);
  transform: translateY(-2px);
}

/* ---------- Cookie consent banner ---------- */
.consent-banner {
  position: fixed;
  z-index: 60;
  left: 1rem;
  right: 1rem;
  bottom: 1rem;
  max-width: 640px;
  margin-inline: auto;
  padding: 1.25rem 1.5rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  background: var(--bg);
  box-shadow: 0 20px 50px rgba(15, 23, 42, 0.18);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1rem 1.5rem;
}
.consent-banner[hidden] { display: none; }
.consent-text {
  flex: 1 1 260px;
  margin: 0;
  font-size: 0.9rem;
  color: var(--text-dim);
}
.consent-actions {
  display: flex;
  gap: 0.6rem;
  flex: 0 0 auto;
}
.consent-actions .btn {
  min-height: 2.6rem;
  padding: 0.6rem 1.2rem;
  font-size: 0.9rem;
}

.footer-legal {
  font-size: 0.85rem;
}
.footer-legal a { color: var(--text-dim); }
.footer-legal a:hover { color: var(--accent); }
.link-btn {
  background: none;
  border: none;
  padding: 0;
  margin: 0;
  font: inherit;
  font-size: 0.85rem;
  color: var(--text-dim);
  cursor: pointer;
  text-decoration: underline;
  text-underline-offset: 2px;
}
.link-btn:hover { color: var(--accent); }

/* ---------- Policy / legal content ---------- */
.policy-body { max-width: 46rem; }
.policy-body h2 {
  margin-top: 2.5rem;
  margin-bottom: 0.75rem;
  font-size: 1.25rem;
}
.policy-body h2:first-child { margin-top: 0; }
.policy-body p { margin-bottom: 1rem; color: var(--text-dim); }
.policy-body ul {
  list-style: disc;
  padding-left: 1.25rem;
  margin-bottom: 1rem;
  color: var(--text-dim);
}
.policy-body li { margin-bottom: 0.4rem; }
.policy-body a { color: var(--accent); text-decoration: underline; text-underline-offset: 2px; }
.policy-body a:hover { color: var(--accent-deep); }
.policy-body strong { color: var(--text); }

/* ---------- Scroll reveal (progressive: only active when JS present) ---------- */
.js .reveal { opacity: 0; transform: translateY(18px); }
.js .reveal.is-in {
  opacity: 1;
  transform: none;
  transition: opacity 0.6s var(--ease), transform 0.6s var(--ease);
}

/* ==========================================================================
   Breakpoints — mobile-first, so these only ever add.
   ========================================================================== */
@media (min-width: 480px) {
  .hero-cta { grid-auto-flow: column; justify-content: start; }
  .hero-cta .btn { padding-inline: 1.75rem; }
  .field-row { grid-template-columns: 1fr 1fr; }
}

@media (min-width: 680px) {
  .grid-2 { grid-template-columns: repeat(2, 1fr); }
  .ai-lab-grid { grid-template-columns: repeat(2, 1fr); }
  .ai-lab-phase-grid { grid-template-columns: repeat(2, 1fr); }
  .ai-lab-syllabus-top { grid-template-columns: minmax(0, 0.85fr) minmax(0, 1.15fr); align-items: start; }
  .ai-lab-syllabus-meta,
  .ai-lab-syllabus-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .ai-lab-syllabus-phase-grid { grid-template-columns: repeat(2, 1fr); }
  .stack-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-inner { grid-template-columns: 1fr auto; align-items: center; }
  .hero-proof { gap: 1.5rem; }
}

@media (min-width: 900px) {
  .hubs-badge { display: inline-flex; }
  .globe-grid { grid-template-columns: 1fr 1fr; }
}

@media (min-width: 1024px) {
  .burger { display: none; }
  .nav-desktop { display: block; }
  .hero-grid { grid-template-columns: 1.05fr 0.95fr; }
  .grid-4 { grid-template-columns: repeat(4, 1fr); }
  .grid-2 { grid-template-columns: repeat(2, 1fr); }
  .ai-lab-grid { grid-template-columns: repeat(3, 1fr); }
  .contact-grid { grid-template-columns: 1.25fr 0.75fr; }
  .stack-grid { grid-template-columns: repeat(3, 1fr); }
}

@media (min-width: 1280px) {
  .card { padding: 2rem; }
}

/* ---------- Motion / contrast preferences ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
  .js .reveal, .js .terminal-body .row { opacity: 1 !important; transform: none !important; }
  .caret { animation: none; }
}

@media (prefers-contrast: more) {
  :root {
    --text-dim: #1e293b;
    --text-faint: #334155;
    --border: rgba(15, 23, 42, 0.3);
    --border-strong: rgba(15, 23, 42, 0.45);
  }
}

/* ---------- Print ---------- */
@media print {
  body::before, .header, .drawer, .hero-cta, .form, .footer-links { display: none !important; }
  body { background: #fff; color: #000; }
  .card, .terminal, .globe, .stack-group { border-color: #ccc; background: none; }
  a { text-decoration: underline; }
}