/* ============================================================
   Dequn Teng — Portfolio
   Shared stylesheet. Serif editorial system.
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Newsreader:ital,opsz,wght@0,6..72,300;0,6..72,400;0,6..72,500;0,6..72,600;1,6..72,300;1,6..72,400;1,6..72,500&family=IBM+Plex+Mono:wght@400;500;600&display=swap');

/* ---------- Tokens ---------- */
:root{
  --paper:        #faf8f3;
  --paper-2:      #f3efe6;
  --paper-3:      #ece6d9;
  --ink:          #1c1a17;
  --ink-soft:     #44403a;
  --muted:        #847d70;
  --muted-2:      #a39b8c;
  --line:         #e3ddd0;
  --line-strong:  #d2cab9;
  --accent:       #7c2d2a;   /* deep claret, used sparingly */
  --accent-soft:  #a85b50;
  --accent-tint:  #f0e6e0;

  --serif: 'Newsreader', Georgia, 'Times New Roman', serif;
  --mono:  'IBM Plex Mono', ui-monospace, 'SFMono-Regular', Menlo, monospace;

  --maxw: 1180px;
  --gutter: clamp(20px, 5vw, 64px);

  --ease: cubic-bezier(.22,.61,.36,1);
}

/* ---------- Reset ---------- */
*,*::before,*::after{ box-sizing:border-box; margin:0; padding:0; }
html{ -webkit-text-size-adjust:100%; scroll-behavior:smooth; overflow-x:clip; }
::selection{ background:var(--accent); color:var(--paper); }
a:focus-visible, button:focus-visible{ outline:2px solid var(--accent); outline-offset:3px; border-radius:1px; }
@media (prefers-reduced-motion: reduce){ html{ scroll-behavior:auto; } }
/* anchored sections clear the sticky header + section nav */
[id]{ scroll-margin-top:138px; }
body{
  font-family:var(--serif);
  background:var(--paper);
  color:var(--ink);
  line-height:1.6;
  font-size:18px;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
  font-variant-ligatures:common-ligatures;
}
img{ max-width:100%; display:block; }
a{ color:inherit; text-decoration:none; }

/* ---------- Paper grain (tactile warmth) ---------- */
body::before{
  content:""; position:fixed; inset:0; z-index:3; pointer-events:none;
  opacity:.04; mix-blend-mode:multiply;
  background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2'/%3E%3C/filter%3E%3Crect width='160' height='160' filter='url(%23n)' opacity='0.5'/%3E%3C/svg%3E");
}
@media print{ body::before{ display:none; } }

/* ---------- Layout helpers ---------- */
.wrap{ max-width:var(--maxw); margin-inline:auto; padding-inline:var(--gutter); }
.wrap-narrow{ max-width:880px; margin-inline:auto; padding-inline:var(--gutter); }
section{ position:relative; }
.divider{ height:1px; background:var(--line); border:0; }

/* ---------- Eyebrow / mono labels ---------- */
.eyebrow{
  font-family:var(--mono);
  font-size:11.5px;
  font-weight:500;
  letter-spacing:.22em;
  text-transform:uppercase;
  color:var(--accent);
  display:inline-flex;
  align-items:center;
  gap:.7em;
}
.eyebrow::before{
  content:"";
  width:22px; height:1px;
  background:var(--accent);
  opacity:.6;
}
.eyebrow.no-rule::before{ display:none; }

.mono{ font-family:var(--mono); }

/* inline + eyebrow links (external org links) */
.eyebrow-link{
  color:inherit; text-decoration:none; display:inline-flex; align-items:center; gap:.5em;
  transition:opacity .22s var(--ease);
}
.eyebrow-link::after{ content:"↗"; font-size:.9em; opacity:.7; }
.eyebrow-link:hover{ opacity:.6; }
.inline-link{
  color:var(--accent); text-decoration:none;
  border-bottom:1px solid color-mix(in srgb, var(--accent) 45%, transparent);
  transition:border-color .22s var(--ease), color .22s var(--ease);
}
.inline-link:hover{ border-color:var(--accent); }
.inline-link.light{
  color:#fff; border-bottom-color:rgba(255,255,255,.45);
}
.inline-link.light:hover{ border-bottom-color:#fff; }

/* ---------- Typography ---------- */
h1,h2,h3,h4{ font-weight:400; line-height:1.08; letter-spacing:-.01em; }
h1,h2,h3{ text-wrap:balance; }
.display{
  font-size:clamp(2.8rem, 7vw, 5.6rem);
  font-weight:300;
  line-height:.98;
  letter-spacing:-.025em;
}
h2.section-title{
  font-size:clamp(1.9rem, 3.6vw, 3rem);
  font-weight:300;
  letter-spacing:-.02em;
}
h3{ font-size:1.5rem; }
.lead{
  font-size:clamp(1.15rem, 1.9vw, 1.5rem);
  line-height:1.5;
  color:var(--ink-soft);
  font-weight:300;
}
.italic{ font-style:italic; }
em,.serif-em{ font-style:italic; }
.accent{ color:var(--accent); }
p{ text-wrap:pretty; }

/* ---------- Header / Nav ---------- */
.site-header{
  position:sticky; top:0; z-index:100;
  background:color-mix(in srgb, var(--paper) 86%, transparent);
  backdrop-filter:saturate(140%) blur(10px);
  -webkit-backdrop-filter:saturate(140%) blur(10px);
  border-bottom:1px solid transparent;
  transition:border-color .4s var(--ease), background .4s var(--ease);
}
.site-header.scrolled{ border-bottom-color:var(--line); }
.nav{
  display:flex; align-items:center; justify-content:space-between;
  height:72px;
}
.brand{
  font-family:var(--serif);
  font-size:1.18rem;
  letter-spacing:-.01em;
  display:flex; align-items:baseline; gap:.55rem;
  white-space:nowrap;
}
.brand .brand-mark{
  font-family:var(--mono);
  font-size:.7rem;
  letter-spacing:.18em;
  text-transform:uppercase;
  color:var(--muted);
  border:1px solid var(--line-strong);
  border-radius:2px;
  padding:.18em .45em;
  position:relative; top:-2px;
}
.nav-links{
  display:flex; align-items:center; gap:clamp(1rem,2.4vw,2.4rem);
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:.14em;
  text-transform:uppercase;
}
.nav-links a{
  color:var(--ink-soft);
  position:relative;
  padding:.4em 0;
  transition:color .25s var(--ease);
}
.nav-links a::after{
  content:""; position:absolute; left:0; right:0; bottom:-2px;
  height:1px; background:var(--accent);
  transform:scaleX(0); transform-origin:left;
  transition:transform .3s var(--ease);
}
.nav-links a:hover{ color:var(--ink); }
.nav-links a:hover::after,
.nav-links a[aria-current="page"]::after{ transform:scaleX(1); }
.nav-links a[aria-current="page"]{ color:var(--accent); }

/* ---------- Nav section dropdowns ---------- */
.nav-item{ position:relative; display:inline-flex; }
.nav-drop{
  position:absolute; top:100%; left:50%; transform:translate(-50%,10px);
  min-width:240px; padding:.55rem 0;
  background:var(--paper); border:1px solid var(--line-strong);
  box-shadow:0 28px 56px -28px rgba(28,26,23,.4);
  opacity:0; visibility:hidden; pointer-events:none;
  transition:opacity .28s var(--ease), transform .28s var(--ease), visibility 0s linear .28s;
  z-index:120;
}
.nav-item:hover .nav-drop,
.nav-item:focus-within .nav-drop{
  opacity:1; visibility:visible; pointer-events:auto;
  transform:translate(-50%,0);
  transition:opacity .28s var(--ease), transform .28s var(--ease), visibility 0s;
}
.nav-drop a{
  display:flex; align-items:baseline; gap:.8em;
  padding:.6em 1.2em; font-size:11px; letter-spacing:.12em;
  color:var(--ink-soft); white-space:nowrap;
  transition:color .2s var(--ease), background .2s var(--ease);
}
.nav-drop a::after{ display:none; }
.nav-drop a:hover{ color:var(--accent); background:var(--paper-2); }
.nav-drop .nd-no{ font-size:9.5px; color:var(--accent); }
/* right-edge tabs: keep the panel inside the viewport */
.nav-drop.nd-right{ left:auto; right:0; transform:translateY(10px); }
.nav-item:hover .nav-drop.nd-right,
.nav-item:focus-within .nav-drop.nd-right{ transform:translateY(0); }
@media (max-width:760px){
  .nav-item{ width:100%; }
  .nav-drop{ display:none; }
}

.nav-toggle{ display:none; }

/* Mobile nav */
@media (max-width:760px){
  .nav{ height:62px; }
  .nav-toggle{
    display:inline-flex; flex-direction:column; gap:5px;
    background:none; border:0; cursor:pointer; padding:8px; margin-right:-8px;
  }
  .nav-toggle span{ width:24px; height:1.5px; background:var(--ink); transition:.3s var(--ease); }
  .nav-toggle[aria-expanded="true"] span:nth-child(1){ transform:translateY(6.5px) rotate(45deg); }
  .nav-toggle[aria-expanded="true"] span:nth-child(2){ opacity:0; }
  .nav-toggle[aria-expanded="true"] span:nth-child(3){ transform:translateY(-6.5px) rotate(-45deg); }
  .nav-links{
    position:fixed; inset:62px 0 auto 0;
    flex-direction:column; align-items:flex-start; gap:0;
    background:var(--paper); border-bottom:1px solid var(--line);
    padding:8px var(--gutter) 24px;
    max-height:0; overflow:hidden; opacity:0;
    transition:max-height .4s var(--ease), opacity .3s var(--ease);
  }
  .nav-links.open{ max-height:340px; opacity:1; }
  .nav-links a{ width:100%; padding:14px 0; border-bottom:1px solid var(--line); font-size:13px; }
  .nav-links a:last-child{ border-bottom:0; }
}

/* ---------- Buttons ---------- */
.btn{
  font-family:var(--mono);
  font-size:12px; letter-spacing:.12em; text-transform:uppercase;
  display:inline-flex; align-items:center; gap:.7em;
  padding:.95em 1.5em;
  border:1px solid var(--ink);
  color:var(--ink); background:transparent;
  border-radius:1px;
  cursor:pointer;
  transition:.3s var(--ease);
}
.btn:hover{ background:var(--ink); color:var(--paper); }
.btn .arrow{ transition:transform .3s var(--ease); }
.btn:hover .arrow{ transform:translateX(4px); }
.btn-ghost{ border-color:var(--line-strong); color:var(--ink-soft); }
.btn-ghost:hover{ background:transparent; color:var(--accent); border-color:var(--accent); }

.link-arrow{
  font-family:var(--mono); font-size:12.5px; letter-spacing:.1em; text-transform:uppercase;
  display:inline-flex; align-items:center; gap:.55em; color:var(--ink);
  border-bottom:1px solid var(--line-strong); padding-bottom:.3em;
  transition:.25s var(--ease);
}
.link-arrow .arrow{ transition:transform .3s var(--ease); color:var(--accent); }
.link-arrow:hover{ border-color:var(--accent); color:var(--accent); }
.link-arrow:hover .arrow{ transform:translateX(4px); }

/* ---------- Footer ---------- */
.site-footer{
  background:var(--ink);
  color:var(--paper);
  padding:clamp(56px,8vw,96px) 0 36px;
  margin-top:0;
}
.site-footer .wrap{ display:grid; gap:48px; }
.footer-top{
  display:grid; grid-template-columns:1.4fr 1fr; gap:48px;
  align-items:end;
}
@media (max-width:760px){ .footer-top{ grid-template-columns:1fr; align-items:start; } }
.footer-cta{
  font-size:clamp(1.8rem,4vw,3rem); font-weight:300; line-height:1.05; letter-spacing:-.02em;
}
.footer-cta a{ color:var(--accent-soft); border-bottom:1px solid color-mix(in srgb, var(--accent-soft) 50%, transparent); transition:.25s var(--ease); }
.footer-cta a:hover{ color:#fff; border-color:#fff; }
.footer-links{ display:flex; flex-direction:column; gap:.6rem; font-family:var(--mono); font-size:12.5px; letter-spacing:.08em; }
.footer-links a{ color:#cfc8ba; display:inline-flex; align-items:center; gap:.6em; width:fit-content; transition:.2s var(--ease); }
.footer-links a:hover{ color:#fff; }
.footer-links a::before{ content:"↗"; color:var(--accent-soft); font-size:.85em; }
.footer-bottom{
  display:flex; justify-content:space-between; flex-wrap:wrap; gap:16px;
  border-top:1px solid rgba(255,255,255,.13); padding-top:28px;
  font-family:var(--mono); font-size:11.5px; letter-spacing:.1em; color:#8f897c; text-transform:uppercase;
}
.footer-bottom .to-top{ color:#cfc8ba; transition:color .25s var(--ease); }
.footer-bottom .to-top:hover{ color:#fff; }
/* ghost signature closing each page */
.site-footer::after{
  content:"Dequn Teng";
  display:block; text-align:center;
  font-family:var(--serif); font-style:italic; font-weight:300;
  font-size:clamp(3.2rem,11vw,8.5rem); line-height:.75; letter-spacing:-.02em;
  color:rgba(243,239,230,.05);
  margin-top:clamp(28px,5vw,56px);
  user-select:none; pointer-events:none;
}

/* ---------- Portrait placeholder ---------- */
.portrait{
  position:relative; background:var(--paper-2);
  border:1px solid var(--line);
  overflow:hidden;
  background-image:repeating-linear-gradient(135deg, transparent 0 11px, color-mix(in srgb,var(--line) 60%, transparent) 11px 12px);
}
.portrait::after{
  content:attr(data-label);
  position:absolute; inset:0; display:flex; align-items:center; justify-content:center;
  font-family:var(--mono); font-size:11px; letter-spacing:.18em; text-transform:uppercase; color:var(--muted);
}
.portrait img{ width:100%; height:100%; object-fit:cover; position:relative; z-index:1; }

/* ---------- Reveal animation ---------- */
.reveal{ opacity:0; transform:translateY(18px); filter:blur(5px); transition:opacity .85s var(--ease), transform .85s var(--ease), filter .85s var(--ease); }
.reveal.in{ opacity:1; transform:none; filter:none; }
.reveal.d1{ transition-delay:.08s; }
.reveal.d2{ transition-delay:.16s; }
.reveal.d3{ transition-delay:.24s; }
.reveal.d4{ transition-delay:.32s; }
@media (prefers-reduced-motion: reduce){
  .reveal{ opacity:1; transform:none; filter:none; transition:none; }
}

/* eyebrow rule draws itself as it reveals */
@media (prefers-reduced-motion: no-preference){
  .reveal .eyebrow::before, .eyebrow.reveal::before{ transform:scaleX(0); transform-origin:left; transition:transform .9s var(--ease) .35s; }
  .reveal.in .eyebrow::before, .eyebrow.reveal.in::before{ transform:scaleX(1); }
}

/* ---------- Generic section spacing ---------- */
.section{ padding-block:clamp(64px, 10vw, 130px); }
.section-tight{ padding-block:clamp(48px, 7vw, 90px); }
.bg-2{ background:var(--paper-2); }
.bg-ink{ background:var(--ink); color:var(--paper); }

/* ---------- Stat row ---------- */
.stats{ display:grid; grid-template-columns:repeat(4,1fr); gap:1px; background:var(--line); border-block:1px solid var(--line); }
@media (max-width:760px){ .stats{ grid-template-columns:repeat(2,1fr); } }
.stat{ background:var(--paper); padding:clamp(24px,3vw,40px) clamp(16px,2vw,28px); }
.bg-2 .stat{ background:var(--paper-2); }
.stat .num{ font-size:clamp(2.2rem,4vw,3.4rem); font-weight:300; line-height:1; letter-spacing:-.02em; }
.stat .num .unit{ color:var(--accent); }
.stat .label{ font-family:var(--mono); font-size:11px; letter-spacing:.12em; text-transform:uppercase; color:var(--muted); margin-top:.9em; line-height:1.5; }

/* ---------- Cards ---------- */
.card{
  background:var(--paper); border:1px solid var(--line); padding:clamp(24px,3vw,38px);
  transition:border-color .3s var(--ease), transform .4s var(--ease), box-shadow .4s var(--ease);
}
.card:hover{ border-color:var(--line-strong); box-shadow:0 24px 48px -32px rgba(28,26,23,.3); }

/* ---------- Tags / chips ---------- */
.chip{
  font-family:var(--mono); font-size:10.5px; letter-spacing:.1em; text-transform:uppercase;
  padding:.32em .7em; border:1px solid var(--line-strong); color:var(--ink-soft);
  border-radius:1px; white-space:nowrap; display:inline-flex; align-items:center; gap:.4em;
}
.chip.claret{ color:var(--accent); border-color:color-mix(in srgb,var(--accent) 35%, var(--line-strong)); background:var(--accent-tint); }
a.chip-link{ text-decoration:none; cursor:pointer; transition:color .22s var(--ease), border-color .22s var(--ease), background .22s var(--ease); }
a.chip-link:hover{ color:var(--accent); border-color:var(--accent); background:var(--accent-tint); }
.chip-dot{ width:5px; height:5px; border-radius:50%; background:currentColor; display:inline-block; }

/* ---------- Utility ---------- */
.measure{ max-width:62ch; }
.muted{ color:var(--muted); }
.ink-soft{ color:var(--ink-soft); }
.center{ text-align:center; }
.mt-s{ margin-top:1rem; } .mt-m{ margin-top:2rem; } .mt-l{ margin-top:3rem; }
.flex{ display:flex; } .gap-s{ gap:.75rem; } .gap-m{ gap:1.25rem; }
.wrapflex{ flex-wrap:wrap; } .items-center{ align-items:center; }

/* skip link */
.skip{ position:absolute; left:-9999px; }
.skip:focus{ left:1rem; top:1rem; z-index:200; background:var(--ink); color:var(--paper); padding:.6em 1em; font-family:var(--mono); font-size:12px; }

/* ---------- Continue (next page) block ---------- */
.continue-block{ border-top:1px solid var(--line); background:var(--paper-2); }
.continue-block .wrap{ padding-block:clamp(44px,6vw,80px); }
.continue-link{ display:flex; align-items:baseline; gap:clamp(1rem,3vw,2.2rem); margin-top:1.2rem; text-decoration:none; flex-wrap:wrap; }
.continue-link .cl-title{ font-family:var(--serif); font-size:clamp(2rem,5vw,3.4rem); font-weight:300; line-height:1; letter-spacing:-.02em; color:var(--ink); transition:color .25s var(--ease); }
.continue-link .cl-sub{ font-family:var(--mono); font-size:11.5px; letter-spacing:.12em; text-transform:uppercase; color:var(--muted); }
.continue-link .cl-arrow{ font-size:clamp(1.5rem,3vw,2.2rem); color:var(--accent); transition:transform .3s var(--ease); line-height:1; }
.continue-link:hover .cl-title{ color:var(--accent); }
.continue-link:hover .cl-arrow{ transform:translateX(10px); }

/* ---------- Back to top ---------- */
.to-top{
  position:fixed; right:clamp(16px,3vw,32px); bottom:clamp(16px,3vw,32px); z-index:90;
  width:44px; height:44px; border-radius:50%;
  border:1px solid var(--line-strong);
  background:color-mix(in srgb, var(--paper) 90%, transparent);
  backdrop-filter:blur(6px); -webkit-backdrop-filter:blur(6px);
  color:var(--ink); font-size:17px; line-height:1; cursor:pointer;
  opacity:0; pointer-events:none; transform:translateY(8px);
  transition:opacity .3s var(--ease), transform .3s var(--ease), color .2s var(--ease), border-color .2s var(--ease);
}
.to-top.show{ opacity:1; pointer-events:auto; transform:none; }
.to-top:hover{ color:var(--accent); border-color:var(--accent); }
@media print{ .to-top,.continue-block{ display:none !important; } }

/* ---------- Lightbox ---------- */
.lightbox{
  position:fixed; inset:0; z-index:300;
  background:color-mix(in srgb, var(--ink) 90%, transparent);
  backdrop-filter:blur(10px); -webkit-backdrop-filter:blur(10px);
  display:none; flex-direction:column; align-items:center; justify-content:center;
  gap:1.1rem; padding:4vmin;
}
.lightbox.open{ display:flex; }
.lightbox img{ max-width:92vw; max-height:76vh; width:auto; height:auto; object-fit:contain; background:#0e0d0b; border:1px solid rgba(255,255,255,.14); }
.lightbox .lb-cap{ font-family:var(--mono); font-size:12px; letter-spacing:.05em; color:#cfc8ba; text-align:center; max-width:72ch; line-height:1.5; }
.lightbox .lb-btn{
  position:absolute; width:42px; height:42px; border-radius:50%;
  border:1px solid rgba(255,255,255,.3); background:transparent; color:#f3efe6;
  font-size:16px; cursor:pointer; display:flex; align-items:center; justify-content:center;
  transition:border-color .2s var(--ease), color .2s var(--ease), background .2s var(--ease);
}
.lightbox .lb-btn:hover{ border-color:#fff; background:rgba(255,255,255,.08); }
.lightbox .lb-close{ top:18px; right:18px; }
.lightbox .lb-prev{ left:18px; top:50%; transform:translateY(-50%); }
.lightbox .lb-next{ right:18px; top:50%; transform:translateY(-50%); }
.gallery .g-frame, .teach-hero-fig .fig-frame{ cursor:zoom-in; }

/* ============ Dynamic effects ============ */
/* ink-up statement words */
.ink-w{ color:var(--muted-2); transition:color .45s var(--ease); }
.ink-w.on{ color:inherit; }

/* cursor spotlight */
.theme, .proj, .conn, .stat{ position:relative; }
.spot{
  position:absolute; inset:0; pointer-events:none; opacity:0;
  background:radial-gradient(260px circle at var(--mx,50%) var(--my,50%), rgba(124,45,42,.07), transparent 72%);
  transition:opacity .45s var(--ease);
}
.theme:hover > .spot, .proj:hover > .spot, .conn:hover > .spot, .stat:hover > .spot{ opacity:1; }

/* ghost signature rises with the footer */
@media (prefers-reduced-motion: no-preference){
  .site-footer::after{ opacity:0; transform:translateY(46px); transition:opacity 1.3s var(--ease) .1s, transform 1.3s var(--ease) .1s; }
  .site-footer.sig-in::after{ opacity:1; transform:none; }
}

/* ============ Item hover dynamics ============ */
@media (hover:hover) and (prefers-reduced-motion: no-preference){
  /* chips lift and warm */
  .chip{ transition:transform .3s var(--ease), border-color .3s var(--ease), background .3s var(--ease), color .3s var(--ease); }
  .chip:hover{ transform:translateY(-2px); border-color:var(--accent); color:var(--accent); background:var(--accent-tint); }

  /* stat tiles: number lifts, label warms */
  .stat .num{ transition:transform .45s var(--ease); }
  .stat:hover .num{ transform:translateY(-3px); }
  .stat .label{ transition:color .3s var(--ease); }
  .stat:hover .label{ color:var(--ink-soft); }

  /* buttons press */
  .btn:active{ transform:translateY(1px); }
}