/* Study slides — bubble field. Warm ink, editorial serif, mono codes. */

:root{
  --ink:#131210;
  --ink-2:#1b1916;
  --bone:#e9e4da;
  --bone-soft:rgba(233,228,218,.82);
  --mut:#8f897d;
  --line:rgba(233,228,218,.16);
  --serif:"Fraunces", Georgia, "Times New Roman", serif;
  --mono:"IBM Plex Mono", ui-monospace, "Cascadia Mono", Consolas, monospace;
  --soft:cubic-bezier(.22,1,.36,1);
  --spring:cubic-bezier(.32,1.3,.35,1);
}

*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;overflow:hidden;
  color:var(--bone);font-family:var(--serif);font-size:17px;line-height:1.5;
  background:radial-gradient(120% 90% at 50% -10%, #1d1a16 0%, var(--ink) 62%);
}
a{color:var(--bone)}
:focus-visible{outline:2px solid var(--bone);outline-offset:3px;border-radius:4px}
button{font:inherit;color:inherit;background:none;border:none;cursor:pointer;padding:0}

/* ---------- masthead / footer ---------- */
.mast{position:fixed;top:0;left:0;padding:34px 38px;z-index:5;pointer-events:none}
.mast h1{margin:0;font-size:clamp(1.7rem,3.4vw,2.5rem);font-weight:560;letter-spacing:.01em}
.mast .tag{margin:6px 0 0;color:var(--mut);font-size:.98rem;font-style:italic;max-width:30ch}
.back{
  pointer-events:auto;margin-top:18px;display:inline-block;
  font-family:var(--mono);font-size:.85rem;color:var(--mut);
  border-bottom:1px solid transparent;transition:color .3s,border-color .3s;
}
.back:hover{color:var(--bone);border-color:var(--bone)}
.back[hidden]{display:none}

.hint{
  position:fixed;right:38px;bottom:64px;z-index:5;margin:0;
  font-family:var(--mono);font-size:.78rem;letter-spacing:.14em;text-transform:uppercase;
  color:var(--mut);opacity:.8;transition:opacity .6s;pointer-events:none;
}
.hint.off{opacity:0}

.foot{
  position:fixed;left:38px;bottom:24px;right:38px;z-index:5;
  font-family:var(--mono);font-size:.75rem;color:var(--mut);
}
.foot a{color:var(--mut);text-decoration:none;border-bottom:1px solid rgba(143,137,125,.4);transition:color .3s,border-color .3s}
.foot a:hover{color:var(--bone);border-color:var(--bone)}
.foot .dot{margin:0 8px;opacity:.5}
.foot .fine{display:block;margin-top:5px;opacity:.6;max-width:64ch}

/* ---------- bubble field ---------- */
#field{position:fixed;inset:0;z-index:1}

.bubble{
  position:absolute;left:var(--x);top:var(--y);
  width:clamp(88px, calc(var(--s) * 15vmin), 178px);aspect-ratio:1;
  transform:translate(-50%,-50%);
  transition:transform .8s var(--soft), opacity .6s, filter .6s;
  z-index:2;border-radius:50%;
  -webkit-tap-highlight-color:transparent;
}
.drift{display:block;width:100%;height:100%;will-change:transform}
.drift.settle{transition:transform .9s var(--soft)}

.shell{
  position:relative;display:flex;flex-direction:column;align-items:center;justify-content:center;
  width:100%;height:100%;border-radius:50%;
  border:1px solid var(--line);
  background:
    radial-gradient(120% 120% at 31% 24%, rgba(255,255,255,.09), rgba(255,255,255,0) 46%),
    radial-gradient(95% 95% at 74% 82%, var(--acc-glow), rgba(0,0,0,0) 60%);
  box-shadow:
    inset 0 0 26px rgba(255,255,255,.045),
    inset -10px -14px 34px rgba(0,0,0,.30);
  transition:border-color .5s, box-shadow .5s;
}
/* thin refraction crescent */
.shell::before{
  content:"";position:absolute;inset:5.5%;border-radius:50%;
  border:1px solid transparent;
  border-top-color:rgba(255,255,255,.18);
  border-left-color:rgba(255,255,255,.05);
  transform:rotate(-18deg);
}
.bubble:hover .shell{border-color:rgba(233,228,218,.34)}

.bubble .code{
  position:relative;z-index:2;
  font-family:var(--mono);font-weight:500;letter-spacing:.06em;
  font-size:clamp(.86rem, calc(var(--s) * 1.25vmin + .35rem), 1.2rem);
}
.bubble .sub{
  position:relative;z-index:2;margin-top:2px;
  font-family:var(--mono);font-size:.66rem;letter-spacing:.1em;color:var(--mut);
}
.bubble .dname,.bubble .dcount{display:none}

.bubble.soon{opacity:.55}
.bubble.soon:hover{opacity:.8}

/* sunk: everything that is not the chosen bubble */
.bubble.sunk{
  opacity:.16;filter:blur(2.5px);
  transform:translate(-50%,-38%) scale(.55);
  pointer-events:none;
}
.bubble.soon.sunk{opacity:.09}

/* focused: glides to center via inline transform, content re-set in em of --k */
.bubble.focus{z-index:6;cursor:default}
.bubble.focus .shell{border-color:rgba(233,228,218,.30)}
.bubble.focus .code{font-size:calc(1.9rem / var(--k,1));letter-spacing:.08em}
.bubble.focus .sub{display:none}
.bubble.focus .dname{
  display:block;position:relative;z-index:2;margin-top:calc(6px / var(--k,1));
  font-family:var(--serif);font-style:italic;font-weight:400;color:var(--bone-soft);
  font-size:calc(1.02rem / var(--k,1));
}
.bubble.focus .dcount{
  display:block;position:relative;z-index:2;margin-top:calc(4px / var(--k,1));
  font-family:var(--mono);font-size:calc(.72rem / var(--k,1));letter-spacing:.14em;
  text-transform:uppercase;color:var(--mut);
}

/* ---------- course (child) bubbles ---------- */
.kid{
  position:absolute;width:118px;aspect-ratio:1;z-index:7;
  transform:translate(-50%,-50%) scale(.12);opacity:0;
  transition:transform .85s var(--spring), opacity .45s;
  border-radius:50%;
  -webkit-tap-highlight-color:transparent;
}
.kid.in{opacity:1}
.kid.merge{opacity:0 !important}
.kshell{
  display:flex;flex-direction:column;align-items:center;justify-content:center;gap:2px;
  width:100%;height:100%;border-radius:50%;
  border:1px solid var(--line);
  background:
    radial-gradient(120% 120% at 30% 25%, rgba(255,255,255,.10), rgba(255,255,255,0) 45%),
    radial-gradient(95% 95% at 72% 80%, var(--acc-glow), rgba(0,0,0,0) 60%);
  box-shadow:inset 0 0 18px rgba(255,255,255,.05), inset -6px -10px 22px rgba(0,0,0,.3);
  transition:border-color .4s;
  animation:bob 5.5s ease-in-out infinite alternate;
}
.kid:hover .kshell,.kid.active .kshell{border-color:var(--acc)}
@keyframes bob{from{transform:translateY(-3px)}to{transform:translateY(3px)}}
.kid .kcode{font-family:var(--mono);font-weight:500;font-size:.95rem;letter-spacing:.05em}
.kid .kmeta{font-family:var(--mono);font-size:.63rem;letter-spacing:.1em;color:var(--mut)}

.fieldnote{
  position:absolute;z-index:6;transform:translate(-50%,0);text-align:center;
  font-family:var(--mono);font-size:.8rem;color:var(--mut);
  opacity:0;transition:opacity .6s .5s;
}
.fieldnote.in{opacity:1}
.fieldnote a{color:var(--bone-soft)}

/* ---------- signature line-art icons ---------- */
.icon{position:absolute;inset:13%;z-index:1;opacity:0;transition:opacity .6s;pointer-events:none}
.icon :is(path,circle,rect,line){
  fill:none;stroke:var(--bone-soft);stroke-width:1.8;
  stroke-linecap:round;stroke-linejoin:round;vector-effect:non-scaling-stroke;
}
.icon .ac{stroke:var(--acc)}
.bubble:hover .icon,.bubble:focus-visible .icon{opacity:.3}
.bubble.focus .icon{opacity:.42}
.bubble:hover .icon :is(path,circle,rect,line),
.bubble.focus .icon :is(path,circle,rect,line){
  stroke-dasharray:1;stroke-dashoffset:1;
  animation:sketch 1.3s var(--soft) forwards;
  animation-delay:calc(var(--d,0) * .22s);
}
@keyframes sketch{to{stroke-dashoffset:0}}

/* per-domain motion once open */
.i-mech g{transform-box:fill-box;transform-origin:center}
.focus .i-mech .gA{animation:spin 8s linear infinite}
.focus .i-mech .gB{animation:spinR 5.2s linear infinite}
@keyframes spin{to{transform:rotate(360deg)}}
@keyframes spinR{to{transform:rotate(-360deg)}}
.focus .i-elec .ac{animation:sketch 1.1s var(--soft) forwards, current 1.9s linear 1.3s infinite}
.focus .i-coen .tr{animation:sketch 1.1s var(--soft) forwards, current 2.1s linear 1.4s infinite}
.focus .i-aero .fl{animation:sketch 1.2s var(--soft) forwards, current 2s linear 1.5s infinite}
@keyframes current{
  from{stroke-dasharray:.12 .12;stroke-dashoffset:0}
  to{stroke-dasharray:.12 .12;stroke-dashoffset:-.96}
}
.i-indu .p{transform-box:fill-box}
.focus .i-indu .p{animation:convey 2.6s ease-in-out infinite alternate}
.focus .i-indu .p2{animation-delay:.3s}
.focus .i-indu .p3{animation-delay:.6s}
@keyframes convey{to{transform:translateX(13px)}}
.focus .i-soen .nd{animation:sketch .6s var(--soft) forwards, pulse 1.8s ease-in-out 1.4s infinite}
@keyframes pulse{50%{opacity:.35}}

/* ---------- reading panel ---------- */
#veil{position:fixed;inset:0;z-index:8;background:rgba(10,9,8,.45);opacity:0;transition:opacity .4s}
#veil.show{opacity:1}
#panel{
  position:fixed;top:0;right:0;bottom:0;z-index:9;
  width:min(480px,100vw);overflow-y:auto;
  background:var(--ink-2);border-left:1px solid var(--line);
  transform:translateX(103%);transition:transform .5s var(--soft);
  padding:34px 34px 44px;
}
#panel.show{transform:translateX(0)}
.pclose{
  position:absolute;top:20px;right:22px;
  font-family:var(--mono);font-size:.85rem;color:var(--mut);
  transition:color .3s;
}
.pclose:hover{color:var(--bone)}
.pkicker{font-family:var(--mono);font-size:.8rem;letter-spacing:.16em;text-transform:uppercase;color:var(--acc,#d9a441);margin:0 0 6px}
.ptitle{font-family:var(--serif);font-weight:560;font-size:1.65rem;line-height:1.2;margin:0 0 4px}
.psub{font-style:italic;color:var(--mut);margin:0 0 26px;font-size:.95rem}

.note{border-top:1px solid var(--line);padding:22px 0}
.note:last-child{border-bottom:1px solid var(--line)}
.note .prev{
  display:block;width:100%;border:1px solid var(--line);margin:0 0 14px;
  aspect-ratio:16/9;object-fit:cover;background:var(--ink);
}
.note h3{font-family:var(--serif);font-weight:560;font-size:1.18rem;margin:0 0 6px}
.note .desc{color:var(--bone-soft);font-size:.92rem;margin:0 0 10px}
.note .meta{font-family:var(--mono);font-size:.72rem;letter-spacing:.08em;color:var(--mut);margin:0 0 14px}
.note .row{display:flex;gap:10px;flex-wrap:wrap;align-items:center}
.nbtn{
  display:inline-block;text-decoration:none;
  font-family:var(--mono);font-size:.82rem;letter-spacing:.04em;
  padding:8px 16px;border:1px solid var(--line);border-radius:99px;
  transition:border-color .3s, background .3s, color .3s, transform .2s var(--soft);
}
.nbtn:hover{transform:translateY(-1px)}
.nbtn.main{border-color:var(--acc);color:var(--ink);background:var(--acc)}
.nbtn.main:hover{filter:brightness(1.08)}
.nbtn.ghost:hover{border-color:var(--bone);color:var(--bone)}
.nrep{font-family:var(--mono);font-size:.74rem;color:var(--mut);text-decoration:none;border-bottom:1px solid rgba(143,137,125,.4)}
.nrep:hover{color:var(--bone);border-color:var(--bone)}

/* ---------- small screens ---------- */
@media (max-width:700px){
  .mast{padding:22px 22px}
  .foot{left:22px;right:22px;bottom:16px}
  .foot .fine{display:none}
  .hint{right:22px;bottom:56px}
  #panel{padding:26px 22px 40px}
  .kid{width:96px}
}

/* applied for the first paint so deep links don't animate */
.noanim *{transition-duration:0s !important;animation-duration:0s !important}

/* ---------- reduced motion: fade, don't fly ---------- */
@media (prefers-reduced-motion:reduce){
  .bubble,.kid,#panel,#veil,.drift{transition:opacity .3s !important}
  .kshell,.icon *,.i-mech g{animation:none !important}
  .icon{opacity:.35}
  .bubble.focus .icon{opacity:.45}
}