/* =========================================================
   MIND = MATH — design tokens
   Palette: deep violet-black stage + teal/magenta duotone glow + gold reveal
   Type: Fraunces (display) / Space Grotesk (ui) / JetBrains Mono (numerals)
   ========================================================= */
:root{
  --bg:            #0B0714;
  --bg-elevated:   #150F24;
  --bg-elevated-2: #1E1730;
  --bg-elevated-3: #241C3A;
  --line:          rgba(242,238,247,0.09);
  --line-strong:   rgba(242,238,247,0.16);

  --teal:      #00E5C7;
  --teal-dim:  rgba(0,229,199,0.14);
  --magenta:   #FF3D9A;
  --magenta-dim: rgba(255,61,154,0.14);
  --gold:      #F5B942;
  --gold-dim:  rgba(245,185,66,0.16);

  --text-1: #F2EEF7;
  --text-2: #B7ACC9;
  --text-3: #776D8C;

  --font-display: 'Fraunces', serif;
  --font-ui: 'Space Grotesk', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  --radius-s: 10px;
  --radius-m: 16px;
  --radius-l: 26px;
  --ease: cubic-bezier(.22,.9,.28,1);
}

*,*::before,*::after{ box-sizing:border-box; }
html,body{ margin:0; padding:0; }
body{
  background:var(--bg);
  color:var(--text-1);
  font-family:var(--font-ui);
  min-height:100vh;
  -webkit-font-smoothing:antialiased;
  overflow-x:hidden;
}
h1,h2,h3{ font-family:var(--font-display); margin:0; font-weight:500; }
p{ margin:0; }
button{ font-family:inherit; }
::selection{ background:var(--teal); color:#04120F; }

a{ color:var(--teal); }

/* focus visibility for a11y */
:focus-visible{ outline:2px solid var(--teal); outline-offset:3px; border-radius:4px; }

/* ---------- ambient background: grain + drifting ghost equations ---------- */
.grain{
  position:fixed; inset:0; z-index:0; pointer-events:none; opacity:.05; mix-blend-mode:overlay;
  background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='120' height='120'%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");
}
.bg-equations{
  position:fixed; inset:0; z-index:0; pointer-events:none; overflow:hidden;
}
.bg-equations span{
  position:absolute; font-family:var(--font-mono); color:var(--text-1); opacity:0;
  font-size:14px; white-space:nowrap; animation:drift 22s linear infinite;
}
@keyframes drift{
  0%{ opacity:0; transform:translateY(10vh) translateX(0); }
  8%{ opacity:.09; }
  92%{ opacity:.07; }
  100%{ opacity:0; transform:translateY(-110vh) translateX(30px); }
}

#app{ position:relative; z-index:1; min-height:100vh; display:flex; flex-direction:column; }

/* ---------- topbar ---------- */
.topbar{
  display:flex; align-items:center; justify-content:space-between;
  padding:18px 20px; position:sticky; top:0; z-index:40;
  background:linear-gradient(to bottom, rgba(11,7,20,.92), rgba(11,7,20,.7) 70%, transparent);
  backdrop-filter:blur(6px);
}
.brand{
  font-family:var(--font-display); font-style:italic; font-weight:500;
  font-size:18px; letter-spacing:.02em; color:var(--text-1);
}
.brand .eq{
  color:var(--teal); font-style:normal; margin:0 3px; font-weight:600;
  text-shadow:0 0 14px var(--teal);
}
.topbar-controls{ display:flex; gap:8px; }
.pill-btn{
  display:inline-flex; align-items:center; gap:6px;
  background:var(--bg-elevated); border:1px solid var(--line);
  color:var(--text-2); border-radius:100px; padding:7px 13px;
  font-size:12px; letter-spacing:.06em; cursor:pointer; transition:border-color .2s var(--ease), color .2s var(--ease);
}
.pill-btn:hover{ border-color:var(--line-strong); color:var(--text-1); }

/* ---------- home ---------- */
.home{ flex:1; display:flex; justify-content:center; padding:8px 20px 40px; }
.home-inner{ max-width:760px; width:100%; padding-top:18px; }
.eyebrow{
  font-family:var(--font-mono); font-size:11px; letter-spacing:.16em; text-transform:uppercase;
  color:var(--teal); margin-bottom:14px;
}
.hero-title{
  font-size:clamp(30px,7vw,46px); line-height:1.08; font-style:italic; font-weight:500;
  background:linear-gradient(100deg, var(--text-1) 40%, var(--teal) 70%, var(--magenta) 100%);
  -webkit-background-clip:text; background-clip:text; -webkit-text-fill-color:transparent;
  margin-bottom:16px;
}
.hero-sub{ color:var(--text-2); font-size:15px; line-height:1.6; max-width:56ch; margin-bottom:34px; }
.home-footnote{ margin-top:30px; color:var(--text-3); font-size:12.5px; line-height:1.6; }

/* ---------- act grid / ticket cards ---------- */
.act-grid{ display:grid; grid-template-columns:repeat(auto-fill,minmax(260px,1fr)); gap:14px; }
.act-card{
  position:relative; text-align:left; background:var(--bg-elevated);
  border:1px solid var(--line); border-radius:var(--radius-m);
  padding:18px 18px 20px; cursor:pointer; color:inherit;
  transition:transform .25s var(--ease), border-color .25s var(--ease), background .25s var(--ease);
  display:flex; flex-direction:column; gap:10px; overflow:hidden;
}
.act-card::before{
  content:""; position:absolute; inset:0; opacity:0; transition:opacity .3s var(--ease);
  background:radial-gradient(140px 90px at 20% 0%, var(--teal-dim), transparent 70%);
}
.act-card:hover, .act-card:focus-visible{
  transform:translateY(-3px); border-color:var(--line-strong); background:var(--bg-elevated-2);
}
.act-card:hover::before{ opacity:1; }
.act-num{
  font-family:var(--font-mono); font-size:11px; letter-spacing:.1em; color:var(--text-3);
}
.act-num b{ color:var(--gold); font-weight:600; }
.act-title{ font-family:var(--font-display); font-size:20px; font-weight:500; color:var(--text-1); }
.act-title .bn{ display:block; }
.act-desc{ font-size:13px; color:var(--text-2); line-height:1.55; }
.act-tag{
  align-self:flex-start; margin-top:auto; font-family:var(--font-mono); font-size:10.5px;
  color:var(--teal); border:1px solid var(--teal-dim); background:var(--teal-dim);
  padding:4px 9px; border-radius:100px; letter-spacing:.04em;
}

/* ---------- stage ---------- */
.stage{ flex:1; display:flex; flex-direction:column; padding:14px 20px 30px; position:relative; }
.stage-bar{ display:flex; align-items:center; justify-content:space-between; gap:14px; margin-bottom:6px; flex-wrap:wrap; }
.back-btn{
  display:inline-flex; align-items:center; gap:6px; background:transparent; border:none;
  color:var(--text-2); font-size:13px; cursor:pointer; padding:8px 4px;
}
.back-btn:hover{ color:var(--text-1); }
.stage-act-label{ font-family:var(--font-mono); font-size:11px; color:var(--text-3); letter-spacing:.08em; }
.stage-inner{ max-width:640px; margin:0 auto; width:100%; padding:22px 0 60px; }

.equation-trace{
  position:fixed; left:0; right:0; bottom:0; z-index:5; pointer-events:none;
  font-family:var(--font-mono); font-size:11px; color:var(--text-3); opacity:.55;
  padding:8px 16px; white-space:nowrap; overflow:hidden; text-overflow:ellipsis;
  border-top:1px solid var(--line); background:linear-gradient(to top, var(--bg) 60%, transparent);
}

/* ---------- shared stage components ---------- */
.act-header{ margin-bottom:22px; }
.act-heading{ font-size:clamp(24px,5vw,32px); font-style:italic; color:var(--text-1); margin-bottom:8px; }
.act-sub{ color:var(--text-2); font-size:14px; line-height:1.6; }

.panel{
  background:var(--bg-elevated); border:1px solid var(--line); border-radius:var(--radius-l);
  padding:26px 22px; position:relative;
}

.spotlight{
  width:100%; display:flex; align-items:center; justify-content:center; flex-direction:column;
  padding:34px 10px; text-align:center;
}
.spotlight-ring{
  width:132px; height:132px; border-radius:50%; position:relative; margin-bottom:22px;
  border:1px solid var(--line-strong);
  display:flex; align-items:center; justify-content:center;
}
.spotlight-ring::before{
  content:""; position:absolute; inset:-1px; border-radius:50%;
  background:conic-gradient(from 0deg, var(--teal), var(--magenta), var(--teal));
  -webkit-mask:radial-gradient(closest-side, transparent calc(100% - 2px), #000 calc(100% - 2px));
  mask:radial-gradient(closest-side, transparent calc(100% - 2px), #000 calc(100% - 2px));
  animation:spin 3.2s linear infinite;
}
.spotlight-ring.pulse::before{ animation:spin 1.4s linear infinite; }
@keyframes spin{ to{ transform:rotate(360deg); } }
.spotlight-glyph{ font-family:var(--font-mono); font-size:13px; color:var(--text-2); z-index:1; }
.spotlight-line{ font-family:var(--font-ui); font-size:14.5px; color:var(--text-2); min-height:22px; }
.spotlight-line .dots::after{ content:''; animation:dots 1.4s steps(4,end) infinite; }
@keyframes dots{ 0%{content:''} 25%{content:'.'} 50%{content:'..'} 75%{content:'...'} 100%{content:''} }

.reveal-number{
  font-family:var(--font-mono); font-weight:700; letter-spacing:.02em;
  font-size:clamp(40px,12vw,72px); line-height:1;
  background:linear-gradient(100deg, var(--gold), #fff2cf 50%, var(--gold));
  -webkit-background-clip:text; background-clip:text; -webkit-text-fill-color:transparent;
  text-shadow:0 0 40px var(--gold-dim);
}
.reveal-caption{ font-size:13px; color:var(--text-2); margin-top:10px; }
.reveal-wrap{ text-align:center; padding:18px 0 6px; }

.field{ margin-bottom:16px; }
.field label{ display:block; font-size:12.5px; color:var(--text-2); margin-bottom:7px; letter-spacing:.02em; }
.field input, .field select{
  width:100%; background:var(--bg); border:1px solid var(--line-strong); color:var(--text-1);
  font-family:var(--font-mono); font-size:16px; padding:12px 13px; border-radius:var(--radius-s);
}
.field input:focus, .field select:focus{ border-color:var(--teal); }
.field-row{ display:flex; gap:12px; }
.field-row .field{ flex:1; }
.hint{ font-size:12px; color:var(--text-3); margin-top:6px; line-height:1.5; }
.error-text{ font-size:12.5px; color:var(--magenta); margin-top:6px; min-height:16px; }

.btn{
  display:inline-flex; align-items:center; justify-content:center; gap:8px;
  border:none; border-radius:100px; padding:13px 24px; font-size:14px; font-weight:600;
  cursor:pointer; font-family:var(--font-ui); transition:transform .18s var(--ease), opacity .18s var(--ease);
  letter-spacing:.01em;
}
.btn:active{ transform:scale(.97); }
.btn-primary{ background:var(--teal); color:#04120F; }
.btn-primary:hover{ opacity:.9; }
.btn-ghost{ background:transparent; border:1px solid var(--line-strong); color:var(--text-1); }
.btn-ghost:hover{ border-color:var(--teal); color:var(--teal); }
.btn-row{ display:flex; gap:10px; flex-wrap:wrap; margin-top:6px; }
.btn:disabled{ opacity:.4; cursor:not-allowed; }
.btn-block{ width:100%; }

.step-list{ margin:18px 0; }
.step-item{
  display:flex; gap:12px; padding:13px 0; border-bottom:1px solid var(--line);
  opacity:.35; transition:opacity .3s var(--ease);
}
.step-item.active{ opacity:1; }
.step-item.done{ opacity:.6; }
.step-index{ font-family:var(--font-mono); color:var(--teal); font-size:12px; padding-top:2px; }
.step-text{ font-size:14.5px; line-height:1.55; color:var(--text-1); }
.step-text .val{ font-family:var(--font-mono); color:var(--gold); font-weight:600; }

.grid-cards{ display:grid; grid-template-columns:repeat(auto-fit,minmax(120px,1fr)); gap:10px; margin:18px 0; }
.num-card{
  background:var(--bg); border:1px solid var(--line-strong); border-radius:var(--radius-s);
  padding:12px; cursor:pointer; user-select:none; transition:border-color .2s, background .2s;
}
.num-card.selected{ border-color:var(--teal); background:var(--teal-dim); }
.num-card h4{ font-family:var(--font-mono); font-size:11px; color:var(--text-2); margin:0 0 8px; letter-spacing:.06em; }
.num-card .nums{ font-family:var(--font-mono); font-size:12.5px; color:var(--text-1); line-height:1.9; word-spacing:4px; }

.grid4{
  display:grid; grid-template-columns:repeat(4,1fr); gap:6px; max-width:320px; margin:20px auto;
}
.grid4 .cell{
  aspect-ratio:1; display:flex; align-items:center; justify-content:center;
  font-family:var(--font-mono); font-weight:700; font-size:clamp(16px,4vw,22px);
  background:var(--bg); border:1px solid var(--line-strong); border-radius:8px; color:var(--gold);
}

.how-toggle{
  margin-top:24px; border-top:1px solid var(--line); padding-top:16px;
}
.how-toggle summary{ cursor:pointer; font-size:13px; color:var(--teal); list-style:none; display:flex; align-items:center; gap:6px; }
.how-toggle summary::-webkit-details-marker{ display:none; }
.how-toggle summary::before{ content:'▸'; transition:transform .2s; }
.how-toggle[open] summary::before{ transform:rotate(90deg); }
.how-body{ font-size:13.5px; color:var(--text-2); line-height:1.7; padding:12px 2px 2px; }
.how-body code{ font-family:var(--font-mono); background:var(--bg); padding:1px 5px; border-radius:4px; color:var(--gold); }

.badge-row{ display:flex; gap:8px; flex-wrap:wrap; margin:14px 0; }
.badge{ font-family:var(--font-mono); font-size:11px; color:var(--text-2); border:1px solid var(--line); padding:5px 10px; border-radius:100px; }

/* yes/no question card (binary search act) */
.question-card{ text-align:center; padding:30px 16px; }
.question-num{ font-family:var(--font-mono); color:var(--text-3); font-size:12px; margin-bottom:10px; }
.question-text{ font-size:clamp(20px,5vw,26px); font-style:italic; font-family:var(--font-display); margin-bottom:26px; }
.range-bar{ height:6px; border-radius:100px; background:var(--bg); overflow:hidden; margin-top:22px; border:1px solid var(--line); }
.range-fill{ height:100%; background:linear-gradient(90deg, var(--teal), var(--magenta)); transition:width .35s var(--ease); }

/* kaprekar / iterative steps */
.iter-row{
  display:flex; align-items:center; justify-content:space-between; gap:10px;
  font-family:var(--font-mono); font-size:14px; padding:10px 4px; border-bottom:1px solid var(--line);
  opacity:0; transform:translateY(6px); animation:riseIn .4s var(--ease) forwards;
}
@keyframes riseIn{ to{ opacity:1; transform:none; } }
.iter-row .op{ color:var(--text-3); }
.iter-row .res{ color:var(--gold); font-weight:700; }

footer.site-footer{ text-align:center; padding:22px 20px 30px; }
footer.site-footer p{ font-size:11.5px; color:var(--text-3); max-width:50ch; margin:0 auto; line-height:1.6; }

/* utility */
.center{ text-align:center; }
.mt-8{ margin-top:8px; } .mt-16{ margin-top:16px; } .mt-24{ margin-top:24px; }
.small{ font-size:12.5px; color:var(--text-2); }
.sr-only{ position:absolute; width:1px; height:1px; overflow:hidden; clip:rect(0,0,0,0); }

@media (max-width:480px){
  .home{ padding-top:0; }
  .field-row{ flex-direction:column; gap:0; }
  .stage-inner{ padding-top:10px; }
}

@media (prefers-reduced-motion: reduce){
  *{ animation-duration:.001ms !important; animation-iteration-count:1 !important; transition-duration:.001ms !important; }
  .bg-equations{ display:none; }
}