:root{
  --ink:#0f172a;
  --muted:#64748b;
  --shadow: 0 18px 45px rgba(15,23,42,.12);
  --shadow2: 0 10px 24px rgba(15,23,42,.10);
  --r:24px;

  --blue: rgba(59,130,246,.18);
  --green: rgba(34,197,94,.18);
  --orange: rgba(251,146,60,.18);
  --red: rgba(239,68,68,.18);
}

*{box-sizing:border-box}
body{
  margin:0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial;
  color:var(--ink);
  background:
    radial-gradient(circle at 12% 12%, rgba(59,130,246,.14), transparent 45%),
    radial-gradient(circle at 88% 18%, rgba(34,197,94,.12), transparent 45%),
    radial-gradient(circle at 30% 92%, rgba(251,146,60,.12), transparent 45%),
    linear-gradient(180deg, #f6fbff, #fff7ff);
  min-height:100vh;
}
.sub{
  font-size:.62em;
  vertical-align:baseline;
  position:relative;
  top:.18em;
  font-weight:1000;
}


/* Topbar */
.topbar{
  max-width:1100px;
  margin:0 auto;
  padding:18px 16px 10px;
  display:flex;
  gap:12px;
  align-items:flex-start;
}
.back{
  text-decoration:none;
  padding:10px 12px;
  border-radius:14px;
  background:rgba(15,23,42,.06);
  color:var(--ink);
  font-weight:900;
  border:1px solid rgba(15,23,42,.08);
}
.pill{
  display:inline-flex;
  padding:7px 10px;
  border-radius:999px;
  font-weight:1000;
  font-size:12px;
  color:#334155;
  background: rgba(15,23,42,.06);
  border:1px solid rgba(15,23,42,.08);
}
.title h1{
  margin:8px 0 0;
  font-size: clamp(24px, 3.6vw, 38px);
  letter-spacing:-.02em;
}
.subtitle{
  margin:6px 0 0;
  color:var(--muted);
  font-size: 14px;
  font-weight:700;
}

/* Layout */
.page{max-width:1100px;margin:0 auto;padding:0 16px 26px;}
.panel{
  background: rgba(255,255,255,.78);
  border: 1px solid rgba(15,23,42,.08);
  border-radius: 28px;
  box-shadow: var(--shadow);
  padding: 18px;
  backdrop-filter: blur(8px);
  margin-top: 10px;
}
.panelTop{
  display:flex;
  justify-content:space-between;
  align-items:baseline;
  gap:12px;
  flex-wrap:wrap;
}
.panelTop h2{margin:0}
.muted{margin:0;color:var(--muted);font-size:13px;font-weight:800}

.labGrid{
  margin-top: 14px;
  display:grid;
  grid-template-columns: 1fr;
  gap: 12px;
}
@media(min-width:980px){
  .labGrid{grid-template-columns: 1fr 1.15fr 1fr;}
}

.card{
  background: rgba(255,255,255,.92);
  border: 1px solid rgba(15,23,42,.08);
  border-radius: var(--r);
  box-shadow: var(--shadow2);
  padding: 16px;
}
.cardTitle{margin:0 0 10px;font-size:16px}

/* Reactants tray */
.tray{
  display:grid;
  gap:14px;
  justify-items:center;
  margin-top: 8px;
}

.reactantStack{
  display:grid;
  gap:14px;
  justify-items:center;
}

.mol{
  width: 210px;
  border-radius: 24px;
  border: 1px solid rgba(15,23,42,.10);
  box-shadow: 0 10px 20px rgba(15,23,42,.08);
  overflow:hidden;
  background: rgba(15,23,42,.04);
}
.molTop{
  padding: 10px 12px;
  font-weight:1000;
  background: rgba(59,130,246,.10);
  border-bottom: 1px solid rgba(15,23,42,.08);
}
.molMain{
  padding: 14px 12px 8px;
  font-weight: 1000;
  font-size: 28px;
  text-align:center;
}
.molHint{
  padding: 0 12px 12px;
  text-align:center;
  color: var(--muted);
  font-weight: 900;
  font-size: 12px;
}

.chipBtn{
  width:78px;height:78px;
  border-radius: 24px;
  border: 1px solid rgba(15,23,42,.10);
  font-weight:1000;
  font-size: 28px;
  cursor:pointer;
  transition: transform .12s ease, box-shadow .12s ease, filter .12s ease;
  box-shadow: 0 10px 20px rgba(15,23,42,.08);
  background: var(--blue);
}
.chipBtn:hover{transform: translateY(-2px)}
.chipBtn:active{transform: translateY(-1px) scale(.99)}
.chipBtn.on{background: var(--green);}

.o2Chip{
  background: rgba(34,197,94,.16);
  border-color: rgba(34,197,94,.22);
  color:#14532d;
}
.o2Chip.on{
  filter: saturate(1.1);
  box-shadow: 0 16px 30px rgba(34,197,94,.18);
}

/* Burner */
.burnerWrap{
  width: 240px;
  border-radius: 26px;
  padding: 12px;
  border: 2px dashed rgba(34,197,94,.25);
  background: rgba(255,255,255,.78);
  text-align:center;
  transition: box-shadow .2s ease, border-color .2s ease;
}
.burnerWrap.dragOver{
  border-color: rgba(251,146,60,.55);
  box-shadow: 0 18px 45px rgba(251,146,60,.18);
}
.burner{
  position:relative;
  height: 220px;
  border-radius: 22px;
  border: 1px solid rgba(15,23,42,.10);
  background: linear-gradient(180deg, rgba(15,23,42,.06), rgba(15,23,42,.02));
  overflow:hidden;
}
.burnerHead{
  position:absolute; left:50%; top:22px;
  width: 140px; height: 22px;
  transform: translateX(-50%);
  border-radius: 999px;
  background: rgba(15,23,42,.12);
  border: 1px solid rgba(15,23,42,.10);
}
.burnerBody{
  position:absolute; left:50%; top:48px;
  width: 90px; height: 120px;
  transform: translateX(-50%);
  border-radius: 24px;
  background: rgba(15,23,42,.09);
  border: 1px solid rgba(15,23,42,.10);
}
.burnerSlot{
  position:absolute; left:50%; bottom:16px;
  transform: translateX(-50%);
  width: 88%;
  padding: 10px 10px;
  border-radius: 16px;
  background: rgba(34,197,94,.10);
  border: 1px dashed rgba(34,197,94,.22);
}
.slotLabel{
  font-weight: 900;
  color:#14532d;
  font-size: 12px;
}

.flame{
  position:absolute;
  left:50%;
  top: 0;
  width: 120px;
  height: 120px;
  transform: translateX(-50%);
  opacity: 0;
  pointer-events:none;
  filter: blur(.1px);
}
.flame::before{
  content:"";
  position:absolute;
  left:50%; top: 64px;
  width: 90px; height: 90px;
  transform: translateX(-50%) rotate(45deg);
  border-radius: 26px;
  background: radial-gradient(circle at 30% 30%, rgba(251,191,36,.95), rgba(251,146,60,.85) 55%, rgba(239,68,68,.65));
  box-shadow: 0 0 30px rgba(251,146,60,.35);
}
.flame.on{
  opacity:1;
  animation: flameFlicker .9s ease-in-out infinite;
}
@keyframes flameFlicker{
  0%,100%{ transform: translateX(-50%) translateY(0) scale(1); }
  50%{ transform: translateX(-50%) translateY(-4px) scale(1.03); }
}

.smoke{
  position:absolute;
  inset:0;
  pointer-events:none;
  opacity:0;
}
.smoke.on{opacity:1}
.puff{
  position:absolute;
  width: 26px; height: 26px;
  border-radius: 999px;
  background: rgba(100,116,139,.35);
  filter: blur(.4px);
  animation: puffUp 1.1s ease-out forwards;
}
@keyframes puffUp{
  0%{ transform: translate(0,0) scale(.9); opacity:.7;}
  100%{ transform: translate(var(--dx), var(--dy)) scale(1.4); opacity:0;}
}

/* Center zone */
.mid{position:relative}
/* Center zone */
.zone{
  position:relative;
  height: 220px;
  border-radius: 26px;
  background: linear-gradient(180deg, rgba(251,146,60,.10), rgba(59,130,246,.06));
  border: 1px solid rgba(15,23,42,.08);
  overflow:hidden;
  display:grid;
  place-items:center;
  text-align:center;
  padding: 12px;
}

.eqBig{
  font-weight: 1000;
  font-size: 16px;              /* smaller */
  letter-spacing: .01em;
  color:#0f172a;
}
.eqRow{
  display:flex;
  align-items:center;
  justify-content:center;
  flex-wrap:wrap;
  gap:6px;
}
.eqLeft,.eqRight{
  white-space: nowrap;           /* important: no wrapping */
}
.eqArrow{opacity:.7; padding:0 6px}

.eqSmall{
  margin-top: 6px;
  font-size: 11px;               /* smaller */
  font-weight: 900;
  color: var(--muted);
}

/* Slots inside reaction zone (smaller + inline) */
.slots{
  margin-top: 10px;
  display:flex;
  gap: 10px;
  justify-content:center;
}

.slot{
  min-width: 84px;
  height: 60px;                  /* smaller */
  padding: 0 10px;
  border-radius: 20px;
  display:flex;                  /* change to flex */
  align-items:center;
  justify-content:center;
  font-weight:1000;
  font-size: 16px;               /* smaller */
  border: 1px solid rgba(15,23,42,.10);
  background: rgba(15,23,42,.05);
  opacity:.55;
  white-space: nowrap;           /* keep formula in one line */
  line-height: 1;                /* avoid weird stacking */
  transition: opacity .2s ease, transform .2s ease, background .2s ease;
}

.slot.on{
  opacity:1;
  transform: scale(1.03);
  background: rgba(34,197,94,.18);
  border-color: rgba(34,197,94,.22);
}

/* Meter */
.meter{
  margin-top: 10px;
  width: min(360px, 92%);
  background: rgba(255,255,255,.72);
  border: 1px solid rgba(15,23,42,.10);
  border-radius: 18px;
  padding: 10px 12px;
}
.meterTop{
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap:12px;
  margin-bottom: 8px;
}
.meterLbl{font-weight:1000; font-size:12px; color:#7c2d12;}
.meterVal{font-weight:1000; font-size:12px; color:#7c2d12;}
.meterTrack{
  height: 10px;
  border-radius: 999px;
  background: rgba(15,23,42,.08);
  overflow:hidden;
}
.meterBar{
  height: 100%;
  width: 0%;
  border-radius: 999px;
  background: linear-gradient(90deg, rgba(34,197,94,.45), rgba(251,146,60,.75), rgba(239,68,68,.70));
  transition: width .35s ease;
}

/* Controls */
.controls{
  margin-top:12px;
  display:flex;
  gap:10px;
  flex-wrap:wrap;
  justify-content:center;
}
.btn{
  border: 1px solid rgba(15,23,42,.10);
  background: rgba(15,23,42,.06);
  border-radius: 18px;
  padding: 10px 14px;
  font-weight: 1000;
  cursor:pointer;
}
.btn.primary{
  background: rgba(251,146,60,.18);
  border-color: rgba(251,146,60,.26);
  color:#7c2d12;
}
.btn:active{transform: scale(.99);}

.status{
  margin-top:10px;
  padding: 8px 10px;
  border-radius: 999px;
  font-weight: 1000;
  font-size: 12px;
  background: rgba(15,23,42,.06);
  border: 1px solid rgba(15,23,42,.10);
  text-align:center;
}

.note{
  margin-top: 12px;
  padding: 10px 12px;
  border-radius: 18px;
  background: rgba(239,68,68,.10);
  border: 1px dashed rgba(239,68,68,.22);
  color:#7f1d1d;
  font-weight:900;
  font-size: 12px;
  text-align:center;
}

/* Products */
/* Products */
.productsBox{
  height: 190px;                 /* smaller */
  border-radius: 24px;
  border: 1px solid rgba(15,23,42,.08);
  background: linear-gradient(180deg, rgba(59,130,246,.06), rgba(34,197,94,.06));
  display:flex;
  align-items:center;
  justify-content:center;
  gap: 14px;
  position:relative;
  overflow:hidden;
}

.productChip{
  width: 88px;                   /* smaller */
  height: 70px;                  /* smaller */
  border-radius: 22px;
  display:flex;                  /* change to flex */
  align-items:center;
  justify-content:center;
  font-weight: 1000;
  font-size: 26px;               /* smaller */
  border: 1px solid rgba(15,23,42,.10);
  background: rgba(255,255,255,.92);
  box-shadow: 0 14px 28px rgba(15,23,42,.10);
  opacity: 0;
  transform: translateY(12px) scale(.94);
  white-space: nowrap;           /* keep CO₂ one line */
  line-height: 1;                /* prevent vertical stacking */
  transition: opacity .25s ease, transform .25s ease;
}

.productChip.show{
  opacity: 1;
  transform: translateY(0) scale(1);
}


.miniExplain{
  margin-top: 12px;
  padding: 12px 12px;
  border-radius: 18px;
  background: rgba(59,130,246,.10);
  border: 1px dashed rgba(59,130,246,.22);
  color:#1e3a8a;
  font-size: 12px;
  font-weight: 900;
  line-height: 1.3;
}

/* FX sparks */
.fx{position:absolute; inset:0; pointer-events:none;}
.spark{
  position:absolute;
  width: 8px;
  height: 8px;
  border-radius: 999px;
  background: rgba(251,191,36,.95);
  box-shadow: 0 0 14px rgba(251,191,36,.65);
  animation: sparkUp .85s ease-out forwards;
}
@keyframes sparkUp{
  0%{ transform: translate(0,0) scale(1); opacity:1;}
  100%{ transform: translate(var(--dx), var(--dy)) scale(.2); opacity:0;}
}