*,*::before,*::after{box-sizing:border-box;margin:0;padding:0;}
:root{
  --bg:#07090f;
  --bg2:#0e1220;
  --surface:rgba(255,255,255,.055);
  --surface2:rgba(255,255,255,.095);
  --border:rgba(255,255,255,.1);
  --border2:rgba(255,255,255,.18);
  --coral:#FF6B6B;
  --teal:#3DD9C0;
  --yellow:#FFD93D;
  --purple:#B088FF;
  --pink:#FF79C6;
  --green:#5EF0A0;
  --orange:#FFB347;
  --blue:#5BC8FF;
  --text:#EEF0FF;
  --muted:rgba(238,240,255,.5);
  --fb:'Baloo 2',cursive;
  --fn:'Nunito',sans-serif;
  --r:16px;
  --r2:24px;
  --shadow:0 8px 40px rgba(0,0,0,.55);
}
html{scroll-behavior:smooth;}
body{font-family:var(--fn);color:var(--text);background:var(--bg);min-height:100vh;overflow-x:hidden;}
::selection{background:rgba(176,136,255,.35);}
::-webkit-scrollbar{width:5px;}
::-webkit-scrollbar-thumb{background:rgba(255,255,255,.12);border-radius:4px;}

/* ── BACKGROUND ───────────────────────────────────────── */
#bg-canvas{position:fixed;inset:0;z-index:0;pointer-events:none;}

/* ── LOADER ──────────────────────────────────────────── */
#loader{
  position:fixed;inset:0;z-index:9999;background:var(--bg);
  display:flex;flex-direction:column;align-items:center;justify-content:center;gap:.7rem;
  transition:opacity .8s ease;
}
#loader.fade{opacity:0;pointer-events:none;}
.ld-ship{font-size:clamp(3rem,8vw,5.5rem);animation:ship-bob 1.2s ease-in-out infinite;}
@keyframes ship-bob{0%,100%{transform:translateY(0) rotate(-10deg)}50%{transform:translateY(-20px) rotate(-10deg)}}
.ld-h{font-family:var(--fb);font-size:clamp(1.6rem,5vw,2.6rem);color:var(--yellow);letter-spacing:.02em;}
.ld-sub{font-size:clamp(.78rem,2.2vw,.95rem);color:var(--muted);}
.ld-track{width:min(320px,80vw);height:10px;background:rgba(255,255,255,.08);border-radius:5px;overflow:hidden;margin-top:.4rem;}
.ld-bar{height:100%;background:linear-gradient(90deg,var(--teal),var(--purple));border-radius:5px;width:0;transition:width .4s ease;}
.ld-stat{font-size:.75rem;color:var(--muted);}

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

/* ── PROGRESS ─────────────────────────────────────────── */ ─────────────────────────────────────────── */
.prog-wrap{height:3px;background:rgba(255,255,255,.06);}
.prog-bar{height:100%;background:linear-gradient(90deg,var(--coral),var(--purple),var(--teal));transition:width .6s ease;width:0;}

/* ── MAIN ────────────────────────────────────────────── */
main{flex:1;padding:clamp(.55rem,2vw,1.35rem) clamp(.65rem,3vw,1.35rem);max-width:960px;margin:0 auto;width:100%;}

/* ── SCREENS ─────────────────────────────────────────── */
.screen{display:none;}
.screen.on{display:block;animation:fade-in .4s ease;}
@keyframes fade-in{from{opacity:0;transform:translateY(12px)}to{opacity:1;transform:translateY(0)}}

/* ── BUTTONS ─────────────────────────────────────────── */
.btn-pri{
  display:inline-flex;align-items:center;gap:.45rem;
  padding:clamp(.6rem,2vw,.85rem) clamp(1.2rem,4vw,2.2rem);
  background:linear-gradient(135deg,var(--coral) 0%,var(--purple) 100%);
  color:#fff;border:none;border-radius:50px;
  font-family:var(--fn);font-size:clamp(.88rem,2.5vw,1.05rem);font-weight:800;
  cursor:pointer;transition:all .22s;
  box-shadow:0 4px 22px rgba(255,107,107,.3);
}
.btn-pri:hover{transform:translateY(-2px) scale(1.02);box-shadow:0 8px 30px rgba(176,136,255,.45);}
.btn-pri:active{transform:scale(.97);}
.btn-sec{
  display:inline-flex;align-items:center;gap:.4rem;
  padding:clamp(.5rem,1.5vw,.65rem) clamp(.9rem,3vw,1.4rem);
  background:var(--surface);color:var(--text);
  border:1px solid var(--border2);border-radius:50px;
  font-family:var(--fn);font-size:clamp(.78rem,2vw,.92rem);font-weight:700;
  cursor:pointer;transition:all .2s;
}
.btn-sec:hover{background:var(--surface2);border-color:rgba(255,255,255,.3);}
.btn-sec:disabled{opacity:.3;cursor:default;}
.btn-aud{
  display:inline-flex;align-items:center;gap:.35rem;
  padding:.35rem .85rem;
  background:rgba(255,217,61,.1);color:var(--yellow);
  border:1px solid rgba(255,217,61,.25);border-radius:50px;
  font-family:var(--fn);font-size:clamp(.7rem,1.8vw,.78rem);font-weight:700;
  cursor:pointer;transition:all .2s;
}
.btn-aud:hover{background:rgba(255,217,61,.2);}
.btn-aud.playing{animation:glow-aud 1.3s ease-in-out infinite;}
@keyframes glow-aud{0%,100%{box-shadow:0 0 0 0 rgba(255,217,61,.4)}50%{box-shadow:0 0 0 8px rgba(255,217,61,0)}}
.mute-toggle{
  position:fixed;top:10px;right:10px;z-index:35;
  padding:.45rem .9rem;
  backdrop-filter:blur(10px);
  box-shadow:0 8px 24px rgba(0,0,0,.22);
}
@media(max-width:640px){
  .mute-toggle{top:8px;right:8px;padding:.4rem .75rem;font-size:.74rem;}
}

/* ── CARDS ───────────────────────────────────────────── */
.card{
  background:var(--surface);
  border:1px solid var(--border);
  border-radius:var(--r2);
  padding:clamp(.75rem,2.4vw,1.25rem);
  backdrop-filter:blur(12px);
}
.card-accent{border-color:rgba(176,136,255,.28);background:rgba(176,136,255,.05);}

/* ── WELCOME SCREEN ──────────────────────────────────── */
.hero{text-align:center;padding:clamp(.2rem,2vh,1.4rem) .55rem .65rem;}
.hero-ship{font-size:clamp(3.5rem,12vw,7rem);display:block;animation:float 3s ease-in-out infinite;}
@keyframes float{0%,100%{transform:translateY(0)}50%{transform:translateY(-18px)}}
.hero-title{
  font-family:var(--fb);font-size:clamp(2rem,7vw,4rem);
  background:linear-gradient(135deg,var(--yellow) 0%,var(--coral) 35%,var(--purple) 70%,var(--teal) 100%);
  background-size:300%;animation:title-flow 6s ease infinite;
  -webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;
  margin:.4rem 0 .6rem;line-height:1.1;
}
@keyframes title-flow{0%,100%{background-position:0%}50%{background-position:100%}}
.hero-sub{color:var(--muted);font-size:clamp(.84rem,2.3vw,1rem);margin-bottom:.9rem;}
.term-badges{display:flex;justify-content:center;gap:.45rem;flex-wrap:wrap;margin:.5rem 0 .9rem;}
.tbadge{
  padding:.38rem 1rem;border-radius:50px;font-weight:800;
  font-size:clamp(.75rem,2vw,.88rem);
  animation:badge-pop .5s cubic-bezier(.34,1.56,.64,1) backwards;
}
@keyframes badge-pop{from{opacity:0;transform:scale(.3) rotate(-15deg)}to{opacity:1;transform:scale(1) rotate(0)}}
.tbadge.dv{background:rgba(255,107,107,.15);border:2px solid var(--coral);color:var(--coral);animation-delay:.1s;}
.tbadge.dr{background:rgba(61,217,192,.15);border:2px solid var(--teal);color:var(--teal);animation-delay:.2s;}
.tbadge.qt{background:rgba(255,217,61,.15);border:2px solid var(--yellow);color:var(--yellow);animation-delay:.3s;}
.tbadge.rm{background:rgba(176,136,255,.15);border:2px solid var(--purple);color:var(--purple);animation-delay:.4s;}
.features-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:.55rem;margin:.8rem 0;}
.feat-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--r);padding:.7rem;text-align:center;animation:badge-pop .5s ease backwards;}
.feat-icon{font-size:clamp(1.6rem,4vw,2.2rem);margin-bottom:.4rem;}
.feat-title{font-weight:800;font-size:clamp(.78rem,2vw,.9rem);}
.feat-desc{font-size:clamp(.66rem,1.7vw,.77rem);color:var(--muted);margin-top:.25rem;}

.home-starts{display:flex;gap:.6rem;justify-content:center;align-items:center;flex-wrap:wrap;}
.home-required-link-wrap{
  margin:.8rem auto 0;
  display:flex;justify-content:center;align-items:center;flex-wrap:wrap;gap:.55rem;
}
.home-required-link{
  display:inline-flex;align-items:center;justify-content:center;
  padding:.55rem 1rem;border-radius:999px;
  background:rgba(91,200,255,.12);
  border:1px solid rgba(91,200,255,.34);
  color:var(--blue);font-weight:800;font-size:clamp(.78rem,2vw,.92rem);
  text-decoration:none;box-shadow:0 8px 20px rgba(0,0,0,.18);
}
.home-required-link:hover{background:rgba(91,200,255,.18);}
.home-link-note{
  font-size:clamp(.72rem,1.9vw,.84rem);
  color:var(--muted);
}
.home-link-lock{
  display:none;
  margin:.75rem auto 0;
  max-width:520px;
  padding:.7rem .9rem;
  border-radius:14px;
  background:rgba(255,107,107,.12);
  border:1px solid rgba(255,107,107,.34);
  color:#ffd7d7;
  font-weight:800;
  font-size:clamp(.76rem,2vw,.9rem);
}
.home-starts button[disabled]{
  opacity:.42 !important;
  cursor:not-allowed !important;
  pointer-events:none !important;
  transform:none !important;
  box-shadow:none !important;
}


/* ── LESSON CARD ─────────────────────────────────────── */
.lesson-wrap{display:flex;flex-direction:column;gap:.7rem;}
.l-header{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:.45rem;margin-bottom:.25rem;}
.l-title{font-family:var(--fb);font-size:clamp(1.2rem,4vw,1.65rem);display:flex;align-items:center;gap:.5rem;}
.l-num{
  width:clamp(26px,5vw,34px);height:clamp(26px,5vw,34px);
  background:linear-gradient(135deg,var(--coral),var(--purple));
  border-radius:50%;display:inline-flex;align-items:center;justify-content:center;
  font-size:clamp(.72rem,2vw,.9rem);font-family:var(--fn);font-weight:900;flex-shrink:0;
}
.l-controls{display:flex;align-items:center;gap:.5rem;flex-wrap:wrap;}

/* ── MATH DISPLAY ────────────────────────────────────── */
.math-eq{
  text-align:center;
  font-family:var(--fb);
  font-size:clamp(2rem,6vw,3.2rem);
  margin:.65rem 0;
  display:flex;align-items:center;justify-content:center;flex-wrap:wrap;gap:.2em;
  letter-spacing:.02em;
}
.math-eq.sm{font-size:clamp(1.5rem,4.5vw,2.3rem);}
.mt{display:inline-flex;flex-direction:column;align-items:center;}
.mv{
  display:inline-block;padding:.08em .3em;
  border-radius:10px;border:2.5px solid transparent;
  transition:all .35s;
}
.mv.dv{background:rgba(255,107,107,.2);border-color:var(--coral);color:var(--coral);box-shadow:0 0 20px rgba(255,107,107,.3);}
.mv.dr{background:rgba(61,217,192,.2);border-color:var(--teal);color:var(--teal);box-shadow:0 0 20px rgba(61,217,192,.3);}
.mv.qt{background:rgba(255,217,61,.2);border-color:var(--yellow);color:var(--yellow);box-shadow:0 0 20px rgba(255,217,61,.3);}
.mv.rm{background:rgba(176,136,255,.2);border-color:var(--purple);color:var(--purple);box-shadow:0 0 20px rgba(176,136,255,.3);}
.ml{
  font-family:var(--fn);font-size:clamp(.55rem,1.5vw,.68rem);
  font-weight:800;text-transform:uppercase;letter-spacing:.1em;margin-top:.28em;
}
.mop{color:var(--muted);display:inline-block;margin:0 .08em;}
.r-badge{font-size:.55em;font-weight:900;color:var(--purple);margin:0 .08em;}

/* ── EXPL BOX ────────────────────────────────────────── */
.expl{
  background:rgba(255,255,255,.04);
  border-left:4px solid var(--teal);
  border-radius:0 12px 12px 0;
  padding:clamp(.7rem,2.5vw,1.1rem);
  margin:.55rem 0;
  font-size:clamp(.8rem,2vw,.94rem);
  line-height:1.7;
}
.expl.dv{border-color:var(--coral);}
.expl.dr{border-color:var(--teal);}
.expl.qt{border-color:var(--yellow);}
.expl.rm{border-color:var(--purple);}
.expl.gn{border-color:var(--green);}
.expl.bl{border-color:var(--blue);}
.expl.or{border-color:var(--orange);}
.expl-title{font-family:var(--fb);font-size:clamp(1rem,3vw,1.2rem);margin-bottom:.4rem;}

/* ── VISUAL GROUPS ───────────────────────────────────── */
.groups-row{display:flex;flex-wrap:wrap;gap:.7rem;justify-content:center;margin:.9rem 0;}
.group-box{
  background:rgba(255,255,255,.04);border:2px dashed var(--border2);
  border-radius:var(--r);padding:.6rem .8rem;min-width:70px;text-align:center;
  transition:all .3s;
}
.group-box.lit{border-style:solid;border-color:var(--teal);background:rgba(61,217,192,.07);}
.group-box.rem-box{border-color:var(--purple);background:rgba(176,136,255,.07);}
.gb-label{font-size:clamp(.6rem,1.6vw,.68rem);font-weight:800;color:var(--muted);text-transform:uppercase;margin-bottom:.3rem;}
.items-grid{display:flex;flex-wrap:wrap;gap:3px;justify-content:center;}
.item{display:inline-block;font-size:clamp(.9rem,2.5vw,1.2rem);animation:item-pop .3s ease backwards;}
@keyframes item-pop{from{opacity:0;transform:scale(0) rotate(-20deg)}to{opacity:1;transform:scale(1) rotate(0)}}
.item.leftover{animation:float-rem 2s ease-in-out infinite;}
@keyframes float-rem{0%,100%{transform:translateY(0)}50%{transform:translateY(-6px)}}

/* ── HINT ────────────────────────────────────────────── */
.hint-box{
  background:rgba(255,255,255,.04);border-radius:var(--r);
  padding:.7rem .9rem;margin:.55rem 0;
  display:flex;align-items:flex-start;gap:.7rem;
  border:1px solid rgba(255,255,255,.08);
}
.hint-icon{font-size:1.4rem;flex-shrink:0;margin-top:.05rem;}
.hint-body{font-size:clamp(.8rem,2vw,.92rem);line-height:1.65;}

/* ── INTERACTIVE DEMOS ────────────────────────────────── */
.slider-demo{background:var(--surface);border:1px solid var(--border);border-radius:var(--r);padding:1.1rem;}
.sl-row{display:flex;align-items:center;gap:.8rem;flex-wrap:wrap;margin-bottom:.8rem;}
.sl-label{font-weight:800;font-size:.82rem;min-width:75px;}
input[type=range]{
  flex:1;min-width:100px;accent-color:var(--purple);
  height:5px;cursor:pointer;
}
.sl-val{font-family:var(--fb);font-size:1.15rem;min-width:32px;text-align:center;}
.live-eq{text-align:center;font-family:var(--fb);font-size:clamp(1.5rem,5vw,2.4rem);margin:.6rem 0;}
.live-items{display:flex;flex-wrap:wrap;gap:.45rem;justify-content:center;margin:.4rem 0;min-height:40px;}
.live-group{
  display:flex;flex-wrap:wrap;gap:2px;padding:.4rem;
  background:rgba(61,217,192,.07);border:2px solid var(--teal);
  border-radius:10px;min-width:38px;justify-content:center;align-items:flex-start;
  font-size:clamp(.8rem,2vw,1rem);
}
.live-rem-group{background:rgba(176,136,255,.07);border-color:var(--purple);}

/* ── DRAG DROP ─────────────────────────────────────────── */
.drag-stage{
  background:var(--surface);border:1px solid var(--border);border-radius:var(--r);
  padding:1.1rem;margin:.8rem 0;
}
.drag-pool{display:flex;flex-wrap:wrap;gap:.5rem;min-height:60px;padding:.6rem;
  background:rgba(255,255,255,.04);border:2px dashed rgba(255,255,255,.14);border-radius:12px;margin-bottom:.8rem;}
.drag-targets{display:flex;flex-wrap:wrap;gap:.6rem;justify-content:center;}
.drag-zone{
  flex:1;min-width:clamp(80px,20vw,110px);min-height:70px;
  border:3px dashed var(--border2);border-radius:14px;
  padding:.55rem;text-align:center;transition:all .25s;
  display:flex;flex-direction:column;align-items:center;justify-content:center;gap:.3rem;
  box-shadow:inset 0 0 0 1px rgba(255,255,255,.03);
}
.drag-zone.over{background:rgba(255,255,255,.1);border-style:solid;transform:translateY(-1px) scale(1.02);box-shadow:0 0 0 4px rgba(255,255,255,.08);}
.drag-zone-label{font-size:clamp(.6rem,1.5vw,.68rem);font-weight:800;text-transform:uppercase;color:var(--muted);letter-spacing:.08em;}
.drag-zone-value{font-family:var(--fb);font-size:1.6rem;min-height:1.8rem;}
.drag-zone.dz-dv{border-color:rgba(255,107,107,.72);background:rgba(255,107,107,.08);}
.drag-zone.dz-dr{border-color:rgba(61,217,192,.72);background:rgba(61,217,192,.08);}
.drag-zone.dz-qt{border-color:rgba(255,217,61,.72);background:rgba(255,217,61,.09);}
.drag-zone.dz-rm{border-color:rgba(176,136,255,.72);background:rgba(176,136,255,.09);}
.drag-zone.ok{background:rgba(94,240,160,.14);border-color:var(--green);border-style:solid;}
.drag-zone.err{background:rgba(255,107,107,.14);border-color:var(--coral);border-style:solid;animation:shk .4s ease;}
.drag-chip{
  padding:.38rem .95rem;border:1px solid rgba(255,255,255,.18);
  border-radius:50px;font-family:var(--fb);font-size:1.15rem;cursor:grab;
  transition:all .2s;user-select:none;font-weight:800;
  color:#fff;box-shadow:0 8px 18px rgba(0,0,0,.18);
}
.drag-chip:nth-child(3n+1){background:linear-gradient(180deg,rgba(255,107,107,.95),rgba(255,107,107,.72));}
.drag-chip:nth-child(3n+2){background:linear-gradient(180deg,rgba(61,217,192,.95),rgba(61,217,192,.72));}
.drag-chip:nth-child(3n+3){background:linear-gradient(180deg,rgba(255,217,61,.95),rgba(233,175,37,.78));color:#2d2200;}
.drag-chip:hover{transform:translateY(-2px) scale(1.06);box-shadow:0 12px 22px rgba(0,0,0,.22);}
.drag-chip.used{opacity:.25;pointer-events:none;box-shadow:none;}

/* ── CLICK LABEL ─────────────────────────────────────── */
.click-label-demo{background:var(--surface);border:1px solid var(--border);border-radius:var(--r);padding:1.1rem;}
.click-eq{display:flex;align-items:center;justify-content:center;gap:.3rem;flex-wrap:wrap;font-family:var(--fb);font-size:clamp(1.6rem,5vw,2.8rem);margin:.6rem 0;}
.click-num{
  display:inline-flex;flex-direction:column;align-items:center;cursor:pointer;
  padding:.06em .2em;border-radius:10px;border:2.5px solid var(--border2);
  transition:all .22s;position:relative;
}
.click-num:hover{background:rgba(255,255,255,.09);border-color:rgba(255,255,255,.35);}
.click-num.revealed.dv{background:rgba(255,107,107,.2);border-color:var(--coral);}
.click-num.revealed.dr{background:rgba(61,217,192,.2);border-color:var(--teal);}
.click-num.revealed.qt{background:rgba(255,217,61,.2);border-color:var(--yellow);}
.click-num.revealed.rm{background:rgba(176,136,255,.2);border-color:var(--purple);}
.click-tag{
  font-family:var(--fn);font-size:clamp(.5rem,1.3vw,.62rem);
  font-weight:800;text-transform:uppercase;letter-spacing:.08em;
  margin-top:.22em;opacity:0;transition:opacity .3s;
}
.click-num.revealed .click-tag{opacity:1;}

/* ── LONG DIVISION VISUAL ────────────────────────────── */
.longdiv-wrap{display:flex;align-items:stretch;font-family:var(--fb);font-size:clamp(1.6rem,5vw,2.6rem);justify-content:center;margin:1rem 0;}
.ld-divisor{display:flex;align-items:center;padding-right:.3em;}
.ld-body{border-top:3px solid var(--text);border-left:3px solid var(--text);padding:.1em .5em .1em .3em;}
.ld-quotient{border-bottom:2px solid rgba(255,255,255,.3);padding-bottom:.15em;margin-bottom:.15em;text-align:right;}
.ld-steps{font-size:.5em;color:var(--muted);text-align:left;font-family:var(--fn);font-weight:700;}
.ld-work{
  margin-top:.25rem;
  font-size:clamp(.78rem,2vw,.96rem);
  line-height:1.28;
  white-space:pre;
  color:var(--text);
  font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,"Liberation Mono","Courier New",monospace;
  text-align:left;
}
.ld-work .rm-line{color:var(--purple);font-weight:800;}

/* ── STEP CARDS ──────────────────────────────────────── */
.steps-list{display:flex;flex-direction:column;gap:.6rem;margin:.8rem 0;}
.step-item{
  display:flex;align-items:flex-start;gap:.75rem;
  background:var(--surface);border:1px solid var(--border);border-radius:14px;
  padding:.8rem 1rem;cursor:pointer;transition:all .25s;
}
.step-item:hover,.step-item.active{background:var(--surface2);border-color:var(--border2);}
.step-num{
  width:clamp(28px,5vw,36px);height:clamp(28px,5vw,36px);
  border-radius:50%;background:var(--surface2);border:2px solid var(--border2);
  display:flex;align-items:center;justify-content:center;
  font-family:var(--fb);font-size:clamp(.85rem,2.5vw,1.1rem);flex-shrink:0;
  transition:all .25s;
}
.step-item.active .step-num{background:linear-gradient(135deg,var(--coral),var(--purple));border-color:transparent;color:#fff;}
.step-body{font-size:clamp(.8rem,2vw,.92rem);line-height:1.6;}
.step-body strong{font-weight:800;}

/* ── QUIZ ───────────────────────────────────────────── */
.quiz-header{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:.6rem;margin-bottom:1rem;}
.q-meta{font-family:var(--fb);font-size:clamp(.85rem,2.5vw,1rem);color:var(--muted);}
.q-score{display:flex;align-items:center;gap:.35rem;font-weight:800;color:var(--yellow);}
.quiz-eq-box{
  text-align:center;margin:.6rem 0 1.1rem;
  background:rgba(255,255,255,.03);border:1px solid var(--border);
  border-radius:var(--r);padding:.9rem 1rem;
}
.quiz-eq-plain{font-family:var(--fb);font-size:clamp(1.8rem,5.5vw,3rem);letter-spacing:.04em;}
.quiz-question{
  font-size:clamp(.9rem,2.5vw,1.05rem);font-weight:800;
  text-align:center;margin-bottom:.9rem;
}
.quiz-opts{display:grid;grid-template-columns:repeat(2,1fr);gap:.65rem;}
.qopt{
  padding:clamp(.65rem,2vw,.95rem);
  background:var(--surface);border:2px solid var(--border);
  border-radius:var(--r);cursor:pointer;
  font-family:var(--fb);font-size:clamp(1.5rem,5vw,2.2rem);
  color:var(--text);text-align:center;transition:all .22s;
  position:relative;overflow:hidden;
}
.qopt::before{content:'';position:absolute;inset:0;background:rgba(255,255,255,0);transition:background .2s;}
.qopt:hover:not(:disabled)::before{background:rgba(255,255,255,.06);}
.qopt:hover:not(:disabled){border-color:var(--border2);transform:translateY(-3px);box-shadow:0 6px 20px rgba(0,0,0,.3);}
.qopt.ok{background:rgba(94,240,160,.15);border-color:var(--green);color:var(--green);animation:opt-pop .5s ease;}
.qopt.err{background:rgba(255,107,107,.15);border-color:var(--coral);color:var(--coral);animation:shk .4s ease;}
.qopt:disabled{cursor:default;}
@keyframes opt-pop{0%,100%{transform:scale(1)}50%{transform:scale(1.04)}}
@keyframes shk{0%,100%{transform:translateX(0)}25%{transform:translateX(-6px)}75%{transform:translateX(6px)}}
.quiz-fb{
  margin-top:.85rem;padding:.75rem 1rem;border-radius:12px;
  font-weight:700;text-align:center;font-size:clamp(.82rem,2.2vw,.95rem);
  display:none;animation:fade-in .3s ease;
}
.quiz-fb.show{display:block;}
.quiz-fb.ok{background:rgba(94,240,160,.12);border:1px solid var(--green);color:var(--green);}
.quiz-fb.err{background:rgba(255,107,107,.12);border:1px solid var(--coral);color:var(--coral);}
.quiz-next-row{text-align:center;margin-top:.9rem;}

/* ── PRACTICE ─────────────────────────────────────────── */
.p-prompt{
  background:rgba(176,136,255,.1);border:1px solid rgba(176,136,255,.3);
  border-radius:11px;padding:.75rem 1rem;margin:.85rem 0;
  font-weight:800;color:var(--purple);text-align:center;
  font-size:clamp(.82rem,2.2vw,.95rem);
}
.clickable-term{
  display:inline-block;cursor:pointer;padding:.06em .22em;
  border-radius:8px;border:2.5px solid transparent;
  transition:all .2s;font-family:var(--fb);
}
.clickable-term:hover{background:rgba(255,255,255,.09);border-color:rgba(255,255,255,.3);}
.clickable-term.ok{background:rgba(94,240,160,.18);border-color:var(--green);color:var(--green);animation:opt-pop .5s ease;}
.clickable-term.err{background:rgba(255,107,107,.18);border-color:var(--coral);color:var(--coral);animation:shk .4s ease;}
.p-fb-box{margin-top:.75rem;padding:.7rem 1rem;border-radius:12px;font-weight:700;font-size:clamp(.8rem,2vw,.92rem);display:none;animation:fade-in .3s ease;}
.p-fb-box.show{display:block;}
.p-fb-box.ok{background:rgba(94,240,160,.12);border:1px solid var(--green);color:var(--green);}
.p-fb-box.err{background:rgba(255,107,107,.12);border:1px solid var(--coral);color:var(--coral);}

/* ── LESSON NAV ──────────────────────────────────────── */
.lesson-nav{
  display:flex;align-items:center;justify-content:space-between;
  margin-top:1.2rem;padding-top:1rem;border-top:1px solid var(--border);
  flex-wrap:wrap;gap:.6rem;
}
.progress-dots{display:flex;gap:5px;flex-wrap:wrap;}
.pd{width:8px;height:8px;border-radius:50%;background:var(--border2);transition:all .3s;cursor:pointer;}
.pd.done{background:var(--green);}
.pd.current{background:var(--purple);transform:scale(1.5);}

/* ── RESULTS ─────────────────────────────────────────── */
.results-hero{text-align:center;padding:1.5rem 1rem 1rem;}
.trophy-big{font-size:clamp(3.5rem,10vw,6rem);display:block;animation:trophy-bounce 1s ease-in-out infinite;}
@keyframes trophy-bounce{0%,100%{transform:scale(1) rotate(-4deg)}50%{transform:scale(1.08) rotate(4deg)}}
.score-circle{
  width:clamp(100px,20vw,140px);height:clamp(100px,20vw,140px);
  border-radius:50%;
  background:conic-gradient(var(--green) 0% var(--pct,0%),rgba(255,255,255,.08) var(--pct,0%));
  display:flex;align-items:center;justify-content:center;
  margin:.8rem auto;position:relative;
}
.score-circle::before{content:'';position:absolute;width:76%;height:76%;border-radius:50%;background:var(--bg);}
.score-inner{position:relative;z-index:1;font-family:var(--fb);font-size:clamp(1.4rem,5vw,2rem);}
.stars-big{font-size:clamp(2rem,6vw,3rem);letter-spacing:.2em;margin:.4rem 0;}
.result-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:.6rem;margin:.8rem 0;text-align:center;}
.rg-num{font-family:var(--fb);font-size:clamp(1.5rem,5vw,2.2rem);}
.rg-lbl{font-size:clamp(.65rem,1.7vw,.75rem);color:var(--muted);}
.answers-list{margin:.8rem 0;}
.ans-row{
  display:flex;align-items:center;gap:.55rem;padding:.32rem .3rem;
  font-size:clamp(.75rem,2vw,.85rem);border-bottom:1px solid var(--border);
}
.ans-row:last-child{border-bottom:none;}

/* ── FORMULA CARD ────────────────────────────────────── */
.formula-card{
  background:rgba(255,255,255,.03);border:1px solid var(--border);
  border-radius:var(--r2);padding:clamp(.9rem,3vw,1.5rem);
  text-align:center;margin:.8rem 0;
}
.fc-tag{font-size:.7rem;font-weight:800;text-transform:uppercase;letter-spacing:.12em;color:var(--muted);margin-bottom:.8rem;}
.term-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:.55rem;margin-top:1rem;}
.term-card{border-radius:12px;padding:.7rem .6rem;text-align:center;border:1px solid;}
.term-card.dv{background:rgba(255,107,107,.07);border-color:rgba(255,107,107,.28);}
.term-card.dr{background:rgba(61,217,192,.07);border-color:rgba(61,217,192,.28);}
.term-card.qt{background:rgba(255,217,61,.07);border-color:rgba(255,217,61,.28);}
.term-card.rm{background:rgba(176,136,255,.07);border-color:rgba(176,136,255,.28);}
.tc-icon{font-size:clamp(1.1rem,3vw,1.5rem);}
.tc-name{font-size:clamp(.68rem,1.8vw,.78rem);font-weight:800;text-transform:uppercase;letter-spacing:.07em;margin:.2rem 0;}
.tc-desc{font-size:clamp(.6rem,1.5vw,.68rem);color:var(--muted);}

/* ── CONFETTI ────────────────────────────────────────── */
.cfti{
  position:fixed;pointer-events:none;border-radius:3px;
  animation:cfti-fall linear forwards;z-index:9000;
}
@keyframes cfti-fall{0%{opacity:1;transform:translateY(-5px) rotate(0)}100%{opacity:0;transform:translateY(100vh) rotate(900deg)}}

/* ── SECTION INTRO ───────────────────────────────────── */
.section-intro{
  display:flex;align-items:center;gap:.8rem;
  background:var(--surface);border:1px solid var(--border);
  border-radius:var(--r);padding:.9rem 1.1rem;margin-bottom:1rem;
}
.si-icon{font-size:clamp(1.5rem,4vw,2rem);flex-shrink:0;}
.si-text{font-size:clamp(.8rem,2vw,.92rem);line-height:1.6;}

/* ── RESPONSIVE ──────────────────────────────────────── */
@media(max-width:480px){
  .quiz-opts{grid-template-columns:1fr 1fr;}
  .term-grid{grid-template-columns:1fr 1fr;}
  .result-grid{grid-template-columns:1fr 1fr 1fr;}
}
@media(max-width:360px){
  .quiz-opts{grid-template-columns:1fr 1fr;}
  .term-grid{grid-template-columns:1fr 1fr;}
}
@media(max-height:760px){
  main{padding:.45rem .65rem .85rem;}
  .hero{padding:0 .35rem .45rem;}
  .hero-ship{font-size:clamp(2.7rem,8vh,5rem);}
  .hero-title{margin:.15rem 0 .35rem;}
  .hero-sub{margin-bottom:.55rem;}
  .features-grid{gap:.45rem;margin:.55rem 0;}
  .feat-card{padding:.6rem;}
  .feat-desc{font-size:clamp(.62rem,1.55vw,.72rem);}
  .card{padding:.68rem .82rem;}
  .math-eq,.math-eq.sm{margin:.45rem 0;}
  .expl{padding:.6rem .75rem;line-height:1.55;}
  .section-intro{padding:.62rem .75rem;margin-bottom:.55rem;}
  .lesson-nav{margin-top:.75rem;padding-top:.65rem;}
  .quiz-eq-box{margin:.35rem 0 .75rem;padding:.7rem .8rem;}
}
@media(max-height:640px){
  main{padding:.3rem .5rem .6rem;}
  .hero{padding:0 .15rem .25rem;}
  .hero-title{font-size:clamp(1.65rem,5vw,2.6rem);}
  .hero-sub br{display:none;}
  .term-badges{margin:.25rem 0 .5rem;}
  .tbadge{padding:.24rem .6rem;font-size:.7rem;}
  .features-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:.35rem;}
  .feat-card{padding:.5rem;}
  .feat-desc{display:none;}
  .feat-icon{margin-bottom:.15rem;}
  .card{padding:.62rem .72rem;border-radius:18px;}
  .l-title{font-size:clamp(1.05rem,3.1vw,1.4rem);}
  .math-eq,.math-eq.sm,.click-eq,.quiz-eq-plain{font-size:clamp(1.28rem,4vw,2rem);}
  .results-hero{padding:.75rem .3rem .35rem;}
  .score-circle{margin:.4rem auto;}
  .stars-big{margin:.15rem 0;}
}
@media(min-width:700px){
  main{padding:1rem 1.3rem;}
}
@media(min-width:960px){
  main{padding:1.1rem 1.4rem;}
}