/* ============ RESET ============ */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html,body{height:100%}
button{font:inherit;cursor:pointer;border:none;background:none;color:inherit}
:focus-visible{outline:3px solid #FFD86B;outline-offset:3px;border-radius:10px}

/* ============ THEME ============ */
:root{
  --bg-grad-1:#FFF5E4;
  --bg-grad-2:#E6F7FF;
  --ink:#2D1E4A;
  --ink-soft:#5A4A7A;
  --card:#ffffff;
  --shadow:0 8px 24px rgba(45,30,74,.10), 0 2px 6px rgba(45,30,74,.06);
  --shadow-lg:0 16px 40px rgba(45,30,74,.14), 0 4px 10px rgba(45,30,74,.08);
  --radius:22px;
  --radius-sm:14px;
  --violet:#7C4DFF;
  --pink:#FF5E93;
  --teal:#00BFA5;
  --orange:#FF9800;
  --blue:#0097E6;
  --yellow:#FFD86B;
  --good:#22C55E;
  --bad:#EF4444;
}

body{
  font-family:'Quicksand',system-ui,sans-serif;
  font-size:18px;
  color:var(--ink);
  background:linear-gradient(135deg,var(--bg-grad-1) 0%,var(--bg-grad-2) 100%);
  background-attachment:fixed;
  min-height:100svh;
  overflow-x:hidden;
  -webkit-tap-highlight-color:transparent;
}
h1,h2,h3{font-family:'Fredoka',system-ui,sans-serif;line-height:1.15;font-weight:600}

/* ============ TOPBAR ============ */
.topbar{
  position:sticky;top:0;z-index:20;
  display:flex;align-items:center;justify-content:space-between;
  padding:14px 20px;
  background:rgba(255,255,255,.82);
  backdrop-filter:blur(14px);
  -webkit-backdrop-filter:blur(14px);
  border-bottom:1px solid rgba(45,30,74,.06);
}
.brand{display:flex;align-items:center;gap:10px;font-family:'Fredoka',sans-serif;font-weight:600;font-size:22px}
.logo{font-size:26px;filter:drop-shadow(0 2px 3px rgba(255,200,0,.5))}
.top-actions{display:flex;gap:12px;align-items:center}
.stars-counter{
  display:flex;align-items:center;gap:6px;
  background:linear-gradient(135deg,#FFE98A,#FFD86B);
  padding:8px 14px;border-radius:999px;
  font-family:'Fredoka',sans-serif;font-weight:600;font-size:18px;
  box-shadow:0 4px 10px rgba(255,180,0,.3);
  min-height:44px;
}
.star-big{font-size:20px}
.lang-btn{
  min-width:56px;height:44px;padding:0 14px;
  background:var(--card);
  border-radius:14px;
  font-family:'Fredoka',sans-serif;font-weight:600;font-size:16px;
  box-shadow:var(--shadow);
  transition:transform .15s;
  color:var(--ink);
}
.lang-btn:active{transform:scale(.94)}

/* ============ HOME ============ */
main{padding:20px 20px 60px;max-width:860px;margin:0 auto}
.hero{text-align:center;padding:20px 0 24px}
.mascot{display:inline-block;animation:bob 4s ease-in-out infinite}
@keyframes bob{0%,100%{transform:translateY(0) rotate(-2deg)}50%{transform:translateY(-8px) rotate(2deg)}}
.hello{font-size:38px;margin-top:12px;background:linear-gradient(90deg,var(--violet),var(--pink));-webkit-background-clip:text;background-clip:text;color:transparent}
.subtitle{font-size:18px;color:var(--ink-soft);margin-top:6px;font-weight:500}

.progress-block{
  background:var(--card);border-radius:var(--radius);
  padding:16px 18px;margin-bottom:24px;box-shadow:var(--shadow);
}
.progress-label{display:flex;justify-content:space-between;margin-bottom:10px;font-weight:600}
.progress-bar{height:14px;background:#F0EBF8;border-radius:999px;overflow:hidden}
.progress-fill{height:100%;width:0;background:linear-gradient(90deg,var(--violet),var(--pink));border-radius:999px;transition:width .6s cubic-bezier(.22,1,.36,1)}

.lessons-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:16px}
.lesson-card{
  display:grid;grid-template-columns:64px 1fr;grid-template-rows:auto auto;
  gap:4px 14px;text-align:left;
  background:var(--card);
  border-radius:var(--radius);padding:18px 20px;
  box-shadow:var(--shadow);
  min-height:100px;
  border-left:6px solid var(--c);
  transition:transform .15s, box-shadow .2s;
  position:relative;overflow:hidden;
}
.lesson-card::after{
  content:"";position:absolute;right:-30px;bottom:-30px;
  width:120px;height:120px;border-radius:50%;
  background:var(--c);opacity:.07;
}
.lesson-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg)}
.lesson-card:active{transform:scale(.97)}
.lesson-icon{
  grid-row:1/3;align-self:center;justify-self:center;
  font-size:44px;width:64px;height:64px;
  display:flex;align-items:center;justify-content:center;
  background:color-mix(in srgb, var(--c) 12%, white);
  border-radius:18px;
}
.lesson-info h3{font-size:20px;color:var(--ink);margin-bottom:2px}
.lesson-info p{color:var(--ink-soft);font-size:15px}
.lesson-stars{grid-column:2;display:flex;gap:3px;margin-top:6px;font-size:16px}
.lesson-stars .on{filter:none}
.lesson-stars .off{filter:grayscale(1) opacity(.25)}

.home-footer{text-align:center;margin-top:40px;color:var(--ink-soft);font-size:14px;display:flex;flex-direction:column;gap:12px;align-items:center}
.reset-btn{
  font-size:12px;color:var(--ink-soft);opacity:.5;
  padding:6px 12px;border-radius:8px;
  background:transparent;border:1px solid rgba(45,30,74,.15);
  transition:opacity .2s;
}
.reset-btn:hover{opacity:1}

/* ============ LESSON VIEW ============ */
.lesson-view{animation:slideUp .4s cubic-bezier(.22,1,.36,1)}
@keyframes slideUp{from{opacity:0;transform:translateY(24px)}to{opacity:1;transform:none}}

.lesson-topbar{display:flex;align-items:center;gap:12px;margin-bottom:18px}
.back-btn{
  width:48px;height:48px;border-radius:14px;background:var(--card);
  font-size:24px;box-shadow:var(--shadow);font-weight:700;
  display:flex;align-items:center;justify-content:center;
}
.lesson-title{font-size:26px;flex:1}
.step-dots{display:flex;gap:6px}
.step-dots .dot{width:10px;height:10px;border-radius:50%;background:#DCD3ED}
.step-dots .dot.active{background:var(--violet);width:28px;border-radius:999px}
.step-dots .dot.done{background:var(--good)}

.lesson-body{
  background:var(--card);border-radius:var(--radius);
  padding:22px;box-shadow:var(--shadow);min-height:260px;
  margin-bottom:18px;
}
.lesson-nav{display:flex;gap:12px}
.nav-btn{
  flex:1;height:56px;border-radius:var(--radius-sm);
  font-family:'Fredoka',sans-serif;font-weight:600;font-size:18px;
  transition:transform .12s, box-shadow .2s;
}
.nav-btn.primary{background:linear-gradient(135deg,var(--violet),var(--pink));color:#fff;box-shadow:0 6px 16px rgba(124,77,255,.35)}
.nav-btn.secondary{background:var(--card);color:var(--ink);box-shadow:var(--shadow)}
.nav-btn:active:not(:disabled){transform:scale(.96)}
.nav-btn:disabled{opacity:.4;cursor:not-allowed}

/* ============ LESSON CONTENT COMPONENTS ============ */
.slide h3{font-size:24px;color:var(--violet);margin-bottom:12px}
.slide p{font-size:18px;line-height:1.55;color:var(--ink);margin-bottom:12px}
.slide strong{color:var(--pink);font-weight:700}
.fact-box{
  background:color-mix(in srgb,var(--yellow) 40%,white);
  border-radius:var(--radius-sm);padding:14px 16px;margin:14px 0;
  border-left:4px solid var(--orange);
}
.fact-box .emoji{font-size:22px;margin-right:6px}

.pill-list{display:flex;flex-wrap:wrap;gap:8px;margin-top:10px}
.pill{
  background:color-mix(in srgb,var(--violet) 14%, white);
  color:var(--violet);padding:8px 14px;border-radius:999px;
  font-weight:600;font-size:16px;
}
.pill.mus{background:color-mix(in srgb,var(--pink) 14%, white);color:var(--pink)}
.pill.joint{background:color-mix(in srgb,var(--teal) 14%, white);color:var(--teal)}

/* Body diagram */
.body-diagram{
  position:relative;max-width:280px;margin:20px auto;
  aspect-ratio:1/2;
}
.body-svg{width:100%;height:100%;display:block}
.part-btn{
  position:absolute;width:44px;height:44px;border-radius:50%;
  background:rgba(124,77,255,.2);border:2px solid var(--violet);
  color:var(--violet);font-weight:700;font-size:14px;
  display:flex;align-items:center;justify-content:center;
  transform:translate(-50%,-50%);
  transition:all .2s;
}
.part-btn.revealed{background:var(--good);border-color:var(--good);color:#fff;transform:translate(-50%,-50%) scale(1.1)}
.part-btn:active{transform:translate(-50%,-50%) scale(.9)}
.part-label{
  position:absolute;transform:translate(-50%,-50%);
  background:var(--ink);color:#fff;padding:4px 10px;border-radius:8px;
  font-size:13px;font-weight:600;white-space:nowrap;
  pointer-events:none;
  animation:popIn .3s;
}
@keyframes popIn{from{opacity:0;transform:translate(-50%,-50%) scale(.5)}}

/* Quiz */
.quiz-question{font-size:22px;font-weight:600;margin-bottom:18px;text-align:center}
.quiz-options{display:grid;gap:10px}
.quiz-opt{
  padding:16px 18px;background:var(--card);border-radius:var(--radius-sm);
  box-shadow:var(--shadow);font-size:17px;font-weight:600;text-align:left;
  display:flex;align-items:center;gap:12px;
  border:2px solid transparent;min-height:56px;
  transition:all .2s;
}
.quiz-opt:hover{border-color:var(--violet)}
.quiz-opt.correct{background:#D5F5DC;border-color:var(--good);color:#0E6B28;animation:pulse .5s}
.quiz-opt.wrong{background:#FEE4E4;border-color:var(--bad);color:#8B1E1E;animation:shake .4s}
.quiz-opt .letter{
  width:34px;height:34px;border-radius:50%;background:var(--violet);color:#fff;
  display:flex;align-items:center;justify-content:center;font-weight:700;flex-shrink:0;
}
.quiz-opt.correct .letter{background:var(--good)}
.quiz-opt.wrong .letter{background:var(--bad)}
@keyframes pulse{0%,100%{transform:scale(1)}50%{transform:scale(1.03)}}
@keyframes shake{0%,100%{transform:translateX(0)}25%{transform:translateX(-6px)}75%{transform:translateX(6px)}}

.feedback-msg{margin-top:14px;padding:12px;border-radius:var(--radius-sm);text-align:center;font-weight:600;font-size:17px}
.feedback-msg.good{background:#D5F5DC;color:#0E6B28}
.feedback-msg.bad{background:#FEE4E4;color:#8B1E1E}

/* Drag & drop classify */
.dnd-bank{display:flex;flex-wrap:wrap;gap:10px;margin-bottom:20px;min-height:54px;padding:10px;background:color-mix(in srgb,var(--violet) 6%,white);border-radius:var(--radius-sm);border:2px dashed color-mix(in srgb,var(--violet) 30%, white)}
.dnd-item{
  padding:10px 16px;background:#fff;border-radius:999px;
  font-weight:600;font-size:16px;box-shadow:var(--shadow);
  user-select:none;touch-action:none;cursor:grab;
  border:2px solid var(--violet);color:var(--violet);
  transition:transform .15s;
}
.dnd-item.dragging{opacity:.6;transform:scale(1.08);cursor:grabbing}
.dnd-item.placed{background:color-mix(in srgb,var(--good) 12%,white);border-color:var(--good);color:var(--good)}
.dnd-categories{display:grid;grid-template-columns:repeat(2,1fr);gap:12px}
.dnd-cat{
  background:var(--card);border-radius:var(--radius-sm);
  padding:14px;min-height:140px;box-shadow:var(--shadow);
  border:2px solid transparent;transition:all .2s;
}
.dnd-cat.over{border-color:var(--violet);background:color-mix(in srgb,var(--violet) 8%,white)}
.dnd-cat h4{font-size:16px;font-weight:700;margin-bottom:10px;text-align:center;color:var(--violet)}
.dnd-cat .drop-zone{display:flex;flex-wrap:wrap;gap:6px;min-height:80px}

/* Reflect self-rating */
.reflect-item{
  background:color-mix(in srgb,var(--blue) 6%,white);
  border-radius:var(--radius-sm);padding:16px;margin-bottom:12px;
  display:flex;align-items:center;gap:14px;
}
.reflect-icon{font-size:32px;flex-shrink:0}
.reflect-text{flex:1;font-weight:600}
.reflect-stars{display:flex;gap:6px}
.reflect-star{font-size:28px;cursor:pointer;filter:grayscale(1) opacity(.4);transition:all .15s}
.reflect-star:hover{transform:scale(1.1)}
.reflect-star.active{filter:none;animation:pop .3s}
@keyframes pop{0%{transform:scale(1)}50%{transform:scale(1.4)}100%{transform:scale(1)}}

/* Completion / award */
.award-screen{text-align:center;padding:20px 0}
.award-trophy{font-size:90px;animation:bob 2s ease-in-out infinite}
.award-title{font-size:30px;color:var(--violet);margin:10px 0}
.award-stars{font-size:44px;margin:18px 0;letter-spacing:6px}
.award-msg{font-size:18px;color:var(--ink-soft);margin-bottom:20px}

/* Odd-one-out grid */
.odd-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(120px,1fr));gap:10px}
.odd-item{
  padding:20px 12px;background:var(--card);border-radius:var(--radius-sm);
  font-size:18px;font-weight:600;text-align:center;box-shadow:var(--shadow);
  border:3px solid transparent;transition:all .2s;
}
.odd-item.correct{background:#D5F5DC;border-color:var(--good);color:#0E6B28;animation:pulse .5s}
.odd-item.wrong{background:#FEE4E4;border-color:var(--bad);color:#8B1E1E;animation:shake .4s}

/* Lab/hypothesis */
.hyp-option{
  display:block;width:100%;padding:16px;margin-bottom:10px;
  background:var(--card);border-radius:var(--radius-sm);box-shadow:var(--shadow);
  text-align:left;font-size:17px;font-weight:600;border:2px solid transparent;
}
.hyp-option.selected{border-color:var(--pink);background:color-mix(in srgb,var(--pink) 8%,white)}

/* Confetti */
#confetti{position:fixed;inset:0;pointer-events:none;z-index:30}

/* Toast */
.toast{
  position:fixed;bottom:32px;left:50%;transform:translateX(-50%) translateY(120%);
  background:var(--ink);color:#fff;padding:14px 22px;border-radius:999px;
  font-weight:600;font-size:17px;z-index:40;box-shadow:var(--shadow-lg);
  transition:transform .4s cubic-bezier(.22,1,.36,1);
  pointer-events:none;max-width:92vw;text-align:center;
}
.toast.show{transform:translateX(-50%) translateY(0)}

/* ============ RESPONSIVE ============ */
@media(max-width:520px){
  .hello{font-size:30px}
  .lesson-title{font-size:20px}
  .lesson-card{grid-template-columns:56px 1fr}
  .lesson-icon{width:56px;height:56px;font-size:36px}
  .dnd-categories{grid-template-columns:1fr 1fr}
  main{padding:16px 14px 60px}
}
@media(min-width:900px){
  .body-diagram{max-width:320px}
}