/* ============================================
   Bio Seeker — design tokens
   ============================================ */
:root{
  --paper:#0A1220;
  --ink:#EAF3F0;
  --ink-soft:#93ACA8;
  --forest:#23D9A0;
  --forest-deep:#5CF0C0;
  --amber:#F2C463;
  --amber-deep:#F2C463;
  --coral:#FF7A56;
  --card:#101B2E;
  --line:rgba(255,255,255,0.10);
  --radius:14px;
  --radius-sm:8px;
  --shadow:0 1px 2px rgba(0,0,0,0.35);
  --glow:0 0 32px rgba(35,217,160,0.18);
  --maxw:1120px;
}

*{box-sizing:border-box;}
html{scroll-behavior:smooth;}
body{
  margin:0;
  background:
    radial-gradient(ellipse 900px 500px at 15% -5%, rgba(35,217,160,0.10), transparent 60%),
    radial-gradient(ellipse 700px 500px at 100% 10%, rgba(76,195,240,0.08), transparent 55%),
    var(--paper);
  color:var(--ink);
  font-family:'Noto Sans Sinhala','Inter',sans-serif;
  font-size:16px;
  line-height:1.7;
  -webkit-font-smoothing:antialiased;
}
h1,h2,h3,.display{
  font-family:'Noto Serif Sinhala','Fraunces',serif;
  font-weight:600;
  line-height:1.3;
  margin:0 0 0.5em;
  color:var(--ink);
}
h1{font-size:clamp(32px,5vw,52px);}
h2{font-size:clamp(24px,3.4vw,34px);}
h3{font-size:20px;}
p{margin:0 0 1em;color:var(--ink-soft);}
a{color:var(--forest-deep);}
img,svg{max-width:100%;display:block;}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 24px;}
.eyebrow{
  display:inline-flex;align-items:center;gap:8px;
  font-size:13px;font-weight:700;letter-spacing:.04em;
  color:var(--forest-deep);
  background:rgba(35,217,160,0.10);
  border:0.5px solid rgba(35,217,160,0.30);
  padding:6px 14px;border-radius:99px;margin-bottom:18px;
}
.section{padding:64px 0;}
.section-head{max-width:640px;margin-bottom:36px;}

/* Buttons */
.btn{
  display:inline-flex;align-items:center;gap:8px;
  font-family:inherit;font-size:15px;font-weight:700;
  padding:12px 22px;border-radius:99px;border:0.5px solid var(--line);
  text-decoration:none;cursor:pointer;background:var(--card);color:var(--ink);
  transition:transform .15s ease, background .15s ease, border-color .15s ease;
}
.btn:hover{border-color:var(--forest);transform:translateY(-1px);}
.btn-primary{background:var(--forest);color:#06231a;border-color:var(--forest);box-shadow:0 0 18px rgba(35,217,160,0.35);}
.btn-primary:hover{background:var(--forest-deep);border-color:var(--forest-deep);}
.btn-coral{background:var(--coral);color:#fff;border-color:var(--coral);}
.btn-coral:hover{background:#E0673F;border-color:#E0673F;}
.btn-ghost{background:transparent;}
.btn:disabled{opacity:.5;cursor:not-allowed;transform:none;}

/* Nav */
header.site{
  position:sticky;top:0;z-index:50;
  background:rgba(10,18,32,0.80);backdrop-filter:blur(10px);
  border-bottom:0.5px solid var(--line);
}
.nav{display:flex;align-items:center;justify-content:space-between;padding:14px 0;}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink);}
.brand-mark{width:36px;height:36px;flex:none;border-radius:50%;object-fit:cover;box-shadow:0 0 12px rgba(35,217,160,0.35);}
.brand-word{font-family:'Noto Serif Sinhala',serif;font-weight:700;font-size:18px;}
.brand-word em{font-family:'Fraunces',serif;font-style:italic;color:var(--forest);}
.nav-links{display:flex;gap:6px;align-items:center;}
.nav-links a{
  text-decoration:none;color:var(--ink-soft);font-weight:500;font-size:15px;
  padding:8px 14px;border-radius:99px;transition:background .15s, color .15s;
}
.nav-links a:hover{background:rgba(35,217,160,0.10);color:var(--forest-deep);}
.nav-links a.active{background:var(--forest);color:#06231a;}
.nav-cta{margin-left:8px;}
.nav-toggle{display:none;background:none;border:0;font-size:24px;color:var(--ink);cursor:pointer;}

@media(max-width:1180px){
  .nav-links{
    position:absolute;top:100%;left:0;right:0;
    background:var(--paper);border-bottom:0.5px solid var(--line);
    flex-direction:column;align-items:stretch;padding:12px 24px 20px;
    display:none;
  }
  .nav-links.open{display:flex;}
  .nav-links a{padding:12px 8px;}
  .nav-toggle{display:block;}
}

/* Hero */
.hero{padding:56px 0 40px;}
.hero-grid{display:grid;grid-template-columns:1.1fr 0.9fr;gap:48px;align-items:center;}
.hero p.lead{font-size:18px;max-width:480px;}
.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:8px;}
@media(max-width:900px){.hero-grid{grid-template-columns:1fr;}}

/* DNA helix signature */
.helix-stage{position:relative;height:340px;perspective:900px;}
.helix{
  position:absolute;left:50%;top:50%;
  transform:translate(-50%,-50%);
  transform-style:preserve-3d;
  animation:spin 14s linear infinite;
  width:100%;height:100%;
}
.rung{
  position:absolute;left:50%;top:50%;
  width:150px;height:6px;margin:-3px 0 0 -75px;
  display:flex;justify-content:space-between;align-items:center;
  transform-style:preserve-3d;
}
.rung i{width:12px;height:12px;border-radius:50%;display:block;}
.rung .bar{flex:1;height:2px;background:var(--line);margin:0 4px;}
@keyframes spin{from{transform:translate(-50%,-50%) rotateY(0deg);}to{transform:translate(-50%,-50%) rotateY(360deg);}}
@media(prefers-reduced-motion:reduce){.helix{animation:none;}}

/* Feature cards */
.grid-4{display:grid;grid-template-columns:repeat(4,1fr);gap:16px;}
.grid-3{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;}
.grid-2{display:grid;grid-template-columns:repeat(2,1fr);gap:16px;}
@media(max-width:900px){.grid-4{grid-template-columns:repeat(2,1fr);}.grid-3{grid-template-columns:1fr;}.grid-2{grid-template-columns:1fr;}}
@media(max-width:520px){.grid-4{grid-template-columns:1fr;}}

.card{
  background:var(--card);border:0.5px solid var(--line);border-radius:var(--radius);
  padding:22px;box-shadow:var(--shadow);
  transition:border-color .2s ease, box-shadow .2s ease, transform .2s ease;
}
.card:hover{border-color:rgba(35,217,160,0.35);box-shadow:var(--glow);transform:translateY(-2px);}
.card .icon{
  width:40px;height:40px;border-radius:10px;background:rgba(35,217,160,0.12);
  display:flex;align-items:center;justify-content:center;color:var(--forest-deep);
  font-size:20px;margin-bottom:14px;
}
.card h3{margin-bottom:6px;}
.card p{margin-bottom:0;font-size:14px;}
.card-link{display:inline-flex;gap:6px;align-items:center;margin-top:12px;font-size:14px;font-weight:700;color:var(--forest-deep);text-decoration:none;}

/* Video embed */
.video-frame{position:relative;width:100%;padding-top:56.25%;border-radius:var(--radius);overflow:hidden;border:0.5px solid var(--line);background:#000;box-shadow:var(--glow);}
.video-frame iframe{position:absolute;inset:0;width:100%;height:100%;border:0;}

/* Lesson tabs */
.lesson-tabs{display:flex;gap:8px;flex-wrap:wrap;margin-top:22px;}
.lesson-tab{
  font-family:inherit;font-size:14px;font-weight:600;color:var(--ink-soft);
  background:var(--card);border:0.5px solid var(--line);padding:9px 16px;border-radius:99px;cursor:pointer;
  transition:.15s;
}
.lesson-tab:hover{border-color:var(--forest);color:var(--ink);}
.lesson-tab.active{background:var(--forest);border-color:var(--forest);color:#06231a;}

/* Notes */
.note-card{background:var(--card);border:0.5px solid var(--line);border-radius:var(--radius);padding:26px;margin-bottom:18px;}
.note-tag{font-size:12px;font-weight:700;color:var(--amber-deep);background:rgba(242,196,99,0.14);padding:4px 10px;border-radius:99px;}

/* Quiz */
.quiz-box{background:var(--card);border:0.5px solid var(--line);border-radius:var(--radius);padding:28px;max-width:640px;margin:0 auto;}
.quiz-progress{font-size:13px;color:var(--ink-soft);margin-bottom:10px;}
.quiz-q{font-size:19px;font-weight:600;margin-bottom:18px;}
.quiz-opts{display:flex;flex-direction:column;gap:10px;}
.quiz-opt{
  text-align:right;font-family:inherit;font-size:15px;padding:13px 16px;border-radius:var(--radius-sm);
  border:0.5px solid var(--line);background:var(--paper);color:var(--ink);cursor:pointer;transition:.15s;
}
.quiz-opt:hover{border-color:var(--forest);}
.quiz-opt.correct{background:rgba(35,217,160,0.14);border-color:var(--forest);color:var(--forest-deep);font-weight:700;}
.quiz-opt.wrong{background:rgba(255,122,86,0.14);border-color:var(--coral);color:#FFB39C;font-weight:700;}
.quiz-explain{font-size:14px;color:var(--ink-soft);margin-top:14px;min-height:20px;}
.quiz-foot{display:flex;justify-content:space-between;align-items:center;margin-top:20px;}

/* Punnett */
.tool-box{background:var(--card);border:0.5px solid var(--line);border-radius:var(--radius);padding:26px;}
.select-row{display:flex;gap:14px;flex-wrap:wrap;margin-bottom:20px;}
.select-field{flex:1;min-width:160px;}
.select-field label{display:block;font-size:13px;color:var(--ink-soft);margin-bottom:6px;}
select,input[type=text]{
  width:100%;font-family:inherit;font-size:15px;padding:10px 12px;border-radius:var(--radius-sm);
  border:0.5px solid var(--line);background:var(--paper);color:var(--ink);
}
table.punnett{border-collapse:collapse;margin:0 auto;}
table.punnett th,table.punnett td{border:0.5px solid var(--line);padding:14px 20px;text-align:center;font-size:16px;}
table.punnett th{background:var(--paper);font-weight:700;}
.geno-tall{background:rgba(35,217,160,0.14);color:var(--forest-deep);font-weight:700;}
.geno-short{background:rgba(242,196,99,0.14);color:var(--amber-deep);font-weight:700;}
.ratio-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin-top:20px;}
.ratio-card{background:var(--paper);border-radius:var(--radius-sm);padding:14px;text-align:center;}
.ratio-card .k{font-size:12px;color:var(--ink-soft);}
.ratio-card .v{font-size:17px;font-weight:700;margin-top:4px;}

/* Cell explorer */
.cell-explorer{display:grid;grid-template-columns:1.2fr 1fr;gap:24px;align-items:start;}
@media(max-width:800px){.cell-explorer{grid-template-columns:1fr;}}
.cell-part{cursor:pointer;transition:opacity .15s;}
.cell-part:hover{opacity:.8;}
.cell-info{background:var(--paper);border-radius:var(--radius);padding:20px;min-height:180px;}
.cell-info .k{font-size:12px;font-weight:700;color:var(--forest-deep);text-transform:uppercase;letter-spacing:.03em;}

/* Mitosis stepper */
.stepper{background:var(--card);border:0.5px solid var(--line);border-radius:var(--radius);padding:26px;}
.stepper-dots{display:flex;gap:8px;justify-content:center;margin-bottom:20px;}
.stepper-dots span{width:9px;height:9px;border-radius:50%;background:var(--line);}
.stepper-dots span.on{background:var(--forest);}
.stepper-nav{display:flex;justify-content:space-between;margin-top:20px;}

/* Footer */
footer.site{border-top:0.5px solid var(--line);padding:40px 0;margin-top:40px;}
.footer-row{display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:16px;}
.footer-note{font-size:13px;color:var(--ink-soft);}

/* Pomodoro timer */
.timer-display{font-family:'Fraunces',serif;font-size:clamp(56px,10vw,96px);font-weight:600;text-align:center;margin:12px 0;letter-spacing:.02em;}
.timer-mode{display:flex;justify-content:center;gap:8px;margin-bottom:8px;}
.mode-pill{font-size:12px;font-weight:700;padding:5px 14px;border-radius:99px;background:var(--paper);color:var(--ink-soft);}
.mode-pill.on{background:var(--forest);color:#06231a;}
.timer-controls{display:flex;justify-content:center;gap:10px;margin-top:8px;flex-wrap:wrap;}
.timer-ring{width:14px;height:14px;border-radius:50%;display:inline-block;margin:0 3px;background:var(--line);}
.timer-ring.done{background:var(--forest);}
.timer-sessions{display:flex;justify-content:center;margin:14px 0 4px;}

/* Flashcards */
.flash-stage{max-width:420px;margin:0 auto;perspective:1400px;}
.flash-card{
  position:relative;width:100%;height:220px;cursor:pointer;
  transform-style:preserve-3d;transition:transform .5s;
}
.flash-card.flipped{transform:rotateY(180deg);}
.flash-face{
  position:absolute;inset:0;backface-visibility:hidden;border-radius:var(--radius);
  border:0.5px solid var(--line);background:var(--card);
  display:flex;align-items:center;justify-content:center;text-align:center;padding:24px;
  box-shadow:var(--shadow);
}
.flash-face.back{transform:rotateY(180deg);background:linear-gradient(155deg,rgba(35,217,160,0.10),rgba(76,195,240,0.08)),var(--card);}
.flash-term{font-family:'Noto Serif Sinhala',serif;font-size:24px;font-weight:600;}
.flash-def{font-size:15px;color:var(--ink-soft);}
.flash-rate{display:flex;gap:8px;justify-content:center;margin-top:18px;flex-wrap:wrap;}
.flash-rate button{flex:1;min-width:90px;font-size:13px;padding:10px 8px;}
.flash-progress{text-align:center;font-size:13px;color:var(--ink-soft);margin-bottom:10px;}

/* Level map (quiz chapter select) */
.level-map{position:relative;width:100%;max-width:640px;margin:0 auto;aspect-ratio:1000/1250;}
.level-map svg{position:absolute;inset:0;width:100%;height:100%;}
.level-node{
  position:absolute;transform:translate(-50%,-50%);
  display:flex;flex-direction:column;align-items:center;gap:4px;
  background:none;border:0;cursor:pointer;padding:0;
}
.level-node .bubble{
  width:64px;height:64px;border-radius:50%;
  background:var(--card);border:1.5px solid var(--line);
  display:flex;align-items:center;justify-content:center;
  font-family:'Fraunces',serif;font-size:24px;font-weight:600;color:var(--ink);
  transition:.18s;box-shadow:var(--shadow);
}
.level-node:hover .bubble{border-color:var(--forest);transform:scale(1.06);box-shadow:var(--glow);}
.level-node.done .bubble{background:var(--forest);border-color:var(--forest);color:#06231a;}
.level-node .stars{font-size:12px;letter-spacing:1px;color:var(--amber);height:14px;}
.level-node .label{
  font-size:11px;color:var(--ink-soft);text-align:center;max-width:88px;line-height:1.25;
}

@media(max-width:520px){
  .level-map{max-width:340px;}
  .level-node .bubble{width:44px;height:44px;font-size:17px;}
  .level-node .stars{font-size:10px;height:12px;}
  .level-node .label{font-size:9.5px;max-width:66px;line-height:1.2;}
}

/* Memory calendar */
.cal-grid{display:grid;grid-template-columns:repeat(7,1fr);gap:6px;margin-top:16px;}
.cal-dow{font-size:11px;text-align:center;color:var(--ink-soft);font-weight:700;padding-bottom:4px;}
.cal-cell{
  aspect-ratio:1;border-radius:8px;display:flex;flex-direction:column;align-items:center;justify-content:center;
  font-size:13px;background:var(--paper);color:var(--ink);border:0.5px solid transparent;position:relative;
}
.cal-cell.today{border-color:var(--forest);font-weight:700;}
.cal-cell.has-due::after{
  content:'';width:5px;height:5px;border-radius:50%;background:var(--amber);position:absolute;bottom:6px;
}
.cal-cell.empty{background:transparent;}
.due-list{display:flex;flex-wrap:wrap;gap:8px;margin-top:14px;}
.due-chip{font-size:13px;background:var(--paper);border:0.5px solid var(--line);border-radius:99px;padding:6px 14px;}

/* Diagram labeling game */
.dg-tabs{display:flex;gap:8px;flex-wrap:wrap;justify-content:center;margin-bottom:22px;}
.dg-stage{position:relative;max-width:420px;margin:0 auto;}
.dg-zone{
  position:absolute;transform:translate(-50%,-50%);
  width:30px;height:30px;border-radius:50%;
  background:rgba(255,122,86,0.85);border:2px solid #fff;
  display:flex;align-items:center;justify-content:center;
  font-size:13px;font-weight:700;color:#2a1206;cursor:pointer;
  transition:.15s;box-shadow:0 0 0 4px rgba(255,122,86,0.2);
}
.dg-zone.filled{background:var(--forest);color:#06231a;box-shadow:0 0 0 4px rgba(35,217,160,0.22);}
.dg-zone.wrong-flash{background:var(--coral);}
.dg-wordbank{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;margin-top:20px;}
.dg-chip{
  font-size:13px;font-weight:600;padding:8px 14px;border-radius:99px;
  background:var(--card);border:0.5px solid var(--line);cursor:pointer;color:var(--ink);
}
.dg-chip.selected{background:var(--forest);border-color:var(--forest);color:#06231a;}
.dg-chip.used{opacity:0.35;cursor:default;}
.dg-status{text-align:center;font-size:14px;color:var(--ink-soft);margin-top:16px;}

.center{text-align:center;}
.mt-32{margin-top:32px;}

/* Ambient bubble background */
.bubble-field{position:fixed;inset:0;z-index:-1;overflow:hidden;pointer-events:none;}
.ambient-bubble{
  position:absolute;
  bottom:-120px;
  border-radius:50%;
  background:radial-gradient(circle at 30% 30%, rgba(35,217,160,0.35), rgba(76,195,240,0.12) 60%, transparent 75%);
  animation:bubble-float linear infinite;
}
@keyframes bubble-float{
  0%{transform:translateY(0) translateX(0);opacity:0;}
  10%{opacity:1;}
  90%{opacity:0.75;}
  100%{transform:translateY(-115vh) translateX(var(--drift,20px));opacity:0;}
}
@media(prefers-reduced-motion:reduce){.ambient-bubble{animation:none;display:none;}}

/* Auth widget */
.auth-widget{display:flex;align-items:center;gap:8px;}
.auth-avatar{width:30px;height:30px;border-radius:50%;object-fit:cover;border:1.5px solid var(--forest);}
.auth-name{font-size:13px;font-weight:600;max-width:110px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;}
.google-btn{
  display:inline-flex;align-items:center;gap:8px;font-size:14px;font-weight:600;
  background:#fff;color:#1F1F1F;padding:9px 16px;border-radius:99px;border:0.5px solid var(--line);cursor:pointer;
}
.google-btn:hover{box-shadow:var(--glow);}

/* Leaderboard */
.lb-table{width:100%;border-collapse:collapse;}
.lb-table th{text-align:right;font-size:12px;color:var(--ink-soft);padding:8px 10px;border-bottom:0.5px solid var(--line);}
.lb-table td{padding:12px 10px;border-bottom:0.5px solid var(--line);font-size:14px;}
.lb-table tr.me{background:rgba(35,217,160,0.08);}
.lb-rank{font-family:'Fraunces',serif;font-weight:600;font-size:16px;width:36px;}
.lb-user{display:flex;align-items:center;gap:10px;}
.lb-user img{width:30px;height:30px;border-radius:50%;object-fit:cover;}


/* ---------- Nav: compact on desktop (more items now) ---------- */
header.site .wrap{max-width:1360px;}
@media(min-width:1181px){
  .nav-links{gap:2px;}
  .nav-links a{padding:8px 10px;font-size:14px;}
  .nav-links .btn{padding:10px 18px;font-size:14px;}
}
@media(max-width:1180px){
  .nav-links .auth-widget-slot{padding:8px 0;}
  .nav-links .btn.nav-cta{margin-left:0;justify-content:center;}
}

/* ---------- Donate button (footer) ---------- */
.donate-btn{
  background:rgba(255,122,86,0.12);border-color:rgba(255,122,86,0.45);color:#FFB39C;
  padding:8px 16px;font-size:13px;
}
.donate-btn:hover{border-color:var(--coral);background:rgba(255,122,86,0.2);}

/* ---------- Login-required panel (Leaderboard / Smart Practice) ---------- */
.lock-panel{max-width:480px;margin:0 auto;text-align:center;padding:32px 24px;}
.lock-icon{font-size:36px;margin-bottom:8px;}
.lock-panel p{font-size:14px;}
.lock-panel .auth-widget-slot{display:flex;justify-content:center;margin-top:18px;}
.lock-panel .auth-widget{justify-content:center;}

/* ---------- Smart Practice ---------- */
.perf-row{display:flex;align-items:center;gap:10px;margin-bottom:9px;font-size:13px;}
.perf-label{flex:0 0 42%;color:var(--ink-soft);line-height:1.3;}
.perf-bar{flex:1;height:8px;background:var(--paper);border-radius:99px;overflow:hidden;}
.perf-fill{height:100%;border-radius:99px;}
.perf-pct{flex:0 0 44px;text-align:right;font-weight:700;}
.stat-pills{display:flex;gap:10px;flex-wrap:wrap;margin-bottom:18px;}
.stat-pill{background:var(--paper);border:0.5px solid var(--line);border-radius:99px;padding:6px 14px;font-size:13px;color:var(--ink-soft);}
.stat-pill strong{color:var(--ink);}
.chapter-tag{display:inline-block;font-size:11px;font-weight:700;color:var(--amber-deep);background:rgba(242,196,99,0.14);padding:3px 10px;border-radius:99px;margin-bottom:10px;}
.notice-box{background:rgba(255,122,86,0.10);border:0.5px solid var(--coral);border-radius:var(--radius-sm);padding:14px;font-size:13px;margin-bottom:16px;}
.notice-box code{background:var(--paper);padding:2px 6px;border-radius:4px;font-size:12px;}

/* ---------- Leaderboard extras ---------- */
.my-rank{display:flex;gap:12px;flex-wrap:wrap;margin-bottom:20px;}
.my-rank .ratio-card{flex:1;min-width:110px;}
.lb-badges{font-size:11px;color:var(--ink-soft);margin-top:2px;}

/* ---------- Cookie donate button (🍪) ---------- */
.cookie-donate{
  background:linear-gradient(135deg,#F2C463,#E3A72E);color:#2b1a00;border:0;font-weight:700;
  box-shadow:0 0 18px rgba(242,196,99,0.45);padding:12px 20px;
}
.cookie-donate:hover{transform:translateY(-2px);box-shadow:0 0 26px rgba(242,196,99,0.7);}