:root{
  --ink:#24224A; --paper:#F5F6FF; --card:#FFFFFF; --muted:#5C5A80;
  --sun:#FFD23F; --sky:#3E64FF; --pop:#FF5C8A; --mint:#16BFA0;
  --t1:#FFF3C4; --t2:#DCE4FF; --t3:#FFE0EA; --t4:#D3F5EC;
  --line:2.5px solid var(--ink); --shadow:4px 4px 0 var(--ink);
  --display:"Bricolage Grotesque", "Be Vietnam Pro", system-ui, sans-serif;
  --body:"Be Vietnam Pro", system-ui, -apple-system, "Segoe UI", sans-serif;
  box-sizing:border-box;
  padding-top:env(safe-area-inset-top,0px); padding-bottom:env(safe-area-inset-bottom,0px);
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --ink:#E9E8FF; --paper:#16152B; --card:#22213F; --muted:#B4B2DA;
    --t1:#4A3F12; --t2:#232F66; --t3:#55223A; --t4:#123F37;
    --sun:#FFD23F; --sky:#7D97FF; --pop:#FF7AA0; --mint:#3ED8BB;
  }
}
:root[data-theme="dark"]{
  --ink:#E9E8FF; --paper:#16152B; --card:#22213F; --muted:#B4B2DA;
  --t1:#4A3F12; --t2:#232F66; --t3:#55223A; --t4:#123F37;
  --sun:#FFD23F; --sky:#7D97FF; --pop:#FF7AA0; --mint:#3ED8BB;
}
*,*::before,*::after{box-sizing:inherit}
html{scroll-padding-top:calc(env(safe-area-inset-top,0px) + 80px)}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--body);font-size:17px;line-height:1.5;-webkit-tap-highlight-color:transparent}
button,select{font:inherit;color:inherit}
button{cursor:pointer}
:focus-visible{outline:3px solid var(--sky);outline-offset:3px}
h1,h2,h3{font-family:var(--display);line-height:1.1;margin:0}

/* top bar */
.top{position:sticky;top:env(safe-area-inset-top,0px);z-index:20;background:var(--paper);border-bottom:var(--line)}
.top-inner{max-width:980px;margin:0 auto;display:flex;align-items:center;gap:14px;padding:10px 16px}
.brand{font-family:var(--display);font-weight:800;font-size:22px;letter-spacing:-.02em;white-space:nowrap}
.brand span{display:inline-block;background:var(--sun);color:#24224A;border:var(--line);border-radius:8px;padding:0 7px;transform:rotate(-3deg);margin-right:4px}
.brand-wrap{min-width:0}
.tagline{margin:2px 0 0;font-size:13px;line-height:1.3;color:var(--muted);font-weight:600}
nav.tabs{display:flex;gap:6px;margin-left:auto}
.tab{border:var(--line);background:var(--card);border-radius:12px;padding:7px 14px;font-weight:700;display:flex;align-items:center;gap:6px}
.tab[aria-current="page"]{background:var(--ink);color:var(--paper)}
.tab .ic{font-size:18px}
@media (max-width:640px){
  .top-inner{flex-direction:column;align-items:stretch;gap:8px;padding:8px 10px}
  .brand{text-align:center;font-size:19px}
  .tagline{text-align:center;font-size:12px}
  nav.tabs{margin:0;display:grid;grid-template-columns:repeat(5,1fr)}
  .tab{flex-direction:column;gap:0;padding:5px 2px;font-size:13px;border-radius:10px}
}
main{max-width:980px;margin:0 auto;padding:20px 16px 60px}
.view[hidden]{display:none}

/* shared bits */
.btn{border:var(--line);background:var(--card);border-radius:12px;padding:10px 18px;font-weight:700;box-shadow:3px 3px 0 var(--ink);transition:transform .08s, box-shadow .08s}
.btn:active{transform:translate(3px,3px);box-shadow:0 0 0 var(--ink)}
.btn.primary{background:var(--sky);color:#fff}
.btn.sun{background:var(--sun);color:#24224A}
.btn.small{padding:6px 12px;font-size:15px}
.btn[disabled]{opacity:.45;cursor:default}
.sel{border:var(--line);background:var(--card);border-radius:12px;padding:8px 12px;font-weight:700;max-width:100%}
.row{display:flex;flex-wrap:wrap;gap:10px;align-items:center}
.muted{color:var(--muted)}
.seg{display:inline-flex;border:var(--line);border-radius:12px;overflow:hidden;background:var(--card)}
.seg button{border:0;background:transparent;padding:8px 14px;font-weight:700}
.seg button+button{border-left:var(--line)}
.seg button[aria-pressed="true"]{background:var(--ink);color:var(--paper)}

/* scene illustration */
.scene{position:relative;border:var(--line);border-radius:16px;overflow:hidden;height:190px;
  background-color:var(--bg,var(--t2));
  background-image:radial-gradient(color-mix(in srgb,var(--ink) 16%,transparent) 1.4px,transparent 1.6px);
  background-size:12px 12px}
.scene .e{position:absolute;line-height:1;user-select:none}
.scene .hero{left:50%;top:52%;font-size:92px;transform:translate(-50%,-50%) rotate(-4deg)}
.scene .s1{left:9%;top:12%;font-size:46px;transform:rotate(-14deg)}
.scene .s2{right:9%;bottom:10%;font-size:52px;transform:rotate(12deg)}
.scene .s3{left:11%;bottom:9%;font-size:40px;transform:rotate(8deg)}
.scene .s4{right:30%;top:8%;font-size:34px;transform:rotate(-8deg)}
.scene.crowd .e{position:static;font-size:56px;transform:none}
.scene.crowd{display:flex;align-items:center;justify-content:center;flex-wrap:wrap;gap:0 4px;padding:10px}
.scene.crowd .e:nth-child(odd){transform:rotate(-10deg) translateY(-6px)}
.scene.crowd .e:nth-child(even){transform:rotate(9deg) translateY(8px) scale(1.15)}
.burst-wrap{position:absolute;right:8px;top:8px;filter:drop-shadow(2px 2px 0 var(--ink));transform:rotate(6deg);max-width:62%}
.burst{display:block;background:var(--sun);color:#24224A;font-family:var(--display);font-weight:800;font-size:15px;line-height:1.05;text-align:center;padding:16px 20px;
  clip-path:polygon(50% 0,60% 14%,78% 4%,80% 22%,100% 20%,90% 38%,100% 52%,88% 62%,98% 80%,78% 80%,74% 100%,60% 88%,48% 100%,38% 86%,20% 98%,20% 80%,0 82%,10% 64%,0 48%,12% 38%,2% 20%,22% 22%,24% 4%,40% 14%)}
.scene.mini{height:120px}
.scene.mini .hero{font-size:60px}
.scene.mini .s1{font-size:32px}.scene.mini .s2{font-size:36px}.scene.mini .s3{font-size:28px}.scene.mini .s4{font-size:26px}
.scene.mini.crowd .e{font-size:40px}
.scene.mini .burst{font-size:12px;padding:12px 14px}
@media (prefers-reduced-motion:no-preference){
  .wobble .hero{animation:wob 1.6s ease-in-out infinite}
  .wobble .s1,.wobble .s3{animation:bob 2.2s ease-in-out infinite}
  .wobble .s2,.wobble .s4{animation:bob 2.6s ease-in-out infinite reverse}
  .wobble .burst-wrap{animation:pulse 1.4s ease-in-out infinite}
}
@keyframes wob{0%,100%{transform:translate(-50%,-50%) rotate(-6deg) scale(1)}50%{transform:translate(-50%,-55%) rotate(5deg) scale(1.08)}}
@keyframes bob{0%,100%{translate:0 0}50%{translate:0 -8px}}
@keyframes pulse{0%,100%{scale:1}50%{scale:1.08}}

/* word detail */
.def{font-size:20px;font-weight:700;margin:0}
.vn{margin:-4px 0 0;font-size:18px;font-weight:700;color:var(--sky)}
.syn{display:inline-block;background:var(--t4);border:2px solid var(--ink);border-radius:999px;padding:1px 10px;font-size:14px;font-weight:700}
.mnem{background:var(--t1);border:var(--line);border-radius:14px;padding:12px 14px;margin:0}
.mnem b{font-family:var(--display)}
.ex{margin:0;font-style:italic}
.ex mark{background:none;color:inherit;font-style:normal;font-weight:700;border-bottom:3px solid var(--pop)}
.lbl{font-family:var(--display);font-weight:700;font-size:14px;color:var(--muted);margin:0 0 2px}
.detail{display:grid;gap:12px}

/* flashcards */
.fc-head{display:flex;flex-wrap:wrap;gap:10px;align-items:center;justify-content:space-between;margin-bottom:14px}
.count{font-family:var(--display);font-weight:700;font-size:18px}
.card-wrap{perspective:1600px;max-width:560px;margin:0 auto}
.card{display:grid;width:100%;border:0;padding:0;background:none;text-align:left;transform-style:preserve-3d;transition:transform .55s cubic-bezier(.3,1.4,.5,1)}
.card.flipped{transform:rotateY(180deg)}
@media (prefers-reduced-motion:reduce){.card{transition:none}}
.face{grid-area:1/1;backface-visibility:hidden;-webkit-backface-visibility:hidden;background:var(--card);border:3px solid var(--ink);border-radius:22px;box-shadow:6px 6px 0 var(--ink);padding:20px;min-height:340px}
.front{display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;gap:10px;
  background-image:radial-gradient(color-mix(in srgb,var(--sky) 22%,transparent) 1.6px,transparent 1.8px);background-size:16px 16px}
.back{transform:rotateY(180deg)}
.word-big{font-family:var(--display);font-weight:800;font-size:clamp(36px,10vw,58px);letter-spacing:-.03em;line-height:1;word-break:break-word}
.pron{font-size:20px;color:var(--muted)}
.pron b{color:var(--ink)}
.gtag{font-family:var(--display);font-weight:700;font-size:14px;background:var(--sun);color:#24224A;border:2px solid var(--ink);border-radius:999px;padding:2px 10px}
.hint{font-size:14px;color:var(--muted);margin-top:8px}
.speak{border:var(--line);background:var(--card);border-radius:999px;width:44px;height:44px;font-size:20px;display:grid;place-items:center}
.back-top{display:flex;justify-content:space-between;align-items:baseline;gap:10px;margin-bottom:8px}
.back-word{font-family:var(--display);font-weight:800;font-size:26px}
.fc-controls{display:flex;justify-content:center;gap:10px;margin-top:22px;flex-wrap:wrap}
.miss-badge{font-size:13px;font-weight:700;color:#fff;background:var(--pop);border:2px solid var(--ink);border-radius:999px;padding:1px 9px}

/* groups */
.groups{display:grid;gap:18px}
.group{background:var(--card);border:var(--line);border-radius:18px;box-shadow:var(--shadow);padding:16px}
.group h2{font-size:24px;display:flex;align-items:center;gap:10px}
.gnum{display:inline-grid;place-items:center;min-width:40px;height:40px;border:var(--line);border-radius:50%;background:var(--sky);color:#fff;font-size:18px}
.group p.sum{margin:8px 0 12px;color:var(--muted)}
.chips{display:flex;flex-wrap:wrap;gap:7px}
.chip{border:2px solid var(--ink);background:var(--paper);border-radius:999px;padding:4px 12px;font-weight:700;font-size:15px}
.chip.missed{background:var(--t3)}
.chip.solid{background:var(--t4)}
.group .row{margin-top:12px}
.legend{display:flex;gap:14px;flex-wrap:wrap;font-size:14px;color:var(--muted);margin:6px 0 16px}
.legend i{display:inline-block;width:12px;height:12px;border:2px solid var(--ink);border-radius:50%;vertical-align:-1px;margin-right:4px}

/* dialog */
dialog{border:3px solid var(--ink);border-radius:22px;box-shadow:6px 6px 0 var(--ink);padding:0;background:var(--card);color:var(--ink);width:min(560px,calc(100vw - 24px));max-height:calc(100dvh - 40px)}
dialog::backdrop{background:rgba(20,18,50,.55)}
.dlg{padding:18px;overflow:auto;max-height:calc(100dvh - 46px)}
.dlg-head{display:flex;justify-content:space-between;align-items:start;gap:10px;margin-bottom:10px}
.x{border:var(--line);background:var(--paper);border-radius:50%;width:40px;height:40px;font-size:20px;flex:none}

/* quiz */
.panel{background:var(--card);border:var(--line);border-radius:18px;box-shadow:var(--shadow);padding:18px;margin-bottom:18px}
.panel h2{font-size:24px;margin-bottom:10px}
.field{display:grid;gap:6px;margin:12px 0}
.field label,.flabel{font-family:var(--display);font-weight:700}
.rot-sum{background:var(--t2);border:2px solid var(--ink);border-radius:12px;padding:10px 12px;margin:10px 0}
.q-meta{display:flex;justify-content:space-between;align-items:center;margin-bottom:10px;font-family:var(--display);font-weight:700}
.progress{height:12px;border:2px solid var(--ink);border-radius:999px;overflow:hidden;background:var(--paper);margin-bottom:16px}
.progress div{height:100%;background:var(--mint);transition:width .3s}
.q-kind{font-family:var(--display);font-weight:700;color:var(--muted);font-size:15px;margin:0 0 4px}
.q-prompt{font-size:22px;font-weight:700;margin:0 0 16px}
.q-prompt .w{font-family:var(--display);font-weight:800;font-size:34px}
.opts{display:grid;gap:10px}
.opt{border:var(--line);background:var(--paper);border-radius:14px;padding:12px 14px;text-align:left;font-weight:700;box-shadow:3px 3px 0 var(--ink)}
.opt.right{background:var(--mint);color:#06231d}
.opt.wrong{background:var(--pop);color:#fff}
.opt[disabled]{cursor:default}
.fb{margin-top:16px;display:grid;gap:12px}
.verdict{font-family:var(--display);font-weight:800;font-size:24px}
.score{font-family:var(--display);font-weight:800;font-size:64px;line-height:1}
.hist{list-style:none;padding:0;margin:0;display:grid;gap:6px}
.hist li{display:flex;justify-content:space-between;gap:10px;border-bottom:2px dashed color-mix(in srgb,var(--ink) 25%,transparent);padding:4px 0}
.linkish{border:0;background:none;padding:0;text-decoration:underline;color:var(--muted);font-size:14px}

.pic{border:var(--line);border-radius:16px;overflow:hidden;background:#fff;display:grid;place-items:center}
.pic img{display:block;width:100%;height:auto;max-height:min(230px,30vh);object-fit:contain;background:#fff}
.pic svg{display:block;width:100%;height:auto}
.pic.mini img{max-height:170px}
.art{border:2.5px solid var(--ink);border-radius:4px;overflow:hidden;line-height:0}
.art svg{display:block;width:100%;height:auto}
.bub{position:relative;background:#fff;color:#24224A;border:2.5px solid var(--ink);border-radius:18px;padding:9px 12px;margin:6px 0 0;font-size:16px}
.bub::before{content:"";position:absolute;top:-13px;left:calc(var(--tx) - 9px);width:16px;height:13px;background:var(--ink);clip-path:polygon(50% 0,100% 100%,0 100%)}
.bub::after{content:"";position:absolute;top:-9px;left:calc(var(--tx) - 6px);width:10px;height:10px;background:#fff;clip-path:polygon(50% 0,100% 100%,0 100%)}
.bub .vw{color:#24224A}
.cast{background:var(--card);border:var(--line);border-radius:14px;padding:8px 12px;margin:12px 0 4px}
.cast summary{font-family:var(--display);font-weight:800;cursor:pointer}
.cast .art{margin:10px 0 8px}
.cast-names{display:flex;flex-wrap:wrap;gap:6px 14px;font-size:14px;color:var(--muted)}
.cast-names b{color:var(--ink)}
/* comics */
.comic-head{display:flex;flex-wrap:wrap;gap:10px;align-items:center;justify-content:space-between;margin-bottom:6px}
.comic-title{font-size:clamp(28px,6vw,42px);font-weight:800;letter-spacing:-.02em;margin:10px 0 4px}
.strip{display:grid;grid-template-columns:repeat(2,1fr);gap:14px;margin-top:16px}
@media (max-width:640px){.strip{grid-template-columns:1fr}}
.pnl{background:var(--card);border:3px solid var(--ink);border-radius:6px;box-shadow:5px 5px 0 var(--ink);padding:12px;display:flex;flex-direction:column;gap:10px;position:relative}
.pnl:nth-child(4n+2){transform:rotate(.6deg)} .pnl:nth-child(4n+3){transform:rotate(-.6deg)}
.pnl-n{position:absolute;left:-8px;top:-10px;background:var(--ink);color:var(--paper);font-family:var(--display);font-weight:800;border-radius:6px;padding:0 8px;font-size:14px}
.cap{background:var(--sun);color:#24224A;border:2px solid var(--ink);padding:8px 10px;font-size:16px;margin:0}
.bubble{position:relative;background:var(--paper);border:2.5px solid var(--ink);border-radius:20px;padding:10px 12px;margin:0 0 6px;font-size:16px}
.bubble::after{content:"";position:absolute;left:28px;bottom:-14px;width:18px;height:14px;background:var(--paper);border-right:2.5px solid var(--ink);border-bottom:2.5px solid var(--ink);transform:skewX(-30deg) rotate(10deg);clip-path:polygon(0 0,100% 0,100% 100%)}
.who{font-family:var(--display);font-weight:800;font-size:14px;display:block}
.vw{border:0;background:none;padding:0;font-weight:700;color:inherit;font-family:inherit;font-size:inherit;text-decoration:underline;text-decoration-thickness:3px;text-decoration-color:var(--pop);text-underline-offset:2px}
.cap .vw{text-decoration-color:var(--sky)}
.comic-nav{display:flex;justify-content:space-between;margin-top:22px;gap:10px}
.flag{width:22px;height:15px;flex:none;border-radius:2px;box-shadow:0 0 0 1px rgba(0,0,0,.15);vertical-align:-2px}
.vn{display:flex;align-items:center;gap:8px}
.vn-prompt{display:inline-flex;align-items:center;gap:10px}
.vn-prompt .flag{width:30px;height:20px}
.chip.small{font-size:14px;padding:3px 10px}
.chip .gn{font-size:11px;font-weight:700;color:var(--muted);margin-left:2px}
.chip.hit{outline:3px solid var(--sky)}
.sim .chips{gap:6px}
/* flashcard front: word + picture, sized to fit phone and laptop screens */
.card-wrap{--pic-h:clamp(118px,25vh,210px)}
.front{gap:8px}
.front-top{display:flex;gap:8px;align-items:center;justify-content:center;flex-wrap:wrap}
.pron-row{display:flex;align-items:center;justify-content:center;gap:10px}
.pron-row .speak{width:38px;height:38px;font-size:17px}
.pic.fit{width:fit-content;max-width:100%;margin:4px auto 0}
.pic.fit img{width:auto;height:var(--pic-h);max-height:none;max-width:100%;object-fit:contain}
.pic.fit svg{width:auto;height:var(--pic-h);max-width:100%;aspect-ratio:400/260}
.front .scene{width:100%;max-width:340px;height:var(--pic-h)}
.front .hint{margin-top:2px}
@media (max-width:640px){.face{padding:16px}}
/* tap-to-open synonyms */
.syn-tog{display:inline-flex;align-items:center;gap:8px;border:2px solid var(--ink);background:var(--t4);color:var(--ink);border-radius:999px;padding:6px 14px;font-family:var(--display);font-weight:700;font-size:15px}
.syn-tog::before{content:"";border-left:7px solid currentColor;border-top:5px solid transparent;border-bottom:5px solid transparent;transition:transform .15s}
.syn-tog[aria-expanded="true"]::before{transform:rotate(90deg)}
.syn-box{margin-top:10px;display:grid;gap:6px;padding:10px 12px 12px;border:2px dashed color-mix(in srgb,var(--ink) 35%,transparent);border-radius:14px}
.syn-box[hidden]{display:none}
.syn-box .lbl{margin:2px 0 0}
/* synonym drills */
.syn-head{display:flex;flex-wrap:wrap;gap:10px 16px;align-items:center;justify-content:space-between;margin-bottom:16px}
.tiles{display:grid;grid-template-columns:repeat(4,1fr);gap:10px}
@media (max-width:720px){.tiles{grid-template-columns:repeat(3,1fr)}}
@media (max-width:480px){.tiles{grid-template-columns:repeat(2,1fr)}}
.tile{border:var(--line);background:var(--paper);border-radius:14px;min-height:62px;padding:10px 8px;font-family:var(--display);font-weight:700;font-size:clamp(15px,4.2vw,18px);line-height:1.15;overflow-wrap:break-word;hyphens:auto;box-shadow:3px 3px 0 var(--ink);transition:transform .08s,box-shadow .08s,background-color .15s}
.tile.sel{background:var(--sun);color:#24224A;transform:translate(2px,2px);box-shadow:1px 1px 0 var(--ink)}
.tile.ok{background:var(--mint);color:#06231d;box-shadow:none;transform:translate(3px,3px);cursor:default}
.tile.bad{background:var(--pop);color:#fff}
@media (prefers-reduced-motion:no-preference){.tile.bad{animation:shake .35s}.tile.ok{animation:popin .3s}}
@keyframes shake{0%,100%{translate:0 0}25%{translate:-6px 0}75%{translate:6px 0}}
@keyframes popin{50%{scale:1.07}}
.mm-fb{min-height:54px;margin:16px 0 12px;padding:10px 12px;border:2px solid var(--ink);border-radius:12px;background:var(--t2);font-size:16px}
.mm-fb .vt{color:var(--muted);font-size:14px}
.opts.six{grid-template-columns:repeat(2,1fr)}
.opts.six .opt{text-align:center;font-family:var(--display);font-size:clamp(15px,4.2vw,18px);min-height:56px;overflow-wrap:break-word;hyphens:auto}
.opt.pick{background:var(--sun);color:#24224A}
.pairs{list-style:none;margin:0;padding:0;display:grid;gap:10px}
.pairs li{display:flex;flex-wrap:wrap;align-items:center;gap:6px 8px;padding-bottom:10px;border-bottom:2px dashed color-mix(in srgb,var(--ink) 25%,transparent)}
.pairs .eq{font-weight:800}
.pairs .mt{color:var(--muted);font-size:14px;font-weight:600;flex-basis:100%}
:lang(vi){font-family:"Be Vietnam Pro",system-ui,sans-serif}
.pos{font-family:var(--body);font-weight:600;font-size:.62em;color:var(--muted);margin-left:.3em;letter-spacing:0;white-space:nowrap;font-style:normal}
.chip .pos,.tile .pos,.opt .pos{font-size:.8em}
.word-big .pos{font-size:.38em;vertical-align:middle}
.svw{cursor:pointer}
.svw:hover{fill:#3E64FF}
.pnl{padding:8px}