/* 아하수학 — 2014년 앱의 디자인을 그대로 가져왔다.
   색·마스코트·버튼 아이콘 전부 앱 원본 리소스(image/iPad/1536x2048)에서 추출.
   노랑 #f5d04e · 주황 #e8502a · 곰갈색 #8b5a2b · 하늘 #7ac5e0 · 크림 #faf3d7 · 베이지 #d8d0b8 */
:root{
  --y:#f5d04e; --y-dark:#e6bb2c; --y-soft:#fdf0bf;
  --o:#e8502a; --o-dark:#cf4220;
  --brown:#4a2c14; --bear:#8b5a2b;
  --sky:#7ac5e0;
  --cream:#faf3d7; --beige:#d8d0b8;
  --ink:#4a4a4c; --ink-2:#8a857c;
  --line:#e8e2d2; --bg:#fdfaf1;
  --ok:#2e8b4f; --no:#d33c1c;
  --radius:18px;
  /* 본문은 가독성(Pretendard), 제목·버튼은 로고와 톤을 맞춘 둥근 글꼴(Jua) */
  --font:'Pretendard Variable',Pretendard,-apple-system,BlinkMacSystemFont,
         "Apple SD Gothic Neo","Malgun Gothic","Noto Sans KR",sans-serif;
  --font-display:'Jua',var(--font);
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  font-family:var(--font);
  color:var(--ink); background:var(--bg); line-height:1.65;
  -webkit-text-size-adjust:100%;
}
/* 제목 계열 — 로고와 같은 둥근 인상 */
.hero h1,.sec-title,.card h3,.price,.btn,.tab,.form-box h2,.study-head h2,
.ch-no,.ch-body b,.final-score b,.sel,.buy-title,.card-grade,.logo{
  font-family:var(--font-display);
  font-weight:400;
  letter-spacing:0;
}
a{color:inherit;text-decoration:none}
img{max-width:100%;display:block}

/* 헤더 */
.top{
  display:flex;align-items:center;justify-content:space-between;gap:16px;
  padding:12px 20px;background:#fff;border-bottom:3px solid var(--y);
  position:sticky;top:0;z-index:20;
}
.logo img{height:30px;width:auto}
.top nav{display:flex;align-items:center;gap:6px}
.top nav a{padding:8px 12px;border-radius:20px;font-size:14px;font-weight:600;color:var(--ink-2)}
.top nav a:hover{background:#f6f2e6;color:var(--brown)}
.top nav .btn-sm{background:var(--y);color:var(--brown);font-weight:800}
.top nav .btn-sm:hover{background:var(--y-dark)}

.wrap{max-width:1000px;margin:0 auto;padding:26px 20px 60px}
.bottom{padding:26px 20px 34px;text-align:center;color:var(--ink-2);font-size:13px;
  border-top:1px solid var(--line);background:#fff}
.bottom p{margin:0}
.foot-bear{width:54px;margin:0 auto 8px;border-radius:50%;opacity:.9}

/* 첫 화면 */
.hero{
  position:relative;background:var(--cream);border:3px solid var(--beige);
  border-radius:26px;padding:40px 220px 40px 34px;margin-bottom:34px;overflow:hidden;
}
.hero h1{margin:0 0 12px;font-size:32px;line-height:1.35;letter-spacing:-1px;color:var(--brown)}
.hero h1 em{font-style:normal;color:var(--o)}
.hero p{margin:0;color:#7a6a4a;font-size:15px}
.hero-bear{position:absolute;right:26px;bottom:-10px;width:180px;border-radius:50%}

.sec-title{font-size:20px;margin:34px 0 16px;letter-spacing:-.5px;color:var(--brown)}
.sec-title::before{content:"";display:inline-block;width:10px;height:10px;border-radius:50%;
  background:var(--o);margin-right:8px;vertical-align:3px}

/* 카드 */
.cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:18px}
.card{background:#fff;border:2px solid var(--line);border-radius:var(--radius);padding:22px;
  text-align:center;transition:border-color .15s}
.card:hover{border-color:var(--y)}
.card-bear{width:96px;margin:0 auto 12px;border-radius:50%}
.card-grade{display:inline-block;background:var(--y-soft);color:#8a6a00;font-size:12px;
  font-weight:800;padding:3px 12px;border-radius:20px;margin-bottom:8px}
.card h3{margin:0 0 6px;font-size:18px;color:var(--brown)}
.card-meta{margin:0;color:var(--ink-2);font-size:13px}
.price{margin:12px 0 16px;font-size:26px;font-weight:800;letter-spacing:-1px;color:var(--brown)}
.price span{font-size:14px;font-weight:600;margin-left:2px}

.btn{
  display:inline-block;background:var(--y);color:var(--brown);font-weight:800;
  border:0;border-radius:24px;padding:11px 24px;font-size:15px;cursor:pointer;text-align:center;
  font-family:inherit;
}
.btn:hover{background:var(--y-dark)}
.btn.full{width:100%;margin-top:8px}
.btn.sub{background:#eeeae0;color:var(--ink)}
.btn.sub:hover{background:#e3ded1}
.btn.warm{background:var(--o);color:#fff}
.btn.warm:hover{background:var(--o-dark)}
.btn:disabled{opacity:.45;cursor:default}
.hide{display:none !important}

/* 설명 */
.steps{list-style:none;margin:0;padding:0;display:grid;
  grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:16px;counter-reset:s}
.steps li{background:#fff;border:2px solid var(--line);border-radius:var(--radius);padding:20px}
.steps li::before{counter-increment:s;content:counter(s);display:flex;align-items:center;
  justify-content:center;width:32px;height:32px;border-radius:50%;background:var(--o);
  color:#fff;font-weight:800;font-size:15px;margin-bottom:10px}
.steps b{display:block;margin-bottom:4px;color:var(--brown)}
.steps span{color:var(--ink-2);font-size:14px}

/* 폼 */
.form-box{max-width:430px;margin:20px auto;background:#fff;border:2px solid var(--line);
  border-radius:var(--radius);padding:30px}
.form-box h2{margin:0 0 18px;font-size:21px;color:var(--brown);text-align:center}
.form-box label{display:block;margin-bottom:14px;font-size:14px;font-weight:700;color:var(--brown)}
.form-box .opt{font-weight:400;color:var(--ink-2)}
.form-box input,.form-box select{width:100%;margin-top:6px;padding:11px 13px;border:2px solid #e2ddcf;
  border-radius:12px;font-size:15px;font-family:inherit;background:#fffdf7}
.form-box input:focus,.form-box select:focus{outline:0;border-color:var(--y)}
.sub-link{margin:16px 0 0;text-align:center;font-size:14px;color:var(--ink-2)}
.sub-link a{color:var(--o);font-weight:800}
.err{background:#fdece7;color:var(--no);padding:10px 13px;border-radius:12px;font-size:14px;margin:0 0 14px}
.flash{background:var(--y-soft);color:#7a5b00;padding:11px 16px;border-radius:12px;font-size:14px;
  font-weight:600;border:1px solid #efd98f}
.hint{color:var(--ink-2);font-size:13px}
.empty{color:var(--ink-2);padding:24px 0;text-align:center}
/* 폼 위에 얹는 곰 */
.form-bear{width:88px;margin:-6px auto 12px;border-radius:50%}
.form-lead{margin:-8px 0 18px;text-align:center;color:var(--ink-2);font-size:13px}
/* 빈 화면 — 그냥 글자만 두지 않는다 */
.blank{text-align:center;background:#fff;border:2px dashed var(--line);
  border-radius:var(--radius);padding:36px 20px}
.blank img{width:110px;margin:0 auto 14px;border-radius:50%}
.blank-title{margin:0 0 4px;font-size:17px;color:var(--brown);font-family:var(--font-display)}
.blank-sub{margin:0 0 18px;color:var(--ink-2);font-size:14px}
.crumb{color:var(--ink-2);font-size:13px;margin:-8px 0 18px}
.bank{background:var(--cream);border:2px solid var(--beige);border-radius:12px;padding:13px;font-size:14px;
  color:var(--brown)}
.buy-sum{border-bottom:2px solid var(--line);padding-bottom:16px;margin-bottom:18px;text-align:center}
.buy-title{margin:0;font-size:18px;font-weight:800;color:var(--brown)}
.buy-meta{margin:2px 0 0;color:var(--ink-2);font-size:13px}

/* 표 */
.tbl{width:100%;border-collapse:collapse;background:#fff;font-size:14px;
  border:2px solid var(--line);border-radius:var(--radius);overflow:hidden}
.tbl th,.tbl td{padding:12px;border-bottom:1px solid var(--line);text-align:left}
.tbl th{background:var(--cream);font-size:13px;color:#8a6a00;font-weight:800}
.tbl tr:last-child td{border-bottom:0}
.tag{display:inline-block;padding:3px 11px;border-radius:20px;font-size:12px;font-weight:800}
.tag.pending{background:var(--y-soft);color:#8a6a00}
.tag.paid{background:#e3f4e8;color:var(--ok)}
.tag.cancel{background:#efece5;color:#8a857c}

/* 단원 목록 */
.chapters{list-style:none;margin:0;padding:0;display:grid;gap:12px}
.chapters a{display:flex;align-items:center;gap:16px;background:#fff;border:2px solid var(--line);
  border-radius:var(--radius);padding:16px 20px}
.chapters a:hover{border-color:var(--y);box-shadow:0 3px 12px rgba(245,208,78,.28)}
.ch-no{flex:none;width:38px;height:38px;border-radius:50%;background:var(--y);color:var(--brown);
  font-weight:800;display:flex;align-items:center;justify-content:center;font-size:16px}
.ch-body{flex:1;min-width:0}
.ch-body b{display:block;font-size:16px;color:var(--brown)}
.ch-meta{display:block;color:var(--ink-2);font-size:13px}
.bar{display:block;height:6px;background:#efeade;border-radius:4px;margin-top:8px;overflow:hidden}
.bar i{display:block;height:100%;background:var(--o);border-radius:4px}
.ch-score{flex:none;color:var(--o);font-weight:800;font-size:15px}

/* ── 학습 화면 ─────────────────────────────────────────────────────────── */
.study-body{background:#3b3b3b}
.study-body .top{background:#2e2e2e;border-bottom-color:var(--y)}
/* 로고 원본이 짙은 회색이라 어두운 배경에서 묻힌다 — 흰색으로 뒤집어 쓴다 */
.study-body .logo img{filter:brightness(0) invert(1);opacity:.92}
.study-body .top nav a{color:#c9c4b8}
.study-body .top nav a:hover{background:#454545;color:#fff}
.study-body .bottom{background:#2e2e2e;border-top-color:#4a4a4a;color:#8d887d}
.study-body .wrap{max-width:1100px}

.study-head{display:flex;align-items:center;gap:14px;margin-bottom:16px;color:#fff}
.study-head h2{margin:0;font-size:19px;flex:1;letter-spacing:-.5px}
.study-head .back{display:flex;align-items:center;gap:6px;color:#c9c4b8;font-size:14px}
.study-head .back img{width:11px}
.study-head .best{color:var(--y);font-weight:800}

.tabs{display:flex;gap:6px;margin-bottom:0}
.tab{flex:1;padding:13px;border:0;border-radius:14px 14px 0 0;background:#4e4e4e;color:#c9c4b8;
  font-size:15px;font-weight:800;font-family:inherit;cursor:pointer}
.tab.on{background:var(--y);color:var(--brown)}

.pane{display:none;background:#2a2a2a;border-radius:0 0 var(--radius) var(--radius);padding:18px}
.pane.on{display:block}
.pane-hint{color:#8d887d;font-size:13px;text-align:center;margin:14px 0 2px}
.pane .empty{color:#8d887d}
#lecture{width:100%;max-height:70vh;background:#000;border-radius:12px}

/* 교재가 1920x1080 가로 이미지라 세로 화면에서는 작아진다.
   화면 높이에서 머리말·탭·슬라이더 몫(약 300px)을 빼고 최대한 크게 잡는다. */
.viewer{position:relative;background:#000;border-radius:12px;overflow:hidden;
  display:flex;align-items:center;justify-content:center;min-height:200px}
.viewer img{max-height:calc(100vh - 300px);width:auto;cursor:zoom-in;
  transform-origin:center center;transition:transform .18s ease-out;touch-action:none}
.viewer.zoomed img{cursor:grab}
.viewer.zoomed.dragging img{cursor:grabbing;transition:none}
.viewer:fullscreen{border-radius:0;min-height:100vh}
.viewer:fullscreen img{max-height:100vh;max-width:100vw}
.viewer:-webkit-full-screen img{max-height:100vh;max-width:100vw}

/* 세로 폰 안내 — 가로로 돌리거나 전체화면으로 보라고 알려준다 */
.rotate-tip{display:none;align-items:center;gap:10px;margin-top:12px;padding:12px 14px;
  background:#3f3f3f;border-radius:12px;color:#e6e1d5;font-size:13px;line-height:1.5}
.rotate-tip b{color:var(--y)}
.rotate-tip .btn{flex:none;padding:9px 16px;font-size:14px}
/* 앱의 원형 화살표 버튼을 그대로 쓴다 */
.nav{position:absolute;top:50%;transform:translateY(-50%);width:56px;height:56px;border:0;
  padding:0;background:none;cursor:pointer;opacity:.75;transition:opacity .12s}
.nav:hover{opacity:1}
.nav img{width:100%}
.nav.prev{left:10px}
.nav.next{right:10px}
.fs{position:absolute;top:10px;right:10px;border:0;padding:0;background:none;
  width:34px;height:34px;cursor:pointer;opacity:.8}
.fs:hover{opacity:1}
.zoom{position:absolute;top:52px;right:10px;width:34px;height:34px;border:0;cursor:pointer;
  border-radius:9px;background:rgba(0,0,0,.42);color:#fff;font-size:19px;line-height:1;
  font-family:inherit;opacity:.85}
.zoom:hover{opacity:1;background:var(--o)}
.seek{display:flex;align-items:center;gap:14px;margin-top:14px}
.seek input[type=range]{flex:1;accent-color:var(--y)}
.counter{color:#c9c4b8;font-size:14px;font-variant-numeric:tabular-nums}
.counter b{color:var(--y)}

/* 테스트 */
.q-head{text-align:center;color:#c9c4b8;font-size:14px;margin-bottom:10px;font-weight:700}
.q-img{position:relative;background:#fff;border-radius:12px;overflow:hidden}
.q-img img.q{width:100%}
/* 정답/오답 도장 — 앱의 O·X 이미지 */
.q-mark-img{position:absolute;top:50%;left:50%;width:34%;max-width:210px;
  transform:translate(-50%,-50%) scale(.6);opacity:0;pointer-events:none;
  transition:transform .18s ease-out,opacity .35s}
/* 찍힐 땐 크게, 잠시 뒤 흐려져 문제를 가리지 않는다 */
.q-mark-img.show{transform:translate(-50%,-50%) scale(1);opacity:1}
.q-mark-img.fade{opacity:.16}
.q-sel{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:18px}
.sel{padding:20px 12px;border:3px solid transparent;border-radius:16px;background:#fff;
  font-size:19px;font-weight:800;font-family:inherit;cursor:pointer;color:var(--brown)}
.sel.picked{border-color:var(--y);background:#fffaea}
.sel.right{border-color:var(--sky);background:#e9f7fc;color:#1d7fa0}
.sel.wrong{border-color:var(--o);background:#fdece7;color:var(--no)}
.sel:disabled{cursor:default}
.q-act{display:flex;gap:10px;justify-content:center;align-items:center;margin-top:18px}
/* 아이콘 버튼(앱 버튼 이미지 + 글자) */
.ibtn{display:flex;flex-direction:column;align-items:center;gap:6px;border:0;background:none;
  padding:0;cursor:pointer;font-family:inherit}
.ibtn img{width:52px}
.ibtn span{background:#9a9a9a;color:#fff;font-size:12px;font-weight:800;
  padding:3px 12px;border-radius:20px}
.ibtn:hover span{background:var(--o)}
.ibtn:disabled{opacity:.4;cursor:default}
.ibtn:disabled:hover span{background:#9a9a9a}
.q-mark{text-align:center;font-weight:800;margin:14px 0 0;min-height:22px}
.q-mark.ok{color:var(--sky)}
.q-mark.no{color:#ff9a8a}

.final{text-align:center;padding:20px 0 10px}
.final-badge{width:220px;margin:0 auto 6px}
.final-score{margin:0;color:#fff;font-size:18px}
.final-score b{font-size:62px;color:var(--y);letter-spacing:-2px}
.final-detail{color:#c9c4b8;margin:2px 0 18px}
.final-bear{width:130px;margin:0 auto 14px;border-radius:50%}

@media (max-width:700px){
  .hero{padding:30px 22px 170px}
  .hero-bear{right:50%;transform:translateX(50%);bottom:16px;width:140px}
}
/* 세로로 든 폰 — 가로 교재가 작아지므로 안내를 띄우고 여백을 줄인다 */
@media (max-width:820px) and (orientation:portrait){
  .rotate-tip{display:flex}
  .viewer img{max-height:none;width:100%}
  .pane-hint{display:none}
}
/* 가로로 눕힌 폰 — 화면을 최대한 교재에 내준다 */
@media (max-height:520px) and (orientation:landscape){
  .top,.bottom,.study-head,.pane-hint{display:none}
  .wrap{padding:8px 10px 10px}
  .tab{padding:7px;font-size:13px}
  .pane{padding:10px}
  .viewer img{max-height:calc(100vh - 110px)}
  .seek{margin-top:8px}
}
@media (max-width:600px){
  .wrap{padding:18px 14px 44px}
  .hero h1{font-size:25px}
  .tab{font-size:14px;padding:11px}
  .study-head h2{font-size:16px}
  .nav{width:44px;height:44px}
  .sel{font-size:16px;padding:16px 8px}
  .final-badge{width:170px}
}