/* Same Math 사이트 공통 스타일: 노트 모눈 위에 한 줄로 쌓는 폰 우선 레이아웃.
   색은 :root 변수만 쓴다 (릴스·게시물과 같은 브랜드 색). */
:root {
  --paper: #FBF8F1;
  --ink: #1E2A44;
  --ink-soft: #5B6680;
  --accent: #FF6B4A;
  --marker: #FFE07A;
  --good: #2BA36B;
  --line: #E6E0D2;
  --card: #FFFFFF;
  --body: "Noto Sans KR", "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
  --brand-en: "Fraunces", Georgia, serif;
  --brand-kr: "Gowun Batang", "Nanum Myeongjo", serif;
  --sign: "Caveat", "Comic Sans MS", cursive;
  color-scheme: light;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background-color: var(--paper);
  background-image:
    linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 28px 28px;
  color: var(--ink);
  font-family: var(--body);
  font-size: 16px;
  line-height: 1.6;
  word-break: keep-all;
  overflow-wrap: break-word;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; }
img { max-width: 100%; display: block; }
.wrap {
  max-width: 620px;
  margin: 0 auto;
  padding: 20px max(16px, env(safe-area-inset-right, 0px)) 48px max(16px, env(safe-area-inset-left, 0px));
  display: flex; flex-direction: column; gap: 36px;
}

/* 머리말 */
.brand { display: flex; align-items: center; gap: 12px; text-decoration: none; }
.brand img { width: 48px; height: 48px; border-radius: 12px; flex: none; }
.brand b { display: block; font-family: var(--brand-en); font-size: 26px; line-height: 1.05; }
.brand .sub { display: flex; align-items: baseline; gap: 8px; }
.brand .kr { font-family: var(--brand-kr); font-size: 15px; }
.brand .sign { font-family: var(--sign); font-size: 20px; color: var(--accent); }
.brand .ep { margin-left: auto; background: var(--ink); color: var(--paper); border-radius: 999px; padding: 3px 14px; font-size: 14px; font-weight: 700; white-space: nowrap; }

/* 첫 질문 */
.hero { display: flex; flex-direction: column; gap: 6px; }
.hero .eq.long { font-size: clamp(28px, 8.5vw, 48px); }
.hero .eq { font-size: clamp(36px, 11vw, 58px); font-weight: 900; letter-spacing: 1px; line-height: 1.15; }
.hero h1 { margin: 0; font-size: clamp(22px, 6vw, 28px); font-weight: 900; line-height: 1.35; text-wrap: balance; }
.hero p { margin: 0; color: var(--ink-soft); }
mark { background: var(--marker); color: var(--ink); padding: 0 5px; border-radius: 5px; }
.hero h1 mark { white-space: nowrap; }

h2 { margin: 0 0 14px; font-size: 22px; font-weight: 900; line-height: 1.3; display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; }
h2 small { font-family: var(--brand-en); font-size: 15px; color: var(--ink-soft); font-weight: 700; }

/* 한 장 정리에 쓰는 카드 */
.box { background: var(--card); border: 2px solid var(--ink); border-radius: 18px; padding: 14px 16px; }
.box + .box, .box + .grid2, .grid2 + .box, .grid2 + .grid2 { margin-top: 12px; }
.box.center { text-align: center; }
.box .big { font-size: clamp(26px, 8vw, 38px); font-weight: 900; letter-spacing: 1px; line-height: 1.3; }
.box .big i { font-style: normal; color: var(--accent); }
.box p { margin: 4px 0 0; font-size: 14px; color: var(--ink-soft); }
.box h3 { margin: 0 0 4px; font-size: 16px; font-weight: 900; }
.box.yellow { background: var(--marker); }
.grid2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }
@media (max-width: 440px) { .grid2 { grid-template-columns: 1fr; } }
.grid2 > .box { margin: 0; min-width: 0; }
.ln { display: block; font-weight: 700; font-variant-numeric: tabular-nums; line-height: 1.5; }
.ln + .ln { margin-top: 4px; }
.ans { font-size: 30px; font-weight: 900; color: var(--accent); line-height: 1.2; }

/* 짝 맞춤 표: 왼쪽(기호·한국어) | 오른쪽(영어). 왼쪽 칸은 내용만큼만, 최대 42% */
.pairs { background: var(--card); border: 2px solid var(--ink); border-radius: 18px; overflow: hidden; display: grid; grid-template-columns: fit-content(42%) minmax(0, 1fr); }
.pairs > div { grid-column: 1 / -1; display: grid; grid-template-columns: subgrid; column-gap: 18px; padding: 10px 16px; border-top: 1px solid var(--line); align-items: baseline; }
.pairs > div:first-child { border-top: none; }
.pairs .k { font-weight: 900; font-variant-numeric: tabular-nums; min-width: 0; }
.pairs .k small { display: block; font-size: 13px; color: var(--ink-soft); font-weight: 700; }
.pairs .e { font-weight: 900; color: var(--accent); min-width: 0; }
.pairs .e small { display: block; font-size: 13px; color: var(--ink-soft); font-weight: 500; }
.pairs .head { background: var(--paper); font-size: 13px; font-weight: 700; color: var(--ink-soft); padding-block: 6px; }

/* 함정 카드 (흰 바탕 + 주황 테두리·그림자 + 딱지) */
.trap { position: relative; margin-top: 26px; background: var(--card); border: 3px solid var(--accent); border-radius: 20px; box-shadow: 6px 6px 0 var(--accent); padding: 26px 18px 18px; }
.trap::before { content: "함정!"; position: absolute; top: -15px; left: 18px; background: var(--accent); color: var(--card); font-weight: 900; font-size: 15px; padding: 2px 12px; border-radius: 999px; }
.trap p { margin: 0; font-weight: 700; }
.trap p span { color: var(--accent); }
.trap p + p { margin-top: 6px; font-weight: 500; color: var(--ink-soft); font-size: 14px; }

/* 도전 문제 */
.score { font-size: 15px; font-weight: 700; color: var(--ink-soft); margin: -6px 0 14px; }
.score b { color: var(--ink); background: var(--marker); border-radius: 6px; padding: 0 6px; }
.qs { display: flex; flex-direction: column; gap: 14px; }
.q { background: var(--card); border: 2px solid var(--ink); border-radius: 18px; padding: 14px 16px 16px; }
.q .head { display: flex; align-items: center; gap: 12px; }
.q .n { width: 32px; height: 32px; border-radius: 50%; background: var(--accent); color: var(--card); display: grid; place-items: center; font-weight: 900; flex: none; }
.q .eq { font-size: clamp(19px, 5.6vw, 23px); font-weight: 900; line-height: 1.35; min-width: 0; overflow-wrap: anywhere; }
.q .eq small { display: block; font-size: 14px; font-weight: 500; color: var(--ink-soft); }
.opts { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 12px; }
.opts.list { flex-direction: column; align-items: stretch; }
.opts.four { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); }
.opts.four .opt { min-width: 0; padding: 6px 4px; }
.opt, .btn {
  font: inherit; font-weight: 900; color: var(--ink); cursor: pointer;
  border: 2px solid var(--ink); border-radius: 12px; background: var(--paper);
  padding: 6px 18px; min-height: 44px;
  transition: transform .08s ease, background .15s ease;
}
.opt { font-size: 20px; min-width: 76px; }
.opts.list .opt { font-size: 16px; text-align: left; }
.opt:hover, .btn:hover { background: var(--marker); }
.opt:active, .btn:active { transform: translateY(1px); }
.opt:focus-visible, .btn:focus-visible, input:focus-visible, a:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
.opt[disabled] { cursor: default; }
.opt.right { background: var(--good); border-color: var(--good); color: var(--card); }
.opt.wrong { border-color: var(--accent); color: var(--accent); background: var(--card); text-decoration: line-through; }
.opts .or { color: var(--ink-soft); font-weight: 700; font-size: 15px; }
.answer { display: flex; gap: 10px; align-items: center; margin-top: 12px; flex-wrap: wrap; font-weight: 900; font-size: 20px; }
.answer label { font-weight: 700; font-size: 16px; }
.answer input { font: inherit; font-size: 20px; font-weight: 900; width: 140px; min-height: 44px; padding: 4px 10px; border: none; border-bottom: 3px solid var(--ink); background: var(--paper); border-radius: 8px 8px 0 0; color: var(--ink); }
.btn.primary { background: var(--ink); color: var(--paper); }
.btn.primary:hover { background: var(--ink); color: var(--marker); }

.fr { display: inline-flex; flex-direction: column; align-items: center; vertical-align: middle; line-height: 1.05; margin: 0 2px; font-size: .9em; }
.fr b { padding: 0 4px; }
.fr b:first-child { border-bottom: 2px solid currentColor; }

.result { margin-top: 12px; font-weight: 900; }
.result.good { color: var(--good); }
.result.bad { color: var(--accent); }
.sol { margin: 10px 0 0; padding: 0; list-style: none; display: flex; flex-direction: column; gap: 6px; }
.sol li { display: flex; align-items: center; gap: 10px; }
.sol .L { min-width: 34px; height: 30px; padding: 0 6px; border-radius: 8px; background: var(--ink); color: var(--marker); display: grid; place-items: center; font-family: var(--brand-en); font-size: 15px; flex: none; white-space: nowrap; }
.sol .m { font-weight: 700; min-width: 0; overflow-wrap: anywhere; }
.sol .k { color: var(--ink-soft); font-size: 14px; margin-left: auto; text-align: right; flex: none; max-width: 40%; }
.sol .fin .m { font-weight: 900; }
.why { margin: 10px 0 0; font-size: 14px; color: var(--ink-soft); }

/* 새 문제 */
.gen { background: var(--marker); border: 2px solid var(--ink); border-radius: 18px; padding: 16px; display: flex; flex-direction: column; gap: 4px; }
.gen .q { margin-top: 8px; }
.gen-top { display: flex; justify-content: space-between; align-items: center; gap: 10px; flex-wrap: wrap; }
.gen-top p { margin: 0; font-weight: 700; }
.streak { font-size: 14px; font-weight: 700; }

/* 용어 */
.terms { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }
@media (max-width: 480px) { .terms { grid-template-columns: 1fr; } }
.term { background: var(--card); border: 2px solid var(--ink); border-radius: 16px; padding: 12px 14px; min-width: 0; }
.term .en { font-family: var(--brand-en); font-size: 19px; }
.term .ko { font-weight: 900; font-size: 18px; }
.term p { margin: 4px 0 0; font-size: 14px; color: var(--ink-soft); }

/* 페이지 끝: 다른 곳으로 가는 버튼 */
.more { display: grid; gap: 10px; }
.go { display: flex; align-items: center; gap: 14px; background: var(--card); border: 2px solid var(--ink); border-radius: 16px; padding: 12px 16px; text-decoration: none; box-shadow: 4px 4px 0 var(--ink); transition: transform .08s ease; }
.go:hover { background: var(--marker); }
.go:active { transform: translate(2px, 2px); box-shadow: 2px 2px 0 var(--ink); }
.go .ic { font-size: 24px; flex: none; }
.go b { display: block; font-size: 17px; font-weight: 900; line-height: 1.3; }
.go small { display: block; font-size: 13px; color: var(--ink-soft); }
.go .ar { margin-left: auto; font-weight: 900; color: var(--accent); flex: none; }
.go.off { box-shadow: none; border-style: dashed; color: var(--ink-soft); pointer-events: none; }

footer { text-align: center; display: flex; flex-direction: column; gap: 2px; padding-top: 12px; border-top: 2px dashed var(--line); }
footer .slogan { font-family: var(--brand-kr); font-size: 18px; }
footer .en { font-family: var(--sign); font-size: 24px; color: var(--accent); }
footer small { color: var(--ink-soft); font-size: 12px; margin-top: 6px; }

/* 첫 화면 */
.intro { font-size: 17px; color: var(--ink-soft); margin: 0; }
.intro b { color: var(--ink); }
.books { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; }
.book { background: var(--card); border: 2px solid var(--ink); border-radius: 18px; padding: 12px; display: flex; flex-direction: column; gap: 10px; min-width: 0; }
.book img { border: 1.5px solid var(--ink); border-radius: 8px; width: 100%; height: auto; }
.peek img { height: auto; }
.book b { font-size: 17px; font-weight: 900; line-height: 1.3; }
.book small { display: block; font-size: 13px; color: var(--ink-soft); font-weight: 500; }
.book .btn { text-align: center; text-decoration: none; display: flex; align-items: center; justify-content: center; margin-top: auto; }
.book .btn.off { background: var(--paper); color: var(--ink-soft); border-style: dashed; pointer-events: none; }
.peek { margin-top: 14px; display: flex; border: 2px solid var(--ink); border-radius: 12px; overflow: hidden; background: #fff; }
.peek img { width: 50%; }
.peek img + img { border-left: 1.5px solid var(--ink); }
.cap { margin: 6px 0 0; font-size: 13px; color: var(--ink-soft); text-align: center; }
.list { display: grid; gap: 10px; }
.go .tag { font-size: 12px; font-weight: 700; color: var(--ink); background: var(--marker); border-radius: 999px; padding: 0 8px; margin-left: 6px; white-space: nowrap; }

@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }