/* 수학 칼럼 정적 페이지 공통 스타일 (본체 앱과 동일한 브랜드 톤) */
:root {
  --primary: #2456A6;
  --primary-dark: #1B3F7A;
  --primary-soft: #5B82C0;
  --ink: #1B2A41;
  --text: #3D4A5C;
  --line: #E3E9F2;
  --bg-soft: #F4F7FB;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Pretendard', 'Noto Sans KR', -apple-system, sans-serif;
  color: var(--text);
  background: #fff;
  line-height: 1.75;
  word-break: keep-all;
}
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

.col-header {
  border-bottom: 1px solid var(--line);
  background: #fff;
  position: sticky; top: 0; z-index: 10;
}
.col-header .inner {
  max-width: 780px; margin: 0 auto; padding: 14px 20px;
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
}
.col-header .brand { font-weight: 800; color: var(--ink); font-size: 17px; }
.col-header .brand:hover { text-decoration: none; }
.col-header nav { display: flex; gap: 16px; font-size: 14px; }

main { max-width: 780px; margin: 0 auto; padding: 40px 20px 64px; }

.breadcrumb { font-size: 13px; color: #8A97A8; margin-bottom: 24px; }
.breadcrumb a { color: #8A97A8; }

article h1 {
  font-size: clamp(24px, 4.5vw, 34px); line-height: 1.35;
  color: var(--ink); margin-bottom: 12px; font-weight: 800;
}
.meta { font-size: 13px; color: #8A97A8; margin-bottom: 28px; }

.answer-box {
  background: var(--bg-soft);
  border-left: 4px solid var(--primary);
  border-radius: 0 10px 10px 0;
  padding: 20px 22px;
  margin-bottom: 36px;
  font-size: 16.5px;
  color: var(--ink);
}

article h2 {
  font-size: clamp(19px, 3.2vw, 24px); color: var(--ink);
  margin: 44px 0 14px; font-weight: 700; line-height: 1.4;
}
article h3 { font-size: 17px; color: var(--ink); margin: 28px 0 10px; }
article p { margin-bottom: 16px; font-size: 15.5px; }
article ul, article ol { margin: 0 0 16px 22px; font-size: 15.5px; }
article li { margin-bottom: 8px; }

.table-wrap { overflow-x: auto; margin: 0 0 16px; }
table { border-collapse: collapse; width: 100%; font-size: 14.5px; }
th, td { border: 1px solid var(--line); padding: 10px 14px; text-align: left; }
th { background: var(--bg-soft); color: var(--ink); font-weight: 700; white-space: nowrap; }

.faq-item { border-bottom: 1px solid var(--line); padding: 18px 0; }
.faq-item h3 { margin: 0 0 8px; font-size: 16px; }
.faq-item p { margin: 0; }

.cta {
  background: var(--ink); color: #fff; border-radius: 14px;
  padding: 28px 26px; margin-top: 48px; text-align: center;
}
.cta strong { display: block; font-size: 19px; margin-bottom: 6px; }
.cta p { color: rgba(255,255,255,0.75); font-size: 14px; margin-bottom: 16px; }
.cta a.btn {
  display: inline-block; background: var(--primary); color: #fff;
  padding: 12px 28px; border-radius: 999px; font-weight: 700; font-size: 15px;
}
.cta a.btn:hover { background: var(--primary-soft); text-decoration: none; }

.related { margin-top: 44px; padding-top: 24px; border-top: 1px solid var(--line); }
.related h2 { margin-top: 0; font-size: 18px; }
.related ul { list-style: none; margin: 0; }
.related li { margin-bottom: 10px; font-size: 15px; }

.author {
  display: flex; gap: 8px; flex-direction: column;
  background: var(--bg-soft); border-radius: 12px;
  padding: 18px 20px; margin-top: 36px; font-size: 14px;
}
.author strong { color: var(--ink); }

.col-footer {
  border-top: 1px solid var(--line); background: var(--bg-soft);
  font-size: 13px; color: #8A97A8;
}
.col-footer .inner { max-width: 780px; margin: 0 auto; padding: 28px 20px; line-height: 2; }

/* 칼럼 목록 카드 */
.card-list { list-style: none; margin: 0; display: grid; gap: 18px; }
.card-list li {
  border: 1px solid var(--line); border-radius: 14px; padding: 22px 24px;
  transition: box-shadow .2s;
}
.card-list li:hover { box-shadow: 0 6px 20px rgba(27,42,65,0.08); }
.card-list a.title { font-size: 18px; font-weight: 700; color: var(--ink); display: block; margin-bottom: 6px; }
.card-list p { font-size: 14.5px; margin: 0; }