/* =============================================================
   바이브 코딩 입문 — 스타일
   1) 디자인 토큰  2) 기본 요소  3) 레이아웃  4) 컴포넌트  5) 반응형
   외부 폰트·CDN을 쓰지 않습니다(오프라인에서도 동일하게 보이도록).
   ============================================================= */

/* ---------- 1) 디자인 토큰 ---------- */
:root {
  --bg:        #FBFAF8;
  --bg-alt:    #F3F1EC;
  --surface:   #FFFFFF;
  --line:      #E5E2DA;
  --line-soft: #EFEDE7;
  --ink:       #15161A;
  --ink-2:     #3A3C44;
  --muted:     #6B6E77;
  --accent:    #2F4BD6;
  --accent-2:  #EDF0FF;
  --warn:      #B4442E;
  --warn-bg:   #FCEFEC;
  --ok:        #1F7A4D;
  --ok-bg:     #E9F6EF;

  --radius:    16px;
  --radius-sm: 10px;
  --shadow:    0 1px 2px rgba(20,20,25,.04), 0 8px 24px rgba(20,20,25,.05);
  --wrap:      1120px;
  --header-h:  64px;

  --font: -apple-system, BlinkMacSystemFont, "Pretendard", "Apple SD Gothic Neo",
          "Noto Sans KR", "Malgun Gothic", "Segoe UI", Roboto, sans-serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

[data-theme="dark"] {
  --bg:        #0E0F12;
  --bg-alt:    #131519;
  --surface:   #16181D;
  --line:      #272A31;
  --line-soft: #1F222833;
  --ink:       #EDEEF1;
  --ink-2:     #C6C9D1;
  --muted:     #969BA6;
  --accent:    #8AA0FF;
  --accent-2:  #1A1F33;
  --warn:      #FF9E85;
  --warn-bg:   #2A1A16;
  --ok:        #6EDCA6;
  --ok-bg:     #142521;
  --shadow:    0 1px 2px rgba(0,0,0,.3), 0 8px 24px rgba(0,0,0,.28);
}

/* ---------- 2) 기본 요소 ---------- */
* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: calc(var(--header-h) + 16px); }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  word-break: keep-all;
  overflow-wrap: break-word;
  transition: background .25s ease, color .25s ease;
}

h1, h2, h3, h4 { line-height: 1.32; letter-spacing: -.02em; margin: 0; }
p { margin: 0 0 1em; }
a { color: inherit; }
ul, ol { margin: 0; padding: 0; list-style: none; }
b, strong { font-weight: 700; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

.skip-link {
  position: absolute; left: -9999px; top: 0; z-index: 999;
  background: var(--accent); color: #fff; padding: 10px 16px; border-radius: 0 0 8px 0;
}
.skip-link:focus { left: 0; }

/* ---------- 3) 레이아웃 ---------- */
.wrap { width: 100%; max-width: var(--wrap); margin: 0 auto; padding: 0 24px; }

.section { padding: 88px 0; border-top: 1px solid var(--line-soft); }
.section.alt { background: var(--bg-alt); }

.section-num {
  font-family: var(--mono); font-size: 12px; letter-spacing: .12em;
  text-transform: uppercase; color: var(--accent); margin: 0 0 12px;
}
.section-title { font-size: clamp(26px, 4vw, 38px); font-weight: 800; margin-bottom: 16px; }
.section-lead { font-size: clamp(15px, 2vw, 17.5px); color: var(--ink-2); max-width: 760px; margin-bottom: 28px; }
.sub-title { font-size: clamp(18px, 2.4vw, 22px); font-weight: 700; margin: 48px 0 14px; }
.muted { color: var(--muted); }
.muted-inline { font-size: 13px; font-weight: 400; color: var(--muted); }
.mb { margin-bottom: 18px; }

/* ---------- 헤더 ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--line);
}
.header-inner {
  height: var(--header-h);
  display: flex; align-items: center; gap: 16px;
}
.logo { display: flex; align-items: center; gap: 8px; text-decoration: none; font-weight: 800; flex: none; }
.logo-mark { color: var(--accent); font-size: 14px; }
.logo-text { font-size: 15px; letter-spacing: -.02em; }

.nav {
  display: flex; align-items: center; gap: 2px;
  margin-left: auto; overflow-x: auto; scrollbar-width: none;
}
.nav::-webkit-scrollbar { display: none; }
.nav a {
  font-size: 13.5px; color: var(--muted); text-decoration: none;
  padding: 7px 10px; border-radius: 8px; white-space: nowrap;
  transition: color .15s ease, background .15s ease;
}
.nav a:hover { color: var(--ink); background: var(--accent-2); }
.nav a.active { color: var(--accent); font-weight: 600; }

.header-actions { display: flex; gap: 6px; flex: none; }
.icon-btn {
  width: 36px; height: 36px; display: grid; place-items: center;
  background: transparent; border: 1px solid var(--line); border-radius: 10px;
  color: var(--ink); cursor: pointer; font-size: 15px;
  transition: background .15s ease, border-color .15s ease;
}
.icon-btn:hover { background: var(--accent-2); border-color: var(--accent); }
.menu-btn { display: none; }

.scroll-progress { height: 2px; background: transparent; }
.scroll-progress span { display: block; height: 100%; width: 0; background: var(--accent); transition: width .1s linear; }

/* ---------- 히어로 ---------- */
.hero { padding: 84px 0 72px; }
.eyebrow {
  display: inline-block; font-size: 12.5px; font-weight: 600; color: var(--accent);
  background: var(--accent-2); padding: 6px 12px; border-radius: 999px; margin-bottom: 22px;
}
.hero-title { font-size: clamp(30px, 5.6vw, 54px); font-weight: 800; letter-spacing: -.035em; margin-bottom: 22px; }
.hero-title .hl { color: var(--accent); }
.hero-desc { font-size: clamp(15.5px, 2vw, 18px); color: var(--ink-2); max-width: 680px; margin-bottom: 30px; }
.hero-cta { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 52px; }

.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 13px 22px; border-radius: 999px; text-decoration: none;
  font-size: 15px; font-weight: 600; border: 1px solid transparent;
  transition: transform .12s ease, background .15s ease, border-color .15s ease;
}
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: color-mix(in srgb, var(--accent) 85%, #000); }
.btn-ghost { border-color: var(--line); color: var(--ink); background: var(--surface); }
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }

.hero-stats {
  display: grid; grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px; background: var(--line); border: 1px solid var(--line);
  border-radius: var(--radius); overflow: hidden;
}
.stat { background: var(--surface); padding: 20px 18px; }
.stat strong { display: block; font-size: 28px; font-weight: 800; letter-spacing: -.03em; }
.stat span { font-size: 13px; color: var(--muted); }

/* ---------- 4) 컴포넌트 ---------- */
.callout {
  border: 1px solid var(--line); background: var(--surface);
  border-radius: var(--radius); padding: 22px 24px; margin: 8px 0 12px;
}
.callout p:last-child { margin: 0; color: var(--ink-2); }
.callout-key { border-left: 4px solid var(--accent); }

.notice {
  font-size: 13.5px; color: var(--muted);
  background: var(--accent-2); border-radius: var(--radius-sm);
  padding: 12px 16px; margin: 0 0 24px;
}

.role-list { display: grid; gap: 12px; }
.role-list li {
  display: flex; gap: 16px; align-items: flex-start;
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 18px 20px;
}
.role-list li > span {
  font-family: var(--mono); font-size: 12px; color: var(--accent);
  padding-top: 4px; flex: none;
}
.role-list strong { display: block; font-size: 15.5px; }
.role-list p { margin: 2px 0 0; font-size: 14px; color: var(--muted); }

.warn-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 10px;
}
.warn-grid li {
  background: var(--warn-bg); color: var(--warn); border-radius: var(--radius-sm);
  padding: 13px 16px; font-size: 14.5px; font-weight: 600;
}

/* 표 */
.table-scroll {
  overflow-x: auto; border: 1px solid var(--line);
  border-radius: var(--radius); background: var(--surface);
}
.table { width: 100%; min-width: 760px; border-collapse: collapse; font-size: 14.5px; }
.table th, .table td { padding: 16px 18px; text-align: left; vertical-align: top; border-bottom: 1px solid var(--line-soft); }
.table thead th { font-size: 12.5px; color: var(--muted); font-weight: 600; letter-spacing: .02em; background: var(--bg-alt); }
.table tbody th { font-weight: 700; white-space: nowrap; }
.table tbody tr:last-child th, .table tbody tr:last-child td { border-bottom: 0; }
.table td { color: var(--ink-2); }

/* 선택 가이드 */
.pick-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 12px; }
.pick { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px 20px; }
.pick-q { font-size: 14px; color: var(--muted); margin: 0 0 8px; }
.pick-a { font-size: 17px; font-weight: 700; color: var(--accent); margin: 0; }

/* 흐름 */
.flow { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; counter-reset: f; }
.flow li {
  background: var(--surface); border: 1px solid var(--line); border-radius: 999px;
  padding: 10px 18px; font-size: 14px; font-weight: 600;
}
.flow li:not(:last-child)::after { content: "→"; margin-left: 14px; color: var(--muted); font-weight: 400; }

/* Claude 101 카드 */
.card-note {
  margin-top: 48px; background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 26px 28px;
}
.card-note h3 { font-size: 20px; margin-bottom: 8px; }
.level-list { display: grid; gap: 8px; margin: 16px 0; }
.level-list li { font-size: 14.5px; color: var(--ink-2); }
.level-list b {
  display: inline-block; min-width: 62px; color: var(--accent);
  font-family: var(--mono); font-size: 12px;
}
.fineprint { font-size: 13px; color: var(--muted); margin: 0; }

/* 툴바 / 필터 */
.toolbar { display: grid; gap: 12px; margin-bottom: 22px; }
.search-box { position: relative; }
.search-box input {
  width: 100%; padding: 14px 44px 14px 44px; font-size: 15px; font-family: inherit;
  background: var(--surface); color: var(--ink);
  border: 1px solid var(--line); border-radius: 999px;
}
.search-box input::placeholder { color: var(--muted); }
.search-icon { position: absolute; left: 18px; top: 50%; transform: translateY(-50%); color: var(--muted); font-size: 16px; }
.clear-btn {
  position: absolute; right: 12px; top: 50%; transform: translateY(-50%);
  width: 26px; height: 26px; border: 0; border-radius: 50%;
  background: var(--line); color: var(--ink); cursor: pointer; font-size: 15px; line-height: 1;
}

.filter-row { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  padding: 8px 15px; font-size: 13.5px; font-family: inherit; font-weight: 500;
  background: var(--surface); color: var(--muted);
  border: 1px solid var(--line); border-radius: 999px; cursor: pointer;
  transition: all .15s ease;
}
.chip:hover { color: var(--ink); border-color: var(--accent); }
.chip[aria-pressed="true"] { background: var(--accent); border-color: var(--accent); color: #fff; font-weight: 600; }

/* 다크 모드에서는 accent가 밝은 색이므로 글자를 어둡게 (명암비 확보) */
[data-theme="dark"] .btn-primary,
[data-theme="dark"] .chip[aria-pressed="true"],
[data-theme="dark"] .step-n,
[data-theme="dark"] .copy-btn.copied { color: #0E0F12; }
[data-theme="dark"] .btn-primary:hover { background: color-mix(in srgb, var(--accent) 88%, #fff); }

/* 진도 바 */
.progress-bar-wrap {
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 16px 20px; margin-bottom: 24px;
}
.progress-label { display: flex; justify-content: space-between; font-size: 13.5px; color: var(--muted); margin-bottom: 10px; }
.progress-track { height: 8px; background: var(--bg-alt); border-radius: 999px; overflow: hidden; }
.progress-track span { display: block; height: 100%; width: 0; background: var(--accent); border-radius: 999px; transition: width .3s ease; }
.link-btn {
  background: none; border: 0; padding: 0; margin-top: 10px;
  color: var(--muted); font-size: 12.5px; font-family: inherit;
  text-decoration: underline; cursor: pointer;
}
.link-btn:hover { color: var(--accent); }

/* 용어 카드 */
.term-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 14px; }
.term-card {
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow);
  display: flex; flex-direction: column; gap: 10px;
  transition: border-color .15s ease, transform .15s ease;
}
.term-card:hover { border-color: color-mix(in srgb, var(--accent) 45%, var(--line)); }
.term-card.done { background: var(--ok-bg); border-color: color-mix(in srgb, var(--ok) 35%, var(--line)); }

.term-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 10px; }
.term-name { font-size: 17px; font-weight: 700; }
.term-en { display: block; font-size: 12px; color: var(--muted); font-family: var(--mono); font-weight: 400; margin-top: 2px; }
.term-desc { font-size: 14.5px; color: var(--ink-2); margin: 0; }
.term-more {
  font-size: 14px; color: var(--muted); margin: 0;
  padding-top: 12px; border-top: 1px dashed var(--line);
}
.term-more[hidden] { display: none; }

.badges { display: flex; flex-wrap: wrap; gap: 6px; }
.badge { font-size: 11.5px; font-weight: 600; padding: 4px 9px; border-radius: 999px; letter-spacing: .01em; }
.badge-cat { background: var(--accent-2); color: var(--accent); }
.badge-must   { background: var(--warn-bg); color: var(--warn); }
.badge-useful { background: var(--ok-bg);   color: var(--ok); }
.badge-later  { background: var(--bg-alt);  color: var(--muted); }
.badge-skip   { background: var(--bg-alt);  color: var(--muted); opacity: .75; }

.term-actions { display: flex; gap: 8px; margin-top: auto; padding-top: 4px; }
.mini-btn {
  flex: 1; padding: 8px 10px; font-size: 13px; font-family: inherit; font-weight: 500;
  background: transparent; color: var(--muted);
  border: 1px solid var(--line); border-radius: 999px; cursor: pointer;
  transition: all .15s ease;
}
.mini-btn:hover { border-color: var(--accent); color: var(--accent); }
.mini-btn.on { background: var(--ok); border-color: var(--ok); color: #fff; }
[data-theme="dark"] .mini-btn.on { color: #0E0F12; }

.empty { text-align: center; color: var(--muted); padding: 48px 0; font-size: 15px; }

/* 단계 */
.step {
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 26px 28px; margin-bottom: 16px;
}
.step h3 { display: flex; align-items: center; gap: 12px; font-size: 19px; margin-bottom: 12px; }
.step-n {
  flex: none; width: 28px; height: 28px; display: grid; place-items: center;
  background: var(--accent); color: #fff; border-radius: 50%;
  font-size: 13px; font-weight: 700;
}
.step > p { color: var(--ink-2); font-size: 15px; }

.chip-list { display: flex; flex-wrap: wrap; gap: 8px; }
.chip-list li {
  background: var(--bg-alt); border: 1px solid var(--line-soft);
  border-radius: 999px; padding: 7px 14px; font-size: 13.5px; color: var(--ink-2);
}

.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.two-col.wide { gap: 18px; }
.do, .dont, .panel {
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 20px 22px; background: var(--bg-alt);
}
.section.alt .do, .section.alt .dont, .section.alt .panel { background: var(--surface); }
.do { border-left: 3px solid var(--ok); }
.dont { border-left: 3px solid var(--warn); }
.do h4, .dont h4, .panel h3 { font-size: 15px; margin-bottom: 12px; }
.do h4 { color: var(--ok); }
.dont h4 { color: var(--warn); }
.do ul li, .dont ul li { font-size: 14.5px; color: var(--ink-2); padding: 4px 0 4px 16px; position: relative; }
.do ul li::before, .dont ul li::before { content: "·"; position: absolute; left: 4px; }
.quote { font-size: 14.5px; color: var(--ink-2); margin: 0; }

.dot-list li { font-size: 14.5px; color: var(--ink-2); padding: 5px 0 5px 18px; position: relative; }
.dot-list li::before { content: ""; position: absolute; left: 2px; top: 14px; width: 5px; height: 5px; border-radius: 50%; background: var(--accent); }

.board-list { display: grid; gap: 4px; }
.board-list li { font-size: 14.5px; color: var(--ink-2); padding: 4px 0; }
.board-list b { font-family: var(--mono); font-size: 12px; color: var(--accent); margin-right: 10px; }

.ref-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 12px; margin-bottom: 20px; }
.ref-card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; }
.ref-card h4 { font-size: 15.5px; color: var(--accent); margin-bottom: 8px; }
.ref-card p { margin: 0; font-size: 14px; color: var(--muted); }

/* 프롬프트 박스 */
.prompt-box {
  border: 1px solid var(--line); border-radius: var(--radius);
  overflow: hidden; background: var(--bg-alt); margin: 18px 0 0;
}
.section.alt .prompt-box { background: var(--surface); }
.prompt-head {
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  padding: 12px 16px; border-bottom: 1px solid var(--line);
  font-size: 13px; color: var(--muted); font-family: var(--mono);
}
.copy-btn {
  padding: 6px 14px; font-size: 12.5px; font-family: inherit; font-weight: 600;
  background: var(--surface); color: var(--ink);
  border: 1px solid var(--line); border-radius: 999px; cursor: pointer; flex: none;
  transition: all .15s ease;
}
.section.alt .copy-btn { background: var(--bg-alt); }
.copy-btn:hover { border-color: var(--accent); color: var(--accent); }
.copy-btn.copied { background: var(--ok); border-color: var(--ok); color: #fff; }
.prompt-box pre {
  margin: 0; padding: 18px; overflow-x: auto;
  font-family: var(--mono); font-size: 13px; line-height: 1.75; color: var(--ink-2);
  white-space: pre-wrap; word-break: break-word;
}

/* 체크리스트 */
.check-list { display: grid; gap: 8px; counter-reset: c; }
.check-list li {
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius-sm); transition: all .15s ease;
}
.section.alt .check-list li { background: var(--bg); }
.check-list li.checked { background: var(--ok-bg); border-color: color-mix(in srgb, var(--ok) 35%, var(--line)); }
.check-list label {
  display: flex; align-items: flex-start; gap: 12px;
  padding: 14px 18px; cursor: pointer; font-size: 14.5px; color: var(--ink-2);
}
.check-list li.checked label { color: var(--ink); }
.check-list input[type="checkbox"] {
  width: 18px; height: 18px; margin: 2px 0 0; flex: none;
  accent-color: var(--accent); cursor: pointer;
}
.check-list.numbered li { counter-increment: c; }
.check-list.numbered label::before {
  content: counter(c); flex: none;
  font-family: var(--mono); font-size: 12px; color: var(--accent); padding-top: 2px;
}

.safety { background: var(--bg-alt); }
.safety-list label { font-weight: 500; }

/* 도구 카드 */
.tool-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 14px; margin-top: 20px; }
.tool-card {
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow);
}
.tool-card h4 { font-size: 16.5px; margin-bottom: 4px; }
.tool-group { font-size: 11.5px; font-weight: 600; color: var(--accent); background: var(--accent-2);
  display: inline-block; padding: 3px 9px; border-radius: 999px; margin-bottom: 10px; }
.tool-use { font-size: 14px; color: var(--ink-2); margin: 0 0 10px; }
.tool-note { font-size: 13px; color: var(--muted); margin: 0; padding-top: 10px; border-top: 1px dashed var(--line); }

/* 조합 카드 */
.combo-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 14px; }
.combo {
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 22px 24px;
}
.combo h4 { font-size: 16.5px; margin-bottom: 4px; }
.combo .best { font-size: 12.5px; color: var(--muted); margin-bottom: 16px; }
.combo ol { display: grid; gap: 0; }
.combo ol li {
  position: relative; padding: 0 0 16px 24px; font-size: 14px; color: var(--ink-2);
}
.combo ol li::before {
  content: ""; position: absolute; left: 4px; top: 8px;
  width: 8px; height: 8px; border-radius: 50%; background: var(--accent);
}
.combo ol li:not(:last-child)::after {
  content: ""; position: absolute; left: 7.5px; top: 18px; bottom: 2px;
  width: 1px; background: var(--line);
}
.combo ol li:last-child { padding-bottom: 0; }

/* 푸터 */
.site-footer { border-top: 1px solid var(--line); padding: 48px 0; background: var(--bg); }
.footer-inner { display: grid; gap: 20px; }
.footer-title { font-weight: 800; margin-bottom: 6px; }
.footer-inner .muted { font-size: 14px; margin: 0; }
.credit {
  margin: 14px 0 0; font-size: 13px; color: var(--muted);
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--accent-2); border-radius: 999px; padding: 6px 14px;
}
.credit b { color: var(--accent); font-weight: 700; letter-spacing: -.01em; }

.to-top {
  position: fixed; right: 20px; bottom: 20px; z-index: 90;
  width: 44px; height: 44px; border-radius: 50%;
  background: var(--surface); color: var(--ink);
  border: 1px solid var(--line); box-shadow: var(--shadow);
  cursor: pointer; font-size: 17px;
}
.to-top:hover { border-color: var(--accent); color: var(--accent); }

/* 토스트 */
.toast {
  position: fixed; left: 50%; bottom: 28px; transform: translate(-50%, 20px);
  background: var(--ink); color: var(--bg);
  padding: 12px 22px; border-radius: 999px; font-size: 14px; font-weight: 600;
  opacity: 0; pointer-events: none; transition: all .25s ease; z-index: 200;
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }

/* ---------- 5) 반응형 ---------- */
@media (max-width: 900px) {
  .menu-btn { display: grid; }
  .nav {
    position: absolute; top: var(--header-h); left: 0; right: 0;
    flex-direction: column; align-items: stretch; gap: 0;
    background: var(--bg); border-bottom: 1px solid var(--line);
    padding: 8px 16px 16px; overflow: hidden;
    max-height: 0; padding-top: 0; padding-bottom: 0;
    transition: max-height .25s ease, padding .25s ease;
  }
  .nav.open { max-height: 600px; padding-top: 8px; padding-bottom: 16px; }
  .nav a { padding: 12px 10px; font-size: 15px; border-radius: 10px; }

  .hero-stats { grid-template-columns: repeat(2, 1fr); }
  .two-col { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .wrap { padding: 0 18px; }
  .section { padding: 60px 0; }
  .hero { padding: 56px 0 48px; }
  .hero-cta .btn { width: 100%; }
  .term-grid, .tool-grid { grid-template-columns: 1fr; }
  .step { padding: 22px 20px; }
  .card-note { padding: 22px 20px; }
  .flow li:not(:last-child)::after { display: none; }
  .stat strong { font-size: 24px; }
}

@media print {
  .site-header, .to-top, .toolbar, .term-actions, .copy-btn, .hero-cta { display: none !important; }
  .section { padding: 24px 0; border: 0; }
  .term-more { display: block !important; }
}