/* AI아크제로 홈페이지 — 공통 스타일 (OPTLOG §28)
 *
 * 색은 제품에서 온다: 명판의 청록(plate)과 전면 4색 LED(녹 정상 · 적 아크 · 황 누전 · 주황 과부하).
 * 기획서(docs/ARCZERO_홈페이지_기획_v0.1.html)와 같은 토큰이다 — 두 벌로 갈라지지 않게 이름을 맞췄다.
 * 🔴 **외부 글꼴을 부르지 않는다** — 방문자 IP 가 글꼴 서버로 간다. 시스템 한글 글꼴을 쓴다.
 * 🔴 LED 색은 **상태를 뜻할 때만** 쓴다(장식으로 쓰면 제품 약속이 흐려진다).
 */
:root {
  --ground: #f3f6f6; --surface: #ffffff; --ink: #15211f; --ink-2: #44524f; --rule: #d3dcdb;
  --plate: #0e5a60; --plate-2: #0a474c; --plate-ink: #eaf5f4; --plate-ink-2: #b9d8d6;
  --led-green: #1f8a45; --led-red: #c42f28; --led-yellow: #b8900f; --led-orange: #c9621a;
  --chip-green: #e3f3e8; --chip-red: #fbe7e5; --chip-yellow: #fbf2d6; --chip-orange: #fdeadb;
  --code-bg: #e8eeee; --link: #0e5a60; --focus: #0e5a60;
  --sans: "Pretendard", "Apple SD Gothic Neo", "Malgun Gothic", "Noto Sans KR", "Noto Sans CJK KR", system-ui, sans-serif;
  --mono: ui-monospace, "SFMono-Regular", "D2Coding", Menlo, Consolas, monospace;
  --wrap: 72rem;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --ground: #0e1515; --surface: #152020; --ink: #e2ebea; --ink-2: #a3b3b1; --rule: #2a3a39;
    --plate: #1b6d73; --plate-2: #12555a; --plate-ink: #e9f6f5; --plate-ink-2: #a9d3d0;
    --led-green: #5fce86; --led-red: #f07a72; --led-yellow: #e7c65a; --led-orange: #f19d5c;
    --chip-green: #173325; --chip-red: #3b1d1b; --chip-yellow: #352e14; --chip-orange: #3a2616;
    --code-bg: #1c2a2a; --link: #7fd0d4; --focus: #7fd0d4;
  }
}
:root[data-theme="dark"] {
  --ground: #0e1515; --surface: #152020; --ink: #e2ebea; --ink-2: #a3b3b1; --rule: #2a3a39;
  --plate: #1b6d73; --plate-2: #12555a; --plate-ink: #e9f6f5; --plate-ink-2: #a9d3d0;
  --led-green: #5fce86; --led-red: #f07a72; --led-yellow: #e7c65a; --led-orange: #f19d5c;
  --chip-green: #173325; --chip-red: #3b1d1b; --chip-yellow: #352e14; --chip-orange: #3a2616;
  --code-bg: #1c2a2a; --link: #7fd0d4; --focus: #7fd0d4;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--ground); color: var(--ink);
  font-family: var(--sans); font-size: 1rem; line-height: 1.75; word-break: keep-all; overflow-wrap: anywhere;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--link); text-underline-offset: .18em; }
a:focus-visible, button:focus-visible, input:focus-visible, select:focus-visible, textarea:focus-visible, summary:focus-visible {
  outline: 3px solid var(--focus); outline-offset: 2px;
}
h1, h2, h3 { line-height: 1.3; margin: 0; text-wrap: balance; letter-spacing: -.015em; }
h1 { font-size: clamp(1.9rem, 1.2rem + 2.6vw, 3rem); font-weight: 800; }
h2 { font-size: clamp(1.4rem, 1.1rem + 1vw, 1.9rem); font-weight: 750; }
h3 { font-size: 1.15rem; font-weight: 700; }
p { margin: 0; }
code, .mono { font-family: var(--mono); font-size: .9em; }
code { background: var(--code-bg); padding: .08em .35em; border-radius: 3px; }
.skip { position: absolute; left: -999px; top: 0; background: var(--surface); padding: .5rem 1rem; z-index: 10; }
.skip:focus { left: .5rem; }
.wrap { max-width: var(--wrap); margin: 0 auto; padding: 0 1.25rem; }
.eyebrow { font-family: var(--mono); font-size: .74rem; letter-spacing: .14em; text-transform: uppercase; color: var(--ink-2); }
.lede { font-size: 1.12rem; color: var(--ink-2); max-width: 40rem; }
.muted { color: var(--ink-2); }
.small { font-size: .88rem; }

/* ── 머리 — 4색 LED 점이 표지다 ───────────────────────────────── */
.site-head { background: var(--surface); border-bottom: 1px solid var(--rule); position: sticky; top: 0; z-index: 5; }
.site-head .wrap { display: flex; align-items: center; gap: 1.5rem; min-height: 3.75rem; flex-wrap: wrap; }
.brand { display: flex; align-items: center; gap: .65rem; color: var(--ink); text-decoration: none; font-weight: 800; letter-spacing: -.01em; }
.leds { display: inline-grid; grid-template-columns: repeat(4, .5rem); gap: .22rem; }
.leds i { width: .5rem; height: .5rem; border-radius: 50%; display: block; }
.leds i:nth-child(1) { background: var(--led-green); }
.leds i:nth-child(2) { background: var(--led-red); }
.leds i:nth-child(3) { background: var(--led-yellow); }
.leds i:nth-child(4) { background: var(--led-orange); }
.nav { display: flex; gap: .15rem; flex-wrap: wrap; margin-left: auto; }
.nav a { color: var(--ink-2); text-decoration: none; padding: .4rem .7rem; border-radius: 6px; font-size: .95rem; }
.nav a:hover { color: var(--ink); background: var(--code-bg); }
.nav a[aria-current="page"] { color: var(--ink); box-shadow: inset 0 -2px 0 var(--plate); border-radius: 0; }
.nav a.cta { background: var(--plate); color: var(--plate-ink); }
.nav a.cta:hover { background: var(--plate-2); color: var(--plate-ink); }

/* ── 첫 화면 — 명판처럼 ─────────────────────────────────────────── */
.hero { background: var(--plate); color: var(--plate-ink); }
.hero .wrap { display: grid; grid-template-columns: minmax(0, 1.25fr) minmax(0, 1fr); gap: 2.5rem; align-items: center; padding-top: 3.5rem; padding-bottom: 3.5rem; }
.hero .eyebrow { color: var(--plate-ink-2); }
.hero .lede { color: var(--plate-ink-2); }
.hero h1 { margin: .6rem 0 1rem; }
.hero figure { margin: 0; justify-self: center; }
.hero figure img { max-height: 26rem; width: auto; filter: drop-shadow(0 18px 30px rgba(0, 0, 0, .35)); }
.hero figcaption { color: var(--plate-ink-2); font-size: .8rem; text-align: center; margin-top: .6rem; }
.silk { font-family: var(--mono); letter-spacing: .06em; border: 1px solid color-mix(in srgb, var(--plate-ink) 45%, transparent); padding: .1rem .5rem; border-radius: 3px; font-size: .85rem; }
.actions { display: flex; gap: .75rem; flex-wrap: wrap; margin-top: 1.75rem; }
.btn { display: inline-flex; align-items: center; gap: .4rem; min-height: 2.75rem; padding: .55rem 1.15rem; border-radius: 6px; text-decoration: none; font-weight: 650; border: 1px solid transparent; font-size: 1rem; cursor: pointer; font-family: inherit; }
.btn-primary { background: var(--surface); color: var(--plate-2); }
.btn-primary:hover { background: var(--plate-ink); }
.btn-ghost { color: var(--plate-ink); border-color: color-mix(in srgb, var(--plate-ink) 50%, transparent); }
.btn-ghost:hover { background: var(--plate-2); }
.btn-solid { background: var(--plate); color: var(--plate-ink); }
.btn-solid:hover { background: var(--plate-2); }
.btn[disabled] { opacity: .55; cursor: not-allowed; }
@media (max-width: 820px) { .hero .wrap { grid-template-columns: 1fr; } .hero figure img { max-height: 18rem; } }

/* ── 절 ──────────────────────────────────────────────────────────── */
.section { padding: 3.5rem 0; }
.section + .section { border-top: 1px solid var(--rule); }
.section-head { display: grid; gap: .5rem; margin-bottom: 1.75rem; max-width: 46rem; }
.grid { display: grid; gap: 1rem; }
.grid-4 { grid-template-columns: repeat(auto-fit, minmax(14rem, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(17rem, 1fr)); }
.grid-2 { grid-template-columns: repeat(auto-fit, minmax(22rem, 1fr)); }
@media (max-width: 480px) { .grid-2 { grid-template-columns: 1fr; } }
.card { background: var(--surface); border: 1px solid var(--rule); border-radius: 8px; padding: 1.25rem 1.3rem; display: grid; gap: .45rem; align-content: start; }
.card h3 { display: flex; align-items: center; gap: .55rem; }

/* 보호 네 가지 — LED 색은 **그 고장의 색**이다(제품 전면 표시와 같다) */
.protect { border-top: 4px solid var(--rule); }
.protect.arc { border-top-color: var(--led-red); }
.protect.leak { border-top-color: var(--led-yellow); }
.protect.over { border-top-color: var(--led-orange); }
.protect.short { border-top-color: var(--ink-2); }
.dot { width: .7rem; height: .7rem; border-radius: 50%; display: inline-block; flex: none; }
.dot.green { background: var(--led-green); } .dot.red { background: var(--led-red); }
.dot.yellow { background: var(--led-yellow); } .dot.orange { background: var(--led-orange); }

/* ── 흐름(차단기 → 화면) ──────────────────────────────────────────── */
.flow { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fit, minmax(10.5rem, 1fr)); gap: .6rem; counter-reset: flow; }
.flow li { background: var(--surface); border: 1px solid var(--rule); border-radius: 8px; padding: .9rem 1rem; position: relative; counter-increment: flow; }
.flow li::before { content: counter(flow); font-family: var(--mono); font-size: .75rem; color: var(--ink-2); display: block; }
.flow strong { display: block; }
.flow .t { font-family: var(--mono); font-size: .85rem; color: var(--plate); }

/* ── 표 ─────────────────────────────────────────────────────────── */
.table-wrap { overflow-x: auto; border: 1px solid var(--rule); border-radius: 8px; background: var(--surface); }
table { border-collapse: collapse; width: 100%; font-size: .95rem; font-variant-numeric: tabular-nums; }
caption { text-align: left; padding: .75rem 1rem; font-weight: 700; caption-side: top; }
th, td { text-align: left; padding: .6rem 1rem; border-top: 1px solid var(--rule); vertical-align: top; }
thead th { background: var(--code-bg); border-top: 0; font-size: .85rem; color: var(--ink-2); font-weight: 650; }
tbody th { font-weight: 600; white-space: nowrap; }
td.num, th.num { text-align: right; }

/* ── 그림 ───────────────────────────────────────────────────────── */
.fig { margin: 1.75rem 0; display: grid; gap: .5rem; }
.fig img { background: #fff; border: 1px solid var(--rule); border-radius: 6px; margin: 0 auto; max-height: 28rem; width: auto; object-fit: contain; }   /* 세로로 긴 제품 그림이 본문을 다 먹지 않게 */
.fig figcaption { font-size: .9rem; color: var(--ink-2); }
.fig figcaption b { color: var(--ink); font-weight: 700; margin-right: .35rem; }
.fig .note { font-size: .8rem; }
.fig-held { border: 1px dashed var(--rule); border-radius: 6px; padding: 1rem 1.1rem; color: var(--ink-2); font-size: .9rem; background: var(--surface); }

/* ── 알림 띠 ─────────────────────────────────────────────────────── */
.notice { border-left: 4px solid var(--led-yellow); background: var(--chip-yellow); padding: .8rem 1rem; border-radius: 0 6px 6px 0; font-size: .95rem; }
.notice.plan { border-left-color: var(--plate); background: var(--code-bg); }
.tag { font-family: var(--mono); font-size: .72rem; letter-spacing: .06em; padding: .1rem .45rem; border-radius: 999px; border: 1px solid var(--rule); color: var(--ink-2); white-space: nowrap; }
.tag.soon { border-color: var(--led-yellow); color: var(--ink); background: var(--chip-yellow); }

/* ── 가이드 문서 ─────────────────────────────────────────────────── */
.doc { display: grid; grid-template-columns: 15rem minmax(0, 1fr); gap: 3rem; padding-top: 2.5rem; padding-bottom: 4rem; }
@media (max-width: 900px) { .doc { grid-template-columns: 1fr; gap: 1.5rem; } .toc { position: static !important; } }
.toc { position: sticky; top: 5rem; align-self: start; font-size: .92rem; }
.toc ol { list-style: none; margin: 0; padding: 0; display: grid; gap: .1rem; }
.toc a { display: block; padding: .3rem .7rem; border-left: 2px solid var(--rule); color: var(--ink-2); text-decoration: none; }
.toc a:hover { color: var(--ink); border-left-color: var(--plate); }
.toc a[aria-current="page"] { color: var(--ink); border-left-color: var(--plate); font-weight: 650; }
.toc .sub a { padding-left: 1.4rem; font-size: .86rem; }
.prose { max-width: 46rem; display: grid; gap: 1.05rem; }
.prose h1 { font-size: clamp(1.7rem, 1.2rem + 1.8vw, 2.4rem); }
.prose h2 { margin-top: 1.6rem; padding-top: 1.2rem; border-top: 1px solid var(--rule); scroll-margin-top: 5rem; }
.prose h3 { margin-top: .6rem; scroll-margin-top: 5rem; }
.prose ul { margin: 0; padding-left: 1.2rem; display: grid; gap: .3rem; }
.chapter-no { font-family: var(--mono); font-size: 3rem; line-height: 1; color: var(--plate); font-weight: 700; }
.pager { display: flex; justify-content: space-between; gap: 1rem; margin-top: 2.5rem; padding-top: 1.25rem; border-top: 1px solid var(--rule); flex-wrap: wrap; }

/* ── 사양표 — 명판의 줄처럼 ─────────────────────────────────────── */
.spec th { width: 34%; color: var(--ink-2); font-weight: 600; white-space: normal; }
.spec td { font-weight: 550; }

/* ── 문의 양식 ───────────────────────────────────────────────────── */
.form { display: grid; gap: 1.15rem; max-width: 42rem; }
.form .grid-2 { grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr)); }   /* 양식 폭(42rem)에서도 두 칸이 서게 */
.field { display: grid; gap: .35rem; }
.field label, .field legend { font-weight: 650; }
.field .hint { font-size: .85rem; color: var(--ink-2); }
.req { color: var(--led-red); margin-left: .15rem; }
input[type="text"], input[type="email"], input[type="tel"], select, textarea {
  font: inherit; color: var(--ink); background: var(--surface); border: 1px solid var(--rule); border-radius: 6px;
  padding: .6rem .75rem; min-height: 2.75rem; width: 100%;
}
textarea { min-height: 9rem; resize: vertical; }
fieldset { border: 0; padding: 0; margin: 0; }
.choices { display: flex; flex-wrap: wrap; gap: .5rem; }
.choice { position: relative; }
.choice input { position: absolute; opacity: 0; inset: 0; }
.choice span { display: inline-flex; align-items: center; min-height: 2.5rem; padding: .35rem .9rem; border: 1px solid var(--rule); border-radius: 999px; background: var(--surface); cursor: pointer; }
.choice input:checked + span { background: var(--plate); color: var(--plate-ink); border-color: var(--plate); }
.choice input:focus-visible + span { outline: 3px solid var(--focus); outline-offset: 2px; }
.consent { background: var(--surface); border: 1px solid var(--rule); border-radius: 8px; padding: 1rem 1.1rem; display: grid; gap: .6rem; font-size: .92rem; }
.consent table { font-size: .88rem; }
.check { display: flex; gap: .55rem; align-items: flex-start; font-weight: 600; }
.check input { width: 1.2rem; height: 1.2rem; margin-top: .3rem; flex: none; }
.hp { position: absolute; left: -10000px; width: 1px; height: 1px; overflow: hidden; }   /* 숨은 칸 — 사람에게 안 보인다 */
.status { padding: .8rem 1rem; border-radius: 6px; }
.status.ok { background: var(--chip-green); border-left: 4px solid var(--led-green); }
.status.err { background: var(--chip-red); border-left: 4px solid var(--led-red); }

/* ── 설계안 화면 — 가린 판에서 뜬 그림 (§160) ─────────────────────── */
h3.group { margin: 2.25rem 0 1rem; display: flex; align-items: baseline; gap: .6rem; }
h3.group:first-of-type { margin-top: .5rem; }
/* 설계안 묶음은 **열 수를 고정**한다 — auto-fit 이면 넓은 화면에서 4장이 3+1 로 서서 한 장이 혼자 남는다 */
.screens-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.screens-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
@media (max-width: 900px) { .screens-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 620px) { .screens-2, .screens-3 { grid-template-columns: 1fr; } }
.screen-card { gap: .75rem; }
.screen-card p { font-size: .95rem; }
.shot { margin: 0; display: grid; gap: .4rem; }
.shot a { display: block; border: 1px solid var(--rule); border-radius: 6px; overflow: hidden; background: #fff; }
.shot a:hover { border-color: var(--plate); }
.shot img { width: 100%; height: auto; }
.shot figcaption { font-size: .95rem; font-weight: 700; color: var(--ink); }
.shot figcaption b { font-family: var(--mono); font-weight: 600; color: var(--plate); margin-right: .35rem; }

/* ── 꼬리 ───────────────────────────────────────────────────────── */
.site-foot { background: var(--surface); border-top: 1px solid var(--rule); margin-top: 2rem; }
.site-foot .wrap { padding-top: 2rem; padding-bottom: 2.5rem; display: grid; gap: 1.25rem; grid-template-columns: minmax(0, 2fr) minmax(0, 1fr); font-size: .9rem; color: var(--ink-2); }
.site-foot nav { display: grid; gap: .25rem; align-content: start; }
@media (max-width: 720px) { .site-foot .wrap { grid-template-columns: 1fr; } }

@media (prefers-reduced-motion: no-preference) {
  .btn, .nav a, .choice span { transition: background-color .15s ease, color .15s ease; }
}
@media print {
  .site-head, .site-foot, .actions, .toc { display: none; }
  body { background: #fff; color: #000; }
}