/* SocialSNS株式会社 コーポレートサイト
   ダーク1色固定。構造は罫線と等幅ラベルだけで作り、カード・影・角丸・グラデーションは使わない。 */

:root {
  --bg: #0e0f11;
  --bg-2: #13151a;
  --fg: #e6e6e6;
  --fg-2: #a3a7ad;
  --fg-3: #6c7078;
  --line: #26282c;
  --line-2: #3b3e45;
  --accent: #9dbb86;
  --w: 1080px;
  --w-narrow: 720px;
  --font: "Inter", "Noto Sans JP", system-ui, -apple-system, "Segoe UI", "Hiragino Sans", "Yu Gothic UI", sans-serif;
  --mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font);
  font-size: 15px;
  line-height: 1.85;
  font-feature-settings: "palt";
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}
@media (min-width: 768px) { body { font-size: 16px; } }

a { color: inherit; text-decoration: none; }
img, svg { display: block; max-width: 100%; }
h1, h2, h3, h4 { margin: 0; font-weight: 500; letter-spacing: -0.01em; line-height: 1.35; }
p { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
dl, dd { margin: 0; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; padding: 0; }
:focus-visible { outline: 1px solid var(--accent); outline-offset: 3px; }

.wrap { width: 100%; max-width: var(--w); margin: 0 auto; padding: 0 20px; }
@media (min-width: 768px) { .wrap { padding: 0 32px; } }

.mono {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: .04em;
  font-variant-numeric: tabular-nums;
}
.label {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--fg-3);
}

/* 本文中のリンクはホバーで下線が現れるだけにする */
.ul { text-decoration: underline; text-decoration-color: transparent; text-underline-offset: 4px; text-decoration-thickness: 1px; transition: text-decoration-color .15s ease, color .15s ease; }
.ul:hover { text-decoration-color: var(--fg-2); }

/* ---------- header ---------- */
.header { position: sticky; top: 0; z-index: 50; background: var(--bg); border-bottom: 1px solid var(--line); }
.header .wrap { display: flex; align-items: center; justify-content: space-between; height: 56px; gap: 16px; }
.brand { display: inline-flex; align-items: baseline; gap: 6px; min-height: 44px; font-weight: 500; letter-spacing: -0.01em; white-space: nowrap; }
.brand small { font-size: 12px; color: var(--fg-3); font-weight: 400; letter-spacing: 0; }

.nav { display: none; gap: 28px; }
.nav a { font-size: 13.5px; color: var(--fg-2); padding: 10px 0; }
.nav a:hover { color: var(--fg); text-decoration-color: var(--fg-3); }
.nav a[aria-current="page"] { color: var(--fg); text-decoration-color: var(--line-2); }
@media (min-width: 860px) { .nav { display: flex; } }

.menu-btn { display: inline-flex; align-items: center; min-height: 44px; min-width: 44px; padding: 0 4px; font-family: var(--mono); font-size: 12px; letter-spacing: .06em; color: var(--fg-2); }
.menu-btn:hover { color: var(--fg); }
.menu-btn .close { display: none; }
.menu-btn[aria-expanded="true"] .open { display: none; }
.menu-btn[aria-expanded="true"] .close { display: inline; }
@media (min-width: 860px) { .menu-btn { display: none; } }

.mobile-nav { display: none; border-bottom: 1px solid var(--line); background: var(--bg); }
.mobile-nav.open { display: block; }
.mobile-nav a { display: block; padding: 14px 20px; min-height: 48px; font-size: 15px; border-top: 1px solid var(--line); color: var(--fg-2); }
.mobile-nav a:first-child { border-top: 0; }
.mobile-nav a:hover { color: var(--fg); }
@media (min-width: 860px) { .mobile-nav { display: none !important; } }

/* ---------- hero ---------- */
.hero { padding: 64px 0 56px; }
@media (min-width: 768px) { .hero { padding: 120px 0 96px; } }
.hero .label { display: block; }
.hero h1 {
  margin-top: 20px;
  font-size: clamp(1.5rem, 3.4vw, 2.5rem);
  font-weight: 500;
  letter-spacing: -0.015em;
  line-height: 1.4;
  max-width: 26em;
}
.hero .lead { margin-top: 28px; color: var(--fg-2); max-width: 42em; }
.hero .lead p + p { margin-top: 12px; }

/* 目次。ボタンの代わりに、仕様書の章立てのように並べる */
.toc { margin-top: 56px; border-top: 1px solid var(--line); }
.toc li { border-bottom: 1px solid var(--line); }
.toc a { display: flex; align-items: center; gap: 20px; min-height: 48px; padding: 6px 0; color: var(--fg-2); }
.toc a:hover { color: var(--fg); }
.toc a:hover .toc-title { text-decoration-color: var(--fg-3); }
.toc .idx { flex: none; width: 2.5em; color: var(--fg-3); }
.toc .toc-title { flex: 1; text-decoration: underline; text-decoration-color: transparent; text-underline-offset: 4px; text-decoration-thickness: 1px; transition: text-decoration-color .15s ease; }
.toc .arrow { font-family: var(--mono); color: var(--fg-3); }
@media (min-width: 768px) {
  .toc { display: grid; grid-template-columns: repeat(4, 1fr); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
  .toc li { border-bottom: 0; border-left: 1px solid var(--line); }
  .toc li:first-child { border-left: 0; }
  .toc a { flex-direction: column; align-items: flex-start; gap: 36px; padding: 16px; min-height: 0; }
  .toc li:first-child a { padding-left: 0; }
  .toc .idx { width: auto; }
  .toc .arrow { display: none; }
}

/* ---------- sections ---------- */
.section { border-top: 1px solid var(--line); padding: 56px 0 64px; }
@media (min-width: 768px) { .section { padding: 88px 0 104px; } }
.section-head { display: grid; gap: 12px; margin-bottom: 40px; }
.section-head .idx { font-family: var(--mono); font-size: 12px; letter-spacing: .06em; color: var(--accent); }
.section-head h2 { font-size: clamp(1.3rem, 2.2vw, 1.75rem); font-weight: 500; }
.section-head p { color: var(--fg-2); max-width: 40em; }
@media (min-width: 900px) {
  .section-head { grid-template-columns: 180px 1fr; gap: 0 48px; align-items: start; margin-bottom: 56px; }
  .section-head .idx { padding-top: 8px; }
  .section-head p { grid-column: 2; margin-top: 16px; }
}

/* 行で区切る一覧。カードにしない */
.rows { border-top: 1px solid var(--line); }
.row { display: grid; gap: 10px; padding: 24px 0; border-bottom: 1px solid var(--line); }
.row .idx { font-family: var(--mono); font-size: 12px; letter-spacing: .06em; color: var(--fg-3); font-variant-numeric: tabular-nums; }
.row h3 { font-size: 1.05rem; font-weight: 500; }
.row p { color: var(--fg-2); }
.row .scope { margin-top: 10px; display: flex; flex-wrap: wrap; gap: 6px 0; }
.row .scope dt { font-family: var(--mono); font-size: 12px; letter-spacing: .04em; color: var(--fg-3); margin-right: 12px; }
.row .scope dd { font-size: 13.5px; color: var(--fg-2); }
.row .more { display: inline-block; margin-top: 14px; font-size: 13.5px; color: var(--fg); }
.row .more::after { content: " →"; font-family: var(--mono); color: var(--fg-3); }
@media (min-width: 900px) {
  .row { grid-template-columns: 180px 1fr; gap: 0 48px; padding: 32px 0; }
  .row .idx { padding-top: 6px; }
  .row .body { display: grid; grid-template-columns: 240px 1fr; gap: 0 40px; }
  .row .body > p, .row .body > .scope, .row .body > .more { grid-column: 2; }
  .row .body > .scope { margin-top: 12px; }
}

/* ---------- definition table ---------- */
.dl { border-top: 1px solid var(--line); }
.dl .dl-row { display: grid; gap: 4px; padding: 16px 0; border-bottom: 1px solid var(--line); }
.dl dt { font-family: var(--mono); font-size: 12px; letter-spacing: .06em; color: var(--fg-3); }
.dl dd { color: var(--fg); overflow-wrap: anywhere; }
.dl dd a { text-decoration: underline; text-decoration-color: var(--line-2); text-underline-offset: 4px; text-decoration-thickness: 1px; }
.dl dd a:hover { text-decoration-color: var(--fg-2); }
.dl dd.mono, .dl dd a.mono { font-size: 14px; }
@media (min-width: 640px) {
  .dl .dl-row { grid-template-columns: 180px 1fr; gap: 0 48px; padding: 18px 0; }
  .dl dt { padding-top: 5px; }
}

/* ---------- contact ---------- */
.contact-body { display: grid; gap: 28px; }
.contact-body .mail { display: inline-block; font-family: var(--mono); font-size: clamp(1.1rem, 2.6vw, 1.75rem); letter-spacing: 0; color: var(--fg); overflow-wrap: anywhere; text-decoration: underline; text-decoration-color: var(--line-2); text-underline-offset: 6px; text-decoration-thickness: 1px; }
.contact-body .mail:hover { text-decoration-color: var(--fg-2); }
.contact-body p { color: var(--fg-2); max-width: 40em; }
.contact-body .notes { border-top: 1px solid var(--line); }
.contact-body .notes li { display: grid; gap: 4px; padding: 14px 0; border-bottom: 1px solid var(--line); color: var(--fg-2); font-size: 14px; }
.contact-body .notes .idx { font-family: var(--mono); font-size: 12px; letter-spacing: .06em; color: var(--fg-3); }
.contact-body .notes a { color: var(--fg); text-decoration: underline; text-decoration-color: var(--line-2); text-underline-offset: 4px; text-decoration-thickness: 1px; }
.contact-body .notes a:hover { text-decoration-color: var(--fg-2); }
@media (min-width: 640px) { .contact-body .notes li { grid-template-columns: 180px 1fr; gap: 0 48px; } }
@media (min-width: 900px) {
  .contact-body { grid-template-columns: 180px 1fr; gap: 0 48px; }
  .contact-body > * { grid-column: 2; }
}

/* ---------- footer ---------- */
.footer { border-top: 1px solid var(--line); padding: 40px 0 32px; color: var(--fg-2); font-size: 13.5px; }
.footer-grid { display: grid; gap: 28px; }
.footer .addr { margin-top: 8px; color: var(--fg-3); font-size: 13px; line-height: 1.8; }
.footer .cols { display: grid; gap: 24px; grid-template-columns: 1fr 1fr; }
.footer h4 { font-family: var(--mono); font-size: 12px; font-weight: 400; letter-spacing: .06em; color: var(--fg-3); margin-bottom: 10px; }
.footer li a { display: inline-block; padding: 4px 0; min-height: 32px; color: var(--fg-2); }
.footer li a:hover { color: var(--fg); text-decoration-color: var(--fg-3); }
.footer-bottom { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 8px 24px; margin-top: 40px; padding-top: 16px; border-top: 1px solid var(--line); color: var(--fg-3); }
@media (min-width: 768px) {
  .footer-grid { grid-template-columns: 1.4fr 2fr; gap: 48px; }
  .footer .cols { grid-template-columns: repeat(3, 1fr); }
}

/* ---------- article pages ---------- */
.page { padding: 56px 0 96px; }
@media (min-width: 768px) { .page { padding: 96px 0 140px; } }
.page .wrap { max-width: var(--w-narrow); }
.page .label { display: block; }
.page h1 { margin-top: 16px; font-size: clamp(1.5rem, 3vw, 2.1rem); font-weight: 500; letter-spacing: -0.015em; line-height: 1.4; }
.page .meta { display: flex; flex-wrap: wrap; gap: 6px 24px; margin-top: 20px; padding: 14px 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); color: var(--fg-3); }
.page .meta a { color: var(--fg-2); text-decoration: underline; text-decoration-color: var(--line-2); text-underline-offset: 4px; text-decoration-thickness: 1px; overflow-wrap: anywhere; }
.page .meta a:hover { color: var(--fg); text-decoration-color: var(--fg-2); }

/* 仕様書のように章番号を付ける。番号は本文を変えずにCSSカウンタで振る */
.spec { counter-reset: h2; margin-top: 48px; }
.spec h2 { counter-increment: h2; counter-reset: h3; margin-top: 56px; padding-top: 24px; border-top: 1px solid var(--line); font-size: 1.2rem; display: grid; grid-template-columns: 3.5em 1fr; gap: 0 12px; }
.spec h2:first-child { margin-top: 0; }
.spec h2::before { content: counter(h2, decimal-leading-zero); font-family: var(--mono); font-size: 12px; letter-spacing: .06em; font-weight: 400; color: var(--fg-3); padding-top: 7px; }
.spec h3 { counter-increment: h3; margin-top: 32px; font-size: 1rem; display: grid; grid-template-columns: 3.5em 1fr; gap: 0 12px; }
.spec h3::before { content: counter(h2, decimal-leading-zero) "." counter(h3); font-family: var(--mono); font-size: 12px; letter-spacing: .06em; font-weight: 400; color: var(--fg-3); padding-top: 5px; }
.spec p { margin-top: 14px; color: var(--fg-2); }
.spec ul, .spec ol { margin-top: 14px; color: var(--fg-2); }
.spec li { position: relative; padding-left: 1.6em; margin-top: 6px; }
.spec ul li::before { content: "–"; position: absolute; left: 0; font-family: var(--mono); color: var(--fg-3); }
.spec ol { counter-reset: li; }
.spec ol li { padding-left: 2.2em; counter-increment: li; }
.spec ol li::before { content: counter(li, decimal-leading-zero); position: absolute; left: 0; font-family: var(--mono); font-size: 12px; letter-spacing: .04em; color: var(--fg-3); top: .35em; }
.spec a { color: var(--fg); text-decoration: underline; text-decoration-color: var(--line-2); text-underline-offset: 4px; text-decoration-thickness: 1px; }
.spec a:hover { text-decoration-color: var(--fg-2); }
.spec code { font-family: var(--mono); font-size: .9em; color: var(--fg); letter-spacing: 0; }
.spec .callout { margin-top: 20px; border: 1px solid var(--line-2); padding: 16px 18px; font-size: 15px; }
.spec .callout strong { display: block; font-family: var(--mono); font-size: 12px; letter-spacing: .06em; font-weight: 400; color: var(--fg-3); }
.spec .callout p { margin-top: 8px; color: var(--fg); overflow-wrap: anywhere; }
.spec .dl { margin-top: 20px; }
@media (min-width: 768px) {
  .spec h2, .spec h3 { grid-template-columns: 4em 1fr; gap: 0 20px; }
  .spec p, .spec ul, .spec ol, .spec .callout, .spec .dl { margin-left: calc(4em + 20px); }
  .spec .callout p { margin-left: 0; }
}

/* 404 */
.notfound .label { color: var(--fg-3); }
.notfound p { margin-top: 16px; color: var(--fg-2); }
.notfound .back { display: inline-block; margin-top: 32px; min-height: 44px; line-height: 44px; color: var(--fg); text-decoration: underline; text-decoration-color: var(--line-2); text-underline-offset: 4px; text-decoration-thickness: 1px; }
.notfound .back:hover { text-decoration-color: var(--fg-2); }

.skip { position: absolute; left: -9999px; top: 8px; background: var(--fg); color: var(--bg); padding: 8px 12px; z-index: 100; }
.skip:focus { left: 8px; }