/* Serendip 紹介サイト
   アプリと同じ、スイス・タイポグラフィ調のトークン：
   明るいグレーの紙色 × 黒の太字 × グレーの副見出し × 赤の差し色。ダークモードでは紙と墨を入れ替える */
:root {
  --paper: #ECECEA;
  --paper-deep: #DDDDDB;
  --ink: #0F0F0F;
  --mute: #7A7A78;
  --hairline: rgba(0, 0, 0, .14);
  --red: #E3301F;
  --surface: #FFFFFF;
  --gutter: 20px;
  --max: 1120px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #131313;
    --paper-deep: #292929;
    --ink: #F0F0ED;
    --mute: #8F8F8C;
    --hairline: rgba(255, 255, 255, .16);
    --red: #F55445;
    --surface: #303030;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #131313;
  --paper-deep: #292929;
  --ink: #F0F0ED;
  --mute: #8F8F8C;
  --hairline: rgba(255, 255, 255, .16);
  --red: #F55445;
  --surface: #303030;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 72px; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue", "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Noto Sans JP", Meiryo, sans-serif;
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  font-feature-settings: "palt";
}
img { display: block; max-width: 100%; }
a { color: inherit; }
h1, h2, h3, h4 { margin: 0; font-weight: 800; letter-spacing: -.01em; line-height: 1.2; }
p { margin: 0; }

.wrap { max-width: var(--max); margin: 0 auto; padding: 0 var(--gutter); }
.muted { color: var(--mute); }
.small { font-size: 13px; }

/* ヘッダー */
/* ページ最上部ではヒーローの上に透明で重ね、スクロールしたらすりガラスにする */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 10;
  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background-color .25s, border-color .25s, backdrop-filter .25s, -webkit-backdrop-filter .25s;
}
/* 透明な間はヒーロー（常に明るい）の上に乗るので、ダークモードでも黒い文字にする */
.site-header:not(.is-scrolled) {
  --ink: #0F0F0F;
  --paper: #ECECEA;
  --mute: #6E6E6E;
  color: var(--ink);
}
.site-header.is-scrolled {
  background: color-mix(in srgb, var(--paper) 72%, transparent);
  backdrop-filter: saturate(1.4) blur(18px);
  -webkit-backdrop-filter: saturate(1.4) blur(18px);
  border-bottom-color: var(--hairline);
}
.header-inner { display: flex; align-items: center; gap: 24px; height: 60px; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; }
.brand-name { font-weight: 800; font-size: 18px; letter-spacing: -.01em; }
.nav { display: flex; gap: 22px; margin-left: auto; font-size: 14px; font-weight: 600; }
.nav a { text-decoration: none; color: var(--ink); }
.nav a:hover { opacity: .6; }
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  background: var(--ink); color: var(--paper);
  font-weight: 700; text-decoration: none; border-radius: 999px;
}
.btn-small { padding: 7px 16px; font-size: 13px; }

/* ヒーロー */
/* 写真の壁と同じグレーを地にして、写真の左端をその色へ溶かす。
   写真に合わせるため、ヒーローだけはダークモードでも明るいまま */
.hero {
  --wall: #D1D1D3;
  --ink: #0F0F0F;
  --paper: #ECECEA;
  --mute: #6E6E6E;
  position: relative; overflow: hidden;
  background: var(--wall); color: var(--ink);
  /* 画面の縦いっぱい。svh はスマホのアドレスバーを除いた高さ */
  min-height: 100vh; min-height: 100svh;
  display: flex; align-items: center;
  padding-top: 60px; /* 重なっているヘッダーの高さぶん */
}
.hero-photo {
  position: absolute; top: 0; right: 0; height: 100%; width: 60%;
  object-fit: cover; object-position: 20% 35%;
  /* 写真の左端は壁だけなので、そこで地のグレーへ溶かす（人物には掛けない） */
  -webkit-mask-image: linear-gradient(to right, transparent 0, #000 6%);
          mask-image: linear-gradient(to right, transparent 0, #000 6%);
}
.hero-inner { position: relative; width: 100%; padding-top: 80px; padding-bottom: 80px; }
.hero-copy { max-width: 40%; }
/* グレーの問いかけ → 黒の太字の説明、の2段 */
.hero h1 { font-size: clamp(36px, 4.6vw, 72px); line-height: 1.15; letter-spacing: -.02em; }
.hero-question { display: block; color: var(--mute); white-space: nowrap; }
/* 見本どおり「、」「。」の後ろを全角でゆったり取る */
.hero-question, .lead { font-feature-settings: normal; }
.lead { font-weight: 800; font-size: clamp(18px, 2.2vw, 26px); margin-top: 24px; line-height: 1.6; }
.cta-row { display: flex; align-items: center; gap: 18px; margin-top: 40px; flex-wrap: wrap; }
.note { color: var(--mute); font-size: 13px; font-weight: 600; }
.store-badge {
  display: inline-flex; align-items: center; gap: 10px;
  background: var(--ink); color: var(--paper);
  padding: 10px 22px 10px 18px; border-radius: 12px;
  font-weight: 700; font-size: 20px; line-height: 1.1;
}
.store-badge svg { width: 26px; height: 26px; }
.store-badge small { display: block; font-size: 11px; font-weight: 600; opacity: .75; }

/* ヒーロー下端のスクロールの合図：縦線の中を点が下へ流れる */
.scroll-cue {
  position: absolute; bottom: 28px;
  left: max(var(--gutter), calc((100vw - var(--max)) / 2 + var(--gutter)));
  display: flex; flex-direction: column; align-items: center; gap: 10px;
  color: var(--ink); text-decoration: none;
}
.scroll-cue-label { font-size: 11px; font-weight: 700; letter-spacing: .2em; text-transform: uppercase; }
.scroll-cue-line {
  position: relative; width: 1px; height: 56px; overflow: hidden;
  background: color-mix(in srgb, currentColor 25%, transparent);
}
.scroll-cue-line::after {
  content: ""; position: absolute; left: 0; top: 0; width: 1px; height: 40%;
  background: currentColor;
  animation: scroll-cue 1.8s cubic-bezier(.6, 0, .4, 1) infinite;
}
@keyframes scroll-cue {
  from { transform: translateY(-100%); }
  to   { transform: translateY(250%); }
}
@media (prefers-reduced-motion: reduce) {
  .scroll-cue-line::after { animation: none; transform: none; }
}

/* セクション共通 */
.section-title { font-size: clamp(30px, 4vw, 44px); letter-spacing: -.02em; }
.section-lead { color: var(--mute); font-weight: 700; margin-top: 16px; max-width: 42em; }

/* 機能 */
.features { border-top: 1px solid var(--hairline); padding: 96px 0 40px; }
.feature {
  display: grid; grid-template-columns: 1fr 1fr; gap: 72px; align-items: center;
  padding-top: 72px; padding-bottom: 72px;
}
.feature + .feature { border-top: 1px solid var(--hairline); }
.feature.reverse .feature-copy { order: 2; }
.kicker { display: flex; align-items: baseline; gap: 12px; font-weight: 800; font-size: 15px; margin-bottom: 16px; }
.kicker .num { color: var(--red); letter-spacing: .08em; }
.feature-copy h3 { font-size: clamp(30px, 3.6vw, 46px); line-height: 1.25; letter-spacing: -.02em; font-feature-settings: normal; }
.feature-copy > p:not(.kicker) { color: var(--mute); font-weight: 600; margin-top: 20px; }
/* スクショの背景と同じグレーのカードに、スマホを下端ではみ出させて置く（ダークモードでも同じ色） */
.feature-visual {
  background: #EBEBE9; border-radius: 32px; overflow: hidden;
  height: clamp(420px, 44vw, 560px);
  display: flex; justify-content: center; padding-top: 40px;
  /* 下端で切れるスマホを、線ではなくふわっと消す */
  -webkit-mask-image: linear-gradient(to bottom, #000 70%, transparent);
          mask-image: linear-gradient(to bottom, #000 70%, transparent);
}
.feature-visual img { width: 78%; max-width: 380px; height: auto; align-self: flex-start; }

/* 安心 */
.safety { background: var(--ink); color: var(--paper); padding: 104px 0; }
.safety .section-lead { color: color-mix(in srgb, var(--paper) 60%, transparent); }
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1px; margin-top: 56px; background: color-mix(in srgb, var(--paper) 18%, transparent); border: 1px solid color-mix(in srgb, var(--paper) 18%, transparent); }
.card { background: var(--ink); padding: 32px 28px; }
.card h4 { font-size: 19px; margin-bottom: 12px; }
.card p { color: color-mix(in srgb, var(--paper) 62%, transparent); font-size: 14px; font-weight: 600; }

.safety-links { display: flex; flex-wrap: wrap; gap: 12px 32px; margin-top: 32px; font-weight: 700; }
.safety-links a { text-decoration: none; border-bottom: 1px solid color-mix(in srgb, var(--paper) 40%, transparent); padding-bottom: 2px; }
.safety-links a:hover { border-bottom-color: var(--paper); }

/* FAQ */
.faq { border-top: 1px solid var(--hairline); padding: 104px 0; }
.faq .section-title { margin-bottom: 32px; }
details { border-bottom: 1px solid var(--hairline); max-width: 820px; }
details:first-of-type { border-top: 2px solid var(--ink); }
summary {
  cursor: pointer; list-style: none; padding: 20px 40px 20px 0; position: relative;
  font-weight: 800; font-size: 17px;
}
summary::-webkit-details-marker { display: none; }
summary::after { content: "+"; position: absolute; right: 4px; top: 14px; font-size: 26px; font-weight: 400; }
details[open] summary::after { content: "−"; }
details p { color: var(--mute); font-weight: 600; padding: 0 0 22px; }

/* ダウンロード */
/* ヒーローと同じ作り：写真の壁と同じグレーを地にして、左側に文字。ダークモードでも明るいまま */
.download {
  --ink: #0F0F0F;
  --paper: #ECECEA;
  --mute: #6E6E6E;
  position: relative; overflow: hidden;
  background: #DAD9DC; color: var(--ink);
  min-height: min(72vh, 640px);
  display: flex; align-items: center;
  padding: 104px 0;
}
.download-photo {
  position: absolute; top: 0; right: 0; height: 100%; width: 72%;
  object-fit: cover; object-position: 30% 30%;
  /* 写真の左側は壁だけなので、そこで地のグレーへ溶かす */
  -webkit-mask-image: linear-gradient(to right, transparent 0, #000 16%);
          mask-image: linear-gradient(to right, transparent 0, #000 16%);
}
.download-inner { position: relative; width: 100%; display: flex; flex-direction: column; align-items: flex-start; gap: 16px; }
.download-inner > * { max-width: 40%; }
.download-inner > .store-badge { max-width: none; }
.app-icon { border-radius: 22px; box-shadow: 0 10px 30px rgba(0,0,0,.12); margin-bottom: 8px; }
.download h2 { font-size: clamp(30px, 4vw, 48px); letter-spacing: -.02em; font-feature-settings: normal; }
.download p { color: var(--mute); font-weight: 700; margin-bottom: 12px; }

/* ガイドラインのページ（アプリの画面と同じ組み方：2色の見出し → 太字のラベルと罫線 → ✓/× の箇条書き） */
.nav a[aria-current="page"] { text-decoration: underline; text-decoration-thickness: 1.5px; text-underline-offset: 6px; }
.doc { max-width: 760px; padding-top: 132px; padding-bottom: 104px; }
.doc-title { font-size: clamp(34px, 5vw, 52px); line-height: 1.15; letter-spacing: -.03em; }
.doc-title span { display: block; }
.doc-title-sub { color: var(--mute); }
.doc-lead { color: var(--mute); font-weight: 600; margin-top: 20px; }
.doc-section { margin-top: 48px; }
.doc-section h2 {
  font-size: 15px; font-weight: 800; letter-spacing: 0;
  padding-bottom: 10px; border-bottom: 1.5px solid var(--ink); margin-bottom: 16px;
}
.doc-note { color: var(--mute); font-size: 13px; font-weight: 600; margin: -6px 0 12px; }
.checks { list-style: none; margin: 0; padding: 0; display: grid; gap: 12px; }
.checks li { position: relative; padding-left: 30px; font-size: 16px; line-height: 1.65; }
.checks li::before {
  position: absolute; left: 0; top: .2em;
  width: 19px; height: 19px; border-radius: 50%;
  display: grid; place-items: center;
  font-size: 11px; font-weight: 900; line-height: 1;
  color: var(--paper);
}
.checks .ok::before { content: "✓"; background: var(--ink); }
.checks .ng::before { content: "✕"; background: var(--red); color: #fff; }
.doc-list { margin: 0; padding-left: 1.2em; display: grid; gap: 8px; }
.doc-section p, .doc-list { font-size: 15px; }
.doc-link { display: inline-block; margin-top: 16px; font-weight: 700; font-size: 14px; text-decoration: none; border-bottom: 1.5px solid var(--ink); padding-bottom: 1px; }
.doc-back { margin-top: 56px; }

/* 利用規約・プライバシーポリシー */
.doc-updated { color: var(--mute); font-size: 13px; font-weight: 600; margin-top: 16px; padding-bottom: 8px; }
.legal-section { margin-top: 40px; }
.legal-section p + p, .legal-section p + .legal-list, .legal-list + p { margin-top: 10px; }
.legal-list { list-style: none; margin: 10px 0 0; padding: 0; display: grid; gap: 6px; font-size: 15px; }
.legal-list li { position: relative; padding-left: 1.1em; }
.legal-list li::before { content: "・"; position: absolute; left: -.25em; }
/* 未確定の箇所。公開前に埋める */
mark.todo { background: color-mix(in srgb, var(--red) 16%, transparent); color: var(--red); font-weight: 700; padding: 0 2px; border-radius: 3px; }

/* フッター */
.site-footer { padding: 48px 0 56px; border-top: 1px solid var(--hairline); }
.footer-inner { display: grid; grid-template-columns: 1fr auto; gap: 24px 40px; align-items: start; }
.footer-inner .muted { font-size: 13px; font-weight: 600; margin-top: 4px; }
.footer-links { display: flex; flex-wrap: wrap; gap: 8px 24px; font-size: 14px; font-weight: 600; }
.footer-links a { text-decoration: none; color: var(--mute); }
.footer-links a:hover { color: var(--ink); }
.footer-inner .small { grid-column: 1 / -1; }

/* レスポンシブ */
@media (max-width: 900px) {
  .feature { grid-template-columns: 1fr; gap: 40px; }
  .feature.reverse .feature-copy { order: 0; }
  /* 狭い画面では文字を上、写真を下に積む（写真の上の壁の部分に文字が乗る） */
  /* 文字を上に置き、残りの高さを写真で埋める */
  .hero { display: flex; flex-direction: column-reverse; align-items: stretch; }
  .hero-photo {
    position: static; width: 100%; flex: 1 1 0; min-height: 260px; height: auto; object-position: 55% 30%;
    -webkit-mask-image: linear-gradient(to bottom, transparent 0, #000 18%);
            mask-image: linear-gradient(to bottom, transparent 0, #000 18%);
    margin-top: -40px;
  }
  .hero-inner { padding-top: 48px; padding-bottom: 0; }
  .scroll-cue { left: 50%; transform: translateX(-50%); bottom: 20px; color: #fff; filter: drop-shadow(0 1px 3px rgba(0,0,0,.45)); }
  .download { flex-direction: column-reverse; min-height: 0; padding-bottom: 0; }
  .download-photo {
    position: static; width: 100%; height: auto; aspect-ratio: 4 / 3; object-position: 50% 20%;
    -webkit-mask-image: linear-gradient(to bottom, transparent 0, #000 20%);
            mask-image: linear-gradient(to bottom, transparent 0, #000 20%);
    margin-top: -24px;
  }
  .download-inner > * { max-width: none; }
  .hero-copy { max-width: none; }
  .cards { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 640px) {
  :root { --gutter: 16px; }
  .nav { display: none; }
  .btn-small { margin-left: auto; }
  .doc { padding-top: 100px; padding-bottom: 72px; }
  /* 「今夜、誰と会う？」（全角8文字）が1行に収まるいっぱいの大きさにする */
  .hero h1 { font-size: calc((100vw - 2 * var(--gutter)) / 8.2); }
  .lead { font-weight: 700; }
  .feature { padding-top: 56px; padding-bottom: 56px; }
  .feature-visual { height: 420px; padding-top: 28px; border-radius: 24px; }
  .features, .safety, .faq { padding-top: 72px; padding-bottom: 72px; }
  .download { padding-top: 72px; }
  .cards { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr; }
}
.nowrap { white-space: nowrap; }