:root {
  --paper: #f4f1e8;
  --ink: #161714;
  --muted: #66685f;
  --line: #d7d2c5;
  --card: #fbfaf6;
  --acid: #d8ff47;
  --blue: #2e48ff;
  --blue-dark: #1730d7;
  --dark: #1c1e1a;
  --green: #347431;
  --green-soft: #ecf6df;
  --amber: #806015;
  --amber-soft: #fff5d7;
  --red: #a43a35;
  --red-soft: #fff0eb;
  --shadow: 0 24px 70px rgba(37, 34, 25, .1);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.72;
}
button, input, select { font: inherit; }
button, a, summary, label { -webkit-tap-highlight-color: transparent; }
button:focus-visible, a:focus-visible, input:focus-visible, select:focus-visible, audio:focus-visible, summary:focus-visible, label:focus-within {
  outline: 3px solid rgba(46, 72, 255, .23);
  outline-offset: 3px;
}
[hidden] { display: none !important; }

.site-header {
  width: min(1180px, calc(100% - 40px));
  height: 82px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--line);
}
.brand, .footer-brand { display: inline-flex; align-items: center; gap: 11px; }
.brand { color: var(--ink); text-decoration: none; font-size: 15px; font-weight: 800; letter-spacing: -.02em; }
.brand-mark {
  width: 28px;
  height: 28px;
  display: block;
  flex: 0 0 auto;
}
nav { display: flex; align-items: center; gap: 30px; font-size: 13px; }
nav a { color: var(--muted); text-decoration: none; transition: color .16s ease; }
nav a:hover { color: var(--blue); }

main { overflow: hidden; }
.hero {
  width: min(1220px, calc(100% - 40px));
  margin: 82px auto 48px;
  text-align: center;
}
.eyebrow, .section-kicker, .step-label, .result-kicker {
  color: var(--blue);
  font-size: 12.5px;
  font-weight: 800;
  letter-spacing: .11em;
  text-transform: uppercase;
}
.eyebrow { display: inline-flex; align-items: center; gap: 9px; margin: 0 0 19px; }
.status-dot { width: 7px; height: 7px; display: inline-block; background: var(--green); border-radius: 50%; box-shadow: 0 0 0 4px rgba(52, 116, 49, .12); }
.hero h1, .content-intro h2, .test-section h2, .faq-section h2 {
  font-family: "Yu Mincho", "Hiragino Mincho ProN", "Noto Serif JP", Georgia, serif;
  font-weight: 600;
}
.hero h1 {
  margin: 0;
  font-size: clamp(49px, 6.3vw, 82px);
  line-height: 1.08;
  letter-spacing: -.065em;
  text-wrap: balance;
}
.hero h1 em { color: var(--blue); font-style: normal; }
.hero-copy { max-width: 780px; margin: 27px auto 0; color: var(--muted); font-size: 17px; line-height: 1.85; }
.hero-copy p { margin: 0; }
.hero-copy p + p { margin-top: 12px; }
.hero-copy strong { color: var(--ink); }
.benefit-row { margin: 24px auto 0; display: flex; justify-content: center; flex-wrap: wrap; gap: 8px; }
.benefit-row span { padding: 7px 12px; border: 1px solid var(--line); border-radius: 999px; background: rgba(251, 250, 246, .72); font-size: 12px; font-weight: 700; }
.hero-features { max-width: 900px; margin: 26px auto 0; padding: 19px 22px; display: grid; grid-template-columns: 105px 1fr; gap: 18px; align-items: start; border: 1px solid var(--line); border-radius: 16px; background: rgba(251, 250, 246, .7); text-align: left; }
.hero-features > strong { color: var(--blue); font-size: 12px; letter-spacing: .08em; }
.hero-features ul { margin: 0; padding: 0; display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 7px 20px; list-style: none; }
.hero-features li { color: var(--muted); font-size: 12px; line-height: 1.55; }
.hero-features b { color: var(--ink); }
.hero-caveat { max-width: 760px; margin: 18px auto 0; color: var(--muted); font-size: 12px; }
.privacy-note { margin: 12px auto 0; display: flex; align-items: center; justify-content: center; gap: 7px; color: var(--muted); font-size: 12px; }
.privacy-note svg { width: 17px; height: 17px; fill: none; stroke: var(--green); stroke-width: 1.7; stroke-linecap: round; stroke-linejoin: round; }

.tool-shell {
  width: min(1060px, calc(100% - 40px));
  margin: 54px auto 96px;
  padding: 34px;
  border: 1px solid #cfcabd;
  border-radius: 30px;
  box-shadow: var(--shadow);
  background: var(--card);
}
.tool-heading, .section-row { display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.tool-heading { margin-bottom: 26px; }
.tool-heading h2, .workspace-section h3 { margin: 0; line-height: 1.3; letter-spacing: -.035em; }
.tool-heading h2 { font-size: 26px; }
.workspace-section h3 { font-size: 23px; }
.step-label { margin: 0 0 4px; }
.engine-tag { margin: 0; padding: 6px 11px; color: var(--muted); border: 1px solid var(--line); border-radius: 999px; font-size: 11px; font-weight: 700; }
.engine-tag span { color: var(--green); font-size: 8px; vertical-align: 2px; }

.drop-zone {
  min-height: 265px;
  padding: 32px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border: 1.5px dashed #a8aa9f;
  border-radius: 20px;
  background: #f8f6ef;
  cursor: pointer;
  text-align: center;
  transition: border-color .18s ease, background .18s ease, transform .18s ease;
}
.drop-zone:hover, .drop-zone.dragover { border-color: var(--blue); background: #f1f2ff; transform: translateY(-2px); }
.drop-zone.busy { opacity: .65; pointer-events: none; }
.drop-zone.compact { min-height: auto; margin-bottom: 28px; padding: 14px; flex-direction: row; justify-content: flex-start; }
.drop-zone.compact .upload-icon, .drop-zone.compact strong, .drop-zone.compact > span:not(.primary-button) { display: none; }
.drop-zone.compact .primary-button { margin: 0 auto; }
.drop-zone input { position: absolute; width: 1px; height: 1px; overflow: hidden; opacity: 0; pointer-events: none; }
.upload-icon { width: 54px; height: 54px; margin-bottom: 8px; display: grid; place-items: center; background: var(--acid); border-radius: 50%; }
.upload-icon svg { width: 25px; height: 25px; fill: none; stroke: var(--ink); stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.drop-zone strong { font-size: 20px; letter-spacing: -.02em; }
.drop-zone > span:not(.primary-button, .upload-icon) { color: var(--muted); font-size: 13px; }
.primary-button { margin-top: 18px; padding: 11px 20px; color: #fff; background: var(--dark); border-radius: 10px; font-size: 13px; font-weight: 800; }

.message { margin: 18px 0 0; padding: 14px 16px; border-radius: 10px; white-space: pre-line; font-size: 13px; font-weight: 650; }
.message.error { color: var(--red); background: var(--red-soft); border: 1px solid #e9c2ba; }
.message.notice { color: var(--amber); background: var(--amber-soft); border: 1px solid #e5d293; }
.workspace-section { padding: 34px 0; border-top: 1px solid var(--line); }
.summary-strip { margin: 20px 0 12px; display: flex; gap: 8px; flex-wrap: wrap; }
.summary-strip span { padding: 6px 10px; color: var(--muted); background: #efede5; border-radius: 7px; font-size: 12px; font-weight: 700; }
.outline-button, .text-button, .icon-button { border: 0; background: transparent; cursor: pointer; font-weight: 750; }
.outline-button { padding: 9px 14px; color: var(--ink); border: 1px solid #c7c2b6; border-radius: 9px; background: #fffefa; }
.outline-button:hover { border-color: var(--ink); }
.text-button { padding: 8px 9px; color: var(--ink); font-size: 12px; }
.text-button.danger { color: var(--red); }
.icon-button { width: 34px; height: 34px; padding: 0; color: #4f524c; border-radius: 8px; font-size: 15px; }
.icon-button:hover, .text-button:hover { background: #efede5; }
button:disabled { cursor: not-allowed; opacity: .45; }

.file-list { margin: 0; padding: 0; list-style: none; display: grid; gap: 9px; }
.file-item { min-width: 0; padding: 14px; display: grid; grid-template-columns: 52px minmax(0, 1fr) auto; gap: 14px; align-items: center; border: 1px solid var(--line); border-radius: 12px; background: #fffefa; }
.file-item.dragging { opacity: .45; }
.file-order { display: flex; align-items: center; gap: 9px; color: var(--muted); }
.file-order strong { color: var(--ink); }
.drag-grip { font-size: 21px; cursor: grab; }
.file-info { min-width: 0; display: flex; flex-direction: column; }
.file-info strong { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: 14px; }
.file-info span { color: var(--muted); font-size: 11px; }
.file-actions { display: flex; align-items: center; }
.source-player { margin-top: 14px; padding: 14px 16px; display: grid; grid-template-columns: minmax(180px, 1fr) minmax(280px, 1.4fr); align-items: center; gap: 18px; background: #efede5; border-radius: 12px; }
.source-player div { min-width: 0; display: flex; flex-direction: column; }
.source-player span { color: var(--muted); font-size: 11px; font-weight: 750; }
.source-player strong { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: 13px; }
audio { width: 100%; height: 40px; }

.compatibility-card { margin-top: 20px; padding: 20px; display: grid; grid-template-columns: 18px 1fr; gap: 14px; border: 1px solid var(--line); border-radius: 14px; background: #f2f0e8; }
.compatibility-card.safe { background: var(--green-soft); border-color: #bdd19e; }
.compatibility-card.unsafe { background: var(--red-soft); border-color: #e9c2ba; }
.status-mark { width: 12px; height: 12px; margin-top: 7px; display: block; background: #8a8e86; border-radius: 50%; box-shadow: 0 0 0 5px rgba(138, 142, 134, .12); }
.safe .status-mark { background: var(--green); box-shadow: 0 0 0 5px rgba(52, 116, 49, .12); }
.unsafe .status-mark { background: var(--red); box-shadow: 0 0 0 5px rgba(164, 58, 53, .12); }
.compatibility-card strong { font-size: 16px; }
.compatibility-card p { margin: 3px 0 0; color: #555850; font-size: 13px; }
.compatibility-card ul { margin: 10px 0 0; padding-left: 18px; color: #555850; font-size: 12px; }

.mode-grid { margin-top: 20px; display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.mode-card { position: relative; cursor: pointer; }
.mode-card input { position: absolute; top: 16px; right: 16px; width: 18px; height: 18px; accent-color: var(--blue); }
.mode-card > span { height: 100%; min-height: 132px; padding: 18px 52px 18px 18px; display: flex; flex-direction: column; border: 1px solid var(--line); border-radius: 14px; background: #fffefa; transition: border-color .15s ease, box-shadow .15s ease, background .15s ease; }
.mode-card input:checked + span { border-color: var(--blue); box-shadow: inset 0 0 0 1px var(--blue); background: #f3f4ff; }
.mode-card input:disabled + span { opacity: .48; cursor: not-allowed; }
.mode-card b { align-self: flex-start; margin-bottom: 8px; padding: 3px 7px; color: var(--ink); background: var(--acid); border-radius: 4px; font-size: 9px; letter-spacing: .08em; }
.mode-card strong { font-size: 17px; }
.mode-card small { margin-top: 3px; color: var(--muted); }
.mode-status { margin-top: 12px; padding: 13px 16px; border-radius: 10px; }
.mode-status.lossless { color: #285a26; background: var(--green-soft); }
.mode-status.reencode { color: #6f5314; background: var(--amber-soft); }
.mode-status strong { font-size: 13px; }
.mode-status p { margin: 2px 0 0; font-size: 12px; }
.reencode-settings { margin-top: 14px; padding: 16px; display: grid; gap: 13px; background: var(--amber-soft); border: 1px solid #e5d293; border-radius: 12px; }
.reencode-settings > label:first-child { display: flex; align-items: center; justify-content: space-between; gap: 20px; font-size: 13px; font-weight: 750; }
select, .form-grid input { color: var(--ink); border: 1px solid #c9c5ba; border-radius: 10px; background: #fffefa; }
select { min-width: 150px; padding: 10px 12px; }
select:focus, .form-grid input:focus { border-color: var(--blue); box-shadow: 0 0 0 3px rgba(46, 72, 255, .1); outline: 0; }
.confirm-row { display: flex; align-items: flex-start; gap: 9px; color: #624716; font-size: 12px; font-weight: 650; }
.confirm-row input { width: 17px; height: 17px; margin-top: 2px; accent-color: var(--blue); }

.form-grid { margin-top: 20px; display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.form-grid label { position: relative; color: #4d504a; font-size: 11px; font-weight: 750; }
.form-grid label.wide { grid-column: 1 / -1; }
.form-grid input { width: 100%; margin-top: 5px; padding: 12px 14px; }
.form-grid .wide input { padding-right: 52px; }
.form-grid .wide > span { position: absolute; right: 14px; bottom: 11px; color: var(--muted); font-size: 13px; }
.join-button, .download-button { min-height: 58px; border: 0; border-radius: 14px; color: #fff; background: var(--blue); cursor: pointer; font-weight: 800; text-align: center; text-decoration: none; transition: background .16s ease, transform .16s ease, box-shadow .16s ease; }
.join-button { width: 100%; margin-top: 18px; box-shadow: 0 12px 28px rgba(46, 72, 255, .2); }
.join-button:not(:disabled):hover, .download-button:hover { background: var(--blue-dark); transform: translateY(-1px); }

.progress-panel { margin-top: 24px; padding: 22px; color: #fff; background: var(--dark); border-radius: 16px; }
.progress-panel > div:first-child { display: flex; justify-content: space-between; gap: 20px; font-size: 13px; }
.progress-track { height: 7px; margin-top: 12px; overflow: hidden; background: #45483f; border-radius: 999px; }
.progress-track span { width: 0; height: 100%; display: block; background: var(--acid); transition: width .2s ease; }
.progress-panel p { margin: 8px 0 0; color: #c6c9c0; font-size: 12px; }
.progress-panel button { margin-top: 8px; color: #ffaaa5; }
.result-card { margin-top: 24px; padding: 28px; color: var(--ink); background: var(--green-soft); border: 1px solid #bdd19e; border-radius: 18px; }
.result-kicker { margin: 0 0 5px; color: var(--green); }
.result-card h3 { margin: 0; font-size: 28px; }
.result-name { margin: 8px 0 0; font-weight: 750; }
.result-mode { margin: 0 0 18px; color: var(--muted); font-size: 12px; }
.seam-preview { margin-top: 20px; padding: 16px; border: 1px solid #bdd19e; border-radius: 12px; background: rgba(255, 255, 255, .48); }
.seam-preview > strong { font-size: 13px; }
.seam-preview > p { margin: 2px 0 10px; color: var(--muted); font-size: 11px; }
.seam-preview ul { margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: 7px; list-style: none; }
.seam-button { padding: 8px 11px; color: var(--ink); background: #fffefa; border: 1px solid #a9bf87; border-radius: 7px; cursor: pointer; font-size: 11px; }
.result-actions { margin-top: 20px; display: flex; gap: 10px; }
.download-button { flex: 1; display: grid; place-items: center; color: #fff; background: var(--dark); box-shadow: none; }
.download-button:hover { background: #000; }
.result-actions .outline-button { background: rgba(255, 255, 255, .58); border-color: #a9bf87; }

.proof-strip { width: min(1180px, calc(100% - 40px)); margin: 0 auto 126px; display: grid; grid-template-columns: repeat(4, 1fr); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.proof-strip div { min-height: 116px; display: flex; flex-direction: column; align-items: center; justify-content: center; border-right: 1px solid var(--line); text-align: center; }
.proof-strip div:last-child { border-right: 0; }
.proof-strip strong { font-family: Georgia, serif; font-size: 28px; font-weight: 500; line-height: 1; }
.proof-strip span { margin-top: 9px; color: var(--muted); font-size: 11px; }

.section-kicker { margin: 0 0 12px; }
.how-section, .content-section, .faq-section, .related-section { width: min(1080px, calc(100% - 40px)); margin: 0 auto 130px; }
.section-intro { display: block; }
.section-number { color: var(--blue); font-family: Georgia, serif; font-size: 44px; line-height: 1; }
.section-intro h2, .content-heading h2, .related-section h2 {
  margin: 0;
  font-family: "Yu Mincho", "Hiragino Mincho ProN", "Noto Serif JP", Georgia, serif;
  font-size: clamp(30px, 3.6vw, 46px);
  font-weight: 500;
line-height: 1.28;
  letter-spacing: -.01em;
  text-wrap: balance;
}
.section-lead { max-width: none; margin: 24px 0 0; color: var(--muted); line-height: 1.9; font-size: 14.5px; }
.steps-grid { margin-top: 52px; display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.steps-grid article { min-height: 360px; padding: 25px; border: 1px solid var(--line); border-radius: 18px; background: rgba(255, 255, 255, .24); }
.steps-grid article > span { width: 31px; height: 31px; display: grid; place-items: center; background: var(--acid); border-radius: 50%; font-size: 12px; font-weight: 900; }
.steps-grid h3 { margin: 48px 0 14px; font-size: 17px; line-height: 1.55; }
.steps-grid p { margin: 0; color: var(--muted); font-size: 13px; line-height: 1.75; }
.steps-grid p + p { margin-top: 10px; }

.guide-section { width: min(1080px, calc(100% - 40px)); margin: 0 auto 130px; padding: 60px; display: grid; grid-template-columns: .85fr 1.15fr; gap: 48px 60px; color: #fff; background: var(--dark); border-radius: 28px; }
.guide-section .section-kicker { color: var(--acid); }
.guide-copy h2, .quality-note h2 {
  margin: 0;
  font-family: "Yu Mincho", "Hiragino Mincho ProN", "Noto Serif JP", Georgia, serif;
  font-size: clamp(36px, 4.5vw, 54px);
  font-weight: 600;
  line-height: 1.15;
  letter-spacing: -.04em;
}
.guide-copy p, .dark-note p { color: #c6c9c0; font-size: 13px; line-height: 1.8; }
.guide-copy p:first-of-type { margin-top: 24px; }
.comparison-wrap h3, .dark-note h3 { margin: 0 0 18px; font-size: 16px; }
.comparison-table { border-top: 1px solid #4a4d46; }
.comparison-row { padding: 13px 9px; display: grid; grid-template-columns: .8fr 1.15fr 1fr; gap: 14px; align-items: start; border-bottom: 1px solid #40433d; font-size: 11px; line-height: 1.55; }
.comparison-row strong { color: #fff; }
.comparison-row span { color: #c0c3ba; }
.comparison-head { color: #92968c; font-size: 9px; font-weight: 800; letter-spacing: .07em; text-transform: uppercase; }
.dark-note { padding: 28px; background: #292c27; border-radius: 16px; }
.dark-note p { margin: 0; }
.dark-note p + p { margin-top: 10px; }
.dark-note strong { color: var(--acid); }
.quality-note h2 { margin-bottom: 20px; font-size: 31px; }

.content-heading { display: block; margin-bottom: 34px; }
.content-copy { max-width: 780px; margin: 0 0 34px; }
.content-copy p { margin: 0; color: var(--muted); font-size: 14px; line-height: 1.9; }
.content-copy p + p { margin-top: 10px; }
.compatibility-section > h3 { margin: 0 0 15px; font-size: 18px; }
.data-table, .trouble-table { border-top: 1px solid var(--ink); }
.data-row, .trouble-row { padding: 17px 10px; display: grid; gap: 18px; align-items: start; border-bottom: 1px solid var(--line); font-size: 13px; line-height: 1.55; }
.data-row { grid-template-columns: .9fr 1.1fr 1.25fr; }
.trouble-row { grid-template-columns: 1fr 1fr 1.35fr; }
.data-row span, .trouble-row span { color: var(--muted); }
.data-head, .trouble-head { color: var(--muted); font-size: 10px; font-weight: 750; letter-spacing: .08em; text-transform: uppercase; }
.editorial-note { margin-top: 24px; padding: 24px 26px; background: #edf0ff; border-left: 4px solid var(--blue); border-radius: 0 14px 14px 0; }
.editorial-note p { margin: 0; font-size: 13px; line-height: 1.8; }
.editorial-note p + p { margin-top: 10px; }
.reason-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; }
.reason-grid article, .info-cards article { padding: 26px; border: 1px solid var(--line); border-radius: 18px; background: rgba(255, 255, 255, .35); }
.reason-grid article > span { color: var(--blue); font-size: 10px; font-weight: 850; letter-spacing: .12em; }
.reason-grid h3, .info-cards h3 { margin: 34px 0 14px; font-size: 17px; line-height: 1.5; }
.reason-grid p, .info-cards p { margin: 0; color: var(--muted); font-size: 13px; line-height: 1.75; }
.reason-grid p + p, .info-cards p + p { margin-top: 10px; }
.reason-grid .accent-card { color: #fff; background: var(--blue); border-color: var(--blue); }
.reason-grid .accent-card > span { color: var(--acid); }
.reason-grid .accent-card p { color: #e6e8ff; }
.info-cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.info-cards h3 { margin-top: 0; }
.load-note { margin-top: 28px; padding: 26px; background: var(--card); border: 1px solid var(--line); border-radius: 16px; }
.load-note h3 { margin: 0 0 12px; font-size: 17px; }
.load-note p { margin: 0; color: var(--muted); font-size: 13px; }
.load-note p + p { margin-top: 8px; }

.test-section { width: min(1080px, calc(100% - 40px)); margin: 0 auto 130px; padding: 60px; display: grid; grid-template-columns: .85fr 1.15fr; gap: 46px 60px; align-items: center; background: #e6ff88; border-radius: 28px; }
.test-section h2, .faq-section h2 { margin: 0; font-size: 40px; line-height: 1.18; letter-spacing: -.045em; }
.test-copy > p:not(.section-kicker) { margin: 18px 0 0; color: #505346; font-size: 13px; }
.tested-date { display: inline-block; margin-top: 18px; padding: 6px 10px; color: #fff; background: var(--ink); border-radius: 999px; font-size: 10px; }
.test-card { margin: 0; background: var(--card); border-radius: 16px; box-shadow: 0 15px 35px rgba(57, 70, 18, .12); overflow: hidden; }
.test-row { padding: 13px 16px; display: grid; grid-template-columns: 1fr 1.25fr; gap: 16px; border-bottom: 1px solid var(--line); font-size: 12px; }
.test-row:last-child { border-bottom: 0; }
.test-row span { color: var(--muted); }
.test-head { color: var(--muted); font-size: 10px; font-weight: 750; letter-spacing: .07em; text-transform: uppercase; }
.test-learning { grid-column: 1 / -1; padding-top: 34px; border-top: 1px solid rgba(22, 23, 20, .22); }
.test-learning h3 { margin: 0 0 12px; font-size: 20px; }
.test-learning p { margin: 0; color: #505346; font-size: 13px; line-height: 1.8; }
.test-learning p + p { margin-top: 9px; }

.faq-section { width: min(820px, calc(100% - 40px)); }
.faq-list { margin-top: 31px; border-top: 1px solid var(--line); }
.faq-list details { border-bottom: 1px solid var(--line); }
.faq-list summary { padding: 23px 2px; display: flex; align-items: center; justify-content: space-between; gap: 20px; cursor: pointer; list-style: none; font-size: 17px; font-weight: 700; }
.faq-list summary::-webkit-details-marker { display: none; }
.faq-list summary span { color: var(--blue); font-size: 24px; font-weight: 400; transition: transform .18s ease; }
.faq-list details[open] summary span { transform: rotate(45deg); }
.faq-list p { margin: -8px 0 22px; color: #75776f; font-size: 13px; }
.faq-list p + p { margin-top: -12px; }

.related-section { padding-top: 4px; }
.related-section > h2 { max-width: 720px; }
.related-grid { margin-top: 42px; display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; }
.related-grid article { min-height: 250px; padding: 28px; border: 1px solid var(--line); border-radius: 18px; background: var(--card); }
.related-icon { display: grid; place-items: center; width: 46px; height: 46px; color: var(--acid); background: var(--ink); border-radius: 50%; font-size: 9px; font-weight: 900; letter-spacing: .08em; }
.related-grid h3 { margin: 30px 0 10px; font-size: 20px; }
.related-grid p { margin: 0; color: var(--muted); font-size: 13px; }
.related-grid p + p { margin-top: 9px; }
.tool-path { display: inline-block; margin-top: 18px; padding: 6px 9px; color: var(--blue); background: #edf0ff; border-radius: 7px; font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 11px; }

footer { width: min(1180px, calc(100% - 40px)); min-height: 120px; margin: 0 auto; display: flex; justify-content: space-between; align-items: center; border-top: 1px solid var(--line); }
footer strong { font-size: 15px; }
footer p { margin: 2px 0 0; color: var(--muted); font-size: 11px; }

@media (max-width: 760px) {
  .site-header { width: calc(100% - 28px); height: 68px; }
  .brand > span:last-child { display: none; }
  nav { display: none; }
  .hero { width: calc(100% - 28px); margin: 58px auto 38px; text-align: left; }
  .eyebrow { margin-bottom: 16px; }
  .hero h1 { font-size: clamp(31px, 9.5vw, 50px); line-height: 1.13; }
  .hero-copy { margin-top: 22px; font-size: 15px; line-height: 1.8; }
  .benefit-row { justify-content: flex-start; }
  .hero-features { padding: 18px; grid-template-columns: 1fr; gap: 10px; }
  .hero-features ul { grid-template-columns: 1fr; }
  .hero-caveat { margin-top: 16px; }
  .privacy-note { align-items: flex-start; justify-content: flex-start; }
  .privacy-note svg { margin-top: 2px; flex: 0 0 auto; }
  .tool-shell { width: calc(100% - 20px); margin: 38px auto 82px; padding: 19px; border-radius: 22px; }
  .tool-heading, .section-row { align-items: flex-start; }
  .tool-heading { gap: 12px; }
  .engine-tag { max-width: 120px; text-align: center; }
  .tool-heading h2 { font-size: 23px; }
  .workspace-section h3 { font-size: 20px; }
  .drop-zone { min-height: 230px; padding: 30px 15px; }
  .drop-zone.compact { min-height: 60px; }
  .drop-zone strong { font-size: 18px; }
  .file-item { grid-template-columns: 38px minmax(0, 1fr); gap: 10px; }
  .file-actions { grid-column: 2; flex-wrap: wrap; }
  .drag-grip { display: none; }
  .source-player { grid-template-columns: 1fr; }
  .mode-grid, .form-grid { grid-template-columns: 1fr; }
  .form-grid label.wide { grid-column: auto; }
  .reencode-settings > label:first-child { align-items: flex-start; flex-direction: column; }
  select { width: 100%; }
  .result-card { padding: 22px 17px; }
  .result-actions { flex-direction: column; }
  .download-button { min-height: 52px; }
  .proof-strip { width: calc(100% - 28px); margin-bottom: 88px; grid-template-columns: 1fr 1fr; }
  .proof-strip div { min-height: 96px; }
  .proof-strip div:nth-child(2) { border-right: 0; }
  .proof-strip div:nth-child(-n+2) { border-bottom: 1px solid var(--line); }
  .how-section, .content-section, .related-section { width: calc(100% - 28px); margin-bottom: 88px; }
  .section-intro { display: block; }
  .section-number { font-size: 29px; }
  .section-intro h2, .content-heading h2, .related-section h2 { font-size: 38px; }
  .section-lead { max-width: none; margin: 24px 0 0; color: var(--muted); line-height: 1.9; font-size: 14.5px; }
  .steps-grid { grid-template-columns: 1fr; margin-top: 34px; }
  .steps-grid article { min-height: 0; }
  .guide-section { width: calc(100% - 20px); margin-bottom: 88px; padding: 34px 20px; grid-template-columns: 1fr; gap: 34px; border-radius: 22px; }
  .guide-copy h2 { font-size: 38px; }
  .comparison-wrap { overflow-x: auto; }
  .comparison-table { min-width: 610px; }
  .dark-note { padding: 23px 19px; }
  .quality-note h2 { font-size: 28px; }
  .content-heading { display: block; margin-bottom: 34px; }
  .data-table, .trouble-table { overflow-x: auto; }
  .data-row, .trouble-row { min-width: 680px; }
  .reason-grid, .info-cards, .related-grid { grid-template-columns: 1fr; }
  .test-section { width: calc(100% - 20px); padding: 31px 20px; grid-template-columns: 1fr; gap: 26px; margin-bottom: 88px; border-radius: 22px; }
  .test-section h2, .faq-section h2 { font-size: 34px; }
  .test-row { grid-template-columns: 1fr; gap: 2px; }
  .faq-section { width: calc(100% - 28px); margin-bottom: 88px; }
  .faq-list summary { align-items: flex-start; font-size: 15px; }
  footer { width: calc(100% - 28px); min-height: 138px; align-items: flex-start; flex-direction: column; justify-content: center; gap: 12px; }
}

@media (prefers-reduced-motion: reduce) {
  * { scroll-behavior: auto !important; transition: none !important; }
}

/* ===== 関連ツール（内部リンク） ===== */
.related-section { width: min(1080px, calc(100% - 40px)); margin: 0 auto 110px; }
.related-kicker { margin: 0 0 14px; color: var(--blue); font-size: 12.5px; font-weight: 800; letter-spacing: .11em; }
.related-section h2 { margin: 0; font-family: "Yu Mincho", "Hiragino Mincho ProN", "Noto Serif JP", Georgia, serif; font-size: clamp(28px, 3.4vw, 42px); font-weight: 500; line-height: 1.3; letter-spacing: -.01em; text-wrap: balance; }
.related-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 290px), 1fr)); gap: 16px; margin-top: 40px; }
.related-card { display: flex; flex-direction: column; padding: 28px; border: 1px solid var(--line); border-radius: 18px; background: var(--card); color: inherit; text-decoration: none; transition: transform .18s ease, border-color .18s ease, box-shadow .18s ease; }
.related-card:hover, .related-card:focus-visible { transform: translateY(-2px); border-color: var(--ink); box-shadow: 0 12px 30px rgba(22, 23, 20, .08); }
.related-icon { display: grid; place-items: center; width: 46px; height: 46px; color: var(--acid); background: var(--ink); border-radius: 50%; font-size: 9px; font-weight: 900; letter-spacing: .08em; }
.related-card h3 { margin: 26px 0 10px; font-size: 19px; line-height: 1.45; }
.related-card p { margin: 0; color: var(--muted); font-size: 13px; line-height: 1.75; }
.related-cta { margin-top: auto; padding-top: 20px; color: var(--blue); font-size: 12.5px; font-weight: 800; }
@media (max-width: 640px) { .related-section { margin-bottom: 80px; } .related-card { padding: 22px; } }

/* フッターの文字サイズ・色を他ページと揃える */
footer { font-size: 12px; color: var(--muted); }
footer .brand { color: var(--ink); }
footer p { font-size: 12px; margin: 0; }

/* 页脚：隐私政策 + 许可入口（2026-10-24） */
.footer-links { display: flex; flex-wrap: wrap; gap: 6px 18px; }
.footer-links a { color: var(--muted); font-size: 12px; text-decoration: underline; text-underline-offset: 3px; }
.footer-links a:hover, .footer-links a:focus-visible { color: var(--ink); }

/* 实测证据下载链接（2026-10-24） */
.evidence-links { display: flex; flex-wrap: wrap; gap: 8px 20px; margin: 16px 0 0; }
.evidence-links a { font-size: 13px; color: var(--blue); text-decoration: underline; text-underline-offset: 3px; }
.evidence-links a:hover, .evidence-links a:focus-visible { text-decoration-thickness: 2px; }

/* ===========================================================
   统一排版（2026-10-24）
   四页共用同一套字体栈与字号阶梯，调整时四份文件保持一致
   =========================================================== */
:root {
  --font-sans: "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Noto Sans JP",
               "Yu Gothic", "YuGothic", Meiryo, system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-serif: "Yu Mincho", "Hiragino Mincho ProN", "Hiragino Mincho Pro",
                "Noto Serif JP", Georgia, serif;
  --fs-h1: clamp(30px, 6.4vw, 74px);
  --fs-h2: clamp(26px, 3.1vw, 40px);
  --fs-h2-ui: 24px;
  --fs-h3: clamp(17px, 1.35vw, 19px);
  --fs-lead: 17px;
}
body { font-family: var(--font-sans); }
h1, .hero h1 {
  font-family: var(--font-serif);
  font-size: var(--fs-h1);
  line-height: 1.12;
  letter-spacing: -.02em;
  font-weight: 500;
}
.section-intro h2, .content-heading h2, .related-section h2, .related-section > h2, .guide-copy h2, .quality-note h2, .test-section h2, .faq-section h2 {
  font-family: var(--font-serif);
  font-size: var(--fs-h2);
  line-height: 1.3;
  letter-spacing: -.01em;
  font-weight: 500;
}
.tool-heading h2 { font-size: var(--fs-h2-ui); line-height: 1.4; letter-spacing: -.02em; }
.workspace-section h3, .result-card h3, .steps-grid h3, .comparison-wrap h3, .dark-note h3, .compatibility-section > h3, .reason-grid h3, .info-cards h3, .load-note h3, .test-learning h3, .related-grid h3, .related-card h3 { font-size: var(--fs-h3); line-height: 1.5; }
.hero-copy, .section-lead { font-size: var(--fs-lead); line-height: 1.8; }
@media (max-width: 640px) {
  .tool-heading h2 { font-size: 21px; }
  .hero-copy { font-size: 15px; line-height: 1.85; }
}