:root {
  --paper: #f4f1e8;
  --ink: #161714;
  --muted: #66685f;
  --line: #d7d2c5;
  --card: #fbfaf6;
  --acid: #d8ff47;
  --blue: #2e48ff;
  --dark: #1c1e1a;
  --radius: 24px;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--paper);
  font-synthesis: none;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; min-width: 320px; background: var(--paper); }
button, input, select { font: inherit; }
a { color: inherit; }
[hidden] { display: none !important; }

.site-header, footer {
  width: min(1180px, calc(100% - 40px));
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-header { height: 82px; border-bottom: 1px solid var(--line); }
.brand { display: inline-flex; align-items: center; gap: 11px; font-size: 15px; font-weight: 800; text-decoration: none; letter-spacing: -.02em; }
.brand-mark { width: 28px; height: 28px; display: block; flex: 0 0 auto; }
nav { display: flex; gap: 30px; }
nav a { font-size: 13px; text-decoration: none; color: #43453e; }
nav a:hover { color: var(--blue); }

main { overflow: hidden; }
.hero { width: min(980px, calc(100% - 40px)); margin: 82px auto 48px; text-align: center; }
.eyebrow, .kicker, .step-label { font-size: 11px; text-transform: uppercase; letter-spacing: .16em; font-weight: 800; }
.eyebrow { display: inline-flex; gap: 8px; align-items: center; }
.status-dot { width: 7px; height: 7px; border-radius: 50%; background: #54b74f; box-shadow: 0 0 0 4px #d9e9d5; }
h1 { margin: 25px 0 24px; font-family: "Yu Mincho", "Hiragino Mincho ProN", "Hiragino Mincho Pro", "Noto Serif JP", Georgia, "Times New Roman", serif; font-size: clamp(54px, 7vw, 90px); line-height: 1.05; letter-spacing: -.02em; font-weight: 500; }
h1 em { color: var(--blue); font-weight: 500; }
.hero-copy { max-width: 680px; margin: 0 auto; font-size: 18px; line-height: 1.7; color: var(--muted); }
.privacy-note { display: inline-flex; gap: 8px; align-items: center; margin-top: 25px; color: #46483f; font-size: 12px; }
.privacy-note svg { width: 17px; fill: #497d45; }

.converter { width: min(820px, calc(100% - 32px)); margin: 54px auto 96px; padding: 34px; background: var(--card); border: 1px solid #cfcabd; border-radius: 30px; box-shadow: 0 24px 70px rgba(37, 34, 25, .1); }
.converter-heading { display: flex; align-items: flex-start; justify-content: space-between; margin-bottom: 26px; }
.converter-heading h2 { margin: 6px 0 0; font-size: 26px; letter-spacing: -.04em; }
.step-label { color: var(--blue); }
.engine-tag { border: 1px solid var(--line); border-radius: 100px; padding: 7px 11px; font-size: 10px; color: var(--muted); }
.drop-zone { min-height: 265px; padding: 32px; border: 1.5px dashed #a8aa9f; border-radius: 20px; display: flex; flex-direction: column; align-items: center; justify-content: center; cursor: pointer; background: #f8f6ef; transition: .2s ease; }
.drop-zone:hover, .drop-zone.dragover { border-color: var(--blue); background: #f1f2ff; transform: translateY(-2px); }
.upload-icon { width: 54px; height: 54px; display: grid; place-items: center; border-radius: 50%; background: var(--acid); margin-bottom: 18px; }
.upload-icon svg { width: 24px; fill: none; stroke: var(--ink); stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.drop-zone strong { font-size: 20px; letter-spacing: -.025em; }
.drop-zone > span:not(.upload-icon) { margin-top: 4px; color: var(--muted); }
.drop-zone small { margin-top: 18px; color: #898b82; }
.file-card { display: flex; gap: 14px; align-items: center; padding: 14px; border-radius: 17px; background: #eeece4; }
.file-thumb { width: 54px; height: 54px; border-radius: 11px; display: grid; place-items: center; background: var(--dark); color: var(--acid); font-size: 10px; font-weight: 900; letter-spacing: .1em; }
.file-details { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 4px; }
.file-details strong { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.file-details span { color: var(--muted); font-size: 12px; }
.icon-button { width: 34px; height: 34px; border: 0; border-radius: 50%; background: transparent; cursor: pointer; font-size: 24px; color: #666; }
.icon-button:hover { background: #ddd9cd; color: #111; }
.source-preview { margin-top: 14px; padding: 16px; border: 1px solid var(--line); border-radius: 16px; background: #f4f2ea; }
.source-preview > div { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 12px; gap: 16px; }
.source-preview strong { font-size: 13px; }
.source-preview span { color: var(--muted); font-size: 11px; }
.source-preview video { display: block; width: 100%; max-height: 300px; border-radius: 11px; background: #111; }
.settings { margin-top: 25px; display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.setting-block > label, .metadata-grid label { display: block; margin-bottom: 9px; font-size: 12px; font-weight: 800; }
.setting-block > label span { color: var(--muted); font-weight: 500; }
select, input { border: 1px solid #c9c5ba; border-radius: 10px; background: #fffefa; color: var(--ink); outline: none; }
select:focus, input:focus { border-color: var(--blue); box-shadow: 0 0 0 3px rgba(46,72,255,.1); }
.select-wrap select { width: 100%; padding: 13px; }
.estimate { margin: 8px 2px 0; font-size: 11px; color: var(--muted); }
.time-row { display: flex; gap: 9px; align-items: center; }
.time-row label { flex: 1; color: var(--muted); font-size: 10px; }
.time-row input { width: 100%; padding: 8px 9px; margin-top: 3px; }
.time-row > span { color: var(--muted); margin-top: 13px; font-size: 11px; }
.metadata { grid-column: 1/-1; border-top: 1px solid var(--line); padding-top: 17px; }
.metadata summary { cursor: pointer; font-size: 13px; font-weight: 800; }
.metadata summary span { color: var(--muted); font-weight: 500; margin-left: 7px; }
.metadata-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; padding-top: 16px; }
.metadata-grid input { width: 100%; padding: 11px; margin-top: 7px; }
.primary-button { grid-column: 1/-1; min-height: 58px; border: 0; border-radius: 14px; display: flex; justify-content: space-between; align-items: center; padding: 0 22px; background: var(--blue); color: white; font-weight: 800; cursor: pointer; box-shadow: 0 8px 18px rgba(46,72,255,.2); transition: .2s; }
.primary-button:hover { background: #1931da; transform: translateY(-1px); }
.primary-button:disabled { opacity: .55; cursor: wait; }
.progress-panel { margin-top: 24px; padding: 22px; border-radius: 16px; background: var(--dark); color: white; }
.progress-top { display: flex; justify-content: space-between; font-size: 13px; }
.progress-track { height: 7px; margin: 14px 0; border-radius: 8px; background: #3d4039; overflow: hidden; }
.progress-track i { display: block; width: 0%; height: 100%; background: var(--acid); transition: width .2s; }
.progress-panel p { margin: 0; color: #afb2a8; font-size: 11px; }
.result-card { margin-top: 24px; padding: 20px; display: grid; grid-template-columns: auto 1fr auto; gap: 16px; align-items: center; border-radius: 18px; background: #ecf6df; border: 1px solid #bdd19e; }
.result-icon { width: 48px; height: 48px; display: grid; place-items: center; border-radius: 50%; background: var(--acid); font-size: 23px; }
.result-info { min-width: 0; }
.result-info > span { font-size: 9px; letter-spacing: .13em; color: #5c6c47; font-weight: 900; }
.result-info strong { display: block; margin: 4px 0 9px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
audio { width: min(100%, 360px); height: 34px; }
.download-button { padding: 12px 16px; border-radius: 10px; background: var(--ink); color: white; text-decoration: none; font-size: 12px; font-weight: 800; white-space: nowrap; }
.error-message { margin-top: 18px; border-radius: 12px; background: #ffe7e1; color: #8c2c1d; padding: 14px; font-size: 13px; }

.proof-strip { width: min(1180px, calc(100% - 40px)); margin: 0 auto 110px; padding: 30px 0; display: grid; grid-template-columns: repeat(4, 1fr); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.proof-strip div { text-align: center; border-right: 1px solid var(--line); }
.proof-strip div:last-child { border: 0; }
.proof-strip strong { display: block; font-family: Georgia, serif; font-size: 30px; font-weight: 500; }
.proof-strip span { color: var(--muted); font-size: 11px; }
.how-section, .guide-section, .faq-section { width: min(1080px, calc(100% - 40px)); margin: 0 auto 130px; }
.section-intro { display: grid; grid-template-columns: 110px 1fr; }
.section-number { font-family: Georgia, serif; color: var(--blue); font-size: 52px; }
.kicker { color: var(--blue); margin: 0 0 16px; }
.section-intro h2, .guide-copy h2, .faq-section h2 { margin: 0; font-family: "Yu Mincho", "Hiragino Mincho ProN", "Hiragino Mincho Pro", "Noto Serif JP", Georgia, serif; font-size: clamp(42px, 6vw, 72px); line-height: 1.12; letter-spacing: -.02em; font-weight: 500; }
.steps-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin-top: 58px; }
.steps-grid article { min-height: 220px; padding: 25px; border: 1px solid var(--line); border-radius: 18px; }
.steps-grid article > span { display: grid; place-items: center; width: 30px; height: 30px; border-radius: 50%; background: var(--acid); font-weight: 900; font-size: 12px; }
.steps-grid h3 { margin: 48px 0 10px; font-size: 18px; }
.steps-grid p { margin: 0; color: var(--muted); line-height: 1.6; font-size: 13px; }
.section-lead { max-width: 680px; margin: 28px 0 0 110px; color: var(--muted); line-height: 1.8; font-size: 14px; }
.guide-section { padding: 64px; display: grid; grid-template-columns: .8fr 1.2fr; gap: 70px; border-radius: 28px; background: var(--dark); color: white; }
.guide-copy h2 { font-size: clamp(38px, 4.2vw, 56px); }
.guide-copy > p:last-child { margin-top: 28px; color: #b7b9b1; line-height: 1.7; font-size: 14px; }
.quality-table { align-self: center; }
.table-row { display: grid; grid-template-columns: 1.1fr 1fr .6fr; gap: 12px; padding: 17px 14px; border-bottom: 1px solid #40433d; align-items: center; font-size: 12px; }
.table-row > span { color: #b6b9b0; }
.table-head { color: #8e9188; font-size: 9px; text-transform: uppercase; letter-spacing: .12em; }
.recommended { background: #292c27; border-radius: 10px; }
.recommended i { display: inline-block; margin-top: 4px; color: var(--acid); font-size: 8px; text-transform: uppercase; letter-spacing: .08em; font-style: normal; }
.table-note { margin: 14px 7px 0; color: #8f9289; font-size: 10px; line-height: 1.6; }
.content-section { width: min(1080px, calc(100% - 40px)); margin: 0 auto 130px; }
.content-heading { display: grid; grid-template-columns: .75fr 1.25fr; gap: 50px; align-items: end; margin-bottom: 42px; }
.content-heading h2 { margin: 0; font-family: "Yu Mincho", "Hiragino Mincho ProN", "Hiragino Mincho Pro", "Noto Serif JP", Georgia, serif; font-size: clamp(36px, 5vw, 62px); line-height: 1.14; letter-spacing: -.02em; font-weight: 500; }
.content-copy { max-width: 760px; margin-left: auto; }
.content-copy p { color: var(--muted); line-height: 1.9; }
.content-copy code { padding: 3px 7px; border-radius: 5px; background: #e7e3d8; color: var(--ink); }
.info-cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.info-cards article { min-height: 220px; padding: 26px; border: 1px solid var(--line); border-radius: 18px; background: rgba(255,255,255,.35); }
.info-cards h3 { margin: 0 0 44px; font-size: 17px; }
.info-cards p { margin: 0; color: var(--muted); line-height: 1.75; font-size: 13px; }
.trouble-table { border-top: 1px solid var(--ink); }
.trouble-row { display: grid; grid-template-columns: 1fr 1fr 1.35fr; gap: 18px; padding: 17px 10px; border-bottom: 1px solid var(--line); font-size: 13px; line-height: 1.5; }
.trouble-row span { color: var(--muted); }
.trouble-head { color: var(--muted); font-size: 10px; text-transform: uppercase; letter-spacing: .08em; }
.section-note { margin: 16px 4px 0; color: var(--muted); font-size: 12px; }
.test-section { width: min(1080px, calc(100% - 40px)); margin: 0 auto 130px; padding: 60px; display: grid; grid-template-columns: .85fr 1.15fr; gap: 65px; border-radius: 28px; background: #e6ff88; }
.test-copy h2 { margin: 0; font-family: "Yu Mincho", "Hiragino Mincho ProN", "Hiragino Mincho Pro", "Noto Serif JP", Georgia, serif; font-size: clamp(38px, 4.3vw, 54px); line-height: 1.12; font-weight: 500; letter-spacing: -.02em; }
.test-copy > p:last-child { margin: 26px 0 0; color: #535744; line-height: 1.75; font-size: 13px; }
.test-card { padding: 26px; border-radius: 18px; background: var(--card); box-shadow: 0 14px 35px rgba(51,60,24,.1); }
.tested-badge { display: inline-block; padding: 6px 9px; border-radius: 100px; background: var(--ink); color: white; font-size: 9px; letter-spacing: .08em; }
.test-card dl { margin: 18px 0 0; }
.test-card dl div { display: grid; grid-template-columns: 1fr 1.2fr; gap: 15px; padding: 12px 2px; border-bottom: 1px solid var(--line); font-size: 12px; }
.test-card dt { color: var(--muted); }
.test-card dd { margin: 0; font-weight: 750; }
.test-card .success { color: #347431; }
.faq-section { max-width: 820px; }
.faq-section > h2 { margin-bottom: 50px; }
.faq-list details { border-top: 1px solid var(--line); }
.faq-list details:last-child { border-bottom: 1px solid var(--line); }
.faq-list summary { list-style: none; cursor: pointer; padding: 23px 0; display: flex; justify-content: space-between; font-weight: 750; }
.faq-list summary::-webkit-details-marker { display: none; }
.faq-list summary span { color: var(--blue); font-size: 22px; font-weight: 400; transition: transform .2s; }
.faq-list details[open] summary span { transform: rotate(45deg); }
.faq-list p { max-width: 680px; margin: -5px 0 24px; color: var(--muted); line-height: 1.65; font-size: 14px; }
footer { min-height: 120px; border-top: 1px solid var(--line); color: var(--muted); font-size: 12px; }
footer .brand { color: var(--ink); }

@media (max-width: 760px) {
  .site-header { height: 68px; }
  nav { display: none; }
  .hero { margin-top: 60px; }
  h1 { font-size: clamp(30px, 9vw, 52px); }
  .hero-copy { font-size: 16px; }
  .converter { padding: 20px; border-radius: 22px; margin-top: 38px; }
  .converter-heading { align-items: flex-end; }
  .engine-tag { display: none; }
  .drop-zone { min-height: 230px; }
  .settings { grid-template-columns: 1fr; }
  .metadata { grid-column: auto; }
  .metadata-grid { grid-template-columns: 1fr; }
  .primary-button { grid-column: auto; }
  .source-preview > div { align-items: flex-start; flex-direction: column; gap: 4px; }
  .result-card { grid-template-columns: auto 1fr; }
  .download-button { grid-column: 1/-1; text-align: center; }
  .proof-strip { grid-template-columns: 1fr 1fr; gap: 22px 0; }
  .proof-strip div:nth-child(2) { border: 0; }
  .section-intro { grid-template-columns: 1fr; gap: 10px; }
  .section-lead { margin-left: 0; }
  .section-number { font-size: 28px; }
  .steps-grid { grid-template-columns: 1fr; }
  .guide-section { grid-template-columns: 1fr; padding: 35px 20px; gap: 44px; }
  .table-row { grid-template-columns: 1fr .85fr .5fr; padding-left: 7px; padding-right: 7px; }
  .content-heading { grid-template-columns: 1fr; gap: 8px; }
  .info-cards { grid-template-columns: 1fr; }
  .info-cards article { min-height: auto; }
  .info-cards h3 { margin-bottom: 20px; }
  .trouble-table { overflow-x: auto; }
  .trouble-row { min-width: 650px; }
  .test-section { grid-template-columns: 1fr; padding: 36px 22px; gap: 38px; }
  footer { padding: 28px 0; gap: 20px; flex-wrap: wrap; }
  footer p { order: 3; width: 100%; margin: 0; }
}

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