/* 系统字体与固定媒体占位避免第三方请求及加载后的布局跳动。 */
:root { color-scheme: light; --ink: #172b40; --muted: #4d6073; --blue: #245b9f; --line: #d9e3ed; }
* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-padding-top: 20px; }
body { margin: 0 auto; max-width: 900px; padding: 20px 28px; color: var(--ink); background: #f7f9fc; font-family: system-ui, -apple-system, "Segoe UI", sans-serif; line-height: 1.65; }
a { color: var(--blue); text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid #a54c00; outline-offset: 4px; }
.sr-only, .skip-link:not(:focus) { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; }
.skip-link:focus { display: block; padding: 12px; background: #fff; }
header.site { display: flex; align-items: center; justify-content: space-between; gap: 16px; padding: 4px 0 24px; }
.brand { display: inline-flex; align-items: center; gap: 8px; font-size: 1.12rem; font-weight: 750; color: var(--ink); text-decoration: none; }
header nav { display: flex; gap: 22px; font-size: .9rem; }
header nav a { padding: 10px 0; }
h1, h2, h3 { line-height: 1.23; text-wrap: balance; }
h1 { font-size: clamp(2rem, 5vw, 2.9rem); letter-spacing: -.035em; margin: .2em 0 .45em; max-width: 780px; }
h2 { font-size: 1.45rem; letter-spacing: -.018em; margin: 0 0 16px; }
h3 { font-size: 1.05rem; margin: 0 0 10px; }
p { margin: 0 0 16px; }
.hero { padding: 16px 0 8px; }
.eyebrow { color: var(--blue); font-size: .82rem; font-weight: 750; letter-spacing: .055em; text-transform: uppercase; margin-bottom: 12px; }
.sub { font-size: 1.1rem; color: var(--muted); max-width: 720px; }
.benefits { list-style: none; display: flex; flex-wrap: wrap; gap: 8px 20px; padding: 0; margin: 18px 0; font-weight: 650; font-size: .93rem; }
.benefits li::before { content: "✓"; color: #237453; margin-right: 7px; }
.tool { margin-top: 10px; padding: 24px; border: 1px solid var(--line); border-radius: 20px; background: #fff; box-shadow: 0 8px 30px #172b4008; }
.drop { border: 2px dashed #87a8cb; border-radius: 12px; padding: 18px; text-align: center; background: #f2f7fd; cursor: pointer; }
.drop.dragover, .drop:hover { border-color: var(--blue); background: #e7f0fb; }
.drop[aria-disabled="true"] { cursor: wait; }
.drop input { display: none; }
.drop p { margin: 4px 0 0; }
.drop p strong { color: var(--blue); font-size: 1.12rem; }
.drop p span { color: var(--muted); font-size: .9rem; }
.upload-icon { display: inline-block; font-size: 1.8rem; line-height: 1; color: var(--blue); }
.hint { color: var(--muted); font-size: .85rem; margin: 10px 0 0; }
.availability { font-size: .9rem; margin: 16px 0 0; }
#queue { list-style: none; padding: 0; margin: 0; }
#queue li { background: #f3f6fa; border: 1px solid var(--line); border-radius: 10px; padding: 12px; margin-top: 14px; }
.row-name { font-weight: 650; overflow-wrap: anywhere; }
.row-status { font-size: .9rem; color: var(--muted); }
#queue progress { display: block; width: 100%; height: 10px; margin: 10px 0; accent-color: var(--blue); }
#queue .row-remove { font-size: .85rem; padding: 8px 12px; margin-top: 8px; background: #fff; color: var(--blue); border-color: var(--line); }
#queue li.failed { border-color: #ba3434; }
#queue li.failed .row-status { color: #902323; }
#actions { margin-top: 22px; padding-top: 18px; border-top: 1px solid var(--line); }
button, .button { font: inherit; font-size: .98rem; padding: 11px 18px; border: 1px solid transparent; border-radius: 8px; cursor: pointer; min-height: 44px; }
button.primary, a.button.primary { background: var(--blue); color: #fff; }
button.secondary { background: #fff; color: var(--blue); border-color: var(--blue); }
button:disabled { background: #e3e9f0; color: #506070; border-color: #cbd6e2; cursor: not-allowed; }
#paid-box > button { margin: 8px 8px 0 0; }
a.button { display: inline-block; text-decoration: none; margin-top: 12px; }
.field { margin: 16px 0; }
.field label { display: block; font-weight: 600; margin-bottom: 6px; }
.field input[type="range"] { width: 100%; min-height: 44px; accent-color: var(--blue); }
.field select { width: 100%; font: inherit; padding: 10px; border: 1px solid #9eb3c9; border-radius: 6px; background: #fff; color: var(--ink); }
.error { color: #902323; padding: 12px; border-radius: 8px; background: #fff0f0; margin: 12px 0; overflow-wrap: anywhere; }
.status { color: #294f78; margin: 16px 0 0; }
.status:empty { margin: 0; }
#result, #ab { border-top: 1px solid var(--line); margin-top: 24px; padding-top: 24px; }
.compare { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 22px; }
.compare > div { min-width: 0; }
video, audio { display: block; width: 100%; }
video { aspect-ratio: 16 / 9; background: #132538; border-radius: 8px; }
video.audio-only, .audio-only video { aspect-ratio: auto; height: 64px; }
audio { height: 54px; }
#result a:not(.button) { overflow-wrap: anywhere; }
.section { padding: 32px 0; border-bottom: 1px solid var(--line); }
.sample { border: 1px solid var(--line); background: #fff; padding: 20px; border-radius: 14px; }
.sample h3 { font-size: .95rem; }
.samples > p:not(.eyebrow) { color: var(--muted); }
.steps { padding-left: 25px; }
.steps li { margin: 14px 0; padding-left: 6px; }
.steps li::marker { color: var(--blue); font-weight: 750; }
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; font-size: .9rem; }
caption { text-align: left; color: var(--muted); padding: 8px 0; }
th, td { text-align: left; padding: 12px 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
thead { background: #eaf0f7; }
tbody th { font-weight: 500; }
td:nth-child(2) { white-space: nowrap; }
details { border-top: 1px solid var(--line); padding: 14px 0; }
summary { cursor: pointer; font-weight: 600; min-height: 32px; }
details p { margin: 12px 0 0; color: var(--muted); }
article.content { margin-top: 28px; }
article.content h2 { margin-top: 1.6em; }
article.content h3 { margin-top: 1.3em; }
article.content li { margin: 7px 0; }
.legal .updated { color: var(--muted); font-size: .9rem; }
code { background: #eaf0f7; padding: 1px 4px; border-radius: 4px; overflow-wrap: anywhere; }
footer.site { padding: 28px 0 20px; color: var(--muted); font-size: .85rem; }
footer nav { line-height: 2.5; }
footer p { margin: 10px 0 0; }
@media (max-width: 600px) {
  body { padding: 16px; }
  header.site { flex-wrap: wrap; gap: 4px 16px; padding-bottom: 14px; }
  header nav { gap: 18px; font-size: .85rem; }
  .hero { padding-top: 4px; }
  h1 { font-size: 2rem; }
  .sub { font-size: 1rem; }
  .tool { padding: 16px; border-radius: 14px; }
  .compare { grid-template-columns: 1fr; gap: 20px; }
  .sample { padding: 16px; }
  .section { padding: 26px 0; }
  .benefits { gap: 8px 14px; font-size: .85rem; }
  th, td { padding: 10px 6px; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }