/* 页面视觉与响应式布局；交互状态由 app.js 通过原生属性控制。 */
:root {
  color-scheme: light;
  --ink: #20352e;
  --muted: #66766c;
  --paper: #f6f5ea;
  --accent: #d4f16c;
  --line: #d6ddd0;
  font-family: "Trebuchet MS", "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--paper);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; }
a { color: inherit; }
button, input, select { font: inherit; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }
button, a { -webkit-tap-highlight-color: transparent; }
:focus-visible { outline: 3px solid #588a27; outline-offset: 4px; }
[hidden] { display: none !important; }
.wrap { width: min(1280px, calc(100% - 80px)); margin-inline: auto; }
.skip-link { position: fixed; top: 8px; left: 8px; z-index: 10; padding: 12px; background: white; transform: translateY(-160%); }
.skip-link:focus { transform: translateY(0); }

.site-header { height: 90px; padding: 0 5.5%; display: flex; align-items: center; justify-content: space-between; border-bottom: 1px solid var(--line); }
.brand { display: inline-flex; align-items: center; gap: 12px; text-decoration: none; font-size: 21px; font-weight: 800; letter-spacing: -1px; }
.brand-accent, .footer-brand span { color: #91ab43; }
.brand-mark { width: 31px; height: 31px; background: var(--ink); border-radius: 50%; display: flex; align-items: center; justify-content: center; gap: 2px; }
.brand-mark i { width: 2px; height: 9px; border-radius: 4px; background: var(--accent); }
.brand-mark i:nth-child(2) { height: 15px; }
.brand-mark i:nth-child(3) { height: 19px; }
.brand-mark i:nth-child(4) { height: 11px; }
.header-actions { display: flex; align-items: center; gap: 24px; }
.header-link { font-size: 13px; font-weight: 700; text-decoration: none; }
.header-link span[aria-hidden] { margin-left: 8px; }
.language-picker select { min-height: 40px; padding: 0 9px; border: 1px solid #cbd6c5; border-radius: 5px; background: #fffef8; color: var(--ink); font-size: 12px; cursor: pointer; }

.hero { min-height: 670px; display: grid; grid-template-columns: 1fr minmax(390px, 520px); gap: 8%; align-items: center; padding-block: 76px 90px; }
.hero-copy { position: relative; }
.eyebrow, .card-kicker, .detail-number, .result-label { font-size: 10px; letter-spacing: .16em; font-weight: 800; }
.eyebrow { display: flex; align-items: center; gap: 10px; color: #566c5c; }
.eyebrow-dot { width: 8px; height: 8px; border-radius: 50%; background: #98b94c; }
h1, h2, h3, p { margin-top: 0; }
h1, .details-intro h2 { font-family: Georgia, "Times New Roman", serif; font-weight: 400; letter-spacing: -.055em; }
h1 { margin: 30px 0 25px; font-size: clamp(58px, 6.8vw, 98px); line-height: .99; }
h1 em, .details-intro em { font-weight: 400; color: #708b54; }
.title-dot { color: #a6c656; }
.hero-description { max-width: 390px; color: #596c60; font-size: 16px; line-height: 1.7; }
.hero-footnote { display: flex; align-items: center; gap: 12px; margin-top: 65px; font-size: 9px; font-weight: 800; letter-spacing: .16em; color: #819083; }
.footnote-line { width: 40px; height: 1px; background: #a5b4a6; }

.converter-card { padding: 34px; background: #fffef8; border: 1px solid #dbe1d4; border-radius: 12px; box-shadow: 0 20px 60px #354b3010; }
.card-heading { display: flex; align-items: center; justify-content: space-between; }
.card-kicker { margin-bottom: 10px; color: #71806c; }
.card-kicker span { color: #abb7a4; }
.card-heading h2 { margin-bottom: 0; font-family: Georgia, serif; font-size: 32px; letter-spacing: -.04em; font-weight: 400; }
.card-symbol { display: grid; place-items: center; width: 43px; height: 43px; background: #edf4db; border-radius: 50%; font-size: 21px; }
.card-description { margin: 10px 0 24px; color: var(--muted); font-size: 13px; }
.upload-zone { position: relative; border: 1px dashed #aabda0; background: #f7faef; border-radius: 7px; transition: background .2s, border-color .2s; }
.upload-zone:hover, .upload-zone:focus-within, .upload-zone.is-dragover { background: #eff7df; border-color: #6e9552; }
.upload-label { min-height: 184px; padding: 20px; display: flex; align-items: center; justify-content: center; flex-direction: column; cursor: pointer; text-align: center; }
.upload-icon { display: grid; place-items: center; width: 38px; height: 38px; margin-bottom: 13px; border: 1px solid #c9d9b7; border-radius: 50%; font-size: 22px; }
.upload-title { font-size: 14px; font-weight: 800; }
.upload-subtitle { margin-top: 6px; color: #78877a; font-size: 12px; }
.browse-text { color: #466b35; text-decoration: underline; text-underline-offset: 3px; font-weight: 700; }
.upload-formats { margin-top: 18px; color: #829080; font-size: 10px; letter-spacing: .06em; }
#file-input { position: absolute; width: 1px; height: 1px; overflow: hidden; clip-path: inset(50%); }
.file-help { margin: 10px 0; font-size: 11px; color: #66766c; line-height: 1.5; }
.selected-file { display: flex; align-items: center; gap: 12px; margin: 16px 0; padding: 14px; border: 1px solid #cbdcc0; border-radius: 7px; background: #f3f8eb; }
.file-icon { display: grid; flex: 0 0 42px; height: 42px; place-items: center; border-radius: 6px; background: #dcebc9; font-size: 20px; }
.file-details { display: grid; min-width: 0; flex: 1; gap: 3px; }
.file-caption { color: #61765b; font-size: 9px; font-weight: 800; letter-spacing: .12em; }
#file-name { color: var(--ink); font-size: 13px; font-weight: 800; overflow-wrap: anywhere; }
#file-meta { color: #5f7062; font-size: 12px; }
.change-file { padding: 10px 4px; border: 0; background: transparent; color: #3e6336; font-size: 12px; font-weight: 800; text-decoration: underline; text-underline-offset: 3px; cursor: pointer; }
.selected-file:focus-within { outline: 3px solid #588a27; outline-offset: 4px; }
.button { display: flex; width: 100%; min-height: 52px; align-items: center; justify-content: space-between; padding: 0 18px; border: 0; border-radius: 5px; text-align: left; text-decoration: none; font-weight: 800; font-size: 13px; cursor: pointer; }
.button-primary { background: var(--ink); color: #fff; }
.button-primary:hover:not(:disabled) { background: #365847; }
.button:disabled { cursor: not-allowed; opacity: .55; }
.button-download { background: var(--accent); color: var(--ink); }
.conversion-status { color: #617363; font-size: 12px; line-height: 1.5; }
.conversion-status p { margin: 12px 0 0; }
progress { display: block; width: 100%; height: 8px; margin-top: 10px; accent-color: #6d9841; }
.result-panel { margin-top: 18px; padding-top: 18px; border-top: 1px solid var(--line); }
.result-label { color: #667c50; }
.reset-button { display: block; margin: 12px auto 0; padding: 5px; border: 0; background: transparent; color: #496743; font-size: 12px; text-decoration: underline; cursor: pointer; }
.card-privacy { margin-top: 20px; padding-top: 18px; border-top: 1px solid #e6ebdf; color: #697b6b; font-size: 11px; line-height: 1.5; }
.card-privacy span { margin-right: 5px; color: #8cab55; }

.details { background: #e8eddf; border-top: 1px solid #dce4d5; }
.details-inner { display: grid; grid-template-columns: 1.5fr repeat(2, 1fr); gap: 40px; padding-block: 68px 76px; }
.details-intro h2 { margin: 20px 0 0; font-size: clamp(30px, 3vw, 43px); line-height: 1.12; }
.detail-item { padding-top: 4px; }
.detail-number { display: block; color: #768a70; }
.detail-item h3 { margin: 29px 0 11px; font-size: 15px; }
.detail-item p { margin-bottom: 0; color: #5f7062; font-size: 13px; line-height: 1.7; }
.site-footer { min-height: 90px; display: flex; align-items: center; justify-content: space-between; gap: 15px; color: #728275; font-size: 11px; }
.footer-brand { color: var(--ink); font-size: 15px; font-weight: 800; letter-spacing: -.05em; }
.site-footer a { text-decoration: none; font-weight: 700; }

@media (max-width: 850px) {
  .hero { grid-template-columns: 1fr 1fr; gap: 35px; }
  h1 { font-size: clamp(52px, 7vw, 70px); }
  .converter-card { padding: 25px; }
  .details-inner { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 640px) {
  .wrap { width: calc(100% - 40px); }
  .site-header { min-height: 70px; height: auto; padding: 12px 20px; gap: 12px; flex-wrap: wrap; }
  .header-actions { gap: 12px; }
  .header-link { font-size: 12px; }
  .hero { grid-template-columns: 1fr; gap: 12px; padding-block: 22px 45px; }
  h1 { margin: 8px 0 10px; font-size: clamp(38px, 10vw, 52px); }
  .hero-copy .eyebrow, .hero-footnote { display: none; }
  .hero-description { margin-bottom: 4px; font-size: 13px; line-height: 1.4; }
  .converter-card { padding: 24px; }
  .details-inner { grid-template-columns: 1fr; gap: 30px; padding-block: 50px; }
  .detail-item h3 { margin-top: 12px; }
  .site-footer { padding-block: 25px; flex-wrap: wrap; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
}