:root {
  --blue: #0071bc;
  --blue-deep: #142b3a;
  --ink: #203746;
  --muted: #596d7b;
  --mist: #f4f7fb;
  --pale: #e9eff8;
  --line: #dbe3eb;
  --red: #eb4841;
  --white: #fff;
  --page: 1160px;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 100px; }
body { margin: 0; color: var(--ink); background: var(--white); font: 16px/1.75 "PingFang SC", "Microsoft YaHei", sans-serif; }
button, input { font: inherit; }
a { color: var(--blue); text-decoration: none; }
a:hover { text-decoration: underline; }
button, a { -webkit-tap-highlight-color: transparent; }
:focus-visible { outline: 3px solid var(--blue); outline-offset: 4px; }
.wrap { width: min(var(--page), calc(100% - 48px)); margin-inline: auto; }
.skip-link { position: fixed; top: -100px; left: 12px; z-index: 50; padding: 8px 16px; background: var(--blue-deep); color: #fff; }
.skip-link:focus { top: 12px; }
.site-header { height: 84px; border-bottom: 1px solid var(--line); background: #fff; position: sticky; top: 0; z-index: 10; }
.header-inner { height: 100%; display: flex; align-items: center; justify-content: space-between; gap: 32px; }
.brand { display: inline-flex; align-items: center; gap: 11px; color: var(--blue-deep); font-weight: 700; font-size: 19px; white-space: nowrap; letter-spacing: -.04em; }
.brand:hover { text-decoration: none; }
.brand-mark { display: block; width: 38px; height: 38px; flex: none; }
.site-nav { display: flex; align-items: center; gap: 32px; }
.site-nav a { color: var(--ink); font-size: 14px; font-weight: 600; padding: 8px 0; position: relative; white-space: nowrap; }
.site-nav a:not(.nav-cta):after { content: ""; position: absolute; left: 0; right: 100%; bottom: 2px; height: 2px; background: var(--blue); transition: right .25s; }
.site-nav a:hover, .site-nav a[aria-current="page"] { color: var(--blue); text-decoration: none; }
.site-nav a:hover:after, .site-nav a[aria-current="page"]:after { right: 0; }
.site-nav .nav-cta { padding: 9px 21px; border-radius: 96px; color: #fff; background: var(--blue-deep); }
.site-nav .nav-cta:hover { background: var(--blue); color: #fff; }
.menu-toggle { display: none; }
.back-to-top { position: fixed; right: calc(20px + env(safe-area-inset-right, 0px)); bottom: calc(20px + env(safe-area-inset-bottom, 0px)); z-index: 11; display: grid; place-items: center; width: 48px; height: 48px; padding: 0; border: 0; border-radius: 50%; background: var(--blue-deep); color: #fff; cursor: pointer; box-shadow: 0 6px 20px rgba(20,43,58,.2); }
.back-to-top:hover { background: var(--blue); }
.back-to-top svg { display: block; width: 22px; height: 22px; }
.hero { padding: 72px 0 70px; background: radial-gradient(circle at 89% 13%, #e8f3fa 0, transparent 32%), linear-gradient(155deg, #fff 45%, #f4f8fc 100%); overflow: hidden; }
.hero-inner { position: relative; }
.hero-copy { max-width: 760px; margin-bottom: 37px; position: relative; z-index: 1; }
.eyebrow, .section-label { color: var(--blue); text-transform: uppercase; letter-spacing: .15em; font: 700 12px/1.4 "Trebuchet MS", "PingFang SC", sans-serif; }
.eyebrow { margin: 0 0 17px; }
h1, h2, h3 { font-family: "Trebuchet MS", "PingFang SC", "Microsoft YaHei", sans-serif; line-height: 1.28; color: var(--blue-deep); letter-spacing: -.035em; }
h1 { font-size: clamp(37px, 4.8vw, 64px); margin: 0 0 17px; font-weight: 700; }
.hero h1 { font-size: clamp(28px, 3.2vw, 40px); }
h2 { font-size: clamp(27px, 3vw, 39px); margin: 0 0 20px; }
h3 { font-size: 21px; margin: 0 0 13px; }
p { margin: 0 0 16px; }
.hero-lead { font-size: 18px; line-height: 1.8; max-width: 670px; color: var(--muted); margin: 0; }
.hero-doodle { position: absolute; width: 215px; height: 180px; right: 5px; top: 10px; opacity: .95; pointer-events: none; }
.tool-panel { background: #fff; border: 1px solid var(--line); border-radius: 12px; overflow: hidden; box-shadow: 0 20px 65px rgba(20,43,58,.075); position: relative; z-index: 1; }
.tool-body { display: grid; grid-template-columns: minmax(0,1.35fr) minmax(280px,.65fr); }
.dropzone { min-height: 350px; margin: 27px; border: 1.5px dashed #a9c5d8; border-radius: 8px; background: linear-gradient(135deg,#f9fcfe,#f2f8fd); display: grid; place-items: center; text-align: center; position: relative; overflow: hidden; transition: background .25s, border-color .25s; }
.dropzone.is-dragging { background: #e3f2fc; border-color: var(--blue); }
.dropzone.has-image { background: #ecf2f6; border-style: solid; border-color: var(--line); }
.dropzone .empty-state { padding: 32px; }
.empty-state svg { width: 82px; margin-bottom: 12px; }
.empty-state h2 { font-size: 24px; margin: 0 0 8px; }
.empty-state p { font-size: 14px; color: var(--muted); margin: 0 0 22px; }
.dropzone img { display: block; max-width: 100%; max-height: 480px; object-fit: contain; }
.dropzone img[hidden], .empty-state[hidden], [hidden] { display: none !important; }
.image-label { position: absolute; bottom: 14px; left: 14px; max-width: calc(100% - 28px); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; background: rgba(20,43,58,.8); color: #fff; border-radius: 4px; padding: 4px 10px; font-size: 12px; }
.tool-controls { padding: 32px 30px 26px 6px; display: flex; flex-direction: column; }
.control-kicker { color: var(--blue); font: 700 12px "Trebuchet MS", sans-serif; letter-spacing: .13em; margin: 0 0 9px; }
.tool-controls h2 { font-size: 24px; margin: 0 0 14px; }
.tool-controls > p:not(.control-kicker) { color: var(--muted); font-size: 14px; line-height: 1.8; }
.file-picker { position: relative; display: inline-flex; align-items: center; justify-content: center; min-height: 48px; border: 1px solid var(--blue); color: var(--blue); background: #fff; border-radius: 96px; font-size: 14px; font-weight: 600; cursor: pointer; padding: 8px 20px; transition: background .25s; }
.file-picker:hover { background: #eaf5fc; }
.file-picker:focus-within { outline: 3px solid var(--blue); outline-offset: 3px; }
.file-picker input { position: absolute; inset: 0; opacity: 0; width: 100%; height: 100%; cursor: pointer; }
.control-actions { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin: 22px 0 12px; }
.btn { min-height: 48px; display: inline-flex; justify-content: center; align-items: center; gap: 6px; border-radius: 96px; border: 1px solid var(--blue-deep); background: var(--blue-deep); color: #fff; padding: 9px 17px; font-size: 14px; font-weight: 600; cursor: pointer; text-decoration: none; transition: background .3s, border-color .3s, color .3s; }
.btn:hover { background: var(--blue); border-color: var(--blue); color: white; text-decoration: none; }
.btn:disabled { opacity: .48; cursor: not-allowed; }
.btn:disabled:hover { background: var(--blue-deep); border-color: var(--blue-deep); }
.btn-outline { background: #fff; color: var(--blue-deep); }
.btn-outline:hover { color: #fff; }
.btn-outline:disabled:hover { background: #fff; border-color: var(--blue-deep); color: var(--blue-deep); }
.tool-controls .file-picker { width: 100%; }
.result-actions { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px;  }
.tool-status { min-height: 44px; font-size: 13px; line-height: 1.5; margin: 8px 0 4px; color: var(--muted); }
.tool-status[data-tone="error"] { color: #aa302b; }
.tool-status[data-tone="success"] { color: #176644; }
.tool-note { border-top: 1px solid var(--line); padding: 15px 28px; display: flex; flex-wrap: wrap; gap: 12px 27px; font-size: 12px; color: var(--muted); }
.tool-note span:before { content: "✓"; font-weight: bold; color: var(--blue); margin-right: 7px; }
.section { padding: 88px 0; }
.section-alt { background: var(--mist); }
.section-head { max-width: 680px; margin-bottom: 37px; }
.section-head > p:last-child { color: var(--muted); font-size: 17px; }
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.step { background: white; border: 1px solid var(--line); border-radius: 8px; padding: 30px; }
.step-num { display: inline-block; color: var(--red); font: 700 28px "Trebuchet MS", sans-serif; margin-bottom: 30px; }
.step p, .card p { color: var(--muted); margin-bottom: 0; }
.split { display: grid; grid-template-columns: .9fr 1.1fr; gap: 85px; align-items: start; }
.split .section-label { margin-top: 9px; }
.text-block p { color: var(--muted); }
.text-block p + p { margin-top: 18px; }
.feature-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.card { padding: 29px; border: 1px solid var(--line); background: #fff; border-radius: 8px; }
.card-icon { display: grid; place-items: center; width: 42px; height: 42px; border-radius: 50%; background: #e7f4fc; color: var(--blue); margin-bottom: 20px; font: 700 20px "Trebuchet MS", sans-serif; }
.callout { background: var(--blue-deep); color: white; padding: 48px; border-radius: 8px; display: flex; align-items: center; justify-content: space-between; gap: 36px; }
.callout h2 { color: white; margin-bottom: 8px; }
.callout p { color: #c7d8e1; margin: 0; }
.callout .btn { flex: none; background: white; border-color: white; color: var(--blue-deep); }
.callout .btn:hover { background: var(--pale); }
.faq-list { border-top: 1px solid var(--line); }
.faq-item { border-bottom: 1px solid var(--line); padding: 24px 0; }
.faq-item h3 { font-size: 18px; margin-bottom: 10px; }
.faq-item p { color: var(--muted); margin: 0; }
.article-hero { padding: 70px 0 56px; background: radial-gradient(circle at 88% 17%, #e1eff8, transparent 30%), var(--mist); }
.article-hero .wrap { max-width: var(--page); }
.article-hero h1 { font-size: clamp(36px,4vw,53px); max-width: 780px; }
.article-hero p:last-child { max-width: 710px; font-size: 18px; color: var(--muted); margin: 0; }
.article-body { padding: 72px 0 90px; }
.article-layout { display: grid; grid-template-columns: minmax(0,740px) minmax(190px,1fr); gap: 76px; align-items: start; }
.article-content h2 { font-size: 29px; margin: 52px 0 16px; scroll-margin-top: 30px; }
.article-content h2:first-child { margin-top: 0; }
.article-content h3 { margin-top: 28px; }
.article-content p, .article-content li { color: #435765; }
.article-content ul, .article-content ol { padding-left: 24px; margin: 0 0 22px; }
.article-content li { padding-left: 4px; margin-bottom: 11px; }
.article-content .info-box { background: var(--mist); border-left: 3px solid var(--blue); padding: 22px 25px; border-radius: 0 6px 6px 0; margin: 26px 0; }
.info-box p:last-child { margin: 0; }
.article-side { border-top: 3px solid var(--blue); padding-top: 18px; position: sticky; top: 108px; }
.article-side strong { display: block; margin-bottom: 13px; }
.article-side a { display: block; font-size: 14px; padding: 8px 0; border-bottom: 1px solid var(--line); }
.article-side .btn { margin-top: 23px; color: white; }
.article-side .btn:hover { color: white; }
.site-footer { background: var(--blue-deep); color: #ccd9e1; padding: 61px 0 26px; }
.footer-grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr; gap: 50px; padding-bottom: 50px; }
.site-footer .brand { color: white; margin-bottom: 17px; }
.site-footer p { font-size: 14px; max-width: 340px; }
.site-footer h2 { font-size: 16px; color: white; margin: 0 0 17px; }
.site-footer a:not(.brand) { display: block; color: #ccd9e1; font-size: 14px; margin: 9px 0; }
.site-footer a:hover { color: white; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,.18); padding-top: 21px; display: flex; justify-content: space-between; gap: 12px; font-size: 12px; }
@media (max-width: 850px) {
  .site-header { height: 72px; }
  .menu-toggle { display: inline-flex; align-items: center; justify-content: center; border: 1px solid var(--line); border-radius: 6px; background: #fff; color: var(--blue-deep); min-width: 44px; min-height: 44px; cursor: pointer; font-size: 22px; }
  .site-nav { display: none; position: absolute; top: 71px; left: 0; right: 0; background: white; padding: 18px 24px 25px; border-bottom: 1px solid var(--line); box-shadow: 0 14px 22px rgba(20,43,58,.08); flex-direction: column; align-items: stretch; gap: 6px; }
  .site-nav.is-open { display: flex; }
  .site-nav a { padding: 10px 0; }
  .site-nav .nav-cta { text-align: center; margin-top: 8px; }
  .hero-doodle { width: 130px; top: 20px; right: -35px; opacity: .32; }
  .tool-body { grid-template-columns: 1fr; }
  .dropzone { height: clamp(300px, 48vh, 400px); min-height: 0; max-height: 400px; margin-bottom: 0; }
  .dropzone img { width: auto; height: auto; max-width: calc(100% - 24px); max-height: min(360px, calc(48vh - 40px)); }
  .tool-controls { padding: 24px 27px 27px; }
  .tool-controls > p:not(.control-kicker) { max-width: 480px; }
  .split, .article-layout { gap: 36px; }
}
@media (max-width: 650px) {
  .wrap { width: min(100% - 32px, var(--page)); }
  .hero { padding: 47px 0 52px; }
  .hero-copy { margin-bottom: 28px; }
  .hero-lead { font-size: 16px; }
  .dropzone { margin: 15px 15px 0; height: 250px; min-height: 250px; max-height: 250px; }
  .dropzone.has-image { height: auto; max-height: 300px; padding: 12px; }
  .dropzone img { max-width: 100%; max-height: 272px; }
  .tool-controls { padding: 22px 18px; }
  .result-actions .btn { padding-inline: 8px; }
  .tool-note { padding: 14px 18px; gap: 4px 16px; }
  .section { padding: 60px 0; }
  .steps, .feature-grid, .split, .article-layout, .footer-grid { grid-template-columns: 1fr; }
  .steps { gap: 12px; }
  .step { padding: 24px; }
  .step-num { margin-bottom: 14px; }
  .split { gap: 24px; }
  .article-hero { padding: 52px 0; }
  .article-body { padding: 53px 0 65px; }
  .article-side { position: static; }
  .callout { display: block; padding: 30px; }
  .callout .btn { margin-top: 22px; }
  .footer-grid { gap: 18px; padding-bottom: 28px; }
  .footer-bottom { display: block; }
}
@media (prefers-reduced-motion: reduce) {
  *, *:before, *:after { scroll-behavior: auto !important; transition-duration: .01ms !important; animation-duration: .01ms !important; }
}