/* ========== 双主题变量 ========== */
:root {
  --bg-grad-from: #eef7f0;   /* 薄荷绿淡渐变 */
  --bg-grad-to: #ffffff;
  --panel: #ffffff;
  --panel-2: #f0f4f1;
  --line: #dde7df;
  --text: #16211b;
  --muted: #5c6f64;
  --accent: #1f9d55;
  --accent-strong: #177a42;
  --accent-soft: #dcf2e5;
  --accent-glow: rgba(31, 157, 85, .35);
  --compare-bg: #1a2420;
  --shadow: 0 8px 30px rgba(22, 33, 27, .08);
  --shadow-btn: 0 8px 24px rgba(31, 157, 85, .38), 0 2px 6px rgba(31, 157, 85, .25);
  --radius: 16px;
}
[data-theme="dark"] {
  --bg-grad-from: #0d1512;
  --bg-grad-to: #101a15;
  --panel: #182219;
  --panel-2: #1f2c22;
  --line: #2c3d31;
  --text: #e9f2ec;
  --muted: #93a89a;
  --accent: #3ecf7a;
  --accent-strong: #2aa862;
  --accent-soft: #1c3325;
  --accent-glow: rgba(62, 207, 122, .3);
  --compare-bg: #000;
  --shadow: 0 8px 30px rgba(0, 0, 0, .4);
  --shadow-btn: 0 8px 24px rgba(62, 207, 122, .28), 0 2px 6px rgba(0, 0, 0, .3);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: linear-gradient(180deg, var(--bg-grad-from) 0%, var(--bg-grad-to) 60%);
  background-attachment: fixed;
  color: var(--text); line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  transition: background .3s, color .3s;
}
.wrap { max-width: 900px; margin: 0 auto; padding: 0 20px; }

/* ========== header ========== */
header {
  padding: 18px 0; position: sticky; top: 0; z-index: 10;
  background: color-mix(in srgb, var(--bg-grad-from) 82%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; }
.logo { font-size: 20px; font-weight: 800; letter-spacing: -0.5px; text-decoration: none; color: var(--text); }
.logo .x { color: var(--accent); }
nav { display: flex; align-items: center; gap: 22px; }
nav a { color: var(--muted); text-decoration: none; font-size: 14px; font-weight: 500; }
nav a:hover { color: var(--text); }
.theme-toggle {
  background: var(--panel); border: 1px solid var(--line); border-radius: 999px;
  width: 38px; height: 38px; cursor: pointer; font-size: 17px;
  display: flex; align-items: center; justify-content: center;
  transition: border-color .15s, transform .15s;
}
.theme-toggle:hover { border-color: var(--accent); transform: scale(1.06); }

/* ========== hero ========== */
.hero { text-align: center; padding: 72px 0 8px; }
.hero h1 { font-size: clamp(34px, 5.6vw, 56px); font-weight: 800; letter-spacing: -2px; line-height: 1.1; }
.hero h1 .hl { color: var(--accent); white-space: nowrap; }
.hero p.sub { color: var(--muted); font-size: 18px; margin-top: 16px; max-width: 560px; margin-left: auto; margin-right: auto; }
.hero p.sub b { color: var(--accent); font-weight: 700; }

/* ========== 上传卡(首屏绝对主角) ========== */
.upload-card {
  background: var(--panel); border: 1px solid var(--line); border-radius: 22px;
  box-shadow: var(--shadow); padding: 46px 32px 30px; margin: 40px 0 20px; text-align: center;
  transition: border-color .2s, background .3s;
}
.upload-card.drag { border-color: var(--accent); background: var(--accent-soft); }
.btn-upload {
  display: inline-block; background: var(--accent); color: #fff;
  font-weight: 700; border: none; border-radius: 14px; padding: 20px 56px;
  font-size: 19px; cursor: pointer;
  box-shadow: var(--shadow-btn);
  transition: background .15s, transform .15s, box-shadow .15s;
}
.btn-upload:hover { background: var(--accent-strong); transform: translateY(-2px); }
.btn-upload:active { transform: translateY(0); }
.upload-hints { margin-top: 16px; color: var(--muted); font-size: 14px; }
.upload-hints button.url-link {
  background: none; border: none; padding: 0; cursor: pointer;
  color: var(--accent); font-size: 14px; font-weight: 600;
  border-bottom: 1px dashed var(--accent);
}
.url-row { display: none; margin: 16px auto 0; max-width: 460px; gap: 8px; }
.url-row.on { display: flex; }
.url-row input {
  flex: 1; border: 1px solid var(--line); border-radius: 10px; padding: 12px 14px;
  font-size: 14px; background: var(--panel-2); color: var(--text); outline: none;
}
.url-row input:focus { border-color: var(--accent); }
.url-row button {
  background: var(--accent); color: #fff; border: none; border-radius: 10px;
  padding: 12px 18px; font-weight: 600; cursor: pointer; font-size: 14px;
}
.url-row button:hover { background: var(--accent-strong); }

.samples { margin-top: 30px; }
.samples p { font-size: 14px; color: var(--muted); margin-bottom: 14px; }
.samples p b { color: var(--text); font-weight: 600; }
.sample-row { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }
.sample-btn {
  border: 2px solid var(--line); border-radius: 14px; padding: 0; cursor: pointer;
  overflow: hidden; background: none; width: 118px; height: 88px;
  transition: border-color .15s, transform .2s, box-shadow .2s;
}
.sample-btn:hover { border-color: var(--accent); transform: translateY(-3px) scale(1.03); box-shadow: 0 8px 18px var(--accent-glow); }
.sample-btn img { width: 100%; height: 100%; object-fit: cover; display: block; }

.trust-line { margin-top: 26px; font-size: 13px; color: var(--muted); display: flex; gap: 18px; justify-content: center; flex-wrap: wrap; }
.trust-line span::before { content: "✓ "; color: var(--accent); font-weight: 700; }

/* ========== workspace ========== */
.workspace { display: none; margin: 36px 0 20px; }
.workspace.on { display: block; }
.compare { position: relative; border-radius: var(--radius); overflow: hidden; user-select: none; background: var(--compare-bg); box-shadow: var(--shadow); }
.compare canvas { display: block; width: 100%; height: auto; }
.compare .after-cv { position: absolute; inset: 0; }
.compare .divider {
  position: absolute; top: 0; bottom: 0; width: 3px; background: var(--accent);
  left: 50%; transform: translateX(-50%); pointer-events: none;
}
.compare .divider::after {
  content: "⟷"; position: absolute; top: 50%; left: 50%; transform: translate(-50%,-50%);
  width: 42px; height: 42px; background: var(--accent); color: #fff; border-radius: 50%;
  display: flex; align-items: center; justify-content: center; font-weight: 700; font-size: 18px;
  box-shadow: 0 2px 10px rgba(0,0,0,.3);
}
.compare .tag {
  position: absolute; top: 12px; font-size: 12px; font-weight: 700; padding: 4px 11px;
  border-radius: 6px; background: rgba(0,0,0,.55); backdrop-filter: blur(4px); color: #fff;
}
.compare .tag.l { left: 12px; color: #a7f3c9; }
.compare .tag.r { right: 12px; }

.controls { display: flex; align-items: center; gap: 16px; margin-top: 22px; flex-wrap: wrap; }
.controls label { font-size: 14px; color: var(--muted); white-space: nowrap; font-weight: 500; }
input[type=range] { flex: 1; min-width: 140px; accent-color: var(--accent); height: 28px; }
.strength-val { font-variant-numeric: tabular-nums; color: var(--accent); font-weight: 700; width: 46px; }
.actions { display: flex; gap: 12px; margin-top: 22px; flex-wrap: wrap; }
.btn {
  display: inline-block; background: var(--accent); color: #fff;
  font-weight: 700; border: none; border-radius: 12px; padding: 14px 28px;
  font-size: 15px; cursor: pointer; text-decoration: none; transition: background .15s, transform .1s;
}
.btn:hover { background: var(--accent-strong); transform: translateY(-1px); }
.btn.ghost { background: var(--panel); color: var(--text); border: 1px solid var(--line); }
.btn.ghost:hover { border-color: var(--accent); }
.btn:disabled { opacity: .45; cursor: not-allowed; transform: none; }
.privacy-note { font-size: 13px; color: var(--muted); margin-top: 14px; display: flex; align-items: center; gap: 6px; }
.privacy-note::before { content: "🔒"; }

/* ========== sections ========== */
section.block { padding: 52px 0; border-top: 1px solid var(--line); }
section.block h2 { font-size: 28px; font-weight: 800; letter-spacing: -0.6px; margin-bottom: 18px; }
section.block p, section.block li { color: var(--muted); }
section.block a { color: var(--accent); }
.steps { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 16px; margin-top: 24px; }
.step { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 24px; transition: background .3s; }
.step .num { font-size: 30px; font-weight: 800; color: var(--accent); opacity: .4; }
.step h3 { font-size: 16px; margin: 8px 0 6px; }
.step p { font-size: 14px; }

.faq details { border: 1px solid var(--line); border-radius: 12px; margin-bottom: 10px; background: var(--panel); }
.faq summary { padding: 17px 18px; cursor: pointer; font-weight: 600; font-size: 15px; list-style: none; }
.faq summary::before { content: "+"; color: var(--accent); margin-right: 10px; font-weight: 700; }
.faq details[open] summary::before { content: "–"; }
.faq details p { padding: 0 18px 17px; font-size: 14px; }

/* ========== hero 案例对比滑块 ========== */
.demo-card {
  background: var(--panel); border: 1px solid var(--line); border-radius: 22px;
  box-shadow: var(--shadow); padding: 22px 22px 18px; margin: 30px 0 10px;
}
.demo-compare {
  position: relative; border-radius: 14px; overflow: hidden; user-select: none;
  background: var(--compare-bg); aspect-ratio: 3/2; max-height: 420px; cursor: ew-resize;
}
.demo-img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; pointer-events: none; }
.demo-after { position: absolute; inset: 0; clip-path: inset(0 0 0 50%); }
.demo-divider {
  position: absolute; top: 0; bottom: 0; width: 3px; background: var(--accent);
  left: 50%; transform: translateX(-50%); pointer-events: none;
}
.demo-divider::after {
  content: "⟷"; position: absolute; top: 50%; left: 50%; transform: translate(-50%,-50%);
  width: 44px; height: 44px; background: var(--accent); color: #fff; border-radius: 50%;
  display: flex; align-items: center; justify-content: center; font-weight: 700; font-size: 18px;
  box-shadow: 0 2px 12px rgba(0,0,0,.35);
}
.demo-tag {
  position: absolute; top: 14px; font-size: 12px; font-weight: 700; padding: 5px 12px;
  border-radius: 8px; background: rgba(0,0,0,.6); backdrop-filter: blur(4px); color: #fff;
}
.demo-tag.l { left: 14px; color: #a7f3c9; }
.demo-tag.r { right: 14px; }
.demo-caption { text-align: center; color: var(--muted); font-size: 14px; margin-top: 14px; }
.demo-switch { display: flex; align-items: center; gap: 10px; justify-content: center; margin-top: 14px; }
.demo-switch span { font-size: 13px; color: var(--muted); }
.demo-thumb {
  border: 2px solid var(--line); border-radius: 10px; padding: 0; cursor: pointer;
  overflow: hidden; background: none; width: 64px; height: 48px;
  transition: border-color .15s, transform .15s;
}
.demo-thumb:hover, .demo-thumb.on { border-color: var(--accent); transform: scale(1.05); }
.demo-thumb img { width: 100%; height: 100%; object-fit: cover; display: block; }

/* ========== 模式切换 ========== */
.mode-tabs { display: flex; gap: 10px; justify-content: center; margin-bottom: 28px; flex-wrap: wrap; }
.mode-tab {
  background: var(--panel-2); color: var(--muted); border: 1.5px solid var(--line);
  border-radius: 999px; padding: 11px 22px; font-size: 14px; font-weight: 600;
  cursor: pointer; transition: all .15s;
}
.mode-tab:hover { border-color: var(--accent); color: var(--text); }
.mode-tab.on { background: var(--accent-soft); border-color: var(--accent); color: var(--accent-strong); font-weight: 700; }
[data-theme="dark"] .mode-tab.on { color: var(--accent); }

.upload-divider { display: flex; align-items: center; gap: 14px; margin: 24px 0 20px; color: var(--muted); font-size: 13px; }
.upload-divider::before, .upload-divider::after { content: ""; flex: 1; height: 1px; background: var(--line); }
.drop-inner.drag .btn-upload { outline: 3px solid var(--accent-glow); }

/* video 页进度条 */
.progress-track { height: 8px; background: var(--panel-2); border-radius: 99px; overflow: hidden; margin-top: 8px; }
.progress-fill { height: 100%; width: 0%; background: var(--accent); transition: width .2s; }

footer { border-top: 1px solid var(--line); padding: 32px 0 54px; color: var(--muted); font-size: 13px; margin-top: 40px; }
footer a { color: var(--muted); }

@media (max-width: 640px) {
  .header-inner { flex-wrap: wrap; gap: 10px; }
  nav { gap: 14px; }
  .upload-card { padding: 32px 18px 24px; }
  .btn-upload { padding: 17px 40px; font-size: 17px; }
  .sample-btn { width: 96px; height: 72px; }
  .hero { padding: 48px 0 4px; }
}