:root {
  color-scheme: light;
  --ink: #172f29;
  --muted: #455f55;
  --green: #08624e;
  --paper: #f8f8f0;
  --line: #cddbd0;
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
}
* { box-sizing: border-box; }
body { margin: 0; color: var(--ink); background: var(--paper); line-height: 1.65; }
a { color: var(--green); text-underline-offset: .2em; }
a:focus-visible, summary:focus-visible { outline: 3px solid #947533; outline-offset: 4px; }
.wrap { width: min(1120px, calc(100% - 48px)); margin-inline: auto; }
.header { min-height: 76px; display: flex; align-items: center; justify-content: space-between; gap: 12px; border-bottom: 1px solid var(--line); }
.brand { display: inline-flex; align-items: center; gap: 9px; color: var(--ink); font-weight: 800; font-size: 1.22rem; text-decoration: none; }
.brand img { border-radius: 8px; }
nav, .footer { display: flex; align-items: center; gap: clamp(12px, 3vw, 32px); }
nav a, .footer a { font-size: .87rem; text-decoration: none; }
nav a:hover, .footer a:hover { text-decoration: underline; }
.hero { display: grid; grid-template-columns: 1.18fr 1fr; align-items: center; gap: clamp(26px, 5vw, 72px); padding-block: 44px 62px; }
.eyebrow { color: var(--green); font-weight: 750; font-size: .88rem; letter-spacing: .08em; margin: 0 0 12px; }
h1, h2, h3 { line-height: 1.28; margin: 0; }
h1 { font-size: clamp(2.25rem, 5.05vw, 4.35rem); letter-spacing: -.045em; }
h2 { font-size: clamp(1.7rem, 3.2vw, 2.55rem); letter-spacing: -.03em; }
h3 { font-size: 1.15rem; }
.lede { color: var(--muted); max-width: 29em; font-size: clamp(1rem, 1.6vw, 1.18rem); margin: 22px 0 28px; }
.button { display: inline-flex; align-items: center; gap: 12px; padding: 12px 20px; min-height: 48px; border-radius: 10px; color: white; background: var(--green); font-weight: 700; text-decoration: none; }
.button:hover { background: #094c3d; }
.demo { margin: 0; padding: 28px 12px 16px; text-align: center; border-radius: 25px; background: radial-gradient(ellipse at 52% 35%, #f2f6df, #dcebe0 78%); }
.demo img { display: block; width: min(230px, 81%); height: auto; margin-inline: auto; border: 5px solid #203630; border-radius: 26px; box-shadow: 0 14px 28px #183b2a30; }
figcaption { font-size: .85rem; color: var(--muted); margin-top: 12px; }
.section { padding-block: 38px 55px; border-top: 1px solid var(--line); }
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 15px; list-style-position: inside; padding: 0; margin: 23px 0 0; }
.steps li { padding: 21px; background: #fffdf7; border: 1px solid var(--line); border-radius: 13px; }
.steps li::marker { color: var(--green); font-weight: 750; }
.steps h3 { display: inline; }
.steps p, .guide p, details p { margin-bottom: 0; color: var(--muted); }
.guide { display: flex; justify-content: space-between; align-items: center; gap: 24px; border-radius: 18px; padding: 28px; margin-bottom: 50px; background: #e5eee2; }
.guide .eyebrow { margin-bottom: 10px; }
.guide-link { flex: none; font-weight: 750; }
.faq h2 { margin-bottom: 16px; }
details { border-bottom: 1px solid var(--line); padding: 12px 0; }
summary { cursor: pointer; font-weight: 650; padding: 4px 0; }
.footer { min-height: 76px; border-top: 1px solid var(--line); }
.footer span { margin-right: auto; font-weight: 750; }
.article { max-width: 700px; padding-block: 48px; }
.article h1 { font-size: clamp(2rem, 6vw, 3.5rem); }
.article h2 { font-size: 1.55rem; margin-top: 32px; }
.article aside { background: #e5eee2; padding: 18px 22px; border-radius: 12px; margin: 24px 0; }
@media (max-width: 700px) {
  .wrap { width: calc(100% - 32px); }
  .header { min-height: 62px; }
  .hero { grid-template-columns: 1fr; padding-block: 34px 42px; }
  .demo { padding-top: 20px; }
  .demo img { width: min(204px, 76%); }
  .steps { grid-template-columns: 1fr; }
  .guide { align-items: flex-start; flex-direction: column; gap: 14px; }
}
.language { font-weight: 750; white-space: nowrap; }
.demo video { display: block; width: min(230px, 81%); height: auto; aspect-ratio: 540 / 1170; margin-inline: auto; border: 5px solid #203630; border-radius: 25px; background: #203630; box-shadow: 0 14px 28px #183b2a30; }
:lang(en) > body h1 { letter-spacing: -.055em; }
@media (max-width: 700px) {
  .demo video { width: min(204px, 85%); }
}
@media (max-width: 380px) {
  .brand img { width: 26px; height: 26px; }
  .brand { font-size: 1rem; gap: 5px; }
  nav { gap: 9px; }
  nav a { font-size: .78rem; }
}

.correction-sheet { padding: clamp(16px, 4vw, 26px); background: #fffdf7; border: 1px solid var(--line); border-radius: 14px; }
.correction-sheet h2 { margin-top: 0; }
.worksheet-actions:not([hidden]) { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 14px; }
.worksheet-button { font: inherit; font-weight: 700; border: 0; cursor: pointer; }
.worksheet-button:focus-visible { outline: 3px solid #947533; outline-offset: 4px; }
.worksheet-fields, .worked-fields { margin-bottom: 0; }
.worksheet-fields div + div { border-top: 1px solid var(--line); margin-top: 10px; padding-top: 10px; }
.worksheet-fields dt, .worked-fields dt { font-weight: 750; }
.worksheet-fields dd, .worked-fields dd { margin: 0; color: var(--muted); }
.worked-fields dd + dt { margin-top: 10px; }

@media print {
  .corrections-guide { background: white; color: black; }
  .corrections-guide .header, .corrections-guide .footer,
  .corrections-guide .article > :not(.correction-sheet), .corrections-guide .worksheet-actions { display: none; }
  .corrections-guide .article { width: auto; max-width: none; padding: 0; }
  .correction-sheet { padding: 0; background: white; border: 0; break-inside: avoid; }
  .correction-sheet h2 { display: none; }
  .correction-sheet::before { content: "Math Test Corrections"; display: block; font-size: 22pt; font-weight: 750; }
  :lang(zh-CN) .correction-sheet::before { content: "数学错题订正模板"; }
  .worksheet-fields div { min-height: 29mm; padding-bottom: 6mm; border-bottom: 1px solid black; }
  .worksheet-fields div + div { border-top: 0; }
  .worksheet-fields dd { color: black; }
}

.section-intro { color: var(--muted); max-width: 60ch; }
.math-example { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 15px; margin-top: 22px; }
.math-example article { padding: 21px; border: 1px solid var(--line); border-radius: 13px; background: #fffdf7; }
.math-example article:nth-child(2) { background: #e5eee2; }
.math-example p:last-child { margin-bottom: 0; }
.equation { font-family: Georgia, serif; font-size: 1.19em; font-variant-numeric: lining-nums; }
.parent-review { display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.parent-review p { max-width: 65ch; margin-bottom: 0; color: var(--muted); }
.parent-review .button { flex-shrink: 0; }
@media (max-width: 700px) {
  .math-example { grid-template-columns: 1fr; }
  .parent-review { flex-direction: column; align-items: flex-start; }
}
.home-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 12px 18px; }
.product-shot { margin: 0; padding: 16px; background: #e5eee2; border-radius: 18px; text-align: center; }
.product-shot img { display: block; width: 100%; height: auto; }
.hero-shot { padding: 18px; background: radial-gradient(ellipse at center, #f2f6df, #dcebe0); }
.hero-shot img { width: min(240px, 100%); margin-inline: auto; }
.product-features { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; margin-top: 22px; }
.product-features article { display: grid; grid-template-columns: minmax(120px, 1fr) 1fr; align-items: center; gap: 18px; padding: 16px; border: 1px solid var(--line); border-radius: 16px; }
.product-features p, .video-section p { color: var(--muted); }
.video-section { display: grid; grid-template-columns: 1fr minmax(240px, .8fr); gap: 24px; align-items: center; }
@media (max-width: 760px) {
  .product-features, .video-section { grid-template-columns: 1fr; }
}
@media (max-width: 380px) {
  .product-features article { gap: 12px; padding: 12px; }
  .product-shot { padding: 10px; }
}

.footer { flex-wrap: wrap; padding-block: 16px; }
.feature-links { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 270px), 1fr)); gap: 14px; padding: 0; list-style: none; }
.feature-links a { display: block; padding: 16px; border: 1px solid var(--line); border-radius: 12px; background: #fffdf7; font-weight: 700; }