@font-face { font-family: 'Noto Sans SC'; src: url('./assets/noto-sans-sc.woff2') format('woff2'); font-weight: 100 900; font-style: normal; font-display: swap; }
:root {
  --font: 'Noto Sans SC', 'Microsoft YaHei', sans-serif;
  --ink: #192d38;
  --muted: #566771;
  --green: #087e6f;
  --green-hover: #06685b;
  --line: #dfe9e9;
  --soft: #f5f9fa;
  --white: #ffffff;
  --blue: #34658d;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 2rem; }
body { margin: 0; color: var(--ink); background: var(--white); font: 400 0.9375rem/1.8 var(--font); letter-spacing: 0; }
h1, h2, h3, h4, p { margin: 0; }
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; }
img { display: block; max-width: 100%; }
button, a, summary { -webkit-tap-highlight-color: transparent; }
:focus-visible { outline: 2px solid var(--green); outline-offset: 5px; }
.container { width: min(calc(100% - 6rem), 80rem); margin-inline: auto; }
.icon { width: 1.25rem; height: 1.25rem; flex: 0 0 auto; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.skip-link { position: fixed; top: -5rem; left: 1rem; background: white; padding: 1rem; z-index: 50; }
.skip-link:focus { top: 1rem; }
.site-header { background: var(--white); border-bottom: 1px solid var(--line); }
.header-inner { min-height: 5rem; display: flex; align-items: center; justify-content: space-between; gap: 2rem; }
.brand img { width: 7.75rem; height: auto; }
nav { display: flex; align-items: center; gap: 2.25rem; font-size: 0.8125rem; font-weight: 500; }
nav a { padding-block: 0.75rem; }
nav a:hover { color: var(--green); }
.nav-student { display: flex; align-items: center; gap: 0.4rem; color: var(--green); }
.nav-student .icon { width: 1rem; height: 1rem; }
.hero { position: relative; isolation: isolate; overflow: hidden; background: #f7fcfd; }
.hero-art { position: absolute; inset: 0; z-index: -2; width: 100%; height: 100%; object-fit: cover; object-position: 68% center; }
.hero::after { content: ''; position: absolute; inset: 0; z-index: -1; background: linear-gradient(90deg, rgb(248 253 254 / 99%) 0%, rgb(248 253 254 / 97%) 31%, rgb(248 253 254 / 80%) 48%, rgb(248 253 254 / 14%) 78%); }
.hero-inner { padding-block: 2.5rem 1.75rem; min-height: 36rem; display: flex; align-items: center; }
.hero-copy { width: 44rem; max-width: 62%; }
.eyebrow { display: flex; gap: 0.6rem; align-items: center; font-size: 0.8125rem; font-weight: 500; color: var(--green); }
.eyebrow > span { width: 0.375rem; height: 0.375rem; border-radius: 50%; background: #0db69c; }
h1 { margin-top: 0.6rem; font-size: 3.75rem; font-weight: 700; line-height: 1.25; }
h1 span { font-weight: 400; }
.hero-tagline { margin-top: 1rem; font-size: 1.5rem; font-weight: 600; line-height: 1.65; }
.hero-description { margin-top: 0.65rem; color: var(--muted); font-size: 0.875rem; }
.download-area { margin-top: 1.6rem; }
.download-button { display: inline-flex; align-items: center; justify-content: center; gap: 0.85rem; background: var(--green); color: white; border-radius: 6px; min-height: 3.75rem; padding: 0.9rem 1.4rem; font-size: 1rem; font-weight: 600; box-shadow: 0 6px 18px rgb(8 126 111 / 16%); transition: background 160ms, transform 160ms; }
.download-button:hover { background: var(--green-hover); transform: translateY(-2px); }
.download-button:active { transform: none; }
.download-button .icon:last-child { width: 1rem; height: 1rem; margin-left: 0.3rem; }
.download-meta { display: flex; flex-wrap: wrap; align-items: center; gap: 0.4rem 1rem; margin-top: 0.6rem; font-size: 0.6875rem; color: var(--muted); }
.download-meta > span { display: inline-flex; gap: 0.4rem; align-items: center; }
.download-meta .icon { width: 0.875rem; height: 0.875rem; }
.download-meta p { padding-left: 1rem; border-left: 1px solid #cedadf; }
.install-guide { margin-top: 2rem; }
.guide-heading { display: flex; align-items: baseline; justify-content: space-between; gap: 1rem; margin-bottom: 0.75rem; }
.guide-heading h2 { font-size: 0.875rem; font-weight: 600; }
.guide-heading > span { font-size: 0.6875rem; color: var(--muted); }
.install-steps { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0.625rem; padding: 0; margin: 0; list-style: none; }
.install-step { position: relative; padding: 0.8rem 0.75rem; border: 1px solid rgb(192 216 220 / 70%); background: rgb(255 255 255 / 87%); border-radius: 6px; min-height: 9.8rem; }
.step-top { display: flex; align-items: center; justify-content: space-between; margin-bottom: 0.65rem; color: var(--green); }
.step-number { font-size: 0.6875rem; font-weight: 600; }
.step-top .icon { width: 1.1rem; height: 1.1rem; }
.install-step h3 { font-size: 0.8125rem; line-height: 1.6; }
.install-step p { color: var(--muted); font-size: 0.6875rem; margin-top: 0.35rem; line-height: 1.85; }
.install-step p br { display: none; }
.step-caption { display: block; margin-top: 0.65rem; font-size: 0.625rem; color: #69808a; }
.help-link { display: inline-flex; align-items: center; gap: 0.4rem; font-size: 0.6875rem; color: var(--muted); margin-top: 0.75rem; }
.help-link .icon { width: 0.875rem; height: 0.875rem; }
.help-link span { color: var(--green); margin-left: 0.3rem; border-bottom: 1px solid #8dc7ba; }
.classroom-section { padding-block: 3.75rem; border-top: 1px solid var(--line); }
.section-heading { display: flex; justify-content: space-between; align-items: end; gap: 2rem; margin-bottom: 2rem; }
.section-kicker { color: var(--green); font-size: 0.75rem; font-weight: 500; margin-bottom: 0.5rem; }
h2 { font-size: 1.875rem; font-weight: 600; line-height: 1.5; }
.section-heading > p { color: var(--muted); font-size: 0.8125rem; }
.classroom-grid { display: grid; grid-template-columns: 1.1fr 1fr; gap: 4rem; }
.teacher-flow { padding-block: 0.75rem; }
.role-heading { display: flex; align-items: center; gap: 0.65rem; color: var(--green); }
.role-heading h3 { font-size: 1rem; color: var(--ink); }
.role-heading > span { margin-left: auto; color: var(--muted); font-size: 0.6875rem; }
.first-use-steps { list-style: none; padding: 0; margin: 1.5rem 0 0; }
.first-use-steps li { display: flex; align-items: start; gap: 1rem; padding-bottom: 1.5rem; }
.first-use-steps li:last-child { padding-bottom: 0; }
.first-use-steps li > span { width: 1.5rem; height: 1.5rem; border: 1px solid #a9ccc5; border-radius: 50%; color: var(--green); display: flex; align-items: center; justify-content: center; font-size: 0.6875rem; flex-shrink: 0; margin-top: 0.15rem; }
h4 { font-size: 0.9375rem; font-weight: 500; }
.first-use-steps p { font-size: 0.8125rem; color: var(--muted); margin-top: 0.3rem; }
.student-entry { padding: 1.75rem 2rem; background: #eef5fa; border-left: 3px solid #83b8d5; }
.student-entry .role-heading { color: var(--blue); }
.student-description { margin-top: 1.1rem; font-size: 0.875rem; color: var(--muted); }
.student-url { display: flex; align-items: center; gap: 0.7rem; width: fit-content; margin-top: 0.65rem; font-size: 1.875rem; font-weight: 600; color: #255779; overflow-wrap: anywhere; line-height: 1.5; }
.student-url .icon { width: 1.5rem; height: 1.5rem; }
.student-actions { display: flex; flex-wrap: wrap; gap: 0.75rem; align-items: center; margin-top: 1.2rem; }
.student-button { background: #285d80; color: white; min-height: 2.8rem; padding: 0.5rem 1rem; display: inline-flex; align-items: center; justify-content: center; gap: 0.75rem; border-radius: 4px; font-size: 0.8125rem; font-weight: 500; }
.student-button:hover { background: #214e6c; }
.student-button .icon { width: 1rem; height: 1rem; }
.copy-button { display: inline-flex; gap: 0.45rem; align-items: center; min-height: 2.8rem; padding: 0.5rem 0.4rem; background: none; border: none; color: #285d80; font-size: 0.8125rem; }
.copy-button .icon { width: 1rem; height: 1rem; }
.copy-button:hover { text-decoration: underline; }
.student-note { margin-top: 1.1rem; color: var(--muted); font-size: 0.75rem; line-height: 1.9; }
.sync-strip { margin-top: 2rem; display: flex; align-items: center; gap: 1rem; padding-block: 1.25rem 0; border-top: 1px solid var(--line); }
.sync-strip > .icon { width: 1.5rem; height: 1.5rem; color: var(--green); }
.sync-strip strong { font-weight: 500; font-size: 0.875rem; }
.sync-strip p > span { display: block; margin-top: 0.25rem; color: var(--muted); font-size: 0.75rem; }
.tools-section { padding-block: 3.75rem; background: var(--soft); border-block: 1px solid var(--line); }
.tools-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 2rem; }
.tool-art { width: 100%; aspect-ratio: 16 / 9; height: auto; object-fit: cover; border-radius: 6px; }
.tool h3 { font-size: 1.0625rem; margin-top: 1.1rem; font-weight: 600; }
.tool p { font-size: 0.8125rem; color: var(--muted); margin-top: 0.4rem; }
.help-section { padding-block: 4rem; }
.help-layout { display: grid; grid-template-columns: 1fr 1.8fr; gap: 4rem; }
.help-intro { margin-top: 1rem; color: var(--muted); font-size: 0.8125rem; }
.text-link { display: inline-flex; align-items: center; gap: 0.5rem; margin-top: 1.5rem; font-size: 0.8125rem; color: var(--green); }
.text-link .icon { width: 1rem; height: 1rem; }
.faq-list { border-top: 1px solid var(--line); }
details { border-bottom: 1px solid var(--line); }
summary { display: flex; justify-content: space-between; align-items: center; gap: 1rem; padding-block: 1.1rem; font-size: 0.875rem; font-weight: 500; list-style: none; cursor: pointer; }
summary::-webkit-details-marker { display: none; }
summary .icon { color: var(--muted); width: 1rem; height: 1rem; transition: transform 160ms; }
details[open] summary .icon { transform: rotate(45deg); }
details p { color: var(--muted); font-size: 0.8125rem; padding-bottom: 1.2rem; line-height: 1.95; }
details p a { color: var(--green); text-decoration: underline; }
.site-footer { border-top: 1px solid var(--line); }
.footer-inner { min-height: 5.5rem; display: flex; align-items: center; gap: 1.5rem; font-size: 0.6875rem; color: var(--muted); }
.footer-inner img { width: 5rem; height: auto; }
.footer-inner > a:nth-last-child(2) { margin-left: auto; display: flex; align-items: center; gap: 0.3rem; }
.footer-inner .icon { width: 0.875rem; height: 0.875rem; }
.toast { position: fixed; z-index: 60; bottom: 1.5rem; left: 50%; transform: translate(-50%, 0.5rem); width: max-content; max-width: calc(100% - 2rem); padding: 0.9rem 1.3rem; background: #203d42; color: white; border-radius: 6px; box-shadow: 0 8px 24px rgb(17 35 43 / 15%); font-size: 0.8125rem; opacity: 0; pointer-events: none; transition: opacity 160ms, transform 160ms; }
.toast.is-visible { opacity: 1; transform: translate(-50%, 0); }
@media (min-width: 1600px) { .hero-inner { min-height: 43rem; } }
@media (max-width: 1100px) {
  .container { width: calc(100% - 4rem); }
  .hero-copy { max-width: 70%; }
  .hero::after { background: linear-gradient(90deg, rgb(248 253 254 / 99%) 0%, rgb(248 253 254 / 94%) 40%, rgb(248 253 254 / 25%) 100%); }
  .classroom-grid { gap: 2rem; }
  .student-entry { padding: 1.5rem; }
  .student-url { font-size: 1.625rem; }
}
@media (max-width: 800px) {
  .hero-copy { max-width: 90%; }
  .hero-art { object-position: 70% center; }
  .hero::after { background: linear-gradient(90deg, rgb(248 253 254 / 98%) 0%, rgb(248 253 254 / 92%) 60%, rgb(248 253 254 / 50%) 100%); }
  .classroom-grid { grid-template-columns: 1fr; gap: 2rem; }
  .section-heading { align-items: start; flex-direction: column; gap: 0.75rem; }
  .help-layout { grid-template-columns: 1fr; gap: 2rem; }
  .tools-grid { gap: 1rem; }
}
@media (max-width: 600px) {
  .container { width: calc(100% - 2.5rem); }
  .header-inner { min-height: 4.25rem; gap: 1rem; }
  .brand img { width: 6rem; }
  nav { gap: 1rem; font-size: 0.75rem; }
  nav a[href='#classroom'] { display: none; }
  .nav-student { gap: 0.2rem; }
  .hero-inner { padding-block: 2.5rem 2rem; min-height: 0; }
  .hero-copy { width: 100%; max-width: 100%; }
  .hero-art { object-position: 68% center; opacity: 0.65; }
  .hero::after { background: linear-gradient(180deg, rgb(248 253 254 / 95%) 0%, rgb(248 253 254 / 93%) 70%, rgb(248 253 254 / 80%) 100%); }
  h1 { font-size: 2.5rem; }
  .eyebrow { font-size: 0.75rem; }
  .hero-tagline { font-size: 1.1875rem; max-width: 19rem; }
  .hero-description { font-size: 0.8125rem; }
  .download-area { margin-top: 1.4rem; }
  .download-button { width: 100%; min-height: 3.5rem; font-size: 0.9375rem; padding-inline: 1rem; }
  .download-meta { font-size: 0.625rem; gap: 0.5rem; }
  .download-meta p { padding-left: 0.5rem; }
  .install-guide { margin-top: 1.75rem; }
  .install-steps { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0.65rem; }
  .install-step { min-height: 9.5rem; padding: 0.9rem; }
  .install-step h3 { font-size: 0.875rem; }
  .install-step p { font-size: 0.75rem; }
  .step-caption { font-size: 0.625rem; }
  .classroom-section, .tools-section, .help-section { padding-block: 2.5rem; }
  h2 { font-size: 1.5rem; }
  .section-heading { margin-bottom: 1.5rem; }
  .section-heading > p { font-size: 0.75rem; }
  .role-heading > span { font-size: 0.625rem; }
  .student-entry { padding: 1.4rem 1.2rem; }
  .student-url { font-size: 1.625rem; }
  .tools-grid { grid-template-columns: 1fr; gap: 1.75rem; }
  .tool h3 { margin-top: 0.9rem; }
  .sync-strip { align-items: start; }
  .help-section h2 br { display: none; }
  .footer-inner { flex-wrap: wrap; gap: 0.75rem 1rem; padding-block: 1.25rem; }
  .footer-inner > a:nth-last-child(2) { margin-left: 0; }
  .footer-inner small { margin-left: auto; }
}
@media (max-width: 360px) {
  .container { width: calc(100% - 2rem); }
  .brand img { width: 5.5rem; }
  nav { gap: 0.65rem; }
  h1 { font-size: 2.125rem; }
  .guide-heading > span { display: none; }
  .download-meta p { padding-left: 0; border-left: 0; }
  .install-step { padding: 0.7rem; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } *, *::before, *::after { transition: none !important; animation: none !important; } }