:root{--ink:#111827;--ink-soft:#334155;--muted:#667085;--paper:#fff;--ground:#f7f7f3;--line:#dcded8;--line-strong:#b9bdb5;--life:#f06a55;--life-soft:#f8d6cd;--study:#14213d;--study-soft:#e8edf5;--project:#315bea;--max-width:1240px;--radius-sm:10px;--radius-md:16px;--radius-lg:24px;--ease-out:cubic-bezier(.16, 1, .3, 1)}*{box-sizing:border-box}html{background:var(--ground);scroll-behavior:smooth;scroll-padding-top:86px}body{background:var(--ground);color:var(--ink);text-rendering:optimizelegibility;min-width:320px;margin:0;font-family:Avenir Next,Segoe UI Variable,PingFang SC,Microsoft YaHei,sans-serif}body,button{font-family:inherit}h1,h2,h3,p,dl,dd,figure{margin:0}a{color:inherit;text-decoration:none}button,summary{-webkit-tap-highlight-color:transparent}:focus-visible{outline-offset:3px;outline:3px solid #315beaa6}.skip-link{background:var(--ink);color:#fff;transition:top .18s var(--ease-out);z-index:100;border-radius:8px;padding:10px 14px;font-size:14px;position:fixed;top:-60px;left:16px}.skip-link:focus{top:12px}.section-shell{max-width:var(--max-width);width:100%;margin-inline:auto;padding-inline:32px}.site-header{z-index:50;background:#f7f7f3f0;border-bottom:1px solid #1118271a;position:sticky;top:0}@supports ((-webkit-backdrop-filter:blur(16px)) or (backdrop-filter:blur(16px))){.site-header{-webkit-backdrop-filter:blur(16px);backdrop-filter:blur(16px)}}.header-inner{height:70px;max-width:var(--max-width);grid-template-columns:1fr auto 1fr;align-items:center;gap:24px;margin-inline:auto;padding-inline:32px;display:grid}.brand{letter-spacing:.11em;justify-self:start;align-items:center;gap:10px;min-height:44px;font-size:14px;font-weight:850;display:inline-flex}.brand img{object-fit:contain;background:#fff;border-radius:11px;width:36px;height:36px;padding:4px}.desktop-navigation{align-items:center;gap:28px;display:flex}.desktop-navigation 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svg{transform:translate(3px,-3px)}.section-label,.context-label{color:var(--muted);letter-spacing:.04em;font-size:12px;font-weight:760}.section-label-study{color:var(--study)}.home-page{background:var(--ground)}.home-hero{grid-template-columns:minmax(280px,.8fr) minmax(0,1.55fr);align-items:center;gap:clamp(32px,5vw,72px);min-height:calc(100svh - 70px);padding-top:48px;padding-bottom:64px;display:grid}.home-hero-copy{align-self:center}.brand-line{color:var(--muted);letter-spacing:.06em;margin-bottom:22px;font-size:12px;font-weight:720}.home-hero h1{letter-spacing:-.035em;max-width:none;font-size:clamp(38px,4vw,52px);line-height:1.08}.home-hero-summary{color:var(--ink-soft);max-width:32rem;margin-top:24px;font-size:17px;line-height:1.75}.home-hero .action-row{margin-top:30px}.commons-visual{min-width:0}.commons-image{animation:commons-reveal .9s var(--ease-out) 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1fr;align-items:start}.release-message>:last-child{grid-column:2;justify-self:start}.help-links{justify-content:flex-start}.footer-inner{grid-template-columns:1fr 1fr;padding-inline:20px}.footer-brand{grid-column:1/-1}}@media (width<=420px){.home-hero .action-row,.conversion-inner .action-row,.help-links{align-items:stretch;width:100%;display:grid}.home-hero .button,.conversion-inner .button,.help-links .button{width:100%}.course-shelf{padding:24px 18px}.book-row{gap:7px;height:220px}.course-book{padding-inline:5px;font-size:10px}.shelf-rule{gap:10px}}@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,:before,:after{scroll-behavior:auto!important;transition-duration:.01ms!important;animation-duration:.01ms!important;animation-iteration-count:1!important}}