:root{--ink:#20272c;--muted:#647078;--line:#e3e8e8;--accent:#087b6c;--warm:#b44b37}
*{box-sizing:border-box}
[hidden]{display:none!important}
body{margin:0;background:#f6f8f8;color:var(--ink);font:16px/1.65 system-ui,"Microsoft YaHei",sans-serif;letter-spacing:0}
button,a,input{font:inherit;touch-action:manipulation}button{cursor:pointer}a{color:inherit;text-decoration:none}
button{border:0}button:focus-visible,a:focus-visible,summary:focus-visible{outline:3px solid var(--accent);outline-offset:4px}
.topbar{height:72px;padding:0 22px;display:flex;align-items:center;justify-content:space-between;max-width:800px;margin:auto}
.brand{display:flex;gap:10px;align-items:center;font-weight:700;font-size:15px}.brand img{border-radius:6px}
.brand-sub{display:block;font-weight:400;font-size:11px;color:var(--muted);line-height:1.2}
.icon-button{width:44px;height:44px;display:grid;place-items:center;background:transparent;color:var(--ink);border-radius:6px}
svg{width:20px;height:20px;flex-shrink:0}
main{max-width:760px;margin:auto;background:#fff;padding:0 24px}
.scene-nav{display:flex;gap:24px;border-bottom:1px solid var(--line);padding-top:8px;overflow-x:auto}
.scene-nav button{min-height:52px;background:none;color:var(--muted);padding:0 0 12px;position:relative;font-size:15px;white-space:nowrap}
.scene-nav button[aria-pressed=true]{color:var(--accent);font-weight:600}
.scene-nav button[aria-pressed=true]:after{content:"";position:absolute;bottom:0;left:0;right:0;height:3px;background:var(--accent)}
.scene-intro{padding:30px 0 26px}.eyebrow{font-size:12px;color:var(--accent);display:flex;align-items:center;gap:7px}
.dot{width:6px;height:6px;border-radius:50%;background:var(--accent)}
h1{font-size:32px;line-height:1.3;margin:10px 0 12px;font-weight:750;overflow-wrap:anywhere}
.scene-intro p{color:var(--muted);font-size:15px;margin:0 0 20px;max-width:480px}
.byline{display:flex;align-items:center;gap:10px;font-size:12px;color:var(--muted)}.byline strong{display:block;font-size:14px;font-weight:500;color:var(--ink)}
.teacher-icon{width:36px;height:36px;background:#edf5f2;display:grid;place-items:center;color:var(--accent);border-radius:50%}
.access-label{margin-left:auto;color:#8d4c28;background:#fff5e9;padding:4px 9px;border-radius:4px}
section{padding-bottom:26px}.section-heading{display:flex;align-items:center;justify-content:space-between;margin-bottom:13px;gap:12px}
h2{font-size:19px;line-height:1.4;margin:0}.section-heading>span{color:var(--muted);font-size:12px}
.media-placeholder{display:flex;align-items:center;justify-content:center;flex-direction:column;gap:8px;border:1px solid var(--line);border-radius:6px;text-align:center;padding:18px}
.media-placeholder>svg{width:30px;height:30px;margin-bottom:4px;color:#77848b}.media-placeholder strong{font-size:15px;font-weight:500}.media-placeholder span{font-size:12px;color:var(--muted)}
.case-media{aspect-ratio:16/10;background:#f0f3f1}.lesson-media{aspect-ratio:16/9;background:#f3f4f6}
.course-video{display:block;width:100%;max-height:70dvh;background:#171b1e;border-radius:6px}.play-course-video{margin-top:6px;max-width:100%;white-space:normal;overflow-wrap:anywhere}
.lesson-section{border-bottom:1px solid var(--line)}
.lesson-caption{display:flex;justify-content:space-between;gap:10px;font-size:12px;color:var(--muted);margin:10px 0 18px}.lesson-caption span:first-child{display:flex;gap:5px;align-items:center}.lesson-caption svg{width:15px;height:15px}
details{border-top:1px solid var(--line);padding-top:4px}summary{min-height:48px;display:flex;align-items:center;justify-content:space-between;cursor:pointer;font-size:14px;list-style:none}summary::-webkit-details-marker{display:none}
details[open] summary svg{transform:rotate(180deg)}details p{font-size:14px;color:var(--muted);margin:4px 0 10px}
details p{white-space:pre-wrap;overflow-wrap:anywhere}
.tool-section{padding-top:26px}.tool-section .section-heading>svg{color:var(--accent)}.tool-section p{color:var(--muted);font-size:14px;margin:0 0 18px}
.tool-row{display:flex;justify-content:space-between;gap:12px;align-items:center}.tool-row>span{font-size:15px}.tool-row small{display:block;font-size:12px;color:var(--muted)}
.secondary{background:#edf5f2;color:var(--accent);border-radius:6px;padding:10px 12px;min-height:44px;display:flex;align-items:center;gap:4px;font-size:13px}
.page-footer{display:flex;gap:8px;align-items:center;justify-content:center;color:var(--muted);font-size:12px;padding:28px 0 120px}
.purchase-bar{position:fixed;bottom:0;left:0;right:0;max-width:760px;margin:auto;background:#fffffffa;border-top:1px solid var(--line);padding:12px 24px calc(12px + env(safe-area-inset-bottom));display:flex;align-items:center;justify-content:space-between;gap:18px}
.price{font-size:28px;font-weight:700;color:var(--warm);line-height:1.2}.price small{font-size:16px;margin-right:2px}.purchase-note{display:block;color:var(--muted);font-size:11px}
.primary{display:flex;gap:14px;align-items:center;justify-content:center;background:var(--accent);color:#fff;padding:12px 22px;min-height:48px;border-radius:6px;font-size:15px;font-weight:600}
.primary:hover{background:#056555}
dialog{border:0;border-radius:8px;width:calc(100% - 32px);max-width:480px;padding:22px;color:var(--ink);max-height:85dvh;overflow:auto}dialog::backdrop{background:#172b3270}
.sheet-header{display:flex;align-items:center;justify-content:space-between;gap:10px}.sheet-header h2{font-size:21px}.sheet-dismiss{width:100%;margin-top:22px}
#sheet-body p{color:var(--muted);font-size:14px}#sheet-body dl{font-size:14px}#sheet-body dt{font-weight:600;margin-top:14px}#sheet-body dd{margin:4px 0;color:var(--muted)}
.profile-form label{display:block;font-size:14px;margin-top:16px}.profile-form input{display:block;width:100%;min-height:48px;margin-top:6px;border:1px solid #b8c3ca;border-radius:6px;padding:10px;font:inherit}.profile-form .primary{width:100%}.profile-form button:disabled{opacity:.6;cursor:wait}.profile-form input:focus-visible{outline:2px solid var(--accent)}
.tool-qr{display:block;width:224px;height:224px;max-width:100%;object-fit:contain;margin:16px auto}.tool-actions{display:flex;flex-wrap:wrap;gap:10px}.tool-actions button:disabled{opacity:.5;cursor:default}.tool-error{color:#a22c26!important;overflow-wrap:anywhere}
@media(min-width:800px){main{padding:0 44px}.topbar{padding-inline:44px}.purchase-bar{padding-inline:44px}.scene-intro{padding-top:38px}.case-media{aspect-ratio:16/8}}
@media(max-width:359px){main{padding-inline:16px}.topbar{padding-inline:16px}.purchase-bar{padding-inline:16px}h1{font-size:28px}.scene-nav{gap:18px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
#platform-account-page{display:none}
.platform-account body{background:#fff}
.platform-account main,.platform-account .purchase-bar,.platform-account #account{display:none!important}
.platform-account .brand-sub{font-size:0}
.platform-account .brand-sub::after{content:"平台账号";font-size:11px}
.platform-account #platform-account-page{display:block;width:100%;max-width:480px;margin:24px auto;padding:0 24px 40px}
.platform-account #platform-account-title{font-size:26px;margin:0 0 24px}
#platform-account-body{margin-bottom:28px}
#platform-account-body p{font-size:15px;color:var(--muted);overflow-wrap:anywhere}
#platform-account-body .primary{margin-top:20px}