:root{font-family:system-ui,-apple-system,"Segoe UI","Microsoft YaHei",sans-serif;color:#24372f;background:white;font-size:16px}*{box-sizing:border-box}body{margin:0}header{max-width:1180px;margin:auto;padding:22px 24px;display:flex;justify-content:space-between;gap:18px;align-items:center;border-bottom:1px solid #e4e9e5}a{color:inherit;text-decoration:none}a:hover{text-decoration:underline}#brand{font-weight:500;white-space:nowrap}#brand strong{margin-left:12px;font-size:18px}nav{display:flex;gap:8px;align-items:center;flex-wrap:wrap}button,select,input{font:inherit}button,select{border:1px solid #d6dfd9;background:white;border-radius:8px;padding:9px 13px;color:inherit}button{cursor:pointer}button:hover{background:#f6f8f6}button:disabled{opacity:.5;cursor:default}button:focus-visible,select:focus-visible,input:focus-visible,a:focus-visible{outline:3px solid #75a38e;outline-offset:3px}main{max-width:1080px;margin:auto;padding:38px 24px}.intro{display:flex;gap:24px;align-items:center;justify-content:space-between}.intro>div{max-width:790px}h1{font-size:clamp(25px,4vw,34px);margin:14px 0 12px;font-weight:600}h2{font-size:22px}p{line-height:1.6}.tag{font-size:13px;color:#57695e}.intro p,.retention{color:#59685f}.retention{font-size:14px;margin:22px 0}#new-chat{white-space:nowrap}.admission{padding:16px;border:1px solid #d6dfd9;border-radius:12px;display:flex;gap:20px;justify-content:space-between;align-items:center}.admission label{display:flex;gap:10px;align-items:flex-start}.admission input{margin-top:5px}#start,#auth-submit{background:#245b45;color:white;border-color:#245b45}#connection{min-height:25px}footer{margin-top:35px;padding-top:20px;border-top:1px solid #e4e9e5;display:flex;gap:20px;justify-content:space-between;font-size:13px;color:#657268}footer span{max-width:780px}footer a{white-space:nowrap}dialog{width:min(480px,calc(100vw - 32px));border:1px solid #d6dfd9;border-radius:16px;padding:24px;background:white;color:inherit}dialog::backdrop{background:#12271e55}.dialog-head{display:flex;justify-content:space-between;gap:20px;align-items:center}form{display:grid;gap:10px}form label{font-weight:500}form input{width:100%;border:1px solid #bbc9c0;padding:12px;border-radius:8px}.hint{font-size:13px;margin:0 0 8px;color:#657268}#auth-status{margin:4px 0 0}.error{color:#962727}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}[hidden]{display:none!important}chat-ai{display:block;min-width:0}@media(max-width:700px){header{align-items:flex-start;padding:18px;flex-direction:column}main{padding:25px 16px}nav{width:100%}nav button,nav select{min-height:42px}.intro{align-items:flex-start;flex-direction:column;gap:6px}.admission{flex-direction:column;align-items:stretch}.admission button{min-height:44px}footer{flex-direction:column}.retention{font-size:13px}}