:root{font-family:-apple-system,BlinkMacSystemFont,'SF Pro Text','Helvetica Neue','PingFang SC','Microsoft YaHei',sans-serif;font-synthesis:none;color:#1d1d1f;background:#f5f5f7;--blue:#0071e3;--muted:#6e6e73;--line:#e5e5ea;-webkit-font-smoothing:antialiased}*{box-sizing:border-box}body{margin:0;font-size:14px;line-height:1.6}button,input,textarea,select{font:inherit}button{cursor:pointer;background:none;border:0;color:inherit}button:disabled{cursor:not-allowed;opacity:.45}button,a,input,textarea,select{-webkit-tap-highlight-color:transparent}a{color:var(--blue);text-decoration:none}h1,h2,h3,h4,p{margin:0}button:focus-visible,a:focus-visible,input:focus-visible,textarea:focus-visible,select:focus-visible{outline:3px solid #80bfff;outline-offset:3px}input,textarea,select{border:1px solid #d2d2d7;border-radius:12px;background:white;padding:12px 14px;color:#1d1d1f;width:100%;max-width:100%}textarea{resize:vertical;line-height:1.85;min-height:130px}input::placeholder,textarea::placeholder{color:#86868b}input:focus,textarea:focus{border-color:var(--blue)}.student-shell{max-width:1080px;margin:auto;padding:0 32px 60px}.student-header{height:82px;display:flex;align-items:center;justify-content:space-between;gap:16px;border-bottom:1px solid var(--line);margin-bottom:44px}.student-brand{font-size:25px;font-weight:650;letter-spacing:-.055em;color:#1d1d1f;display:flex;align-items:center;gap:10px}.student-brand svg{width:28px;height:28px;color:var(--blue)}.student-brand small{font-weight:400;font-size:11px;color:var(--muted);letter-spacing:0;padding-left:12px;border-left:1px solid #d2d2d7}.student-account{display:flex;align-items:center;gap:16px;color:var(--muted);font-size:12px}.student-link-button{color:var(--blue);padding:9px 0;font-size:13px}.student-intro{display:flex;justify-content:space-between;gap:25px;align-items:flex-end;margin-bottom:30px}.student-intro h1{font-size:44px;line-height:1.2;letter-spacing:-.05em;font-weight:650}.student-intro p{font-size:14px;color:var(--muted);margin-top:15px;max-width:48ch}.student-primary,.student-button{display:inline-flex;align-items:center;justify-content:center;gap:7px;min-height:44px;border-radius:99px;padding:11px 21px;font-size:13px;white-space:nowrap}.student-primary{background:var(--blue);color:#fff;border:1px solid var(--blue)}.student-primary:hover{background:#0077ed}.student-button{background:white;border:1px solid #d2d2d7}.student-panel{background:#fff;border:1px solid #e6e6eb;border-radius:24px;padding:30px;min-width:0}.student-panel-head{display:flex;align-items:center;justify-content:space-between;gap:20px;margin-bottom:22px}.student-panel-head h2{font-size:23px;font-weight:600;letter-spacing:-.035em}.student-muted{font-size:12px;color:var(--muted);line-height:1.85}.student-tabs{display:flex;gap:4px;border-radius:12px;background:#eaeaec;padding:4px;width:fit-content;margin-bottom:24px}.student-tabs button{padding:9px 19px;font-size:13px;border-radius:9px}.student-tabs button[aria-selected=true]{background:white;box-shadow:0 1px 4px #0000000a;font-weight:550}.student-task{border-top:1px solid #eeeef1;padding:24px 0;display:flex;align-items:center;justify-content:space-between;gap:25px}.student-task:first-child{padding-top:0;border:0}.student-task:last-child{padding-bottom:0}.student-task h3{font-size:19px;font-weight:550;letter-spacing:-.025em;overflow-wrap:anywhere}.student-task p{margin-top:9px;color:var(--muted);font-size:12px}.student-task-actions{display:flex;align-items:center;gap:15px;flex-shrink:0}.student-status{display:inline-block;padding:4px 9px;border-radius:7px;font-size:11px;background:#f2f2f7;color:#6e6e73;white-space:nowrap}.student-status.blue{background:#edf5ff;color:#0067cd}.student-status.warm{background:#fff7e8;color:#966114}.student-empty{padding:42px 18px;text-align:center}.student-empty h3{font-size:25px;font-weight:550;letter-spacing:-.04em}.student-empty p{max-width:38ch;margin:12px auto 0;color:var(--muted);font-size:13px}.student-back{display:inline-flex;gap:6px;align-items:center;padding:0;margin-bottom:24px;color:var(--blue);font-size:13px}.student-detail-heading{margin-bottom:26px}.student-detail-heading h1{font-size:34px;letter-spacing:-.045em;line-height:1.3;overflow-wrap:anywhere}.student-detail-heading p{color:var(--muted);font-size:12px;margin-top:12px}.student-note{padding:15px 18px;background:#f5f5f7;border-radius:13px;font-size:12px;line-height:1.8;color:#616166;margin:18px 0}.student-question{padding:27px 0;border-top:1px solid #eeeef1}.student-question:first-child{padding-top:0;border:0}.student-question h2{font-size:19px;font-weight:550;line-height:1.5;margin-bottom:16px;overflow-wrap:anywhere}.student-question-head{display:flex;align-items:baseline;gap:12px}.student-question-head>span{color:#86868b;font-size:13px}.student-rich{font-size:15px;line-height:1.95;overflow-wrap:anywhere;max-width:75ch}.student-rich .katex-display{overflow-x:auto;max-width:100%;padding:3px 0}.student-source-image{display:block;max-width:100%;max-height:550px;object-fit:contain;margin:17px 0;border-radius:10px}.student-answer-label{display:block;font-size:12px;color:#616166;margin:22px 0 8px}.student-upload-tools{display:flex;flex-wrap:wrap;gap:10px;align-items:center;margin-top:14px}.student-file-button{display:inline-flex;gap:7px;align-items:center;justify-content:center;cursor:pointer;background:#f5f5f7;border:1px solid #e5e5ea;border-radius:99px;padding:9px 16px;font-size:12px;min-height:40px}.student-file-button:focus-within{outline:3px solid #80bfff;outline-offset:3px}.student-file-button input{position:absolute;width:1px;height:1px;opacity:0;overflow:hidden}.student-file-button.is-disabled{opacity:.45;pointer-events:none}.student-image-list{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px;margin-top:16px}.student-image-item{min-width:0;border:1px solid #e5e5ea;border-radius:12px;overflow:hidden;background:#fafafa}.student-image-item img{width:100%;height:180px;object-fit:contain;display:block}.student-image-actions{display:flex;justify-content:space-between;gap:5px;border-top:1px solid #e5e5ea;background:white;padding:6px 10px}.student-image-actions button{font-size:11px;padding:5px;color:var(--blue)}.student-image-actions button[data-s-action=remove-image]{color:#b43d31}.student-submit-bar{display:flex;align-items:center;justify-content:space-between;gap:20px;border-top:1px solid var(--line);padding-top:24px;margin-top:24px}.student-submit-bar p{max-width:56ch}.student-feedback{margin-top:20px;border-left:3px solid #0071e3;background:#f4f8fd;padding:17px 20px;border-radius:0 12px 12px 0}.student-feedback h3{font-size:14px;margin-bottom:10px}.student-feedback p{font-size:13px;line-height:1.8;overflow-wrap:anywhere}.student-feedback details{margin-top:16px}.student-feedback summary{cursor:pointer;color:var(--blue);font-size:12px}.student-feedback .student-rich{margin-top:12px;font-size:13px}.student-form-grid{display:grid;grid-template-columns:1fr 1fr;gap:18px}.student-form-grid label,.student-form-label{display:flex;flex-direction:column;gap:8px;font-size:12px;color:#515154}.student-form-grid .full{grid-column:1/-1}.student-login{max-width:450px;margin:74px auto 40px}.student-login h1{font-size:42px;line-height:1.18;letter-spacing:-.05em;margin-bottom:17px;font-weight:650}.student-login>.student-muted{font-size:14px;max-width:32ch;margin-bottom:31px}.student-login-form{display:grid;gap:18px;background:#fff;border:1px solid #e5e5ea;padding:29px;border-radius:22px}.student-login-form label{font-size:12px;color:#515154;display:grid;gap:10px}.student-login-form input{font-size:21px;letter-spacing:.02em}.student-login-form .student-primary{width:100%;margin-top:3px}.student-login-footer{margin:22px 8px;color:var(--muted);font-size:11px;line-height:1.9}.student-error{background:#fff8f7;border:1px solid #efd8d5;color:#a23429;font-size:13px;padding:14px 16px;border-radius:12px;margin:16px 0;overflow-wrap:anywhere}.student-error:empty{display:none}.student-storage-warning{font-size:12px;color:#966114;margin-top:10px}.student-loading{text-align:center;color:var(--muted);padding:80px 24px}.student-footer{margin-top:30px;color:var(--muted);font-size:11px;display:flex;justify-content:space-between;gap:15px}.student-preview-head{margin-bottom:20px}.student-preview-head h2{font-size:22px;letter-spacing:-.035em}.student-preview-head p{margin-top:9px}.student-preview-answer{white-space:pre-wrap;font-size:14px;line-height:1.85;overflow-wrap:anywhere}.student-pending{padding:17px 19px;background:#f4f8fd;border:1px solid #dbe8fa;border-radius:14px;font-size:13px;line-height:1.8;margin:18px 0}#student-toast{position:fixed;bottom:max(25px,env(safe-area-inset-bottom));left:50%;transform:translate(-50%,15px);opacity:0;pointer-events:none;background:#29292dcc;color:white;border-radius:99px;padding:12px 22px;font-size:12px;backdrop-filter:blur(12px);max-width:calc(100% - 32px);width:max-content;z-index:20;transition:.2s}#student-toast.visible{transform:translate(-50%,0);opacity:1}
@media(max-width:700px){.student-shell{padding:0 20px 35px}.student-header{height:72px;margin-bottom:31px}.student-brand{font-size:23px}.student-brand small{display:none}.student-intro{align-items:flex-start;flex-direction:column;gap:19px}.student-intro h1{font-size:35px}.student-intro p{font-size:13px}.student-panel{padding:23px 18px;border-radius:19px}.student-task{align-items:flex-start;flex-direction:column;gap:15px}.student-task-actions{width:100%;justify-content:space-between}.student-task h3{font-size:18px}.student-detail-heading h1{font-size:28px}.student-image-list{grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.student-image-item img{height:175px}.student-submit-bar{align-items:stretch;flex-direction:column;gap:15px}.student-submit-bar .student-primary,.student-submit-bar .student-button{width:100%}.student-form-grid{grid-template-columns:1fr}.student-form-grid .full{grid-column:auto}.student-login{margin:42px auto 25px}.student-login h1{font-size:36px}.student-login-form{padding:25px 22px}.student-account{gap:13px;font-size:11px}.student-footer{flex-direction:column;gap:5px}.student-rich{font-size:14px}.student-tabs{width:100%}.student-tabs button{flex:1}.student-question{padding:23px 0}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}
.student-image-full summary{list-style:none;cursor:zoom-in}.student-image-full[open] summary img{display:none}.student-image-full[open] summary:after{content:'收起大图';font-size:12px;color:#0071e3;display:block;padding:10px;cursor:zoom-out}.student-image-item:has(.student-image-full[open]){grid-column:1/-1}.student-image-full[open]>img{width:100%;height:auto;max-height:75vh;object-fit:contain}
.student-intro h1{overflow-wrap:anywhere}.student-account>span{max-width:40vw;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}

.student-intro h1{font-size:36px;max-width:18ch}.student-agenda{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));margin:0 0 32px;border-top:1px solid #dddde2;border-bottom:1px solid #dddde2;padding:23px 0}.student-agenda button{text-align:left;padding:0 24px;border-right:1px solid #dddde2}.student-agenda button:first-child{padding-left:0}.student-agenda button:last-child{border:0}.student-agenda span{display:block;color:#515154;font-size:12px}.student-agenda b{display:block;font-size:32px;font-weight:600;line-height:1.4;letter-spacing:-.045em;margin-top:6px}.student-agenda small{display:block;color:#6e6e73;font-size:11px;margin-top:3px}.student-pagination{display:flex;align-items:center;justify-content:space-between;gap:12px;border-top:1px solid #e5e5ea;padding-top:22px;margin-top:25px}.student-pagination>span{font-size:12px;color:#6e6e73}.student-pagination .student-button{padding:8px 15px}
@media(max-width:700px){.student-intro h1{font-size:29px}.student-agenda{margin-bottom:24px;padding:19px 0}.student-agenda button{padding:0 13px}.student-agenda b{font-size:28px}.student-agenda small{font-size:10px;line-height:1.6}.student-pagination{gap:7px}.student-pagination>span{font-size:11px}.student-pagination .student-button{padding:8px 12px;font-size:12px}}

.student-photo-actions{display:flex;flex-wrap:wrap;gap:10px;align-items:center}.student-typeset-callout{display:flex;align-items:center;justify-content:space-between;gap:20px;margin:24px 0;padding:20px;border:1px solid #d9e4f5;background:#f5f8fd;border-radius:16px}.student-typeset-callout p{color:#606b7d;font-size:14px;line-height:1.65;margin:6px 0 0}.student-typeset-callout button{flex-shrink:0}@media(max-width:640px){.student-photo-actions,.student-typeset-callout{align-items:stretch;flex-direction:column}.student-typeset-callout{padding:16px}}

.student-original-check{margin:16px 0;padding:12px 16px;border:1px solid #e6e8ed;border-radius:12px;color:#626a76}.student-original-check summary{cursor:pointer;font-size:14px}.student-standard-figure{margin:16px 0}.student-standard-figure figcaption{font-size:13px;color:#626a76;margin-top:6px}@media print{.student-original-check{display:none!important}}

/* Personal paper controls and on-screen proof share the same renderer as print. */
.personal-save-bar>div{flex:1;min-width:0}.personal-save-bar [data-n-save-error]{margin:10px 0 0}.personal-save-bar [data-n-save-error][hidden]{display:none}
.personal-paper-options{display:flex;align-items:center;flex-wrap:wrap;gap:16px;margin:22px 0}.personal-paper-options>label,.personal-paper-order-row label{display:grid;gap:7px;font-size:13px}.personal-paper-options select,.personal-paper-order-row select{min-height:44px;font-size:16px}
.personal-paper-order{margin:20px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:12px 0}.personal-paper-order>summary{cursor:pointer;min-height:44px;display:flex;align-items:center;font-size:14px;color:#515154}.personal-paper-order>summary::before{content:'▸';margin-right:9px}.personal-paper-order[open]>summary::before{content:'▾'}
.personal-paper-order-row{display:flex;gap:18px;justify-content:space-between;align-items:center;padding:16px 0;border-top:1px solid #eeeef1}.personal-paper-order-row>div:first-child{flex:1;min-width:0}.personal-paper-order-row h3{font-size:14px;margin-bottom:12px;overflow-wrap:anywhere}.personal-paper-order-row label{max-width:130px}.personal-paper-order-actions{display:flex;flex-wrap:wrap;gap:8px}.personal-paper-order-actions .student-button{padding:9px 14px}
.personal-paper-preview{background:#fff;border:1px solid #e5e5ea;padding:28px;margin-top:24px;overflow-wrap:anywhere;min-width:0}.personal-paper-preview .paper-masthead{display:flex;justify-content:space-between;gap:15px;border-bottom:1px solid var(--line);padding-bottom:12px;font-size:11px;color:#6e6e73}.personal-paper-preview h1{font-size:25px;margin:25px 0 16px}.personal-paper-preview .paper-student{display:flex;align-items:baseline;flex-wrap:wrap;gap:12px;font-size:12px}.personal-paper-preview .paper-student strong{font-size:15px}.personal-paper-preview .paper-instructions{font-size:12px;color:#6e6e73;margin:18px 0}.personal-paper-preview .paper-question{margin:28px 0}.personal-paper-preview .paper-question>header{display:flex;gap:12px;margin-bottom:16px}.personal-paper-preview .paper-question>header>b{font-size:16px;color:#6e6e73;white-space:nowrap;flex-shrink:0}.personal-paper-preview .paper-question h3,.personal-paper-preview .paper-solution h3{font-size:16px;line-height:1.7}.personal-paper-preview .paper-question>header span{font-size:11px;color:#6e6e73}.personal-paper-preview .paper-prompt,.personal-paper-preview .paper-solution{font-size:14px;line-height:1.9}.personal-paper-preview figure{margin:16px 0;max-width:100%}.personal-paper-preview figure img{max-width:100%;height:auto;object-fit:contain}.personal-paper-preview figcaption{font-size:12px;line-height:1.7;color:#6e6e73}.personal-paper-preview .paper-writing{height:calc(var(--writing-lines)*24px);position:relative;border-top:1px solid #e5e5ea;margin-top:18px}.personal-paper-preview .paper-writing span{position:absolute;right:0;top:2px;padding:0 4px;background:white;font-size:10px;color:#86868b}.personal-paper-preview .paper-footer{border-top:1px solid #e5e5ea;padding-top:12px;color:#86868b;text-align:center;font-size:10px}.personal-paper-preview .paper-answer{margin-top:40px;padding-top:26px;border-top:2px solid #dedee4}.personal-paper-preview .paper-answer h2{font-size:22px;margin-top:18px}.personal-paper-preview .paper-solution{margin:24px 0}.personal-paper-preview .paper-explanation{margin-top:16px}.personal-paper-preview .paper-explanation h4{font-size:14px}.personal-paper-preview .katex-display{overflow-x:auto;max-width:100%;padding:4px 0}
@media(max-width:700px){.personal-paper-preview{padding:18px 13px;margin:20px -5px 0}.personal-paper-options{align-items:stretch;flex-direction:column}.personal-paper-order-row{align-items:stretch;flex-direction:column;gap:12px}.personal-paper-order-actions .student-button{flex:1}.personal-paper-preview h1{font-size:21px}}
@media print{#student-print-root .paper-question,#student-print-root .paper-solution{break-inside:auto}#student-print-root .paper-question>header,#student-print-root .paper-solution>h3{break-after:avoid}#student-print-root .paper-question>header>b{white-space:nowrap;flex-shrink:0}#student-print-root figure,#student-print-root .paper-prompt p,#student-print-root .paper-prompt .katex-display{break-inside:avoid}#student-print-root .paper-prompt{orphans:3;widows:3}}

.personal-paper-options select,.personal-paper-order-row select{appearance:none;-webkit-appearance:none;padding-right:32px;background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' fill='none' stroke='%236e6e73' stroke-width='1.5'/%3E%3C/svg%3E");background-position:right 12px center;background-repeat:no-repeat}.personal-learning-hints{margin:20px 0}.personal-learning-hints>h4{font-size:14px;margin-bottom:10px}.personal-review [data-n-aided][hidden]{display:none}.personal-review [data-n-answer-details]{margin:20px 0}.personal-review [data-n-answer-details]>summary{min-height:44px;cursor:pointer;display:flex;align-items:center}