:root{--ink:#3c3337;--muted:#7a6b71;--brand:#873d50;--brand-dark:#6a2f3f;--brand-soft:#f8f3f4;--art:#9a596b;--art-soft:#f9f5f6;--art-line:#d4b8bf;--green:#21594e;--green-dark:#153d35;--paper:#faf7f5;--line:#e8ddde;--soft:#e8eee5;--white:#fff;--amber:#9a6d27}*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font-family:system-ui,-apple-system,"Segoe UI","Microsoft YaHei",sans-serif;font-size:15px;line-height:1.75}a{color:var(--brand);text-decoration:none}a:hover{text-decoration:underline}button,input,select,textarea{font:inherit}button,a,input,select,textarea,summary{outline-offset:4px}:focus-visible{outline:3px solid var(--brand)}button{cursor:pointer}h1,h2,h3,p{margin-top:0}h1{font-size:38px;letter-spacing:-1px;line-height:1.35;font-weight:650}h2{font-size:21px;line-height:1.5}hr{border:0;border-top:1px solid var(--line);margin:28px 0}.site-header{min-height:88px;padding:14px 5%;display:flex;align-items:center;justify-content:space-between;gap:24px;flex-wrap:wrap;border-bottom:1px solid var(--line);background:var(--white)}.brand{display:flex;gap:16px;align-items:center;flex-shrink:0;color:var(--ink)}.brand:hover{text-decoration:none}.brand-logo{display:block;width:auto;height:56px;flex-shrink:0;object-fit:contain}.brand-sub{font-size:15px;font-weight:500;line-height:1.5;padding-left:16px;border-left:1px solid var(--line);white-space:nowrap}.site-header nav{display:flex;gap:26px;align-items:center;flex-wrap:wrap;font-size:14px}.site-header nav>a{color:var(--ink)}.site-header nav>.button{color:white}.button{background:var(--brand);color:white;border:1px solid var(--brand);border-radius:7px;display:inline-flex;align-items:center;justify-content:center;gap:24px;padding:12px 22px;font-weight:550;line-height:1.5;white-space:nowrap}.button:hover{background:var(--brand-dark);text-decoration:none}.button.small{padding:10px 17px}.button.full{width:100%;margin-top:20px}.button.secondary{color:var(--brand);background:white;border-color:#d6c7cb}.button.secondary:hover{background:var(--brand-soft)}.button.danger{background:#8d3c32;border-color:#8d3c32}.inline-form{margin:0;display:inline}.text-button{border:0;background:none;padding:0;color:var(--muted);font-size:14px}.eyebrow{font-size:11px;letter-spacing:2px;font-weight:650;color:var(--brand);margin-bottom:20px}.muted{color:var(--muted)}.small-text{font-size:13px}.mono,code{font-family:Consolas,monospace}.actions{display:flex;align-items:center;gap:26px;margin:28px 0}.quiet-link{font-size:14px;font-weight:550}.site-footer{padding:27px 5%;border-top:1px solid var(--line);display:flex;justify-content:space-between;color:var(--muted);font-size:12px;margin-top:80px}.landing{max-width:1330px;margin:auto;min-height:620px;padding:85px 5% 70px;display:grid;grid-template-columns:1.2fr 1fr;align-items:center;gap:55px}.hero-copy h1{font-size:49px;line-height:1.42;letter-spacing:-1.5px;margin-bottom:30px}.lead{font-size:17px;line-height:2;color:var(--muted)}.physics-art{height:420px;position:relative;border:1px solid var(--line);border-radius:50%;background:radial-gradient(ellipse,var(--art-soft) 0,var(--paper) 65%);overflow:hidden;display:flex;align-items:center;justify-content:center}.physics-art:before,.physics-art:after{content:"";position:absolute;background:var(--line)}.physics-art:before{height:1px;width:92%}.physics-art:after{width:1px;height:92%}.orbit{width:78%;height:42%;border:1px solid var(--art-line);border-radius:50%;position:absolute}.orbit-one{transform:rotate(-25deg)}.orbit-two{transform:rotate(35deg)}.orbit-three{transform:rotate(95deg)}.orbit-one:after{content:"";height:12px;width:12px;border-radius:50%;position:absolute;top:4%;left:21%;background:var(--art);box-shadow:0 0 0 8px var(--art-soft)}.orbital-center{width:84px;height:84px;border-radius:50%;background:var(--art);color:white;font:66px Georgia;text-align:center;z-index:1;box-shadow:0 0 0 13px var(--art-soft)}.diagram-note{position:absolute;z-index:1;background:var(--paper);font-size:9px;letter-spacing:1px;color:var(--muted);padding:4px 9px}.note-one{top:10%;left:35%}.note-two{top:64%;left:7%}.note-three{top:58%;right:1%}.art-caption{position:absolute;bottom:11%;font-size:12px;color:var(--muted);letter-spacing:3px}.features{display:grid;grid-template-columns:repeat(3,1fr);max-width:1200px;margin:0 auto;border-top:1px solid var(--line)}.features article{padding:34px 38px 10px}.features article+article{border-left:1px solid var(--line)}.feature-number{display:block;color:var(--muted);font-size:11px;letter-spacing:2px;margin-bottom:24px}.features p{font-size:14px;color:var(--muted)}.auth-layout{display:grid;grid-template-columns:1fr 1fr;max-width:1100px;margin:65px auto;padding:0 30px;gap:110px;align-items:center}.auth-layout aside h1{font-size:39px;line-height:1.5}.auth-layout aside p{color:var(--muted);line-height:2}.aside-note{font-size:13px;padding-top:30px;border-top:1px solid var(--line);margin-top:36px;color:var(--muted)}.auth-card,.center-card{background:white;border:1px solid var(--line);border-radius:12px;padding:36px}.auth-card h2{font-size:26px}.auth-links{display:flex;justify-content:space-between;font-size:13px;margin:20px 0}.center-card{max-width:560px;margin:80px auto}.center-card h1{font-size:30px}.success-icon{font-size:42px;color:var(--green)}label{display:block;font-size:13px;font-weight:550;margin:15px 0 7px}input,select,textarea{border:1px solid #d6c7cb;border-radius:6px;background:#fff;color:var(--ink);padding:10px 12px;width:100%;max-width:100%}input[type=checkbox]{width:auto}select{min-height:45px}select[multiple]{height:135px}textarea{resize:vertical;line-height:1.7}.helptext{display:block;font-size:11px;color:var(--muted);margin-top:6px}.helptext ul{padding-left:17px}.errorlist{color:#a13728;padding-left:20px;font-size:13px}.messages{max-width:1250px;margin:18px auto;padding:0 30px}.notice{padding:12px 18px;background:#e7efe8;border:1px solid #bdd2c1;border-radius:7px;margin-bottom:8px}.notice.error{background:#fff1e9;border-color:#e1b8a5}.page-heading{max-width:1330px;padding:46px 5% 28px;margin:auto;display:flex;justify-content:space-between;align-items:center;gap:20px}.page-heading h1{font-size:33px;margin-bottom:14px}.page-heading .eyebrow{margin-bottom:12px}.page-marker{font-size:11px;color:var(--muted);letter-spacing:2px;writing-mode:vertical-rl}.library-layout{max-width:1330px;padding:0 5%;margin:auto;display:grid;grid-template-columns:265px minmax(0,1fr);gap:36px}.filter-panel{background:white;border:1px solid var(--line);border-radius:10px;padding:22px;height:fit-content}.filter-title{display:flex;justify-content:space-between;align-items:center}.filter-title h2{font-size:17px;margin:0}.filter-title a{font-size:12px}.filter-panel label{font-size:12px;color:var(--muted);margin-top:18px}.filter-panel select,.filter-panel input{font-size:13px;padding:9px}.field-row{display:grid;grid-template-columns:1fr 1fr;gap:10px}.results-toolbar{display:flex;align-items:center;justify-content:space-between;padding:8px 2px 18px}.question-card{background:white;border:1px solid var(--line);border-radius:9px;padding:26px 29px;margin-bottom:16px;transition:border-color .15s}.question-card:hover{border-color:#9fb9a6}.card-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:15px}.card-top .eyebrow{margin:0;font-size:10px;color:#7a887d}.difficulty-label{font-size:12px;color:var(--green)}.question-card h2{font-size:22px;margin:0 0 14px}.question-card h2 a{display:flex;justify-content:space-between;color:var(--ink)}.card-arrow{color:#84958a}.excerpt{color:var(--muted);font-size:14px;line-height:1.9;margin-bottom:20px;overflow-wrap:anywhere}.tags{display:flex;flex-wrap:wrap;gap:7px}.tag{display:inline-block;background:#edf2e9;color:#416444;border:1px solid #e0e8dc;border-radius:4px;font-size:11px;padding:3px 9px;white-space:nowrap}.tag.neutral{background:#f5f6f4;color:#69766a;border-color:#e9ece6}.card-footer{display:flex;justify-content:space-between;margin-top:20px;padding-top:15px;border-top:1px solid #edf0e9;font-size:11px;color:#7b857a}.empty-state{padding:65px 25px;text-align:center;background:white;border:1px dashed #cbd7ca;border-radius:10px}.empty-state p{color:var(--muted);font-size:14px}.empty-symbol{font:58px Georgia;color:#8ea78e;display:block;margin-bottom:20px}.pagination{display:flex;justify-content:center;gap:26px;margin:28px 0;font-size:13px}.reading-layout{max-width:940px;margin:35px auto;padding:0 30px}.back-link{font-size:13px;display:inline-block;margin-bottom:26px}.reading-header{margin:12px 0 30px}.reading-header h1{font-size:37px}.reading-header .tags{margin-bottom:16px}.reading-card,.answer-panel{background:#fff;border:1px solid var(--line);border-radius:10px;padding:34px;margin-bottom:20px}.section-caption{font-size:11px;letter-spacing:2px;color:#7e8e81;margin-bottom:25px}.prose{font-size:16px;line-height:2;overflow-wrap:anywhere}.prose p{margin-bottom:1.3em}.prose img{display:block;max-width:100%;max-height:560px;object-fit:contain;margin:25px auto;cursor:zoom-in}.prose table{border-collapse:collapse;display:block;overflow-x:auto}.prose td,.prose th{padding:7px 14px;border:1px solid var(--line)}.arithmatex{overflow-x:auto;overflow-y:hidden;max-width:100%}div.arithmatex{padding:8px 0}.answer-panel summary{display:flex;justify-content:space-between;cursor:pointer;gap:12px;font-weight:550}.answer-panel[open] summary{padding-bottom:27px;margin-bottom:25px;border-bottom:1px solid var(--line)}.answer-panel summary .muted{font-size:11px;letter-spacing:1px}.source-box,.feedback-box{padding:20px 2px;border-bottom:1px solid var(--line);margin-bottom:20px;font-size:13px;color:var(--muted)}.source-box h2{font-size:14px;color:var(--ink)}.source-box p{margin-bottom:5px}.feedback-box summary{cursor:pointer}.workspace{max-width:1250px;margin:auto;padding:0 30px}.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:18px;margin-bottom:30px}.stats>div{background:white;border:1px solid var(--line);border-radius:8px;padding:20px 25px}.stats span{display:block;font-size:12px;color:var(--muted)}.stats strong{font-size:32px;font-weight:500}.toolbar{display:flex;gap:12px;align-items:center;margin:20px 0}.toolbar input{max-width:330px}.toolbar select{max-width:170px}.toolbar label{margin:0;white-space:nowrap}.table-scroll{overflow-x:auto;background:white;border:1px solid var(--line);border-radius:8px}.data-table{width:100%;border-collapse:collapse;font-size:13px}.data-table td,.data-table th{padding:17px 20px;text-align:left;border-bottom:1px solid #e8ece5;white-space:nowrap}.data-table th{font-size:11px;letter-spacing:1px;color:#6c7c6e;background:#fafbf8;font-weight:500}.data-table td small{display:block;color:var(--muted);margin-top:5px;font-size:11px}.data-table tr:last-child td{border-bottom:0}.editor-layout{max-width:1330px;padding:0 4%;margin:auto;display:grid;grid-template-columns:minmax(260px,.7fr) minmax(0,1.3fr);gap:24px}.panel{background:white;border:1px solid var(--line);border-radius:8px;padding:26px;margin-bottom:22px;overflow-wrap:anywhere}.panel h2{font-size:19px}.panel li{font-size:13px;line-height:1.8;margin:9px 0}.panel.warning{background:#fcf8ee;border-color:#e7d9b9}.code-input{font-family:Consolas,"Microsoft YaHei",monospace;font-size:13px}.asset-row{border-bottom:1px solid var(--line);padding-bottom:15px;margin-bottom:18px}.asset-row img{max-width:100%;max-height:200px;display:block;cursor:zoom-in;margin:12px auto}.asset-row code{font-size:11px;word-break:break-all}.checkbox-label{display:flex;align-items:flex-start;gap:10px;font-size:13px;font-weight:400;margin:20px 0}.checkbox-label input{margin-top:5px}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0)}dialog{max-width:95vw;max-height:94vh;border:1px solid var(--line);padding:20px;border-radius:10px}dialog::backdrop{background:#132b24bb}dialog img{max-width:100%;max-height:80vh;display:block}dialog button{display:block;margin-left:auto;margin-bottom:15px;border:0;background:var(--soft);padding:6px 12px;border-radius:5px}@media(min-width:1450px){.landing{min-height:690px}.hero-copy h1{font-size:54px}}@media(max-width:900px){.site-header{padding:14px 24px}.site-header nav{gap:15px}.landing{gap:25px;padding:60px 5%;min-height:540px}.hero-copy h1{font-size:37px}.physics-art{height:330px}.features article{padding:28px 22px}.auth-layout{gap:50px}.library-layout{grid-template-columns:230px minmax(0,1fr);gap:22px}.page-heading h1{font-size:28px}.editor-layout{grid-template-columns:1fr}.editor-layout>div:first-child{display:grid;grid-template-columns:1fr 1fr;gap:18px}.editor-layout>div:first-child .panel{margin:0}.editor-layout>div:first-child .panel:last-child{grid-column:1/-1}}@media(max-width:640px){.site-header{height:auto;min-height:76px;padding:16px 20px;gap:16px;flex-wrap:wrap}.brand{gap:10px}.brand-logo{height:44px}.brand-sub{font-size:12px;padding-left:10px}.site-header nav{gap:14px;flex-wrap:wrap;font-size:12px}.site-header .button.small{padding:8px 11px;font-size:12px}.site-footer{padding:22px;gap:15px;flex-direction:column;margin-top:45px}.landing{display:block;padding:47px 24px 28px}.hero-copy h1{font-size:clamp(27px,8.2vw,36px);text-wrap:balance}.lead{font-size:15px}.physics-art{height:auto;aspect-ratio:1;max-width:360px;margin:40px auto 0}.actions{gap:18px;flex-wrap:wrap}.features{display:block;margin:0 24px}.features article{padding:25px 0}.features article+article{border-left:0;border-top:1px solid var(--line)}.feature-number{margin-bottom:12px}.auth-layout{display:block;margin:32px auto;padding:0 20px}.auth-layout aside{display:none}.auth-card{padding:27px 23px}.center-card{margin:35px 20px;padding:27px}.page-heading{padding:33px 24px 20px}.page-heading h1{font-size:26px}.page-marker{display:none}.library-layout{display:block;padding:0 20px}.filter-panel{margin-bottom:25px;padding:20px}.filter-panel form{display:grid;grid-template-columns:1fr 1fr;gap:0 12px}.filter-title,.filter-panel .field-row,.filter-panel button{grid-column:1/-1}.filter-panel label{grid-column:1/-1}.filter-panel input,.filter-panel select{grid-column:1/-1}.filter-panel .field-row select{width:100%}.filter-panel select{min-height:40px}.question-card{padding:22px}.question-card h2{font-size:20px}.card-footer{gap:15px}.reading-layout{padding:0 20px;margin-top:25px}.reading-header h1{font-size:30px}.reading-card,.answer-panel{padding:24px 20px}.prose{font-size:15px}.workspace{padding:0 20px}.stats{grid-template-columns:1fr 1fr;gap:12px}.stats>div{padding:16px}.toolbar{flex-wrap:wrap}.toolbar input{max-width:100%}.editor-layout{padding:0 20px}.editor-layout>div:first-child{display:block}.editor-layout>div:first-child .panel{margin-bottom:18px}.panel{padding:22px}.page-heading .button{font-size:12px;padding:9px}.page-heading{align-items:flex-start}.messages{padding:0 20px}}

.editor-layout>div,.panel,.prose{min-width:0}.prose mjx-container[display="true"]{max-width:100%;overflow-x:auto;overflow-y:hidden}
.prose span.arithmatex{display:inline-block;max-width:100%;overflow-x:auto;overflow-y:hidden;vertical-align:middle}.prose pre{max-width:100%;overflow-x:auto;white-space:pre-wrap;overflow-wrap:anywhere}
.prose table{display:block;max-width:100%;overflow-x:auto;border-collapse:collapse}.prose td,.prose th{padding:12px;min-width:110px;border:1px solid var(--line)}
.source-metadata{margin:0;font-size:13px}.source-metadata>div{display:grid;grid-template-columns:6.5em minmax(0,1fr);gap:12px;margin:9px 0}.source-metadata dt{color:var(--muted)}.source-metadata dd{margin:0}.source-record+.source-record{border-top:1px solid var(--line);padding-top:16px}

/* Preserve adjacent source diagrams in their original left-to-right order. */
.prose .center p:has(>img+img){display:grid;grid-auto-flow:column;grid-auto-columns:minmax(0,1fr);gap:12px;align-items:center}.prose .center p:has(>img+img)>img{width:100%;min-width:0;height:auto;margin:20px 0}

.portal-page,.login-page{min-height:100vh;min-height:100svh;display:flex;flex-direction:column}
.portal-page>main,.login-page>main{flex:1;min-width:0}
.portal-page>.site-header,.portal-page>.site-footer,.login-page>.site-header,.login-page>.site-footer{flex-shrink:0}
.portal-page .site-footer,.login-page .site-footer{margin-top:40px}
.portal-heading{max-width:860px;margin:0 auto;padding:48px 24px 24px;text-align:center}
.portal-heading h1{font-size:32px;line-height:1.4;margin:0;letter-spacing:0}
.portal-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px;max-width:860px;padding:0 24px;margin:0 auto}
.portal-card{padding:28px;background:white;border:1px solid var(--line);border-radius:10px}
.portal-card-staff{background:var(--brand-soft)}
.portal-card h2{font-size:24px;margin-bottom:10px}.portal-card p{font-size:14px;color:var(--muted);margin-bottom:24px}
.portal-card .button{width:100%;justify-content:space-between}
.portal-note{padding:0 24px;text-align:center;margin:18px auto 0;max-width:860px}
.login-layout{width:calc(100% - 40px);max-width:420px;margin:48px auto 0;padding:32px}
.login-layout h1{font-size:26px;letter-spacing:0;margin-bottom:24px}
.login-layout .button.full{margin-top:8px}
.login-help{font-size:12px;margin:20px 0 16px}
.login-links{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;font-size:13px}
@media(max-width:640px){.portal-heading{padding:32px 20px 22px}.portal-heading h1{font-size:27px}.portal-grid{grid-template-columns:1fr;gap:16px;padding:0 20px}.portal-card{padding:24px}.portal-card h2{font-size:23px}.portal-card p{margin-bottom:20px}.portal-note{font-size:12px;margin-top:16px}.login-layout{margin-top:28px;padding:26px 24px}.login-layout h1{font-size:25px}.portal-page .site-footer,.login-page .site-footer{margin-top:32px}}