/* Geometry shares the Isbot learning interface and adds its own visual identity. */
body.dark{--paper:#0d1923;--card:#152733;--ink:#edf2ef;--muted:#a5b9bb;--line:#2b424f;--teal:#8bd3c3;--light:#203c43;--navy:#091b28;--gold:#e8c680}
.brand{font-size:25px;gap:10px}.brand>b,.brand b{display:block;font-size:12px;letter-spacing:.16em;margin-top:2px;color:var(--gold)}.brand img{width:52px;height:52px;border-radius:14px;background:#0c2232}.brand small{font-size:10px;margin-top:4px}.sidebar{padding:26px 22px 19px}.nav-links{margin-top:25px}.sidebar-foot p{font-size:18px}.sidebar-course{margin-top:20px}.sidebar-course select{font-size:12px;padding:9px 8px;width:100%}
.topbar{min-height:84px;height:auto;padding-block:12px}.header-institute{gap:10px!important}.header-institute img{width:60px!important;height:60px!important}.header-institute>span{font-size:11px!important;line-height:1.5}.topbar-tools{gap:20px!important}.breadcrumb{max-width:45%;line-height:1.5}
.collection-summary{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));border:1px solid var(--line);border-radius:16px;overflow:hidden;margin:0 0 23px;background:var(--card)}.collection-summary>div{padding:18px 20px;border-right:1px solid var(--line)}.collection-summary>div:last-child{border:0}.collection-summary b{display:block;font-size:28px;letter-spacing:-.04em;line-height:1.1;font-weight:650;color:var(--gold)}.collection-summary span{font-size:11px;color:var(--muted);display:block;margin-top:6px}
.course-catalog{display:grid!important;grid-template-columns:repeat(4,minmax(0,1fr))!important;gap:10px!important;margin-bottom:27px!important}.course-choice{position:relative;min-height:128px;padding:17px 16px!important;text-align:left;border:1px solid var(--line)!important;border-radius:12px!important;transition:background .15s,border-color .15s}.course-choice:hover{border-color:var(--teal)!important}.course-choice.selected{background:var(--light)!important;border-color:var(--teal)!important}.course-choice .eyebrow{font-size:8px!important;letter-spacing:.12em!important;margin-bottom:9px!important}.course-choice strong{font-size:14px!important;line-height:1.35;display:block;min-height:38px}.course-choice small{display:block;font-size:10px!important;line-height:1.5;margin-top:8px!important;color:var(--muted)}
.book-cover{background:radial-gradient(ellipse at 85% 60%,#22657455,transparent 62%),#102e3f;box-shadow:0 7px 0 -3px #314852,0 17px 30px -18px #0007;min-height:350px}.cover-number{font-size:145px;color:#8ed3c026;bottom:80px;right:28px}.cover-orbit{border-color:#7bc5ba35!important}.cover-title{max-width:380px;font-size:clamp(32px,3vw,43px)}.cover-bottom>span{font-size:9px;letter-spacing:.1em}.book-cover>p{font-size:13px}.btn{border-radius:9px}.dark .btn:not(.secondary):not(.ghost):not(.danger):not(.gold){color:#102c35}.dark .btn.secondary{border-color:#45656d}.btn.gold{background:var(--gold)}
.reader.prose img,.prose figure img{display:block;max-width:100%;width:auto;max-height:650px;margin:16px auto;background:#fff;padding:12px;border-radius:10px}.prose figure{margin:26px 0;overflow-x:auto}.prose figcaption{font-size:13px;color:var(--muted);text-align:center;line-height:1.6}.prose table{display:block;max-width:100%;overflow-x:auto}.prose .katex-display{max-width:100%;overflow-x:auto;overflow-y:hidden;padding:5px 1px}.prose .theorem,.prose .definition,.prose .proposition,.prose .lemma,.prose .example,.prose .exercise{border-left:3px solid var(--teal);padding:14px 18px;margin:20px 0;background:var(--light);border-radius:0 9px 9px 0}.problem-link{cursor:pointer}.problem-link:hover{border-color:var(--teal)}
@media(min-width:1500px){.course-catalog{grid-template-columns:repeat(4,minmax(0,1fr))!important}}
@media(max-width:1100px){.course-catalog{grid-template-columns:repeat(3,minmax(0,1fr))!important}.topbar-tools{gap:10px!important}.offline{display:none}.header-institute>span{font-size:10px!important}}
@media(max-width:760px){.course-catalog{grid-template-columns:repeat(2,minmax(0,1fr))!important;gap:8px!important}.course-choice{padding:13px!important;min-height:115px}.course-choice strong{font-size:13px!important}.collection-summary{grid-template-columns:repeat(2,minmax(0,1fr))}.collection-summary>div{padding:14px 16px}.collection-summary>div:nth-child(2){border-right:0}.collection-summary>div:nth-child(-n+2){border-bottom:1px solid var(--line)}.collection-summary b{font-size:25px}.topbar{padding:10px 17px;min-height:78px}.mobile-brand img{width:43px;height:43px}.mobile-brand{font-size:22px!important}.mobile-brand b{font-size:8px;letter-spacing:.13em}.header-institute img{width:43px!important;height:43px!important}.header-institute>span{font-size:8px!important;max-width:122px}.topbar .breadcrumb{display:none}.course-strip{padding:12px 19px!important}.course-strip select{font-size:13px}.cover-title{font-size:36px}.reader.prose{padding:21px 17px}.prose figure img{padding:6px}.prose .theorem,.prose .definition,.prose .proposition,.prose .lemma,.prose .example,.prose .exercise{padding:12px}.intro{margin-bottom:22px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}

.question-context{margin:8px 0 24px;padding:18px 20px;border:1px solid var(--line);border-left:3px solid var(--teal);border-radius:10px;background:var(--light)}.question-context .eyebrow{font-size:9px;margin-bottom:10px}.question-context .prose{font-size:calc(var(--reading-size) - 2px);line-height:1.7}.question-context .prose p:last-child{margin-bottom:0}.reader .question-context{margin-top:12px;margin-bottom:18px}.question-context .katex{font-size:1.05em}