/* Shared learning surfaces: the typography carries the hierarchy. */
.course-compass{display:flex;align-items:center;gap:18px;flex-wrap:wrap;font:500 11px/1.5 Manrope,sans-serif;margin:0 0 24px;color:var(--muted)}.course-compass a{text-decoration:none;color:var(--muted);display:inline-flex;align-items:center;gap:7px}.course-compass a:hover{color:var(--geometry)}.course-compass .hugeicon{width:16px;height:16px}.course-compass>span{margin-right:auto}.chapter-bridges{font:500 12px/1.7 Manrope,sans-serif;margin:0 0 35px;color:var(--muted)}.chapter-bridges summary{cursor:pointer;width:fit-content}.chapter-bridges>div{display:grid;gap:10px;padding-top:14px}.chapter-bridges a{display:flex;align-items:center;gap:9px;text-decoration:none}.chapter-bridges .hugeicon{width:15px}.return-to-lesson{display:flex;align-items:center;justify-content:space-between;font:500 12px/1.6 Manrope,sans-serif;background:var(--wash);padding:12px 16px;border-radius:12px;margin:0 0 25px}.return-to-lesson button{border:0;background:none;font-size:20px}.return-to-lesson[hidden]{display:none}
.guided-lesson{margin:38px 0 64px;padding:30px 0 0;position:relative;min-width:0;scroll-margin-top:90px}.lesson-topline{display:flex;align-items:center;justify-content:space-between;gap:15px}.lesson-topline .eyebrow{color:var(--curvature)}.lesson-save{border:0;background:none;color:var(--muted);padding:8px;border-radius:10px;line-height:1}.lesson-save:hover,.lesson-save[aria-pressed=true]{color:var(--curvature);background:color-mix(in srgb,var(--curvature) 9%,transparent)}.prose .guided-lesson .lesson-title{font:450 clamp(1.9rem,3vw,2.6rem)/1.13 Newsreader,Georgia,serif;margin:9px 0 16px;letter-spacing:-.035em;text-wrap:balance}.prose .lesson-question{font:450 1.22rem/1.6 Newsreader,Georgia,serif;color:var(--muted);margin:0 0 18px}.lesson-prerequisites{display:flex;gap:8px 14px;flex-wrap:wrap;align-items:center;font:500 11px/1.6 Manrope,sans-serif;margin:0 0 24px}.lesson-prerequisites>span{color:var(--muted)}.lesson-prerequisites a{display:inline-flex;gap:4px;align-items:center;text-decoration:none}.lesson-prerequisites .hugeicon{width:12px;height:12px}.lesson-depths{display:flex;gap:4px;background:var(--wash);padding:4px;border-radius:13px;width:fit-content;max-width:100%;margin:0 0 23px}.lesson-depths button{border:0;background:transparent;padding:9px 15px;border-radius:10px;font:650 11px/1.5 Manrope,sans-serif;white-space:nowrap;color:var(--muted);transition:color .2s,background .2s}.lesson-depths button[aria-selected=true]{background:var(--paper);color:var(--geometry);box-shadow:0 2px 6px #00000008}.lesson-panel[hidden]{display:none}.lesson-panel{scroll-margin-top:90px;min-width:0}.lesson-panel>p:first-child{margin-top:0}.prose .derivation-steps{list-style:none;padding:0;margin:0;display:grid;gap:28px}.prose .derivation-steps>li{display:grid;grid-template-columns:28px minmax(0,1fr);gap:15px;margin:0;padding:0}.step-number{font:600 11px/1.6 Manrope,sans-serif;color:var(--curvature);padding-top:5px}.derivation-steps strong{font:650 14px/1.5 Manrope,sans-serif}.derivation-steps p{margin:12px 0}.derivation-steps .step-reason{font:450 13px/1.75 Manrope,sans-serif;color:var(--muted);margin:10px 0 0}.step-reason>span{color:var(--geometry);font-weight:650;margin-right:6px}.guided-lesson .equation{margin:20px 0}.lesson-sources{display:flex;flex-wrap:wrap;gap:9px 16px;font:500 11px/1.65 Manrope,sans-serif;color:var(--muted);padding:10px 0}.lesson-sources a{display:inline-flex;align-items:center;gap:5px}.lesson-sources .hugeicon{width:12px;height:12px}.lesson-reference{margin:20px 0;color:var(--muted);font:500 11px/1.7 Manrope,sans-serif}.lesson-reference summary{cursor:pointer}.lesson-reference .diagram{margin:22px 0}.lesson-practice{margin:28px 0;background:color-mix(in srgb,var(--geometry) 5%,var(--paper));border-radius:18px;padding:0 23px}.lesson-practice>summary{list-style:none;display:flex;align-items:center;justify-content:space-between;padding:18px 0;font:650 13px/1.6 Manrope,sans-serif;color:var(--geometry);cursor:pointer}.lesson-practice>summary::-webkit-details-marker{display:none}.lesson-practice>summary .hugeicon{width:18px}.lesson-practice[open]>summary .hugeicon{transform:rotate(90deg)}.practice-body{padding:2px 0 22px}.prose .practice-label{font:750 9px/1.6 Manrope,sans-serif;letter-spacing:1.6px;color:var(--muted);margin:10px 0}.practice-choices{display:grid;gap:9px;margin:18px 0}.practice-choices button{background:var(--paper);border:1px solid transparent;border-radius:11px;padding:12px 15px;text-align:left;font:450 1.05rem/1.6 Newsreader,Georgia,serif}.practice-choices button[aria-pressed=true]{border-color:var(--geometry)}.practice-choices button:hover{background:var(--wash)}.practice-feedback,.transfer-feedback{font:450 13px/1.7 Manrope,sans-serif;color:var(--ink)}.practice-feedback:empty,.transfer-feedback:empty{display:none}.practice-feedback p{font:450 1.1rem/1.65 Newsreader,Georgia,serif;margin:8px 0 15px}.practice-body details{font:500 12px/1.7 Manrope,sans-serif;margin:16px 0}.practice-body details>summary{width:fit-content;cursor:pointer;color:var(--geometry)}.practice-body details p{font:450 1.1rem/1.7 Newsreader,Georgia,serif}.transfer-problem{margin:32px 0 0}.transfer-input{display:flex;gap:8px;align-items:stretch;margin:8px 0}.transfer-input input{background:var(--paper);color:var(--ink);width:160px;min-width:0;border:1px solid var(--line);border-radius:10px;padding:10px 12px;font:500 16px/1.5 Manrope,sans-serif}.transfer-input button{border:0;border-radius:10px;padding:10px 15px;background:var(--geometry);color:var(--paper);font:650 12px/1.5 Manrope,sans-serif;display:flex;align-items:center;gap:6px}.transfer-input .hugeicon{width:16px;height:16px}.transfer-problem label{font:500 12px/1.6 Manrope,sans-serif}.transfer-problem small{font:450 10px/1.6 Manrope,sans-serif;color:var(--muted);display:block}.transfer-feedback{margin-top:14px}.transfer-feedback[data-correct=true]{color:var(--geometry)}.prose .lesson-takeaway{font:500 1.18rem/1.65 Newsreader,Georgia,serif;color:var(--geometry);margin:26px 0 0}.lesson-save-status{font:500 11px/1.6 Manrope,sans-serif;color:var(--muted);margin-top:14px}
.course-route-picker{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.course-route-picker button{border:1px solid transparent;border-radius:16px;background:var(--wash);text-align:left;padding:20px;display:flex;flex-direction:column;gap:10px}.course-route-picker button[aria-pressed=true]{border-color:var(--geometry);background:color-mix(in srgb,var(--geometry) 6%,var(--paper))}.course-route-picker strong{font:600 14px/1.5 Manrope,sans-serif}.course-route-picker span{font:450 12px/1.75 Manrope,sans-serif;color:var(--muted)}.route-status{font:500 11px/1.6 Manrope,sans-serif;color:var(--muted);margin:24px 0 32px}.course-node{display:grid;grid-template-columns:40px minmax(0,1fr);gap:20px;padding:24px 0}.course-node[hidden]{display:none}.course-node-number{font:600 12px/1.5 Manrope,sans-serif;color:var(--node-accent);padding-top:8px;position:relative}.course-node-number::after{content:'';display:block;width:2px;min-height:40px;height:calc(100% - 40px);margin:15px 0 0 8px;background:color-mix(in srgb,var(--node-accent) 25%,transparent)}.course-node-title{display:flex;justify-content:space-between;gap:12px;text-decoration:none;color:var(--ink);font:450 1.8rem/1.25 Newsreader,Georgia,serif}.course-node-title .hugeicon{width:17px;height:17px;margin-top:6px;color:var(--node-accent)}.course-node p{font:450 14px/1.75 Manrope,sans-serif;color:var(--muted);margin:10px 0 13px}.course-node-requires{display:flex;gap:5px 10px;flex-wrap:wrap;font:500 10px/1.7 Manrope,sans-serif;color:var(--muted)}.course-node-requires a{text-decoration:none;color:var(--muted)}.course-node-requires a:hover{color:var(--geometry)}.map-lesson{display:flex;gap:12px;justify-content:space-between;text-decoration:none;padding:12px 0 0;font:550 12px/1.7 Manrope,sans-serif}.map-lesson small{font-size:10px;color:var(--muted);text-align:right;flex-shrink:0}.course-conventions{font:450 13px/1.8 Manrope,sans-serif;margin:40px 0 70px}.course-conventions summary{cursor:pointer;color:var(--geometry)}.notebook-actions{display:flex;gap:10px;flex-wrap:wrap}.notebook-actions button,.notebook-import{border:0;border-radius:10px;background:var(--wash);padding:10px 13px;font:550 11px/1.6 Manrope,sans-serif;cursor:pointer}.notebook-import input{display:block;font-size:11px;margin-top:7px;max-width:230px}.notebook-status{font:500 12px/1.6 Manrope,sans-serif;color:var(--geometry)}.field-notebook section>h2{margin-top:45px;font-size:2.3rem}.notebook-help,.notebook-empty{font:450 14px/1.85 Manrope,sans-serif;color:var(--muted)}.notebook-entry{margin:25px 0 40px;background:var(--wash);border-radius:18px;padding:25px}.notebook-entry>a{display:flex;justify-content:space-between;gap:15px;font:450 1.6rem/1.3 Newsreader,Georgia,serif;text-decoration:none}.notebook-entry>p{font:450 13px/1.8 Manrope,sans-serif;color:var(--muted)}.notebook-entry label{display:block;font:600 11px/1.7 Manrope,sans-serif;margin:18px 0 8px}.notebook-entry textarea{width:100%;min-height:145px;resize:vertical;padding:14px;border:1px solid var(--line);border-radius:12px;background:var(--paper);color:var(--ink);font:450 16px/1.65 Newsreader,Georgia,serif}.notebook-entry button{border:0;background:none;color:var(--muted);font:450 11px/1.6 Manrope,sans-serif;padding:10px 0}.notebook-entry small{display:block;font:450 11px/1.6 Manrope,sans-serif;color:var(--muted);margin-top:8px}.review-item{display:flex;justify-content:space-between;gap:15px;text-decoration:none;padding:15px 0;font:500 14px/1.6 Manrope,sans-serif}.review-item small{font-size:11px;color:var(--muted)}
@media(max-width:650px){.course-compass{gap:12px;font-size:10px}.course-compass>span{order:3;width:100%}.lesson-depths button{padding:9px 12px;font-size:10px}.guided-lesson{margin:25px 0 50px}.lesson-practice{padding:0 16px;border-radius:14px}.prose .derivation-steps>li{grid-template-columns:20px minmax(0,1fr);gap:8px}.course-route-picker{grid-template-columns:1fr}.course-route-picker button{padding:16px;gap:5px}.course-node{grid-template-columns:24px minmax(0,1fr);gap:12px}.course-node-title{font-size:1.55rem}.map-lesson{display:block}.map-lesson small{display:block;text-align:left}.review-item{display:block}.review-item small{display:block}.notebook-entry{padding:18px}.lesson-prerequisites{font-size:10px}}
@media(prefers-reduced-motion:reduce){.lesson-depths button{transition:none}}
.notebook-import{position:relative;display:inline-flex;align-items:center}.notebook-import input{position:absolute;width:1px;height:1px;opacity:0;overflow:hidden;padding:0;margin:0;max-width:1px}.notebook-import:focus-within{outline:3px solid var(--curvature);outline-offset:4px}.contents-path{font:500 12px/1.6 Manrope,sans-serif;text-decoration:none;display:inline-block;margin-top:6px}

/* The authored lesson is complete before progressive enhancement succeeds. */
.lesson-depths[hidden], .guided-lesson form[hidden]{display:none}
.guided-lesson[data-enhanced="true"]:not([data-sequential="true"]) .lesson-depth-title,
.guided-lesson[data-enhanced="true"] .practice-static{display:none}
.lesson-depth-title{font:650 14px/1.5 Manrope,sans-serif;color:var(--geometry);margin:32px 0 14px}
.visual-summary{border:1px solid var(--line);border-radius:18px;padding:22px;overflow-wrap:anywhere}
.visual-summary dl{display:grid;gap:18px;margin:24px 0}
.visual-summary dt{font:550 12px/1.6 Manrope,sans-serif;color:var(--muted)}
.visual-summary dd{margin:5px 0;overflow-x:auto}
.practice-choices button:disabled{cursor:default;color:var(--ink)}
@media print{.guided-lesson .lesson-panel[hidden]{display:block}.guided-lesson .lesson-depths,.lesson-save{display:none}.guided-lesson[data-enhanced="true"] .lesson-depth-title{display:block}}

.transfer-next[hidden],.notebook-import-preview[hidden]{display:none}
.transfer-heading{display:flex;gap:12px;align-items:baseline;justify-content:space-between;flex-wrap:wrap}
[data-transfer-item-label]{font:500 11px/1.5 Manrope,sans-serif;color:var(--muted)}
.transfer-next{display:flex;align-items:center;gap:12px;flex-wrap:wrap;margin:24px 0 10px}
.transfer-next button,.notebook-import-preview button{border:1px solid var(--line);border-radius:10px;padding:10px 14px;background:var(--paper);color:var(--geometry);font:600 12px/1.5 Manrope,sans-serif}
.transfer-next span{font:450 11px/1.5 Manrope,sans-serif;color:var(--muted)}
.notebook-import-preview{background:var(--wash);padding:24px;border-radius:18px;margin:24px 0}
.notebook-import-preview label{display:grid;gap:8px;font:500 12px/1.7 Manrope,sans-serif}
.notebook-import-preview select{background:var(--paper);color:var(--ink);border:1px solid var(--line);border-radius:9px;padding:10px;max-width:100%}
.notebook-import-preview>div{display:flex;gap:12px;flex-wrap:wrap}

.attempt-history{border-block-end:1px solid var(--line);padding:1rem 0}.attempt-history summary{cursor:pointer;font-weight:600}.attempt-history li{padding:.6rem 0}.attempt-history li p{margin:.25rem 0}.attempt-history time{font-size:.78rem;opacity:.7}

.skill-preparation{list-style:none;padding:0!important;margin:1rem 0!important;display:grid;gap:.8rem}.skill-preparation li{margin:0!important}.skill-preparation a{font:600 12px/1.6 Manrope,sans-serif}.skill-preparation span{display:block;font:400 12px/1.6 Manrope,sans-serif;color:var(--muted);margin-top:.15rem}.entry-diagnostics{margin:3rem 0}.entry-diagnostics>p{max-width:65ch}.diagnostic-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}.diagnostic-grid>details{border:1px solid var(--line);padding:18px;border-radius:14px;min-width:0;align-self:start}.diagnostic-grid>details>summary{font:600 13px/1.6 Manrope,sans-serif;cursor:pointer}.diagnostic-grid p{font-size:1rem}.diagnostic-return{font:500 12px/1.6 Manrope,sans-serif;display:block;margin-top:1rem}.diagnostic-grid label{display:block;font:500 12px/1.6 Manrope,sans-serif;margin:1rem 0 .5rem}.diagnostic-grid form[hidden]{display:none}@media(max-width:650px){.diagnostic-grid{grid-template-columns:1fr}}

/* Preserve old links without making a relocated advanced lesson part of the opening. */
.relocated-lesson{display:none}
.relocated-lesson:target{display:block;padding:1.25rem;border:1px solid var(--border);border-radius:1rem;scroll-margin-top:6rem}
/* The first experiment has two short columns; both fit on a phone. */
body[data-page="chapter-0"] .prose table{min-width:0;table-layout:fixed}

/* Worked examples stay connected to the section that prepares them. */
.guided-lesson{border-top:1px solid var(--line);margin:36px 0 44px;padding-top:22px}
.prose>.guided-lesson+h3{margin-top:1.6em}
.lesson-depths button{min-height:44px;font-size:12px;padding:9px 13px}
@media(max-width:650px){.guided-lesson{margin:30px 0 36px}.lesson-depths button{font-size:11px;padding:9px 12px}}
/* The notebook also works independently of a laboratory. */
[data-journal]{width:100%;min-height:115px;border:1px solid var(--line);background:var(--paper);color:var(--ink);border-radius:12px;padding:13px;font:450 16px/1.6 Newsreader,Georgia,serif;resize:vertical}