/* OFF BY ONE family: neutral base, service accent, wordmark, information first. */
header{max-width:none;padding:0 32px;height:76px}.brand{gap:16px}.brand b{color:var(--accent);font-size:19px;letter-spacing:1px}.brand-sub{margin:0;display:block;color:var(--muted)}
.shell{max-width:1540px;grid-template-columns:280px minmax(0,1fr);padding:0 28px;gap:36px}aside{padding-right:12px}.cat{padding:12px 10px;font-size:14px}.nav-category-row{gap:0}.nav-toggle{width:32px}.nav-lessons{padding-left:0}.nav-lesson{padding:10px 10px}.nav-home,.cat,.nav-lesson{border-radius:3px}.nav-lesson.active{border-left:2px solid var(--accent)}
main{padding-top:30px}.lesson-flow{max-width:1100px;gap:0}.lesson-section{padding:28px 0;border:0;border-top:1px solid var(--line);border-radius:0;background:none;min-width:0}.lesson-section.situation{padding-top:12px;border-top:0}.lesson-section h2{font-size:20px;margin:0 0 14px}.lesson-section p{max-width:800px;line-height:1.85}.lesson-heading{margin-bottom:16px}.lesson-level,.category-count{font-size:13px;color:var(--muted)}.lesson-position{margin-bottom:8px}.step{display:none}
.lesson-flow .demo-stage{max-width:940px;min-height:0;border:0;border-radius:4px;background:#111a1d;padding:20px;margin:18px 0}.lesson-flow .controls{max-width:940px;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px 28px}.formula{border:0;border-radius:0;background:none;padding:12px 0;margin:12px 0 0;color:var(--accent)}.code{border-radius:4px;border:0;margin:14px 0}.btn{border-radius:4px;box-shadow:none}.badge{border:0;background:none;padding:0;border-radius:0}.activity-observation{color:var(--muted);font-size:14px}.source{display:inline-block;margin:4px 6px 4px 0}.quiz-choices{display:flex;gap:12px;flex-wrap:wrap}.quiz-choice{min-width:96px;min-height:44px}.quiz [hidden]{display:none}
.home-intro{margin-bottom:24px}.home-intro h1{font-size:36px}.home-intro p{color:var(--muted)}.overall-progress{max-width:760px;font-size:14px;color:var(--muted);margin-bottom:28px}.resume-line{padding:24px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line);margin-bottom:34px}.resume-line h2{font-size:15px;color:var(--muted);margin-bottom:12px}.resume-line>a{font-size:24px;color:var(--accent)}.curriculum-heading{font-size:15px;margin:0 0 12px}.curriculum-row{display:grid;grid-template-columns:32px minmax(0,1fr) auto;gap:20px;padding:20px 0;border-bottom:1px solid var(--line);align-items:center}.curriculum-row>span{font:14px monospace;color:var(--muted)}.curriculum-row h3{font-size:19px}.curriculum-row p{font-size:14px;color:var(--muted);margin-top:5px}.curriculum-row:hover h3{color:var(--accent)}
.lesson-list{gap:0}.lesson-card{border:0;border-bottom:1px solid var(--line);border-radius:0;background:none;padding:18px 0;gap:18px}.lesson-card:hover{border-color:var(--line)}.lesson-card:hover h3{color:var(--accent)}.lesson-card h3{font-size:19px}.lesson-card p{font-size:14px}.row-meta{display:flex;gap:18px;font-size:12px;color:var(--muted);margin-top:6px}.api-guide{border-radius:0}.stats{gap:0;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}.stats .panel{border:0;border-radius:0;background:none}.panel{border-radius:4px}.resume-card,.featured{background:var(--panel);box-shadow:none}.gauge{border-radius:2px}.example-steps{padding-left:24px;line-height:2}.example-steps li{padding:8px 0;border-bottom:1px solid #293438}.candidate-pair,.position-pair{display:flex;gap:36px;flex-wrap:wrap;padding:22px 0;font-size:24px;color:var(--accent)}.value-bar{position:relative;margin:12px 0;padding-bottom:13px;overflow:hidden}.value-bar:after{content:'';position:absolute;bottom:0;left:0;right:0;height:7px;background:#35434a}.value-bar i{position:absolute;left:0;bottom:0;height:7px;background:var(--accent);z-index:1}.relation-steps{display:flex;align-items:center;gap:24px;flex-wrap:wrap;color:var(--accent);padding:20px 0;font-size:22px}.mod-groups{display:flex;flex-wrap:wrap;gap:16px;padding:20px 0}.full-group{border-bottom:2px solid #536166;padding:8px;color:#c3cfd3}.remainder{padding:8px;color:var(--accent)}.weighted-interval{display:flex;min-height:48px}.weighted-interval span{display:flex;align-items:center;justify-content:center;background:#23414b;min-width:0;border-right:1px solid #7dd3fc;overflow:hidden}.weighted-interval span:nth-child(2){background:#35434a}.weighted-interval span:nth-child(3){background:#45533b}.hp-readout{font:28px monospace}.gold-steps [aria-pressed=true]{background:#19303b}
footer{max-width:none;padding:24px 32px}.aside-note a{color:var(--accent)}
@media(max-width:1050px){.shell{grid-template-columns:250px minmax(0,1fr);gap:24px;padding:0 22px}.brand-sub{display:none}}
@media(max-width:760px){header{padding:0 20px;height:72px}.brand b{font-size:17px}.shell{display:block;padding:0 20px}aside{padding:20px;width:min(350px,90vw)}.lesson-section{padding:24px 0}.lesson-flow .demo-stage{padding:14px}.lesson-flow .controls{grid-template-columns:minmax(0,1fr)}.curriculum-row{grid-template-columns:25px minmax(0,1fr) auto;gap:12px}.curriculum-row h3{font-size:17px}.curriculum-row p{font-size:13px}.resume-line>a{font-size:21px}.lesson-card h3{font-size:18px}.lesson-heading{gap:10px}.lesson-level{flex-shrink:0}.formula{overflow-wrap:anywhere}.candidate-pair{gap:20px;font-size:22px}.example-steps{font-size:15px}.relation-steps{gap:15px;font-size:19px}footer{padding:20px}.quiz form input{width:100%}.mobile-toolbar span{min-width:0}.source{overflow-wrap:anywhere}.lesson-section,.demo-stage,.quiz{min-width:0;max-width:100%}}

.candidate small{display:block;font-size:14px;color:var(--muted);margin-top:8px}.candidate{border-bottom:2px solid var(--accent);padding-bottom:10px}

.formula-disclosure summary{cursor:pointer;min-height:44px;display:flex;align-items:center;color:var(--accent)}.formula-disclosure summary::before{content:"+";margin-right:12px}.formula-disclosure[open] summary::before{content:"−"}.concept-name{color:var(--accent)}

.brand b{letter-spacing:0;font-weight:700}.home-intro h1{color:var(--accent)}