:root{color-scheme:light;--paper:#f4f6f0;--surface:#fff;--ink:#12271d;--muted:#51655a;--line:#d8e3d8;--deep:#0c261b;--mint:#a4f2b8;--green:#226646;--soft:#e5f5e8;--sans:system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;--mono:ui-monospace,"SFMono-Regular",Consolas,monospace}
*{box-sizing:border-box} [hidden]{display:none!important}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--sans);line-height:1.55}
a{color:inherit;text-decoration:none} button,input{font:inherit}
:focus-visible{outline:3px solid #3f8a62;outline-offset:4px}
h1,h2,h3,p{margin:0} h2,h3{line-height:1.2;letter-spacing:-.025em}
.frame{width:min(1120px,calc(100% - 56px));margin-inline:auto}
.skip{position:fixed;top:12px;left:12px;z-index:10;background:white;padding:10px;transform:translateY(-200%)} .skip:focus{transform:none}
.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap}
.topbar{background:#fbfcf8;border-bottom:1px solid var(--line)}
.topbar-inner{min-height:75px;display:flex;align-items:center;justify-content:space-between;gap:24px}
.brand{display:block;flex:none;width:184px}.brand img{display:block;width:100%;height:auto}
nav{display:flex;align-items:center;gap:6px} nav a{padding:8px 12px;font-size:14px;font-weight:680;color:var(--muted);border-radius:7px} nav a:hover,nav a[aria-current=page]{background:#e9f1e8;color:#174c30}
.preview-tag{font-size:12px;font-weight:730;color:#365848;border:1px solid var(--line);padding:5px 9px;border-radius:6px;white-space:nowrap}.preview-tag i,.dot{display:inline-block;width:7px;height:7px;border-radius:50%;background:#40a567;margin-right:6px;vertical-align:1px}
main{padding-top:30px;min-height:65vh}
.hero,.lesson-banner{position:relative;isolation:isolate;color:#fff;background:var(--deep);border-radius:18px;overflow:hidden}
.hero{display:grid;grid-template-columns:1.1fr .9fr;min-height:421px;align-items:center;gap:20px;padding:47px 50px}
.hero:before,.lesson-banner:before{content:"";position:absolute;z-index:-1;inset:0;background:radial-gradient(ellipse at 88% 22%,#24573b 0,transparent 54%)}
.eyebrow{font:700 12px/1.35 var(--mono);letter-spacing:.11em;color:#35634d;margin-bottom:10px}
.hero .eyebrow,.lesson-banner .eyebrow{color:#b0e6bc}.hero .dot,.lesson-banner .dot{background:#a6edac}
h1{font-size:clamp(44px,6vw,77px);font-weight:800;letter-spacing:-.069em;line-height:.99}
.hero h1 span{color:#a7f2b8}.lede{font-size:17px;color:#d3e6d9;max-width:440px;margin:20px 0 22px}.hero-note{font-size:12px;color:#c4d8cb;margin-top:10px}
.button{display:inline-flex;align-items:center;justify-content:center;gap:13px;min-height:43px;padding:8px 14px;border-radius:8px;font-weight:760;font-size:14px;line-height:1.3}.button span{font-size:17px}.primary{background:#236444;color:#fff}.primary:hover{background:#164b32}.hero .primary{background:var(--mint);color:#102a1b}.hero .primary:hover{background:#c4ffd0}.secondary{background:#eaf5ed;color:#185139;border:1px solid #cde4d2}.secondary:hover{background:#d9efdd}
.hero-art{position:relative;padding:20px 0 4px}.hero-art:before{content:"";position:absolute;inset:-38px -65px -56px -18px;background-image:linear-gradient(#7bbe9129 1px,transparent 1px),linear-gradient(90deg,#7bbe9129 1px,transparent 1px);background-size:24px 24px;mask-image:radial-gradient(ellipse,#000 24%,transparent 72%);z-index:-1}
.sheet{position:relative;background:#f3faf2;color:#163324;border:1px solid #a0c5a6;border-radius:12px;max-width:405px;margin-inline:auto;box-shadow:0 18px 35px #03180eaa;overflow:hidden;transform:rotate(-2deg)}
.sheet-top{display:flex;align-items:center;gap:9px;padding:11px 12px;background:#d5f0d9;font-size:14px;font-weight:800}.sheet-icon{font-size:18px;color:#2d7449}.sheet-pill{margin-left:auto;font:700 10px var(--mono);color:#2d5e43}
.sheet-grid{display:grid;grid-template-columns:34px 1fr 1.35fr .75fr;font-size:13px}.sheet-grid>*{border-right:1px solid #dcebdc;border-bottom:1px solid #dcebdc;min-width:0;padding:8px 6px;white-space:nowrap}.sheet-grid>*:nth-child(4n+1){text-align:center;color:#557865;background:#e9f2e8}.sheet-grid>*:nth-child(-n+4){background:#e9f2e8;color:#557865;text-align:center}.sheet-grid b{background:#dff2e0;font-size:12px}.sheet-grid .active-cell{background:#e6fadf;box-shadow:inset 0 0 0 2px #3c8c55;font-weight:750}.sheet-footer{padding:11px 12px;font-size:11px;color:#365c48}.sheet-footer span{color:#23814e;font-weight:bold;margin-right:5px}
.section-title{display:flex;align-items:end;justify-content:space-between;gap:18px;margin:35px 0 17px}.section-title h2,.panel h2{font-size:clamp(24px,3.8vw,34px)}.quiet{color:var(--muted);font-size:14px}.roadmap{list-style:none;padding:0;margin:0;display:grid;gap:8px}.roadmap li,.roadmap li a{display:flex;align-items:center;gap:14px}.roadmap li{background:#fbfcf8;border:1px solid var(--line);border-radius:9px;min-height:64px;padding:9px 14px}.roadmap li.current{background:#e6f4e8;border-color:#a2caaa;padding:0}.roadmap li.current a{padding:9px 14px;width:100%;min-height:62px}.roadmap li.current a:hover{background:#d9eedc;border-radius:8px}.day-num,.step-num{display:grid;place-items:center;background:#e9efe7;color:#3b5c4d;border-radius:6px;width:38px;height:35px;flex:0 0 38px;font:700 14px var(--mono)}.current .day-num{background:#26734a;color:#fff}.day-text{display:grid;gap:2px}.day-text b{font-size:15px}.day-text small,.planned{font-size:12px;color:var(--muted)}.planned,.day-state{margin-left:auto;white-space:nowrap}.day-state{color:#205c3b;font-size:13px;font-weight:760}.roadmap-note{margin-top:14px}
.back{display:inline-flex;gap:8px;color:#235f43;font-size:14px;font-weight:750;margin:0 0 15px}.back:hover,.text-link:hover{text-decoration:underline}.lesson-banner{padding:33px 42px;display:flex;align-items:center;justify-content:space-between;gap:20px}.lesson-banner h1{font-size:clamp(40px,6vw,66px)}.lesson-banner p:not(.eyebrow){margin-top:14px;color:#d5e8dc}.lesson-time{border-left:1px solid #74ab82;padding-left:24px;min-width:150px}.lesson-time strong,.lesson-time span{display:block}.lesson-time strong{font-size:36px;letter-spacing:-.065em;color:#c2f4c7;line-height:1.1}.lesson-time span{font-size:13px;color:#c5e1cd}
.lesson-layout{display:grid;grid-template-columns:minmax(0,1fr) minmax(230px,292px);gap:20px;margin-top:22px;align-items:start}
.lesson-main,.lesson-side{display:grid;gap:13px}.lesson-side{position:sticky;top:16px}
.panel{background:#fff;border:1px solid var(--line);border-radius:12px;padding:20px}.panel-top{display:flex;justify-content:space-between;align-items:center;gap:12px}.desktop-label{border-radius:5px;padding:5px 8px;background:#edf4eb;color:#36614d;font-size:12px;font-weight:700;white-space:nowrap}
.steps{list-style:none;margin:21px 0 0;padding:0}.steps li{display:flex;align-items:start;gap:12px;padding:17px 0;border-top:1px solid #e5ebe2}.steps li:last-child{padding-bottom:3px}.step-num{background:#e3f5e7;color:#296144}.step-body{flex:1;min-width:0}.step-body h3{font-size:19px}.step-body p,.disclosure p,.help-panel p:not(.eyebrow){font-size:14px;color:#42594d;margin:6px 0 11px}.check{display:flex;align-items:center;gap:9px;font-size:13px;font-weight:680;color:#315746;margin-top:11px;cursor:pointer;min-height:34px}.check input{accent-color:#226746;width:18px;height:18px;margin:0;flex:none}.text-link{display:inline-block;color:#225f41;font-weight:740;font-size:13px}.step-body .text-link{margin:6px 0 0 8px}kbd,code{font-family:var(--mono);font-size:.89em;background:#edf4eb;padding:1px 4px;border-radius:3px}
.table-wrap{overflow-x:auto;border:1px solid var(--line);border-radius:7px}table{border-collapse:collapse;min-width:390px;width:100%;text-align:left;font-size:12px;line-height:1.35}th,td{padding:7px 8px;white-space:nowrap}thead{background:#e5f3e7;color:#24583e}tbody tr+tr{border-top:1px solid #e4ebe3}tbody th{font:700 12px var(--mono);color:#396650}
.progress-value{display:flex;align-items:baseline;gap:8px}.progress-value strong{font:800 30px var(--sans);letter-spacing:-.06em}.progress-value span,.micro{font-size:12px;color:var(--muted)}progress{width:100%;height:10px;appearance:none;display:block;margin:11px 0;background:#e5eee3;border:0;border-radius:12px;overflow:hidden}progress::-webkit-progress-bar{background:#e5eee3}progress::-webkit-progress-value{background:#43865b}progress::-moz-progress-bar{background:#43865b}.micro{margin-top:7px}.help-panel h2{font-size:21px}
.disclosure summary{display:flex;justify-content:space-between;gap:14px;align-items:center;cursor:pointer;list-style:none}.disclosure summary::-webkit-details-marker{display:none}.disclosure summary:after{content:"+";font:700 24px var(--mono);color:#347858}.disclosure[open] summary:after{content:"−"}.disclosure summary b,.disclosure summary small{display:block}.disclosure summary small{color:var(--muted);font-size:13px;margin-top:2px}.disclosure[open] summary{margin-bottom:12px}.footer{display:flex;justify-content:space-between;gap:12px;margin-top:33px;margin-bottom:22px;padding-top:17px;border-top:1px solid var(--line);color:#5c7064;font-size:12px}
@media(max-width:820px){.hero{padding:35px 32px}.lesson-layout{grid-template-columns:minmax(0,1fr) 227px}.lesson-banner{padding:30px}.hero-art{padding-left:0}}
@media(max-width:660px){.frame{width:calc(100% - 28px)}.topbar-inner{min-height:62px;gap:6px}.brand{width:clamp(128px,39vw,172px)}.preview-tag{font-size:10px;padding:3px 5px}.preview-tag i{width:5px;height:5px;margin-right:3px}nav{gap:1px}nav a{font-size:12px;padding:6px 7px}main{padding-top:16px}.hero{grid-template-columns:1fr;gap:11px;padding:25px 22px 22px}.hero h1{font-size:clamp(42px,12.5vw,61px)}.lede{font-size:15px;margin:14px 0 16px}.hero-art{padding:4px 3px 2px}.sheet{max-width:350px}.sheet-grid>*{padding:5px 4px;font-size:11px}.sheet-top{padding:6px 8px}.sheet-footer{padding:7px 9px}.section-title{align-items:start;gap:4px;flex-direction:column;margin-top:26px}.section-title .quiet{font-size:12px}.roadmap li,.roadmap li a{gap:8px}.roadmap li,.roadmap li.current a{padding-inline:8px}.day-text b{font-size:14px}.day-text small{font-size:11px}.planned,.day-state{font-size:10px}.day-num,.step-num{width:31px;flex-basis:31px}.lesson-banner{padding:24px 17px}.lesson-banner h1{font-size:clamp(32px,9.8vw,49px)}.wide{display:none}.lesson-time{padding-left:10px;min-width:75px}.lesson-time strong{font-size:23px}.lesson-time span{font-size:10px}.lesson-banner p:not(.eyebrow){font-size:14px}.lesson-layout{grid-template-columns:1fr;margin-top:13px}.lesson-side{position:static;grid-row:1}.panel{padding:14px}.steps li{gap:8px}.step-body h3{font-size:17px}.footer{margin-top:25px}.desktop-label{font-size:10px}}
@media(max-width:350px){.preview-tag{display:none}.planned{display:none}.day-state{white-space:normal}.lesson-banner{display:block}.lesson-time{border-left:0;border-top:1px solid #3d6d50;margin-top:15px;padding:8px 0 0}.lesson-time strong,.lesson-time span{display:inline}.lesson-time span{margin-left:4px}}

.roadmap li.roadmap-item{padding:0}.roadmap li.roadmap-item a{width:100%;padding:9px 14px;min-height:62px;border-radius:8px}.roadmap li.roadmap-item a:hover{background:#eaf4e9}.roadmap li.done .day-num{background:#d5eedb;color:#1d5b3d}
.home-help{margin-top:20px;display:flex;align-items:center;justify-content:space-between;gap:16px}.home-help h2{font-size:22px}.home-help .quiet{margin-top:5px}
.resource-links{display:flex;gap:12px;align-items:center;flex-wrap:wrap;margin:10px 0}.step-body .resource-links .text-link{margin:0}.formula{max-width:100%;overflow-x:auto;padding:6px 8px;background:#edf4eb;border-radius:5px;font-size:14px;white-space:nowrap}.formula code{padding:0}
.lesson-navigation{display:flex;align-items:center;justify-content:space-between;gap:10px;margin:4px 0}.lesson-banner h1{max-width:750px}
.inline-details{border-top:1px solid var(--line);margin-top:12px;padding-top:9px;font-size:14px}.inline-details summary{font-weight:700;cursor:pointer}.inline-details a{margin-top:7px}.subject code{overflow-wrap:anywhere}
@media(max-width:660px){.topbar-inner{gap:5px}.topbar nav a{padding-inline:6px}.lesson-side{grid-row:auto}.lesson-layout .lesson-side .progress-panel{position:static}.home-help{flex-wrap:wrap}.roadmap li.roadmap-item a{padding-inline:9px}.lesson-banner h1{font-size:clamp(33px,8vw,50px)}}












.hero h1{font-size:clamp(44px,5.9vw,76px);line-height:1.02}
.start-panel,.simulation-grid{margin-top:20px}
.start-panel{max-width:820px}
.start-steps{list-style:none;padding:0;margin:14px 0;display:grid;gap:10px}
.start-steps li{display:flex;gap:12px;align-items:flex-start;padding:13px 0;border-bottom:1px solid var(--line)}
.start-steps p,.simulation-card p{margin-top:6px;color:var(--muted)}
.glossary{display:grid;gap:9px}
.glossary dt{font-weight:750}
.glossary dd{margin:0;color:var(--muted)}
.skill-tags{display:flex;flex-wrap:wrap;gap:6px;list-style:none;margin:14px 0 0;padding:0}
.skill-tags li{padding:4px 9px;border:1px solid #74ab82;border-radius:6px;color:#d5e8dc;font-size:12px;font-weight:700}
.file-panel,.teaching-header{display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap}
.file-panel h2{font-size:24px}
.file-panel .quiet,.teaching-header .quiet{margin-top:5px}
.teaching-header{margin-bottom:16px;align-items:flex-end}
.separator{font-size:12px;font-weight:720;color:var(--muted);display:grid;gap:3px}
.separator select{font:inherit;color:var(--ink);background:var(--surface);border:1px solid var(--line);border-radius:6px;padding:6px 8px;min-height:37px}
.guided-steps{display:grid;gap:8px}
.guided-step{border:1px solid var(--line);border-radius:9px;background:#fbfdfb}
.guided-step[open]{border-color:#a7cbb0;background:var(--surface)}
.guided-step>summary{list-style:none;cursor:pointer;min-height:55px;display:flex;align-items:center;gap:10px;padding:9px 12px;font-weight:740}
.guided-step>summary::-webkit-details-marker{display:none}
.guided-step>summary::after{content:"+";color:var(--green);font:700 20px var(--mono);margin-left:auto}
.guided-step[open]>summary::after{content:"−"}
.guided-title{display:flex;align-items:center;flex-wrap:wrap;column-gap:8px}
.guided-title small:not(:empty){color:var(--green);font-size:11px;background:var(--soft);padding:2px 5px;border-radius:4px}
.guided-body{padding:4px 14px 14px}
.instruction-list{padding-inline-start:21px;color:#365247;font-size:14px;margin:8px 0 12px}
.instruction-list li+li{margin-top:7px}
.step-actions{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:7px;border-top:1px solid var(--line);padding-top:9px;margin-top:12px}
.step-actions .check{margin:0}
.step-actions button,.practice-actions button,.copy-button{cursor:pointer}
.step-hint{margin-top:12px;border-left:3px solid #9bc5a7;background:#f2f7f0;padding:8px 10px;border-radius:0 7px 7px 0;font-size:13px}
.step-hint summary{cursor:pointer;color:var(--green);font-weight:740}
.step-hint p{margin-top:4px}
.formulas{display:grid;gap:7px;margin:11px 0}
.formula-group>p{font-size:12px;font-weight:740;color:var(--muted);margin-bottom:4px}
.formula-group .formula{display:flex;align-items:center;gap:6px;justify-content:space-between;overflow:visible;white-space:normal}
.formula-group code{overflow-wrap:anywhere;user-select:text}
.copy-button{border:1px solid #a8cdb3;border-radius:5px;background:var(--surface);color:var(--green);font-size:12px;font-weight:750;min-height:32px;padding:4px 7px;flex:none}
.copy-button:hover{background:var(--soft)}
.practice-box{margin-top:11px;padding:12px;border:1px solid var(--line);border-radius:8px;background:#f4f9f3}
.practice-box h4{margin:0;font-size:15px}
.practice-box p{font-size:13px;color:var(--muted);margin:4px 0 8px}
.practice-actions,.practice-fields{display:flex;flex-wrap:wrap;gap:6px;margin-top:8px}
.practice-actions .button[aria-pressed=true]{background:#236444;color:#fff}
.practice-fields label{display:grid;gap:3px;font-size:12px;font-weight:700}
.practice-fields input{width:126px;max-width:100%;border:1px solid #a8cdb3;border-radius:5px;padding:7px;color:var(--ink);background:var(--surface)}
.practice-box .demo-result{font-weight:720;margin:7px 0 0}
.quiz{border:0;margin:12px 0 0;padding:0;min-width:0}
.quiz legend{margin-bottom:6px;font-weight:700}
.quiz-option{display:flex;align-items:center;gap:8px;border:1px solid var(--line);border-radius:7px;padding:7px 9px;margin:5px 0;min-height:39px;cursor:pointer;font-size:14px}
.quiz-option input{accent-color:var(--green);margin:0}
.quiz-option:has(:checked){background:var(--soft);border-color:#a8cdb3}
.quiz-feedback:not(:empty){margin-top:8px;padding:7px 9px;border-radius:6px;background:#f7f3e6;font-size:14px}
.quiz-feedback.correct:not(:empty){background:var(--soft);color:#215b3b}
.simulation-intro{margin-top:14px}
.simulation-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}
.simulation-card h2{font-size:25px}
.simulation-card .eyebrow{color:var(--green)}
@media(max-width:570px){.topbar .preview-tag{display:none}.simulation-grid{grid-template-columns:1fr}.hero h1{font-size:clamp(39px,9.5vw,57px)}}
@media(max-width:385px){.topbar-inner{flex-wrap:wrap;justify-content:center;padding:6px 0}.topbar nav{width:100%;justify-content:center}.guided-step>summary{padding-inline:8px}.guided-body{padding-inline:9px}}
.lesson-main,.teaching-panel,.guided-step,.guided-body,.formula-group{min-width:0}
.separator span{font-weight:500}
@media(max-width:660px){.lesson-layout{grid-template-columns:minmax(0,1fr)}}
.practice-panel > p:not(.eyebrow){margin-top:6px}
.practice-panel blockquote{margin:12px 0;padding:10px 14px;border-inline-start:4px solid var(--green);background:var(--soft);border-radius:6px;color:var(--ink)}
.practice-panel > .button{margin-top:4px}
.project-solution > .panel{margin-top:10px}
.project-solution .teaching-header{margin-bottom:8px}
.project-solution .guided-steps{margin-top:12px}
.rubric-list{display:grid;gap:5px;margin-top:10px}
.rubric-check{padding:8px 10px;border:1px solid var(--line);border-radius:7px;align-items:flex-start}
.rubric-check input{margin-top:3px}
.rubric-check small{display:block;font-weight:500;color:var(--muted)}
.assessment-panel > p{margin-top:8px}
.assessment-panel button{cursor:pointer}
.assessment-fields{padding-inline-start:24px;margin:14px 0}
.assessment-fields li+li{margin-top:10px}
.assessment-fields label{display:block;font-weight:700}
.assessment-fields input{display:block;margin-top:5px;width:min(100%,300px);padding:8px 10px;border:1px solid #a8cdb3;border-radius:6px;color:var(--ink);background:var(--surface)}
.assessment-score{font-size:1.18rem;font-weight:750;color:var(--green)}
.assessment-results strong{color:var(--ink)}