@font-face{font-family:"Open Sans";font-style:normal;font-weight:400;font-display:swap;src:url("fonts/open-sans-400.woff") format("woff");}
@font-face{font-family:"Open Sans";font-style:normal;font-weight:600;font-display:swap;src:url("fonts/open-sans-600.woff") format("woff");}
@font-face{font-family:"Open Sans";font-style:normal;font-weight:700;font-display:swap;src:url("fonts/open-sans-700.woff") format("woff");}
:root{--ink:#193d49;--muted:#536973;--accent:#006f7b;--tint:#eaf7f8;--paper:#fffdf8;--line:#d7e4e3;--side:#125668;--grass:#4b653f;--sand:#eee1cb;--dune:#82603c;--lake:#66c8d0;--sidebar-width:244px;font-family:"Open Sans",ui-sans-serif,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;color:var(--ink);background:var(--paper);font-synthesis:none;scroll-behavior:smooth;scroll-padding-top:30px}
*{box-sizing:border-box}body{margin:0;font-size:18px;line-height:1.65}body[data-platform=claude]{--accent:#486741;--tint:#eef4e9}button,input{font:inherit}button,a,input{-webkit-tap-highlight-color:transparent}a{color:var(--accent);text-underline-offset:4px}a:hover{text-decoration-thickness:2px}button{cursor:pointer}button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid var(--dune);outline-offset:4px}p{margin:0 0 17px}h1,h2,h3,h4{line-height:1.2;letter-spacing:-.025em;margin:0;color:var(--ink)}h2{font-size:32px;font-weight:680}h3{font-size:21px;margin:30px 0 12px;letter-spacing:-.015em}h4{font-size:21px}strong{font-weight:680}code{font-family:ui-monospace,SFMono-Regular,Consolas,monospace;font-size:.88em;overflow-wrap:anywhere;background:var(--tint);padding:2px 5px;border-radius:4px}button{border:0}button:disabled{cursor:wait}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.skip{position:fixed;top:-80px;left:16px;background:white;padding:10px 18px;z-index:100}.skip:focus{top:10px}
.sidebar{position:fixed;inset:0 auto 0 0;width:var(--sidebar-width);padding:42px 22px 24px;background:linear-gradient(165deg,#e8f6f5 0%,#b5e2e8 68%,#8acbd7 100%);border-right:1px solid #9ccbd0;color:var(--ink);display:flex;flex-direction:column;overflow-y:auto;z-index:30}.brand{color:#174651;display:block;font-size:27px;line-height:1.12;letter-spacing:-1px;text-decoration:none;font-weight:650;padding:0 14px}.brand-icon{display:block;width:31px;height:33px;border:1px solid #1f697a;border-radius:7px;background:#1f697a;color:#fff;font-size:26px;line-height:25px;text-align:center;margin-bottom:18px;font-weight:400}.brand-sub{display:block;font-size:12px;letter-spacing:0;font-weight:400;color:#214e5b;margin-top:14px;line-height:1.4}nav{margin-top:37px;display:grid;gap:4px}nav a{display:flex;gap:12px;align-items:center;text-decoration:none;color:#214e5b;padding:10px 12px;font-size:16px;line-height:1.35;border-radius:6px;min-height:42px}.nav-number{font-size:12px;color:#214e5b;font-variant-numeric:tabular-nums}nav a:hover{background:#ffffff70;color:#153e4b}nav a[aria-current=location]{background:#fffffff0;color:#174b57;font-weight:650;box-shadow:inset 3px 0 0 var(--grass),0 2px 8px #1a69770a}.sidebar-note{font-size:13px;color:#214e5b;line-height:1.6;margin:auto 12px 0;padding-top:36px}.mobile-header,.backdrop{display:none}main{margin-left:var(--sidebar-width);background:linear-gradient(180deg,#edf9fa 0,#fffdf8 780px)}.page{max-width:970px;margin:0 auto;padding:34px 66px 40px}.platform-bar{display:flex;align-items:center;justify-content:space-between;gap:20px;padding-bottom:25px;border-bottom:1px solid var(--line);font-size:15px;color:var(--muted)}.platform-switch{display:flex;min-width:0;margin:0;padding:4px;background:#dfeff0;border:1px solid #b4cfd2;border-radius:10px}.platform-switch legend{position:absolute}.platform-switch label{position:relative;cursor:pointer}.platform-switch input{position:absolute;opacity:0;width:1px;height:1px}.platform-switch span{display:block;padding:8px 17px;border-radius:7px;font-size:14px;font-weight:650;color:#315b68;transition:background .18s,color .18s}.platform-switch input:checked+span{background:var(--accent);color:#fff;box-shadow:0 1px 3px #0001}.platform-switch input:focus-visible+span{outline:3px solid var(--dune);outline-offset:2px}
.welcome{padding:65px 0 52px}.eyebrow{text-transform:uppercase;letter-spacing:.11em;font-size:12px;font-weight:700;color:var(--dune);margin-bottom:19px}h1{font-size:clamp(45px,5vw,64px);font-weight:680;letter-spacing:-.04em;line-height:1.12;margin-bottom:25px}.welcome-text{font-size:22px;line-height:1.55;max-width:650px}.how-to-read{color:var(--muted);font-size:17px;max-width:630px}.first-idea{border-left:3px solid var(--dune);border-radius:0 9px 9px 0;background:#f5ecdd;padding:15px 19px;display:grid;gap:3px;font-size:16px;margin-top:28px}.first-idea span{color:var(--muted)}.lesson{border-top:1px solid var(--line);padding:44px 0 48px;scroll-margin-top:20px}.lesson-heading{display:flex;gap:17px;align-items:baseline;margin-bottom:20px}.lesson-number{flex:none;font-size:14px;font-variant-numeric:tabular-nums;color:var(--grass);font-weight:650;background:#edf2e6;border:1px solid #d7e1cb;border-radius:8px;min-width:34px;padding:7px 6px;text-align:center;line-height:1}.definition{font-size:20px;line-height:1.55;margin-bottom:25px;color:#355663}.plain-list{padding-left:22px;margin:0 0 26px}.plain-list li{padding-left:3px;margin-bottom:10px}.environment-pair{display:grid;grid-template-columns:1fr 1fr;border:1px solid var(--line);border-radius:10px;margin:18px 0 22px;overflow:hidden}.environment-pair article{padding:22px 23px;background:#f8efdf}.environment-pair article+article{border-left:1px solid var(--line);background:#e6f5f8}.environment-pair h4{margin-bottom:15px;font-size:20px}.environment-pair h4 span{display:block;font-weight:500;letter-spacing:0;font-size:14px;color:var(--muted);margin-top:6px}.environment-pair p{font-size:16px;line-height:1.55}.environment-pair p:last-child{margin-bottom:0}.tip{font-size:16px;line-height:1.6;color:var(--muted);margin:21px 0 0}.small{font-size:14px;line-height:1.6;color:var(--muted);margin-top:14px}.example{margin:23px 0 18px}.example strong{display:block;font-size:15px;line-height:1.5;color:var(--grass);margin-bottom:4px}.prompt{border:1px solid #c5dce0;border-top:3px solid var(--lake);border-radius:10px;background:#fff;margin:24px 0;overflow:hidden}.prompt-heading{display:flex;gap:14px;align-items:center;justify-content:space-between;padding:14px 20px;border-bottom:1px solid #d1e4e6;background:linear-gradient(105deg,#e2f5f7,#eff8f2)}.prompt h3{font-size:15px;letter-spacing:0;margin:0;font-weight:650;line-height:1.4}.prompt button{white-space:nowrap;flex:none;background:#fff;color:var(--accent);border:1px solid var(--line);border-radius:6px;padding:8px 14px;font-size:14px;line-height:1.5;min-height:40px;font-weight:650}.prompt button:hover{border-color:var(--accent)}.prompt pre{margin:0;padding:21px 22px 25px;white-space:pre-wrap;overflow-wrap:anywhere;font:400 16px/1.65 "Open Sans",ui-sans-serif,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;user-select:text}.steps{margin:18px 0 23px;padding-left:25px}.steps li{padding-left:6px;margin-bottom:13px}.steps li::marker{color:var(--accent);font-weight:650}.long-steps li{margin-bottom:18px}.table-wrap{border-block:1px solid var(--line);margin:22px 0 30px;overflow-x:auto}table{border-collapse:collapse;width:100%;font-size:16px;line-height:1.5;text-align:left}th,td{padding:15px 12px;vertical-align:top;border-bottom:1px solid var(--line)}thead th{font-size:13px;color:var(--muted);font-weight:600}th:first-child,td:first-child{padding-left:0}tbody th{width:26%;font-size:15px}tr:last-child th,tr:last-child td{border-bottom:0}
.final-check{background:#4b653f;border-radius:12px;padding:35px 36px;margin:12px 0 45px;color:#f0f5e9}.final-check .eyebrow{color:#edf0ce;margin-bottom:13px}.final-check h2{color:#fff;font-size:29px;margin-bottom:18px}.final-check p:last-child{margin:0;font-size:17px}footer{padding-top:10px;font-size:12px;line-height:1.7;color:var(--muted)}footer p{margin-bottom:8px}footer h2{font-size:20px;margin-bottom:7px}.download-row{display:flex;justify-content:space-between;gap:25px;align-items:center;border-bottom:1px solid var(--line);padding-bottom:28px;margin-bottom:24px}.download-row p{font-size:14px;margin:0;max-width:360px}.download{display:inline-flex;gap:15px;align-items:center;flex:none;text-decoration:none;border:1px solid var(--line);border-radius:7px;background:#f4e8d4;border-color:#d9c7a7;color:#694c2e;padding:11px 15px;font-weight:650;font-size:14px;min-height:44px}.download:hover{border-color:var(--accent)}.source-links{font-size:13px;margin-bottom:12px}.toast{position:fixed;bottom:24px;left:calc(50% + var(--sidebar-width)/2);transform:translate(-50%,15px);background:#125668;color:#fff;padding:12px 22px;border-radius:8px;box-shadow:0 4px 25px #0002;font-size:15px;opacity:0;pointer-events:none;transition:opacity .2s,transform .2s;z-index:60;max-width:calc(100vw - 32px);width:max-content}.toast.show{opacity:1;transform:translate(-50%,0)}[hidden]{display:none!important}
@media(min-width:1600px){.page{max-width:1030px;padding-inline:85px}}
@media(max-width:1150px){:root{--sidebar-width:218px}.sidebar{padding-inline:14px}.brand{font-size:25px}.brand-sub{font-size:12px}.page{padding-inline:40px}.platform-bar{gap:15px}.platform-switch span{padding-inline:12px}.platform-bar>span{font-size:14px}}
@media(max-width:850px){:root{--sidebar-width:0px;scroll-padding-top:86px}.mobile-header{display:flex;position:sticky;top:0;z-index:35;height:64px;padding:0 22px;align-items:center;justify-content:space-between;background:var(--paper);border-bottom:1px solid var(--line)}.mobile-header>a{color:var(--ink);text-decoration:none;font-size:17px;font-weight:650}.mobile-header button{border:1px solid var(--line);border-radius:6px;padding:7px 11px;background:white;color:var(--ink);min-height:40px;font-size:14px}.mobile-header button span{margin-left:8px}.sidebar{width:265px;top:64px;transform:translateX(-100%);transition:transform .2s;padding:26px 18px;visibility:hidden}.sidebar .brand{display:none}.sidebar nav{margin-top:0}.sidebar nav a{font-size:16px;padding-block:13px;min-height:46px}.sidebar-note{padding-top:22px}.menu-open .sidebar{transform:translateX(0);visibility:visible}.backdrop{display:block;position:fixed;inset:64px 0 0;background:#123d5066;z-index:25}.menu-open{overflow:hidden}main{margin-left:0}.page{padding:22px 32px 32px;max-width:790px}.welcome{padding-top:48px}.lesson{scroll-margin-top:10px}.toast{left:50%}}
@media(max-width:540px){body{font-size:17px}.page{padding:20px 22px 30px}.platform-bar{align-items:flex-start;flex-direction:column;gap:10px;padding-bottom:22px}.platform-switch{width:100%}.platform-switch label{flex:1;text-align:center}.platform-switch span{padding:10px 13px;font-size:14px}.welcome{padding:40px 0}h1{font-size:46px}.welcome-text{font-size:20px}.eyebrow{font-size:12px;letter-spacing:.07em}.how-to-read{font-size:16px}.first-idea{font-size:15px}.lesson{padding-block:34px}h2{font-size:27px}.lesson-heading{gap:12px}.lesson-number{font-size:12px}.definition{font-size:19px}.environment-pair{grid-template-columns:1fr}.environment-pair article+article{border-left:0;border-top:1px solid var(--line)}.environment-pair article{padding:20px}.prompt-heading{padding:12px 14px;gap:10px}.prompt h3{font-size:14px}.prompt button{font-size:13px;padding:7px 10px;min-height:40px}.prompt pre{padding:18px 17px 21px;font-size:15px}.tip{font-size:15px}table{font-size:15px}tbody th{font-size:14px;width:29%}th,td{padding:13px 8px}.download-row{display:block}.download{margin-top:17px}.final-check{padding:26px 24px;margin-bottom:32px}.final-check h2{font-size:27px}.final-check p:last-child{font-size:16px}.source-links{line-height:2}}
@media(prefers-reduced-motion:reduce){:root{scroll-behavior:auto}*,*::before,*::after{transition:none!important}}
@media print{.sidebar,.mobile-header,.platform-bar,.prompt button,.toast,.backdrop,.skip{display:none!important}main{margin:0}.page{max-width:none;padding:0}body{font-size:12pt;background:white}main{background:white}.welcome{padding-top:0}h1{font-size:32pt}.lesson{padding:20px 0}h2{font-size:22pt}.definition{font-size:14pt}.prompt,.environment-pair,.final-check{break-inside:avoid}.prompt pre{font-size:11pt}.final-check{background:white;color:#222;border:1px solid #bbb}.final-check h2,.final-check .eyebrow{color:#222}a{color:inherit}.download-row{display:none}}