:root{--bg:#02050b;--panel:#07101d;--line:rgba(132,168,219,.17);--text:#f4f7fb;--muted:#aeb9c9;--blue:#168cff;--cyan:#00d6d1;--gold:#ff9d25;--green:#59d879;--red:#ff4059;--purple:#9a55ff;--accent:#168cff;--shadow:0 22px 60px rgba(0,0,0,.38);--max:1320px}
*{box-sizing:border-box}html{scroll-behavior:smooth}html,body{margin:0;padding:0}body{min-height:100vh;color:var(--text);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;background:radial-gradient(circle at 8% 4%,rgba(0,106,255,.20),transparent 28%),radial-gradient(circle at 92% 12%,rgba(100,44,220,.15),transparent 30%),linear-gradient(145deg,#020711,#02050b 50%,#000)}a{color:inherit;text-decoration:none}button,input,select{font:inherit}.wrap{width:min(100%,var(--max));margin:auto;padding:24px 20px 80px}
.appbar{position:sticky;top:12px;z-index:20;display:flex;align-items:center;justify-content:space-between;gap:18px;margin-bottom:28px;padding:12px 16px;border:1px solid var(--line);border-radius:16px;background:rgba(4,10,20,.82);backdrop-filter:blur(20px);box-shadow:0 14px 35px rgba(0,0,0,.30)}.appbar-brand{display:flex;align-items:center;gap:12px}.appbar-brand img{width:44px;height:44px;object-fit:contain}.appbar-title{display:block;font-size:15px;font-weight:850}.appbar-sub{display:block;margin-top:2px;color:var(--muted);font-size:11px}.appbar-links{display:flex;align-items:center;gap:8px;flex-wrap:wrap}.appbar-links a{padding:9px 12px;border:1px solid transparent;border-radius:10px;color:var(--muted);font-size:12px;font-weight:750}.appbar-links a:hover{color:#fff;border-color:rgba(22,140,255,.35);background:rgba(22,140,255,.10)}
.hero{display:grid;grid-template-columns:auto 1fr;align-items:center;gap:34px;padding:44px;border:1px solid rgba(40,112,230,.26);border-radius:26px;background:radial-gradient(circle at 12% 0,rgba(18,126,255,.24),transparent 40%),linear-gradient(145deg,rgba(7,18,35,.98),rgba(2,7,15,.99));box-shadow:var(--shadow)}.hero-logo{width:150px;height:150px;display:grid;place-items:center;border:1px solid rgba(101,166,255,.45);border-radius:34px;background:linear-gradient(145deg,#09265f,#020916);box-shadow:inset 0 1px rgba(255,255,255,.15),0 25px 60px rgba(0,0,0,.45)}.hero-logo img{width:108px;height:108px;object-fit:contain;filter:drop-shadow(0 0 18px rgba(52,160,255,.6))}.eyebrow{color:var(--accent);font-size:12px;font-weight:850;letter-spacing:.16em;text-transform:uppercase}h1{margin:8px 0 12px;font-size:clamp(38px,6vw,72px);line-height:.98;letter-spacing:-.045em}.hero p{max-width:820px;margin:0;color:var(--muted);font-size:18px;line-height:1.65}
.lesson{margin-top:22px;padding:30px;border:1px solid var(--line);border-radius:22px;background:linear-gradient(145deg,rgba(8,18,32,.96),rgba(3,9,18,.98));box-shadow:var(--shadow)}.lesson-head{display:grid;grid-template-columns:58px 1fr;gap:16px;align-items:start;margin-bottom:22px}.lesson-number{width:58px;height:58px;display:grid;place-items:center;border-radius:16px;color:var(--accent);border:1px solid color-mix(in srgb,var(--accent) 38%,transparent);background:color-mix(in srgb,var(--accent) 10%,transparent);font-size:18px;font-weight:900}.lesson h2{margin:0;font-size:30px;letter-spacing:-.025em}.lesson-lead{max-width:900px;margin:7px 0 0;color:var(--muted);font-size:16px;line-height:1.65}.lesson h3{margin:28px 0 9px;font-size:18px}.lesson p,.lesson li{color:var(--muted);font-size:15px;line-height:1.75}.lesson strong{color:#fff}
.concept-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;margin-top:20px}.concept{padding:20px;border:1px solid var(--line);border-radius:16px;background:rgba(255,255,255,.025)}.concept h3{margin:0 0 8px;color:var(--accent);font-size:16px}.concept p{margin:0;font-size:14px}.flow{display:flex;align-items:stretch;gap:10px;margin:22px 0;overflow:auto;padding:8px 2px 12px}.flow-step{flex:1 0 145px;min-height:110px;display:grid;place-items:center;padding:16px;border:1px solid var(--line);border-radius:15px;background:#08111e;text-align:center;font-size:13px;font-weight:800}.flow-arrow{align-self:center;color:var(--accent);font-size:24px}.callout{margin-top:20px;padding:17px 18px;border-left:3px solid var(--accent);border-radius:12px;background:color-mix(in srgb,var(--accent) 8%,transparent)}.callout strong{display:block;margin-bottom:5px;color:var(--accent);font-size:12px;letter-spacing:.12em;text-transform:uppercase}.callout p{margin:0}
.tool{margin-top:24px;padding:22px;border:1px solid color-mix(in srgb,var(--accent) 30%,transparent);border-radius:18px;background:rgba(3,11,23,.82)}.tool h3{margin:0 0 8px;font-size:20px}.fields{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.field label{display:block;margin-bottom:7px;color:#c8d4e3;font-size:12px;font-weight:800}.field input,.field select{width:100%;padding:12px;border:1px solid var(--line);border-radius:10px;background:#030914;color:#fff;outline:none}.result{margin-top:15px;padding:17px;border:1px solid var(--line);border-radius:13px;background:rgba(255,255,255,.025)}.result-value{font-size:26px;font-weight:900;color:var(--accent)}.result-copy{margin-top:5px;color:var(--muted);font-size:13px;line-height:1.55}.mistakes{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px;margin-top:18px}.mistake{padding:16px;border:1px solid rgba(255,64,89,.22);border-radius:13px;background:rgba(255,64,89,.045);color:#d9e0e9;font-size:14px}.mistake b{color:var(--red)}
.quiz-question{margin-top:18px;padding:18px;border:1px solid var(--line);border-radius:15px;background:rgba(255,255,255,.02)}.quiz-question h3{margin:0 0 12px;font-size:16px}.quiz-options{display:grid;gap:8px}.quiz-options button{width:100%;padding:11px 13px;border:1px solid var(--line);border-radius:10px;background:#050d18;color:var(--muted);text-align:left;cursor:pointer}.quiz-options button.correct{border-color:rgba(89,216,121,.55);background:rgba(89,216,121,.10);color:#fff}.quiz-options button.wrong{border-color:rgba(255,64,89,.55);background:rgba(255,64,89,.10);color:#fff}.next-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.next-card{padding:22px;border:1px solid var(--line);border-radius:16px;background:rgba(255,255,255,.025)}.next-card strong{display:block;font-size:18px}.next-card span{display:block;margin-top:7px;color:var(--muted);font-size:13px;line-height:1.5}.next-card b{display:block;margin-top:20px;color:var(--accent)}.footer{margin-top:36px;padding:22px 14px;border-top:1px solid var(--line);color:#8f9bad;font-size:12px;line-height:1.8;text-align:center}.footer a{color:inherit}
@media(max-width:900px){.appbar-links{display:none}.hero{grid-template-columns:1fr;text-align:center;padding:34px 24px}.hero-logo{margin:auto}.concept-grid,.fields,.next-grid{grid-template-columns:1fr}}@media(max-width:620px){.wrap{padding:14px 12px 60px}.hero-logo{width:120px;height:120px}.hero-logo img{width:86px;height:86px}.lesson{padding:22px 17px}.lesson-head{grid-template-columns:46px 1fr}.lesson-number{width:46px;height:46px}.lesson h2{font-size:24px}.concept-grid,.mistakes{grid-template-columns:1fr}}

.home-button{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:8px;
  min-height:42px;
  padding:10px 15px;
  border:1px solid rgba(22,140,255,.40);
  border-radius:11px;
  background:rgba(22,140,255,.12);
  color:#fff;
  font-size:12px;
  font-weight:850;
  white-space:nowrap;
}
.home-button:hover{
  background:rgba(22,140,255,.22);
  border-color:rgba(22,140,255,.65);
}
@media(max-width:900px){
  .home-button-text{display:none}
}





/* Builders lessons: shared responsive and accessible controls. */
:root{--accent:#ffb454}.skip-link{position:absolute;left:12px;top:-100px;padding:14px;background:#fff;color:#071018;z-index:100}.skip-link:focus{top:12px}
a:focus-visible,button:focus-visible,input:focus-visible,summary:focus-visible,[tabindex]:focus-visible{outline:3px solid #ffcc66;outline-offset:4px}a,button{touch-action:manipulation}main{min-width:0}p,li,a,code{overflow-wrap:anywhere}section{scroll-margin-top:125px}.lesson a:not(.next-card),.source-list a{color:#85c8ff;text-decoration:underline;text-underline-offset:3px}.lesson a:hover{color:#fff}.lesson p{max-width:84ch}.hero .eyebrow{color:#ffb454}.hero h1{font-size:clamp(32px,5vw,60px)}.lesson-nav{margin:22px 0;padding:20px;border:1px solid var(--line);border-radius:18px;background:#07101d}.lesson-nav ol{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:10px;list-style:none;padding:0;margin:12px 0 0}.lesson-nav a{display:block;padding:12px;border:1px solid var(--line);border-radius:10px;color:#c8d4e3;min-height:48px}.lesson-nav a[aria-current=page]{border-color:#ffb454;color:#ffcf8d;background:#2a2114}.lesson-nav .track{display:block;font-size:11px;text-transform:uppercase;letter-spacing:.1em;color:#adbcd1;margin-bottom:4px}.lesson-nav a:hover,.next-card:hover{background:#11213a}.practice{border-color:rgba(255,180,84,.4)}details{margin-top:18px;padding:16px;border:1px solid var(--line);border-radius:12px}summary{cursor:pointer;font-weight:750;min-height:30px}.checklist{border:0;padding:0;margin:20px 0}.checklist legend{font-size:20px;font-weight:800;margin-bottom:12px}.checklist label{display:flex;gap:12px;padding:13px 10px;border-bottom:1px solid var(--line);line-height:1.6;cursor:pointer}.checklist input{flex:0 0 auto;width:22px;height:22px;margin-top:3px;accent-color:#168cff}.progress-note,.quiz-feedback{color:#d2dfef;font-size:14px;line-height:1.6}.quiz-feedback{min-height:2em}.quiz-options button{min-height:48px}.quiz-options button.correct{border-width:2px}.quiz-options button.wrong{border-width:2px}.source-list{padding-left:22px;line-height:1.9}.source-note{font-size:13px!important}.flow{flex-wrap:wrap;overflow:visible}.flow-step{min-width:0}.reading-note{color:#aeb9c9;line-height:1.6}.footer a{text-decoration:underline}.action-grid{margin-top:20px}.noscript-note{padding:12px;border:1px solid var(--gold)}
@media(max-width:900px){.lesson-nav ol{grid-template-columns:repeat(2,minmax(0,1fr))}.appbar{position:static;flex-wrap:wrap}.home-button-text{display:inline}.hero{text-align:left}.hero-logo{margin:0}.hero-logo img{width:80px;height:80px}.hero-logo{width:100px;height:100px}section{scroll-margin-top:20px}}
@media(max-width:480px){.lesson-nav ol{grid-template-columns:1fr}.appbar{gap:10px}.appbar-brand img{width:34px;height:34px}.home-button{white-space:normal}.hero{padding:26px 20px}.lesson-nav{padding:16px}.flow-arrow{display:none}.flow-step{flex-basis:100%}.lesson h2{font-size:23px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important}}
@media print{.appbar,.lesson-nav,.skip-link{display:none}body{background:#fff;color:#111}.hero,.lesson{background:#fff;box-shadow:none;border:1px solid #bbb}.lesson p,.lesson li,.hero p{color:#222}.lesson h2,.lesson h3,h1{color:#111}.lesson a{color:#0645ad}}

/* Plain-language lesson reference blocks; retain the established House theme. */
.glossary{max-width:84ch;line-height:1.75}.glossary dt{font-weight:750;color:var(--text);margin-top:14px}.glossary dd{margin:3px 0 0;color:var(--muted);font-size:15px}.lesson ol>li+li{margin-top:14px}.lesson :target{scroll-margin-top:125px}@media(max-width:900px){.lesson :target{scroll-margin-top:20px}}