/* Study Pitstop — "Pit Board". One stylesheet, no framework.
   Barlow and Barlow Condensed are self-hosted (OFL, see /assets/fonts/OFL.txt). */
@font-face{font-family:"Barlow";font-style:normal;font-weight:400;font-display:swap;src:url(/assets/fonts/barlow-400.woff2) format("woff2")}
@font-face{font-family:"Barlow";font-style:italic;font-weight:400;font-display:swap;src:url(/assets/fonts/barlow-400-italic.woff2) format("woff2")}
@font-face{font-family:"Barlow";font-style:normal;font-weight:500;font-display:swap;src:url(/assets/fonts/barlow-500.woff2) format("woff2")}
@font-face{font-family:"Barlow";font-style:normal;font-weight:600;font-display:swap;src:url(/assets/fonts/barlow-600.woff2) format("woff2")}
@font-face{font-family:"Barlow Condensed";font-style:normal;font-weight:600;font-display:swap;src:url(/assets/fonts/barlow-condensed-600.woff2) format("woff2")}
@font-face{font-family:"Barlow Condensed";font-style:normal;font-weight:700;font-display:swap;src:url(/assets/fonts/barlow-condensed-700.woff2) format("woff2")}
:root{
  --bg:#fff; --fg:#0b1730; --ink:#012556; --on-ink:#fff; --muted:#47536b; --line:#8b96ab; --soft:#eef1f6;
  --accent:#ffd60a; --on-accent:#012556; --focus:#1a5fd6;
  --board:#012556; --board-fg:#fff; --board-line:#5a6f96; --board-muted:#d5dcea;
  --fig-accent:#012556; --fig-muted:#47536b; --fig-grid:#cfd6e2; --fig-fill:#e3e8f1;
  --font-body:"Barlow",system-ui,-apple-system,"Segoe UI",sans-serif;
  --font-head:"Barlow Condensed","Arial Narrow",system-ui,sans-serif;
  --rule:3px solid var(--ink);
}
@media (prefers-color-scheme:dark){:root{
  --bg:#0a1220; --fg:#e8ecf4; --ink:#e8ecf4; --on-ink:#0a1220; --muted:#a3aec4; --line:#55617a; --soft:#141d30;
  --focus:#ffd60a;
  --board:#16233f; --board-fg:#fff; --board-line:#3f5078; --board-muted:#c3cce0;
  --fig-accent:#9db9dc; --fig-muted:#a3aec4; --fig-grid:#2f3a50; --fig-fill:#1c2740;
}}
*{box-sizing:border-box}
html{font-size:112.5%;-webkit-text-size-adjust:100%;scroll-padding-top:1rem}
body{margin:0;background:var(--bg);color:var(--fg);font-family:var(--font-body);font-size:1rem;line-height:1.55}
a{color:inherit;text-underline-offset:.15em}
a:hover{text-decoration-thickness:2px}
:focus-visible{outline:3px solid var(--focus);outline-offset:2px}
img,svg{max-width:100%}
.skip{position:absolute;left:-999px;top:0;background:var(--ink);color:var(--on-ink);padding:.5rem .8rem;z-index:2}
.skip:focus{left:.5rem;top:.5rem}
.wrap{max-width:62rem;margin:0 auto;padding:0 1.25rem}
.wrap.narrow{max-width:42rem}

/* type */
h1,h2,h3,h4{font-family:var(--font-head);font-weight:700;line-height:1.08;color:var(--ink);text-wrap:balance;margin:0}
h1{font-size:clamp(2.3rem,6vw,3.3rem);text-transform:uppercase}
h2{font-size:clamp(1.7rem,4vw,2.2rem);text-transform:uppercase}
h3{font-size:1.5rem}
p{margin:.6rem 0}
.kicker{font-family:var(--font-head);font-weight:600;font-size:1.1rem;letter-spacing:.08em;text-transform:uppercase;color:var(--muted);margin:0 0 .5rem}
.kicker a{text-decoration:none}
.kicker a:hover{text-decoration:underline}
.lede{font-size:1.15rem;max-width:32em}
.meta,.status,.aside,.trust{color:var(--muted);font-size:.9rem}
.code{font-family:var(--font-head);font-weight:700;font-size:1.1em;font-variant-numeric:tabular-nums;margin-right:.35em;white-space:nowrap}
.num{font-variant-numeric:tabular-nums}
.hi{background:var(--accent);color:var(--on-accent);padding:0 .18em;box-decoration-break:clone;-webkit-box-decoration-break:clone}
h1 .num.hi{margin-right:.2em}

/* header and footer */
.top{border-bottom:var(--rule)}
.top-in{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:.4rem 1.5rem;padding-top:.7rem;padding-bottom:.7rem}
.brand{display:inline-flex;align-items:center;min-height:2.75rem}
.brand img{display:block;height:2rem;width:auto}
.site-nav{display:flex;gap:1.5rem;font-family:var(--font-head);font-weight:600;font-size:1.1rem;letter-spacing:.06em;text-transform:uppercase}
.site-nav a{text-decoration:none;padding:.55rem 0}
.site-nav a:hover{text-decoration:underline}
.foot{border-top:var(--rule);margin-top:4rem;padding:1.4rem 0 2.5rem;color:var(--muted);font-size:.9rem}
.foot p{margin:.3rem 0}
.foot .tm{max-width:46em}

/* buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:2.9rem;padding:.3rem 1.5rem;border:0;background:var(--ink);color:var(--on-ink);font-family:var(--font-head);font-weight:700;font-size:1.2rem;letter-spacing:.08em;text-transform:uppercase;text-decoration:none;cursor:pointer}
.btn:hover{text-decoration:underline}
.btn.accent{background:var(--accent);color:var(--on-accent)}

/* chips: unit and topic numbers */
.chips{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:.35rem}
.chips a{display:flex;align-items:center;justify-content:center;min-width:2.5rem;height:2.5rem;padding:0 .4rem;background:var(--soft);color:var(--ink);font-family:var(--font-head);font-weight:700;font-size:1.2rem;font-variant-numeric:tabular-nums;text-decoration:none}
.chips a:hover{outline:2px solid var(--ink)}
.chips a[aria-current="true"]{background:var(--accent);color:var(--on-accent)}
.chips a[aria-current="page"]{background:var(--ink);color:var(--on-ink)}

/* lane: where you are */
.lane{background:var(--soft);padding:.7rem 0}
.lane .chips a{background:var(--bg)}
.lane .chips a[aria-current="true"]{background:var(--accent)}
.lane .chips a[aria-current="page"]{background:var(--ink)}
.lane-row{display:flex;flex-wrap:wrap;align-items:center;gap:.35rem .6rem}
.lane-row+.lane-row{margin-top:.45rem}
.lane-course{font-family:var(--font-head);font-weight:700;font-size:1.2rem;letter-spacing:.06em;text-transform:uppercase;text-decoration:none;padding:.4rem 0;margin-right:.4rem}
.lane-course:hover{text-decoration:underline}
.lane-label{font-family:var(--font-head);font-weight:600;font-size:1rem;letter-spacing:.08em;text-transform:uppercase;color:var(--muted);min-width:2.6rem}

/* home */
.hero{display:grid;grid-template-columns:1fr;gap:2rem;align-items:center;padding:2.5rem 0 3rem}
.hero h1{font-size:clamp(2.9rem,9vw,4.6rem);line-height:1}
.hero h1 .hi{white-space:nowrap}
.hero .lede{margin:1rem 0 1.2rem}
@media (min-width:56rem){.hero{grid-template-columns:1.05fr 1fr;gap:3rem;padding:3.5rem 0 4rem}}
.band{border-top:var(--rule);padding:1.1rem 0 3rem}
.band>h2{margin-bottom:1.2rem}
.course-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(min(100%,18rem),1fr));gap:1rem}
.course-card{border:2px solid var(--ink);padding:1.1rem 1.2rem 1.2rem;display:flex;flex-direction:column;gap:.6rem}
.course-card h3 a{text-decoration:none}
.course-card h3 a:hover{text-decoration:underline}
.course-card .meta{margin:0}
.steps{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(auto-fit,minmax(min(100%,15rem),1fr));gap:1.5rem 2rem}
.steps li{display:flex;gap:.9rem;align-items:flex-start}
.steps h3{text-transform:uppercase}
.steps p{margin:.2rem 0 0}
.step-n{flex:none;display:flex;align-items:center;justify-content:center;width:3rem;height:3rem;background:var(--accent);color:var(--on-accent);font-family:var(--font-head);font-weight:700;font-size:2rem}
.trust{margin-top:1.8rem}

/* the board */
.board{background:var(--board);color:var(--board-fg);padding:1.4rem 1.4rem 1.2rem;margin:1.5rem 0}
figure.board{margin:0}
.board h3,.board figcaption{font-family:var(--font-head);font-weight:700;font-size:1.25rem;letter-spacing:.08em;text-transform:uppercase;color:var(--board-fg);padding-bottom:.7rem;border-bottom:2px solid var(--board-fg);margin:0}
.board-list{list-style:none;margin:0;padding:0}
.board-list li{display:flex;align-items:center;justify-content:space-between;gap:1rem;padding:.6rem 0;border-bottom:1px solid var(--board-line)}
.board-list li:last-child{border-bottom:0}
.board-list a{text-decoration:none;color:inherit}
.board-list a:hover{text-decoration:underline}
.board .demo-foot{margin:.7rem 0 0;font-size:.9rem;color:var(--board-muted)}
.board-next{margin:1rem 0 0}
.mark{flex:none;min-width:3.6rem;padding:0 .4rem;text-align:center;border:2px solid currentColor;font-family:var(--font-head);font-weight:700;font-size:1rem;letter-spacing:.08em;text-transform:uppercase;white-space:nowrap}
.mark:empty{display:none}
.mark.fix{background:var(--accent);border-color:var(--accent);color:var(--on-accent)}
.mark.none{border-style:dashed;font-weight:600;color:var(--board-muted)}
h3 .mark{display:inline-block;vertical-align:middle;margin-left:.4rem}
h3 .mark[hidden]{display:none}

/* course and unit pages */
.page-head,.topic-head{padding:2rem 0 1.2rem}
/* Course, unit and topic titles keep their own capitals: "pH and pKa" must never become "PH AND PKA". */
.page-head h1,.topic-head h1{text-transform:none;font-size:clamp(2.1rem,5.5vw,3rem)}
.page-head h1 .num,.topic-head h1 .num{text-transform:uppercase}
.unit-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(min(100%,19rem),1fr));gap:1rem}
.unit-card{border:2px solid var(--ink);padding:1rem 1.2rem}
.unit-card h2{font-size:1.5rem;text-transform:none}
.unit-card h2 a{text-decoration:none;display:flex;gap:.6rem;align-items:baseline}
.unit-card h2 a:hover{text-decoration:underline}
.unit-card h2 .num{flex:none;display:inline-flex;align-items:center;justify-content:center;min-width:2rem;height:2rem;padding:0 .3rem;background:var(--accent);color:var(--on-accent)}
.topic-list{list-style:none;margin:.6rem 0 0;padding:0}
.topic-list a{display:block;padding:.3rem 0;text-decoration:none}
.topic-list a:hover{text-decoration:underline}
.topic-rows{list-style:none;margin:0;padding:0;border-top:var(--rule)}
.topic-rows li{display:flex;flex-wrap:wrap;align-items:baseline;justify-content:space-between;gap:.2rem 1rem;padding:.2rem 0;border-bottom:1px solid var(--line)}
.topic-rows a{text-decoration:none;padding:.55rem 0;flex:1 1 16rem}
.topic-rows a:hover{text-decoration:underline}
.topic-rows .meta{flex:none}
.topic-rows .ideas{flex:1 1 100%;margin:0 0 .6rem;color:var(--muted);font-size:.9rem}
.exam-box{border-top:var(--rule);margin-top:2.5rem;padding-top:1rem;max-width:42rem}
.exam-box h2{font-size:1.5rem}
.nextprev{display:flex;flex-wrap:wrap;justify-content:space-between;gap:.5rem 1.5rem;margin-top:1.5rem}
.nextprev a{font-weight:600;padding:.5rem 0}

/* topic page */
.summary{font-size:1.1rem;margin:.9rem 0 .6rem}
.modes{display:grid;grid-template-columns:repeat(3,1fr);gap:.4rem;margin:.6rem 0 1.8rem}
.modes a{display:flex;flex-direction:column;justify-content:center;min-height:3.6rem;padding:.4rem .8rem;border:2px solid var(--ink);text-decoration:none;font-size:.85rem;line-height:1.25;color:var(--ink)}
.modes a strong{font-family:var(--font-head);font-weight:700;font-size:1.4rem;letter-spacing:.06em;text-transform:uppercase}
.modes a[aria-current]{background:var(--ink);color:var(--on-ink)}
.modes a[aria-current] .mode-n{color:var(--accent)}
@media (max-width:30rem){.modes a{padding:.4rem .5rem}.modes a strong{font-size:1.2rem}.modes a>span{display:none}}
.panel{margin:0 0 2.5rem}
.panel-h{border-top:var(--rule);padding-top:.8rem;margin-bottom:.4rem}
.panel-h small{font-family:var(--font-body);font-weight:400;font-size:.9rem;text-transform:none;letter-spacing:0;color:var(--muted);margin-left:.4rem}
body.js .panel[hidden]{display:none}
body.js .panel-h{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%)}
.notice{border:1px solid var(--line);background:var(--soft);padding:.7rem 1rem;font-size:.9rem}
.actions{margin:1.5rem 0}

/* Fix sections */
.stmt{border-top:var(--rule);padding:1rem 0 .4rem;margin-top:1.2rem}
.stmt h3{font-size:1.6rem;margin-bottom:.5rem}
.points{margin:.5rem 0;padding-left:1.2rem}
.points li{margin:.3rem 0}
.eq{display:table;border:2px solid var(--ink);padding:.6rem 1rem;font-size:1.25rem;margin:.8rem 0}
.callout{background:var(--soft);border:1px solid var(--line);padding:.7rem 1rem}
.terms{margin:.6rem 0}
.terms dt{font-weight:600;margin-top:.6rem}
.terms dd{margin:0}

/* questions */
.q{border:2px solid var(--ink);padding:1.2rem;margin:1.2rem 0}
.q-n{font-family:var(--font-head);font-weight:700;font-size:1rem;letter-spacing:.1em;text-transform:uppercase;color:var(--muted);margin:0 0 .4rem}
.stem{font-weight:500;margin:0 0 .8rem}
.fig{margin:.6rem 0 .9rem;max-width:24rem}
.fig svg{display:block;width:100%;height:auto;color:var(--fg);font-family:var(--font-body)}
.opts{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:.45rem}
.opt{display:flex;gap:.8rem;align-items:baseline;width:100%;min-height:2.9rem;padding:.6rem .8rem;border:1px solid var(--line);background:var(--bg);color:var(--fg);font:inherit;text-align:left;cursor:pointer}
.opt:hover:not(:disabled){border-color:var(--ink);outline:1px solid var(--ink)}
.opt:disabled{cursor:default;color:var(--muted)}
.letter{flex:none;font-family:var(--font-head);font-weight:700;font-size:1.2rem;min-width:.9rem}
.opt .letter{color:var(--ink)}
.opt-text{flex:1}
.tag{flex:none;font-family:var(--font-head);font-weight:700;font-size:.95rem;letter-spacing:.08em;text-transform:uppercase;white-space:nowrap}
.tag:empty{display:none}
.opt.right,.opt.reveal{background:var(--ink);border-color:var(--ink);color:var(--on-ink)}
.opt.right .letter,.opt.reveal .letter{color:inherit}
.opt.wrong{background:var(--accent);border-color:var(--ink);color:var(--on-accent);border-width:2px}
.opt.wrong .letter{color:inherit}
.answer{margin-top:.9rem}
.answer summary{cursor:pointer;font-weight:600;padding:.5rem 0}
.why{list-style:none;margin:.3rem 0 0;padding:0}
.why li{display:flex;gap:.8rem;padding:.6rem 0;border-top:1px solid var(--line);font-size:.95rem}
.why li.correct{border-top:2px solid var(--ink)}
.tag-inline{font-family:var(--font-head);font-weight:700;font-size:.9rem;letter-spacing:.08em;text-transform:uppercase;background:var(--ink);color:var(--on-ink);padding:0 .35rem;margin-left:.3rem}
.working{background:var(--soft);padding:.6rem .8rem;font-size:.95rem}
.q .meta{margin:.6rem 0 0}
.sendoff{border-top:var(--rule);padding-top:1rem;margin-top:2rem}
.sendoff h3{font-size:1.9rem;text-transform:uppercase}
.foot-status{border-top:1px solid var(--line);padding-top:.8rem;margin-top:2.5rem}

/* prose pages */
.prose{padding-top:2rem}
.prose h2{font-size:1.5rem;margin:1.8rem 0 .3rem}
.prose ul{padding-left:1.2rem}
.prose li{margin:.35rem 0}
.which{border-top:var(--rule);margin-top:1.5rem;padding-top:.2rem}
.which h2 a{text-decoration:none}
.which h2 a:hover{text-decoration:underline}
.chips-list{list-style:none;margin:.4rem 0;padding:0}
.chips-list a{display:block;padding:.3rem 0;text-decoration:none}
.chips-list a:hover{text-decoration:underline}

@media print{
  .top nav,.lane,.modes,.actions,.skip,.board-next,.nextprev{display:none!important}
  body.js .panel[hidden]{display:block}
  .q{break-inside:avoid}
  .answer:not([open])>*:not(summary){display:block}
}