/* Shared header, footer, and base styles for every page. Tool-specific styles stay inline in each page. */
:root{
  --bg:#F2F4F5; --surface:#FFFFFF; --surface-2:#E8ECEE; --text:#1C2227; --muted:#58626A; --line:#D2D8DC;
  --accent:#7B1E2E; --accent-ink:#FFFFFF; --accent-soft:#F4E4E7;
  --chart:#2B55A3; --chart-faint:rgba(43,85,163,.16); --ok:#17733F; --focus:#2B55A3;
  --sans:"Barlow","Segoe UI",system-ui,-apple-system,sans-serif;
  --cond:"Barlow Semi Condensed","Arial Narrow","Segoe UI",system-ui,sans-serif;
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    color-scheme:dark;
    --bg:#14171A; --surface:#1D2125; --surface-2:#272C31; --text:#E5E8EA; --muted:#9BA5AC; --line:#353B41;
    --accent:#CF6B7B; --accent-ink:#1A0B0E; --accent-soft:#3A2329;
    --chart:#82A8E8; --chart-faint:rgba(130,168,232,.16); --ok:#5CCB86; --focus:#82A8E8;
  }
}
:root[data-theme="dark"]{
  color-scheme:dark;
  --bg:#14171A; --surface:#1D2125; --surface-2:#272C31; --text:#E5E8EA; --muted:#9BA5AC; --line:#353B41;
  --accent:#CF6B7B; --accent-ink:#1A0B0E; --accent-soft:#3A2329;
  --chart:#82A8E8; --chart-faint:rgba(130,168,232,.16); --ok:#5CCB86; --focus:#82A8E8;
}
*,*::before,*::after{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--text);font:400 17px/1.55 var(--sans);-webkit-font-smoothing:antialiased}
a{color:var(--chart)}
a:focus-visible,button:focus-visible{outline:2px solid var(--focus);outline-offset:2px}

.site-head{border-bottom:1px solid var(--line);background:var(--surface)}
.site-head-in{max-width:1200px;margin:0 auto;padding:0 16px;min-height:56px;display:flex;align-items:center;justify-content:space-between;gap:8px 24px;flex-wrap:wrap}
.wordmark{font:700 1.3rem/1 var(--cond);color:var(--text);text-decoration:none;letter-spacing:-.01em;padding:14px 0}
.site-nav{display:flex;gap:4px 20px;flex-wrap:wrap}
.site-nav a{font:600 1rem/1 var(--cond);color:var(--muted);text-decoration:none;padding:16px 0 14px;border-bottom:3px solid transparent}
.site-nav a:hover{color:var(--text)}
.site-nav a[aria-current="page"]{color:var(--text);border-bottom-color:var(--accent)}
@media (max-width:520px){.site-nav a{padding:6px 0 10px}}

/* Aircraft dropdown: opens on hover or keyboard focus. On touch, tapping the label goes to the aircraft list. */
.site-head{position:relative;z-index:10}
.nav-drop{position:relative;display:flex}
.nav-drop > a::after{content:"";display:inline-block;width:0;height:0;margin-left:6px;vertical-align:3px;border:4px solid transparent;border-top:5px solid currentColor;border-bottom:0}
.nav-menu{display:none;position:absolute;top:100%;left:-14px;min-width:200px;margin:0;padding:6px 0;list-style:none;background:var(--surface);border:1px solid var(--line);border-radius:0 0 8px 8px;box-shadow:0 8px 20px rgba(0,0,0,.12)}
.nav-drop:hover .nav-menu,.nav-drop:focus-within .nav-menu{display:block}
.site-nav .nav-menu a{display:block;padding:10px 14px;border:0;color:var(--text);white-space:nowrap}
.site-nav .nav-menu a:hover,.site-nav .nav-menu a[aria-current="page"]{background:var(--surface-2);color:var(--accent)}
@media (max-width:520px){.nav-menu{left:0}}

.site-foot{max-width:1200px;margin:0 auto;padding:20px 16px 40px;color:var(--muted);font-size:.9rem;border-top:1px solid var(--line);display:flex;justify-content:space-between;gap:8px 24px;flex-wrap:wrap}
.site-foot p{margin:0;max-width:70ch}

/* Lesson pages: contents sidebar, article, tables, steps, callouts */
.page{max-width:1200px;margin:0 auto;padding:40px 16px 64px;display:grid;grid-template-columns:220px minmax(0,1fr);gap:56px;align-items:start}
@media (max-width:900px){.page{grid-template-columns:minmax(0,1fr);gap:24px}}
.toc{position:sticky;top:24px;font-size:.95rem}
.toc h2{font:700 1rem/1.2 var(--cond);margin:0 0 10px;color:var(--muted)}
.toc ol{margin:0;padding:0;list-style:none;border-left:2px solid var(--line)}
.toc a{display:block;padding:5px 0 5px 14px;margin-left:-2px;border-left:2px solid transparent;color:var(--muted);text-decoration:none}
.toc a:hover{color:var(--text);border-left-color:var(--accent)}
@media (max-width:900px){.toc{position:static}.toc ol{display:flex;flex-wrap:wrap;gap:4px 16px;border:0}.toc a{padding:2px 0;border:0;margin:0;text-decoration:underline;text-underline-offset:3px}}

article{max-width:72ch}
article h1{font:700 clamp(2.6rem,7vw,4.2rem)/.95 var(--cond);margin:0;letter-spacing:-.02em}
article .lede{font-size:1.2rem;color:var(--muted);margin:16px 0 0}
article h2{font:700 clamp(1.6rem,3.5vw,2rem)/1.1 var(--cond);margin:56px 0 12px;padding-top:20px;border-top:3px solid var(--text);scroll-margin-top:16px}
article h3{font:700 1.25rem/1.2 var(--cond);margin:28px 0 6px}
article p,article li{max-width:68ch}
article ul{padding-left:1.2em}
article li{margin-bottom:6px}

dl.terms{margin:0}
dl.terms dt{font:700 1.15rem/1.2 var(--cond);margin-top:18px}
dl.terms dd{margin:4px 0 0}

.formula{font:600 1.15rem/1.4 var(--cond);background:var(--surface);border:1px solid var(--line);border-left:4px solid var(--chart);border-radius:6px;padding:12px 16px;margin:14px 0}

.example-note{background:var(--accent-soft);border-radius:6px;padding:12px 16px;margin:16px 0}
.example-note strong{color:var(--accent)}

.table-wrap{overflow-x:auto;margin:14px 0}
table{border-collapse:collapse;width:100%;min-width:460px;font-variant-numeric:tabular-nums;background:var(--surface);border:1px solid var(--line)}
th,td{padding:9px 12px;text-align:right;border-bottom:1px solid var(--line)}
th:first-child,td:first-child{text-align:left}
thead th{font:700 .98rem/1.2 var(--cond);background:var(--surface-2)}
tfoot td{font-weight:600;border-top:2px solid var(--text);border-bottom:0}
caption{text-align:left;font:600 .95rem/1.3 var(--sans);color:var(--muted);padding-bottom:8px}

ol.steps{list-style:none;counter-reset:step;padding:0;margin:20px 0 0}
ol.steps > li{counter-increment:step;position:relative;padding-left:56px;margin:0 0 36px;max-width:none}
ol.steps > li::before{content:counter(step);position:absolute;left:0;top:-2px;width:38px;height:38px;border-radius:50%;background:var(--text);color:var(--bg);font:700 1.2rem/38px var(--cond);text-align:center}
ol.steps h3{margin:4px 0 6px}
.answer{font:600 1.1rem/1.4 var(--cond);color:var(--ok)}

.crumb{font:600 .95rem/1 var(--cond);margin:0 0 14px}
.crumb a{color:var(--muted);text-decoration:none}
.crumb a:hover{color:var(--accent)}
.callout{background:var(--surface);border:1px solid var(--line);border-left:4px solid var(--accent);border-radius:6px;padding:12px 16px;margin:16px 0}
.callout p{margin:0}
.callout p + p{margin-top:8px}
.tool-link{display:inline-block;margin-top:4px;font:600 1rem/1 var(--cond);color:var(--accent)}
.next-prev{display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap;margin-top:64px;padding-top:20px;border-top:1px solid var(--line)}
.next-prev a{font:600 1.05rem/1.3 var(--cond);color:var(--text);text-decoration:none;max-width:45%}
.next-prev a:hover{color:var(--accent)}
.next-prev small{display:block;font:500 .9rem/1.2 var(--sans);color:var(--muted)}
.next-prev .next{text-align:right;margin-left:auto}

/* Jump-to bar: a sticky "On this page" dropdown under the header, used instead of the contents sidebar */
.jump{position:sticky;top:0;z-index:9;background:var(--surface);border-bottom:1px solid var(--line)}
.jump-in{max-width:1200px;margin:0 auto;padding:0 16px}
.jump-menu{position:relative;display:inline-block}
.jump-menu summary{list-style:none;cursor:pointer;display:flex;align-items:baseline;gap:10px;padding:13px 0 12px;font:600 1rem/1.2 var(--cond)}
.jump-menu summary::-webkit-details-marker{display:none}
.jump-menu summary::after{content:"";align-self:center;width:0;height:0;border:4px solid transparent;border-top:5px solid currentColor;border-bottom:0}
.jump-menu[open] summary::after{border-top:0;border-bottom:5px solid currentColor}
.jump-label{color:var(--muted)}
.jump-current{color:var(--text)}
.jump-menu summary:hover .jump-current{color:var(--accent)}
.jump-menu ol{position:absolute;top:100%;left:-14px;min-width:280px;max-height:70vh;overflow-y:auto;margin:0;padding:6px 0;list-style:none;background:var(--surface);border:1px solid var(--line);border-radius:0 0 8px 8px;box-shadow:0 8px 20px rgba(0,0,0,.12)}
.jump-menu ol a{display:block;padding:9px 14px;color:var(--text);text-decoration:none;font:600 1rem/1.25 var(--cond);white-space:nowrap}
.jump-menu ol a:hover,.jump-menu ol a[aria-current]{background:var(--surface-2);color:var(--accent)}
@media (max-width:520px){.jump-menu ol{left:-16px;min-width:0;width:100vw}}
.page-single{grid-template-columns:minmax(0,1fr)}
.page-single article h2{scroll-margin-top:64px}
.jump-menu ol{min-width:340px}
.jump-menu ol a{display:flex;justify-content:space-between;align-items:baseline;gap:24px}
.jump-menu ol small{font:500 .9rem/1.2 var(--cond);color:var(--muted)}
@media (max-width:520px){.jump-menu ol{min-width:0}}
/* Official regulation titles under a heading */
article .regs{margin:-2px 0 14px;font:500 .98rem/1.35 var(--cond);color:var(--muted);max-width:none}
article .regs span{display:block}
article .regs span + span{margin-top:3px}
article .regs b{font-weight:700;color:var(--chart);margin-right:6px}
article .regs{display:grid;grid-template-columns:auto minmax(0,1fr);gap:3px 8px}
article .regs span{display:contents}
article .regs b{margin-right:0}