/* HVACLoadCalc — dark-first, mobile-first. Matches generatorsizer network identity. */
:root{
  --bg:#0d1117; --card:#161b22; --fg:#e6edf3; --mut:#8b949e;
  --acc:#58a6ff; --ok:#3fb950; --warn:#d29922; --bd:#30363d;
  --okbg:#121a12; --maxw:900px;
}
@media (prefers-color-scheme: light){
  :root{ --bg:#f6f8fa; --card:#ffffff; --fg:#1f2328; --mut:#57606a; --bd:#d0d7de; --acc:#0969da; --okbg:#eaf5ea; }
}
*{margin:0;box-sizing:border-box}
html{scroll-behavior:smooth}
@media (prefers-reduced-motion: reduce){html{scroll-behavior:auto}}
body{
  background:var(--bg); color:var(--fg); line-height:1.6;
  font-family:system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
  max-width:var(--maxw); margin:0 auto; padding:1.5rem 1.1rem 3rem;
  font-size:16px;
}
a{color:var(--acc)}
h1{font-size:1.85rem;line-height:1.2;margin-bottom:.4rem}
h2{font-size:1.3rem;margin:2.2rem 0 .8rem;padding-bottom:.3rem;border-bottom:1px solid var(--bd)}
h3{font-size:1.05rem;margin:1.4rem 0 .5rem}
p{margin:.6rem 0}
.sub{color:var(--mut);margin-bottom:1.4rem}
.small{font-size:.85rem;color:var(--mut)}

/* header / nav */
.site-head{display:flex;flex-wrap:wrap;align-items:baseline;gap:.4rem 1rem;margin-bottom:1.6rem}
.site-head .brand{font-weight:700;font-size:1.05rem;color:var(--fg);text-decoration:none}
.site-head nav{display:flex;flex-wrap:wrap;gap:.2rem 1rem;font-size:.9rem;margin-left:auto}

/* tabs */
.tabs{display:flex;flex-wrap:wrap;gap:.4rem;margin:1.2rem 0 1rem}
.tabs button{
  background:var(--card);color:var(--fg);border:1px solid var(--bd);border-radius:8px;
  padding:.5rem .9rem;font-size:.92rem;cursor:pointer;font-family:inherit;
}
.tabs button[aria-selected="true"]{border-color:var(--acc);color:var(--acc);font-weight:600}
.tabs button:focus-visible, a:focus-visible, input:focus-visible, select:focus-visible, button:focus-visible{
  outline:2px solid var(--acc); outline-offset:2px;
}
.panel{display:none}
.panel.active{display:block}

/* forms */
.field{margin:.9rem 0}
.field label{display:block;font-weight:600;font-size:.92rem;margin-bottom:.25rem}
input[type=number],input[type=text],select{
  background:var(--card);color:var(--fg);border:1px solid var(--bd);border-radius:8px;
  padding:.55rem .6rem;font-size:1rem;width:100%;max-width:420px;font-family:inherit;
}
.row2{display:grid;grid-template-columns:1fr 1fr;gap:.8rem}
.row3{display:grid;grid-template-columns:1fr 1fr 1fr;gap:.8rem}
@media(max-width:560px){.row2,.row3{grid-template-columns:1fr}}
fieldset{border:1px solid var(--bd);border-radius:10px;padding:.8rem 1rem;margin:1rem 0}
legend{font-weight:600;font-size:.9rem;padding:0 .4rem}

/* results */
.ans{background:var(--okbg);border:1px solid var(--ok);border-radius:10px;padding:1.1rem;margin:1.2rem 0}
.ans .big{font-size:2rem;font-weight:700;font-variant-numeric:tabular-nums;line-height:1.15}
.ans .unit{font-size:1rem;color:var(--mut);font-weight:400}
.grid2{display:grid;grid-template-columns:1fr 1fr;gap:.8rem;margin-top:.8rem}
@media(max-width:560px){.grid2{grid-template-columns:1fr}}
.stat{background:var(--card);border:1px solid var(--bd);border-radius:8px;padding:.6rem .8rem}
.stat b{display:block;font-size:1.15rem;font-variant-numeric:tabular-nums}
.stat span{color:var(--mut);font-size:.82rem}
.note{color:var(--mut);font-size:.85rem;margin-top:.6rem}
.disclaim{border:1px solid var(--warn);border-radius:8px;padding:.7rem .9rem;margin:1.2rem 0;font-size:.88rem;background:rgba(210,153,34,.06)}
.disclaim b{color:var(--warn)}

/* tables */
table{width:100%;border-collapse:collapse;margin:.8rem 0;font-size:.93rem}
th,td{text-align:left;padding:.5rem .6rem;border-bottom:1px solid var(--bd)}
th{color:var(--mut);font-weight:600;font-size:.8rem;text-transform:uppercase;letter-spacing:.05em}
.num{font-variant-numeric:tabular-nums;text-align:right}
.tbl-wrap{overflow-x:auto}

/* cards / footer */
.card{background:var(--card);border:1px solid var(--bd);border-radius:10px;padding:1rem 1.1rem;margin:.7rem 0}
.card h3{margin:.1rem 0 .3rem}
.card p{color:var(--mut);font-size:.94rem}
.tag{display:inline-block;font-size:.7rem;letter-spacing:.06em;text-transform:uppercase;color:var(--warn);border:1px solid var(--warn);border-radius:20px;padding:.05rem .55rem;margin-left:.4rem;vertical-align:middle}
footer{margin-top:3rem;padding-top:1.2rem;border-top:1px solid var(--bd);color:var(--mut);font-size:.85rem}
.affil{border-left:3px solid var(--warn);padding-left:.8rem;margin:1rem 0}
.affil .tag{margin:0 0 .3rem}
code{background:var(--card);border:1px solid var(--bd);border-radius:5px;padding:.05rem .3rem;font-size:.9em}