#ra-btc{
  /* ---- Theming: override these on your site to match brand ---- */
  --ra-bg:#ffffff;
  --ra-fg:#1c2024;
  --ra-muted:#5c6470;
  --ra-line:#e4e7ec;
  --ra-accent:#7c4dff;         /* primary action / highlight */
  --ra-accent-ink:#ffffff;
  --ra-soft:#f6f4ff;           /* result panel wash */
  --ra-ok:#1a8f5a;
  --ra-warn:#b26a00;
  --ra-radius:14px;
  --ra-figure:#c9bdf5;         /* silhouette fill */
  --ra-figure-line:#7c4dff;    /* silhouette stroke */
  --ra-font:inherit;

  all:unset;
  display:block;
  box-sizing:border-box;
  font-family:var(--ra-font);
  color:var(--ra-fg);
  background:var(--ra-bg);
  max-width:760px;
  margin:0 auto;
  line-height:1.5;
}
#ra-btc *,#ra-btc *::before,#ra-btc *::after{box-sizing:border-box}
#ra-btc h2{font-size:1.35rem;margin:0 0 .25rem;font-weight:700}
#ra-btc p.ra-sub{margin:0 0 1.1rem;color:var(--ra-muted);font-size:.95rem}

#ra-btc .ra-tabs{display:flex;gap:.35rem;margin-bottom:1rem}
#ra-btc .ra-tab{
  flex:1;padding:.6rem .5rem;border:1px solid var(--ra-line);
  background:transparent;color:var(--ra-fg);border-radius:10px;
  font:inherit;font-weight:600;cursor:pointer;text-align:center;
}
#ra-btc .ra-tab[aria-selected="true"]{
  background:var(--ra-accent);color:var(--ra-accent-ink);border-color:var(--ra-accent);
}
#ra-btc .ra-tab:focus-visible{outline:3px solid var(--ra-accent);outline-offset:2px}

#ra-btc .ra-units{display:flex;justify-content:flex-end;gap:.4rem;margin-bottom:.75rem;font-size:.85rem}
#ra-btc .ra-units button{
  border:1px solid var(--ra-line);background:transparent;color:var(--ra-muted);
  padding:.3rem .7rem;border-radius:999px;font:inherit;cursor:pointer;
}
#ra-btc .ra-units button[aria-pressed="true"]{
  background:var(--ra-fg);color:var(--ra-bg);border-color:var(--ra-fg);font-weight:600;
}

#ra-btc .ra-grid{display:grid;grid-template-columns:1fr 1fr;gap:.85rem}
@media(max-width:520px){#ra-btc .ra-grid{grid-template-columns:1fr}}
#ra-btc .ra-field{display:flex;flex-direction:column;gap:.3rem}
#ra-btc .ra-field label{font-size:.9rem;font-weight:600}
#ra-btc .ra-field .ra-hint{font-size:.78rem;color:var(--ra-muted);font-weight:400}
#ra-btc .ra-field input{
  font:inherit;padding:.65rem .7rem;border:1px solid var(--ra-line);
  border-radius:10px;background:var(--ra-bg);color:var(--ra-fg);width:100%;
  -moz-appearance:textfield;
}
#ra-btc .ra-field input::-webkit-outer-spin-button,
#ra-btc .ra-field input::-webkit-inner-spin-button{-webkit-appearance:none;margin:0}
#ra-btc .ra-field input:focus-visible{outline:3px solid var(--ra-accent);outline-offset:1px;border-color:var(--ra-accent)}
#ra-btc .ra-field input[aria-invalid="true"]{border-color:#d64545}
#ra-btc .ra-err{color:#d64545;font-size:.78rem;min-height:1em}

#ra-btc .ra-actions{display:flex;gap:.6rem;margin-top:1rem;flex-wrap:wrap}
#ra-btc .ra-calc{
  flex:1;min-width:160px;padding:.8rem 1rem;border:none;border-radius:10px;
  background:var(--ra-accent);color:var(--ra-accent-ink);font:inherit;font-weight:700;
  font-size:1rem;cursor:pointer;
}
#ra-btc .ra-calc:focus-visible{outline:3px solid var(--ra-fg);outline-offset:2px}
#ra-btc .ra-reset{
  padding:.8rem 1rem;border:1px solid var(--ra-line);border-radius:10px;
  background:transparent;color:var(--ra-muted);font:inherit;cursor:pointer;
}

#ra-btc .ra-result{
  margin-top:1.25rem;border:1px solid var(--ra-line);border-radius:var(--ra-radius);
  background:var(--ra-soft);padding:1.15rem;display:none;
  grid-template-columns:132px 1fr;gap:1.15rem;align-items:start;
}
#ra-btc .ra-result.is-open{display:grid}
@media(max-width:520px){#ra-btc .ra-result{grid-template-columns:1fr;text-align:center}}
#ra-btc .ra-figwrap{display:flex;justify-content:center}
#ra-btc svg.ra-fig{width:120px;height:280px;display:block}
#ra-btc .ra-shape{font-size:1.5rem;font-weight:800;margin:0 0 .2rem;line-height:1.1}
#ra-btc .ra-desc{margin:.1rem 0 .8rem;color:var(--ra-fg);font-size:.95rem}
#ra-btc .ra-stats{display:flex;gap:1.2rem;flex-wrap:wrap;margin:0 0 .9rem;font-size:.88rem}
#ra-btc .ra-stats b{display:block;font-size:1.15rem}
#ra-btc .ra-stats .ra-muted{color:var(--ra-muted);font-weight:600;font-size:.72rem;text-transform:uppercase;letter-spacing:.03em}
#ra-btc .ra-whrnote{font-size:.8rem;margin:.1rem 0 0}
#ra-btc .ra-whrnote.ok{color:var(--ra-ok)}
#ra-btc .ra-whrnote.warn{color:var(--ra-warn)}
#ra-btc a.ra-cta{
  display:inline-block;margin-top:.9rem;padding:.55rem .95rem;border-radius:9px;
  background:var(--ra-accent);color:var(--ra-accent-ink);text-decoration:none;
  font-weight:700;font-size:.9rem;
}
#ra-btc a.ra-cta:focus-visible{outline:3px solid var(--ra-fg);outline-offset:2px}
#ra-btc .ra-disc{font-size:.72rem;color:var(--ra-muted);margin:1rem 0 0}
@media (prefers-reduced-motion:no-preference){
  #ra-btc svg.ra-fig path{transition:d .4s ease}
  #ra-btc .ra-result.is-open{animation:ra-in .35s ease}
  @keyframes ra-in{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}
}
#ra-btc .ra-margin{font-size:.88rem;margin:0 0 .4rem;font-weight:600}
#ra-btc .ra-flag{font-size:.82rem;margin:0 0 .6rem;padding:.45rem .6rem;border-radius:8px;background:#fff4e0;color:var(--ra-warn)}
#ra-btc .ra-flag[hidden],#ra-btc a.ra-cta[hidden]{display:none}