:root{
  --bg:#0f1720; --panel:#16212e; --card:#1d2b3a; --line:#2c3e50;
  --accent:#1fb6a6; --accent2:#3a8dde; --text:#e8eef4; --muted:#9fb0c0;
  --red:#ff6b6b; --green:#7ee787;
}
*{box-sizing:border-box}
body{margin:0;font-family:"Segoe UI",system-ui,Arial,sans-serif;color:var(--text);
  min-height:100vh;display:flex;flex-direction:column;
  background:radial-gradient(1200px 600px at 50% -10%,#16242f,var(--bg))}
.topbar{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:16px 28px;background:linear-gradient(90deg,#10212e,#13303a);border-bottom:2px solid var(--accent)}
.brand{display:flex;align-items:center;gap:14px}
.logo-mark{height:50px;width:50px;flex:none;filter:drop-shadow(0 2px 6px rgba(0,0,0,.4))}
.title-block h1{margin:0;font-size:1.6rem;letter-spacing:.5px}
.subtitle{margin:2px 0 0;color:var(--muted);font-size:.85rem}
.byline{display:flex;flex-direction:column;align-items:flex-end;text-align:right;line-height:1.25;padding-left:18px;border-left:1px solid var(--line)}
.by-label{font-size:.68rem;text-transform:uppercase;letter-spacing:1px;color:var(--muted)}
.by-name{font-size:1.05rem;font-weight:700;color:var(--accent)}
.by-role{font-size:.72rem;color:var(--muted)}
@media(max-width:640px){.topbar{flex-direction:column;align-items:flex-start}.byline{align-items:flex-start;text-align:left;border-left:none;padding-left:0}.hero{height:200px}.hero-title{font-size:1.4rem}}

/* hero band that fades seamlessly into the content */
.hero{position:relative;height:300px;
  background:url('assets/hero.jpg') center 82%/cover no-repeat;
  border-bottom:1px solid var(--line)}
.hero::after{content:"";position:absolute;inset:0;
  background:linear-gradient(180deg,rgba(11,17,24,.30) 0%,rgba(11,17,24,.55) 45%,var(--bg) 100%)}
.hero-overlay{position:absolute;inset:0;z-index:1;display:flex;flex-direction:column;justify-content:flex-end;
  max-width:1100px;margin:0 auto;left:0;right:0;padding:0 28px 30px}
.hero-kicker{margin:0;font-size:.72rem;letter-spacing:2px;color:var(--accent);font-weight:700}
.hero-title{margin:6px 0 4px;font-size:1.9rem;font-weight:800;text-shadow:0 2px 12px rgba(0,0,0,.6)}
.hero-sub{margin:0;color:var(--text);opacity:.85;font-size:.95rem;text-shadow:0 1px 8px rgba(0,0,0,.6)}
.tabs{display:flex;flex-wrap:wrap;gap:4px;padding:10px 16px 0;background:var(--panel);position:sticky;top:0;z-index:5;box-shadow:0 4px 16px rgba(0,0,0,.3)}
.tab{background:transparent;border:none;color:var(--muted);padding:10px 16px;font-size:.92rem;cursor:pointer;border-radius:8px 8px 0 0;border-bottom:3px solid transparent}
.tab:hover{color:var(--text);background:#1b2937}
.tab.active{color:var(--text);background:var(--bg);border-bottom-color:var(--accent);font-weight:600}
main{padding:32px 24px;max-width:1100px;margin:0 auto;width:100%;flex:1 0 auto}
.panel{display:none;animation:fade .2s ease}
.panel.active{display:block}
@keyframes fade{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}
h2{margin:0 0 6px;font-size:1.3rem}
h3{color:var(--accent);font-size:1rem;margin:18px 0 8px}
.note{color:var(--muted);font-size:.9rem;margin:0 0 18px;line-height:1.5}
.formula{color:var(--muted);font-size:.78rem;margin-top:14px;font-style:italic}
.calc-card{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:22px;margin-bottom:8px;box-shadow:0 10px 30px rgba(0,0,0,.25)}
.calc-card.interp{display:grid;grid-template-columns:1fr 1fr;gap:16px;align-items:end}
label{display:flex;flex-direction:column;gap:6px;font-size:.85rem;color:var(--muted);font-weight:600}
.input-row{display:grid;grid-template-columns:1fr 2fr;gap:16px}
@media(max-width:600px){.input-row{grid-template-columns:1fr}}
input,select{margin-top:2px;padding:11px 12px;border-radius:8px;border:1px solid var(--line);background:#0c151e;color:var(--text);font-size:1.05rem}
input:focus,select:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 2px rgba(31,182,166,.25)}
.results{display:flex;flex-wrap:wrap;gap:14px;margin-top:18px;grid-column:1/-1}
.result{flex:1;min-width:150px;background:#0c151e;border:1px solid var(--line);border-radius:10px;padding:12px 14px;display:flex;flex-direction:column;gap:2px}
.result span{font-size:.72rem;color:var(--muted);text-transform:uppercase;letter-spacing:.5px}
.result b{font-size:1.5rem;color:var(--green)}
.result i{font-size:.75rem;color:var(--muted);font-style:normal}
.two-col{display:grid;grid-template-columns:1fr 1fr;gap:24px}
.table-wrap{overflow:auto;border:1px solid var(--line);border-radius:10px;max-height:560px}
table{border-collapse:collapse;width:100%;font-size:.85rem}
th,td{padding:8px 12px;text-align:right;border-bottom:1px solid var(--line);white-space:nowrap}
th{position:sticky;top:0;background:#13202c;color:var(--accent);font-weight:600;text-align:right}
tbody tr:hover{background:#1b2937}
td:first-child,th:first-child{text-align:left}
footer{padding:24px;border-top:1px solid var(--line);margin-top:30px;flex-shrink:0;background:linear-gradient(90deg,#10212e,#13303a)}
.foot-inner{max-width:1100px;margin:0 auto;text-align:center;display:flex;flex-direction:column;gap:6px}
.foot-brand{font-weight:700;color:var(--text);letter-spacing:.5px}
.foot-credit{color:var(--accent);font-size:.95rem}
.foot-credit strong{color:#fff}
.foot-note{color:var(--muted);font-size:.75rem}
@media(max-width:760px){.two-col,.calc-card.interp{grid-template-columns:1fr}}