:root{
  --navy:#15324a;--navy2:#0e2435;--blue:#dce9ef;--blue2:#edf4f7;
  --cream:#f4ead6;--cream2:#fbf7ef;--paper:#fffdf8;--muted:#5b6872;
  --line:#d7d1c6;--gold:#9b6938;--green:#2f6b57;--red:#8b3e36;--max:1120px
}
*{box-sizing:border-box}
body{margin:0;font-family:Arial,Helvetica,sans-serif;color:var(--navy);background:var(--paper);line-height:1.5}
a{color:inherit;text-decoration:none}
.wrap{width:min(var(--max),calc(100% - 40px));margin:0 auto}
.topbar{border-bottom:1px solid var(--line);background:#fffdf8}
.nav{min-height:66px;display:flex;align-items:center;justify-content:space-between;gap:20px}
.brand{font-family:Georgia,"Times New Roman",serif;font-size:1.35rem;font-weight:700}
.back{font-size:.92rem;font-weight:700;color:#315c72}
.intro{padding:58px 0 42px;background:linear-gradient(180deg,#f6efe2,#fffdf8)}
.intro-grid{display:grid;grid-template-columns:1.3fr .7fr;gap:50px;align-items:end}
.eyebrow,.step{margin:0 0 8px;font-size:.74rem;font-weight:800;letter-spacing:.13em;text-transform:uppercase;color:var(--gold)}
.step.light{color:#d5e4eb}
h1,h2,h3{font-family:Georgia,"Times New Roman",serif;letter-spacing:-.025em}
h1{margin:0;font-size:clamp(2.7rem,5vw,4.7rem);line-height:1}
.lede{max-width:760px;color:var(--muted);font-size:1.08rem}
.note{padding:22px;border:1px solid #dfd3bd;border-radius:12px;background:#f4ead5}
.note p{margin-bottom:0;color:var(--muted)}
.calculator-shell{padding:30px 0 70px}
.basic-panel{padding:30px;border:1px solid #d8c7a4;border-radius:18px;background:var(--cream)}
.section-title{display:flex;justify-content:space-between;gap:20px;align-items:flex-start;margin-bottom:24px}
.section-title h2,.advanced-panel h2{margin:0;font-size:2rem}
.section-title p:last-child,.advanced-panel summary p:last-child{margin:5px 0 0;color:var(--muted)}
.badge{padding:7px 11px;border-radius:999px;background:#fffdf8;border:1px solid #d6c6a5;color:var(--gold);font-size:.75rem;font-weight:800;text-transform:uppercase;white-space:nowrap}
.basic-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}
label{display:block;font-weight:700;font-size:.91rem;min-width:0}
.help{display:block;min-height:40px;margin:4px 0 8px;color:var(--muted);font-size:.76rem;font-weight:400;line-height:1.32}
.input-wrap{display:flex;align-items:center;border:1px solid #cfc5b4;border-radius:9px;background:white}
.input-wrap:focus-within{border-color:#6f8797;box-shadow:0 0 0 3px rgba(21,50,74,.08)}
.input-wrap span{padding-left:12px;color:var(--muted)}
.input-wrap span:last-child{padding:0 12px 0 4px}
input{width:100%;min-width:0;border:0;outline:0;background:transparent;padding:12px;font:inherit;color:var(--navy)}
input[aria-invalid="true"]{background:#fff4f2}
.form-error,.warnings{margin:0 0 18px;padding:13px 15px;border-radius:9px;font-size:.88rem}
.form-error{background:#fff0ee;border:1px solid #e3b8b2;color:var(--red)}
.result-panel{margin:20px 0;padding:30px;border-radius:18px;background:var(--navy);color:white}
.live-result-card{padding:24px 26px;border-radius:14px;background:var(--cream);color:var(--navy);border:2px solid #d7b97d}
.live-result-meta{display:flex;align-items:center;justify-content:space-between;gap:16px;margin-bottom:12px}
.live-result-badge{display:inline-flex;align-items:center;gap:8px;font-size:.78rem;font-weight:800;letter-spacing:.1em;text-transform:uppercase;color:var(--green)}
.live-dot{width:9px;height:9px;border-radius:50%;background:var(--green);box-shadow:0 0 0 4px rgba(47,107,87,.12)}
.updates-note{font-size:.82rem;font-weight:700;color:var(--gold)}
.live-result-card h2{margin:0;font-size:clamp(2rem,3.6vw,3rem);line-height:1.05}
.live-result-card>p:last-child{margin:12px 0 0;color:var(--muted)}
.cost-cards{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:18px}
.cost-card{padding:20px;border:1px solid rgba(255,255,255,.2);border-radius:12px;background:rgba(255,255,255,.08)}
.cost-card span,.cost-card small{display:block;color:#d4e0e7}
.cost-card strong{display:block;margin:4px 0;font-family:Georgia,"Times New Roman",serif;font-size:2rem}
.result-bottom{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:14px}
.difference,.breakeven{padding:18px;border-radius:12px;background:white;color:var(--navy)}
.difference span,.breakeven span,.breakeven small{display:block;color:var(--muted)}
.difference strong,.breakeven strong{display:block;margin:3px 0;font-family:Georgia,"Times New Roman",serif;font-size:1.6rem}
.advanced-panel{margin-top:20px;border:1px solid #c6d7df;border-radius:18px;background:var(--blue2);overflow:hidden}
.advanced-panel summary{list-style:none;cursor:pointer;padding:26px 30px;display:flex;align-items:center;justify-content:space-between;gap:20px}
.advanced-panel summary::-webkit-details-marker{display:none}
.summary-action{padding:9px 12px;border-radius:8px;background:white;border:1px solid #c6d7df;font-size:.8rem;font-weight:700;white-space:nowrap}
.advanced-panel[open] .summary-action::after{content:" less"}
.advanced-content{padding:0 30px 30px;border-top:1px solid #cedde4}
.advanced-intro{display:flex;justify-content:space-between;gap:20px;align-items:center;padding:20px 0}
.advanced-intro p{margin:0;color:var(--muted);font-size:.9rem}
.text-button{border:0;background:transparent;color:#315c72;text-decoration:underline;text-underline-offset:3px;font:inherit;font-weight:700;cursor:pointer}
.advanced-groups{display:grid;grid-template-columns:1fr 1.35fr;gap:18px}
.assumption-group{padding:22px;border-radius:12px;background:white;border:1px solid #cedde4}
.assumption-group h3{margin:0 0 18px;font-size:1.25rem}
.assumption-group label+label{margin-top:16px}
.assumption-group .help{min-height:0}
.optional{font-size:.7rem;color:var(--muted);font-weight:400}
.warnings{margin:20px 0 0;background:#fff8e9;border:1px solid #e8d4a9;color:var(--navy)}
.warnings p{margin:3px 0}
.page-actions{display:flex;align-items:center;justify-content:space-between;gap:18px;padding:20px 4px 0}
.secondary{min-height:44px;padding:0 16px;border:1px solid var(--line);border-radius:8px;background:white;color:var(--navy);font:inherit;font-weight:700;cursor:pointer}
.guide-link{font-weight:700;color:#315c72}
.method-strip{padding:38px 0 54px;background:#f6f3ed;border-top:1px solid var(--line)}
.method-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.method-grid>div{padding:0 16px;border-left:2px solid #d6ccba}
.method-grid p:last-child{color:var(--muted);font-size:.88rem}
@media(max-width:900px){
 .intro-grid{grid-template-columns:1fr}
 .basic-grid{grid-template-columns:1fr 1fr}
 .advanced-groups{grid-template-columns:1fr}
 .method-grid{grid-template-columns:1fr}
 .help{min-height:0}
}
@media(max-width:620px){
 .wrap{width:min(var(--max),calc(100% - 28px))}
 .intro{padding-top:42px}
 .basic-panel,.result-panel{padding:22px}
 .section-title,.advanced-panel summary,.advanced-intro,.page-actions{flex-direction:column;align-items:flex-start}
 .basic-grid,.cost-cards,.result-bottom{grid-template-columns:1fr}
 .advanced-panel summary{padding:22px}
 .advanced-content{padding:0 22px 22px}
 .summary-action{width:100%;text-align:center}
 .secondary{width:100%}
}

@media(max-width:620px){
 .live-result-meta{align-items:flex-start;flex-direction:column}
 .updates-note{font-size:.78rem}
}


/* V5: clearer decision hierarchy and visual feedback */
.comparison-visual{
  margin:18px 0 4px;padding:18px;border-radius:12px;
  background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.16)
}
.compare-row+.compare-row{margin-top:14px}
.compare-label{display:flex;justify-content:space-between;gap:16px;align-items:center;margin-bottom:7px;color:#dce7ed;font-size:.9rem}
.compare-label strong{color:white}
.bar-track{height:12px;border-radius:999px;background:rgba(255,255,255,.14);overflow:hidden}
.bar-fill{height:100%;width:0;border-radius:999px;transition:width .18s ease}
.bar-fill.keep{background:#9dc1b3}
.bar-fill.replace{background:#d8b47b}
.decision-sensitivity{
  margin-top:14px;padding:18px 20px;border-radius:12px;background:#eef5f7;color:var(--navy);
  display:grid;grid-template-columns:.8fr 1.2fr;gap:18px;align-items:center
}
.sensitivity-label{display:block;color:var(--gold);font-size:.72rem;font-weight:800;letter-spacing:.1em;text-transform:uppercase;margin-bottom:4px}
.decision-sensitivity strong{font-family:Georgia,"Times New Roman",serif;font-size:1.15rem;line-height:1.2}
.decision-sensitivity p{margin:0;color:var(--muted);font-size:.88rem}
.assumption-summary{
  margin:20px 0;padding:18px 20px;border:1px solid #d8c7a4;border-radius:14px;background:#fffaf0;
  display:grid;grid-template-columns:1.1fr 1.5fr auto;gap:18px;align-items:center
}
.assumption-summary p{margin:0}
.assumption-summary>div:first-child p:last-child{color:var(--muted);font-size:.86rem}
.assumption-chips{display:flex;flex-wrap:wrap;gap:8px}
.assumption-chips span{
  padding:7px 10px;border-radius:999px;background:white;border:1px solid #e0d2b7;
  color:#566674;font-size:.76rem
}
.assumption-button{
  min-height:42px;padding:0 14px;border:1px solid #c8b38c;border-radius:8px;background:white;
  color:var(--navy);font:inherit;font-weight:700;cursor:pointer;white-space:nowrap
}
@media(max-width:900px){
  .assumption-summary{grid-template-columns:1fr}
  .assumption-button{justify-self:start}
}
@media(max-width:620px){
  .decision-sensitivity{grid-template-columns:1fr}
  .comparison-visual{padding:15px}
  .assumption-button{width:100%}
}
@media(prefers-reduced-motion:reduce){
  .bar-fill{transition:none}
}

/* V6: heat pump calculator */
.hp-basic-grid{grid-template-columns:repeat(3,1fr)}
@media(max-width:900px){.hp-basic-grid{grid-template-columns:1fr 1fr}}
@media(max-width:620px){.hp-basic-grid{grid-template-columns:1fr}}