/* Solar Payback: white daylight pages, a sun-yellow header band, and results on solar-panel blue with a faint cell grid. The 25-year sun path is the one bold element. */
:root{
  --bg:#ffffff; --sky:#eef4fa; --ink:#1c2430; --muted:#5b6573; --line:#dde3ea;
  --link:#1f4e8c; --sun:#f6b400; --sun-ink:#1c2430; --panel:#0f2f57; --panel-2:#16406f; --panel-ink:#e9f0f8; --panel-muted:#a9bdd6; --cell:#ffffff10;
  --f:"Figtree","Segoe UI",Roboto,Arial,sans-serif;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --bg:#0d141c; --sky:#142030; --ink:#e8edf3; --muted:#9fb0c2; --line:#26364a; --link:#8db8f0; --panel:#0a2242; --panel-2:#12345f; color-scheme:dark}}
:root[data-theme="dark"]{--bg:#0d141c; --sky:#142030; --ink:#e8edf3; --muted:#9fb0c2; --line:#26364a; --link:#8db8f0; --panel:#0a2242; --panel-2:#12345f; color-scheme:dark}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);font:400 18px/1.65 var(--f);font-variant-numeric:tabular-nums;
  padding-left:max(16px,env(safe-area-inset-left,0px));padding-right:max(16px,env(safe-area-inset-right,0px))}
.wrap{max-width:1080px;margin:0 auto}
a{color:var(--link);text-underline-offset:3px}
a:focus-visible,button:focus-visible,select:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid var(--sun);outline-offset:2px;border-radius:4px}

/* Sun-yellow header band, full width */
header.site{display:flex;flex-wrap:wrap;gap:10px 26px;align-items:center;justify-content:space-between;padding-block:16px;background:var(--sun);color:var(--sun-ink);box-shadow:0 0 0 100vmax var(--sun);clip-path:inset(0 -100vmax)}
.logo{font:800 24px/1 var(--f);letter-spacing:-.02em;color:var(--sun-ink);text-decoration:none;display:flex;align-items:center;gap:10px}
.logo i{position:relative;width:26px;height:26px;border-radius:50%;background:var(--sun-ink);box-shadow:0 0 0 4px #1c243022}
.logo i::after{content:"";position:absolute;inset:7px;border-radius:50%;background:var(--sun)}
nav.site{display:flex;flex-wrap:wrap;gap:2px 4px;font-size:16px;font-weight:600}
nav.site a{color:var(--sun-ink);text-decoration:none;padding:7px 12px;border-radius:999px}
nav.site a:hover{background:#ffffff55}
nav.site a[aria-current="page"]{background:var(--sun-ink);color:var(--sun)}
footer.site{border-top:1px solid var(--line);margin-top:44px;padding-block:24px 44px;font-size:15px;color:var(--muted);display:flex;flex-wrap:wrap;gap:8px 22px;justify-content:space-between}
footer.site a{color:var(--muted)}

/* Headings */
.hero{padding-block:40px 20px;display:grid;gap:12px;max-width:740px}
h1{font:800 clamp(34px,5.6vw,56px)/1.06 var(--f);margin:0;letter-spacing:-.03em;text-wrap:balance}
h2{font:800 clamp(24px,3.1vw,32px)/1.15 var(--f);margin:0 0 10px;letter-spacing:-.02em;text-wrap:balance}
h3{font:700 19px/1.35 var(--f);margin:0 0 6px}
.lede{font-size:20px;line-height:1.55;color:var(--muted);margin:0;max-width:62ch}
.updated{font-size:14px;color:var(--muted)}
section{padding-block:26px}
.hint{font-size:15px;line-height:1.5;color:var(--muted);margin:0}

/* Calculator: questions left, answer right (stacked on phones) */
.tool{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,.95fr);gap:22px;align-items:start}
@media (max-width:860px){.tool{grid-template-columns:1fr}}
.panel{background:var(--sky);border-radius:18px;padding:24px;display:grid;gap:22px;min-width:0}
.field{display:grid;gap:8px}
.field label,.lbl{font:700 17px/1.3 var(--f);color:var(--ink)}
select,input[type=number]{font:500 17px/1.2 var(--f);color:var(--ink);background:var(--bg);border:1.5px solid var(--line);border-radius:12px;padding:13px 14px;width:100%;min-width:0;min-height:52px}
select:hover,input[type=number]:hover{border-color:var(--muted)}
.row2{display:grid;grid-template-columns:1fr 1fr;gap:14px;align-items:start}
@media (max-width:520px){.row2{grid-template-columns:1fr}}
.check{display:flex;gap:10px;align-items:center;font-size:17px;font-weight:500}
.check input{width:22px;height:22px;accent-color:var(--panel)}
.seg{display:flex;flex-wrap:wrap;gap:8px}
.seg button{font:600 16px/1 var(--f);padding:13px 16px;min-height:48px;border-radius:999px;border:1.5px solid var(--line);background:var(--bg);color:var(--ink);cursor:pointer}
.seg button:hover{border-color:var(--muted)}
.seg button[aria-pressed="true"]{background:var(--panel);border-color:var(--panel);color:#fff}
.adv{border:1.5px dashed #b9c6d4;border-radius:14px;padding:14px 16px}
.adv>summary{font:700 17px/1.3 var(--f);list-style:none;display:flex;align-items:center;gap:10px;cursor:pointer}
.adv>summary::-webkit-details-marker{display:none}
.adv>summary::before{content:"+";display:inline-grid;place-items:center;width:26px;height:26px;border-radius:50%;background:var(--bg);font:800 18px/1 var(--f);color:var(--link)}
.adv[open]>summary::before{content:"\2212"}
.adv>summary::after{content:"For people who know their figures";font:400 14px/1.3 var(--f);color:var(--muted);margin-left:auto;text-align:right}
@media (max-width:480px){.adv>summary::after{display:none}}
.advbody{display:grid;gap:16px;margin-top:16px}

/* The answer, on solar-panel blue with a faint cell grid */
.result{position:sticky;top:16px;color:var(--panel-ink);border-radius:18px;padding:26px;display:grid;gap:14px;min-width:0;
  background:linear-gradient(var(--cell) 1px,transparent 1px) 0 0/36px 36px,linear-gradient(90deg,var(--cell) 1px,transparent 1px) 0 0/36px 36px,linear-gradient(160deg,var(--panel-2),var(--panel))}
@media (max-width:860px){.result{position:static}}
.result .cap{margin:0;font-size:17px;color:var(--panel-muted)}
.big{font:800 clamp(52px,9vw,80px)/1 var(--f);letter-spacing:-.03em;color:var(--sun)}
.big small{font-size:.42em;font-weight:700;letter-spacing:0;color:var(--panel-ink)}
.result .sub{margin:-4px 0 0;color:var(--panel-muted)}
.sunpath{margin-top:4px}
.sunpath .track{position:relative;height:14px;border-radius:999px;background:var(--sun);overflow:visible}
.sunpath .paid{position:absolute;left:0;top:0;bottom:0;border-radius:999px 0 0 999px;background:repeating-linear-gradient(135deg,#6f8fbf 0 6px,#5c7ba6 6px 12px);transition:width .5s ease}
.sunpath .mark{position:absolute;top:50%;width:26px;height:26px;margin:-13px 0 0 -13px;border-radius:50%;background:var(--sun);box-shadow:0 0 0 4px var(--panel),0 0 18px #f6b40088;transition:left .5s ease}
.sunpath .ticks{position:relative;height:18px;font-size:13px;color:var(--panel-muted);margin-top:10px}
.sunpath .ticks span{position:absolute;top:0;transform:translateX(-50%);white-space:nowrap}
.sunpath .ticks span:nth-child(1){left:0;transform:none}.sunpath .ticks span:nth-child(2){left:40%}.sunpath .ticks span:nth-child(3){left:80%}.sunpath .ticks span:nth-child(4){left:100%;transform:translateX(-100%)}
.pathkey{margin:0;font-size:14px;color:var(--panel-muted);display:flex;flex-wrap:wrap;gap:6px 14px;align-items:center}
.pathkey span{display:inline-block;width:14px;height:10px;border-radius:3px;margin-right:-8px;vertical-align:-1px}
.pathkey .k1{background:#6f8fbf}.pathkey .k2{background:var(--sun)}
.grid4{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}
.grid4 div{background:#ffffff12;border-radius:12px;padding:12px 14px;display:grid;gap:2px}
.grid4 span{font-size:14px;color:var(--panel-muted)}
.grid4 b{font:800 24px/1.2 var(--f);color:#fff}
.result .foot{margin:0;font-size:16px;line-height:1.5;color:var(--panel-ink)}

/* Guide lists */
.cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:14px}
.card{display:grid;gap:4px;align-content:start;padding:18px 18px 18px 20px;border-radius:14px;background:var(--sky);text-decoration:none;color:var(--ink);border-left:5px solid var(--sun)}
.card b{font:700 19px/1.3 var(--f);color:var(--ink)}
.card:hover b{text-decoration:underline;text-underline-offset:3px}
.card span{font-size:16px;line-height:1.5;color:var(--muted)}
section>h2+.hint{margin-bottom:12px}

/* Articles */
article.post{max-width:720px;display:grid;gap:6px}
article.post h2{margin-top:30px}
article.post p,article.post li{font-size:18px;line-height:1.7}
article.post ul,article.post ol{padding-left:1.25em;display:grid;gap:8px;margin:6px 0}
article.post .tablewrap{margin-block:12px}
.strip{color:var(--panel-ink);border-radius:18px;padding:20px 22px;display:flex;flex-wrap:wrap;gap:16px 34px;align-items:flex-end;margin-bottom:10px;
  background:linear-gradient(var(--cell) 1px,transparent 1px) 0 0/30px 30px,linear-gradient(90deg,var(--cell) 1px,transparent 1px) 0 0/30px 30px,linear-gradient(160deg,var(--panel-2),var(--panel))}
.strip .k{display:block;font-size:15px;color:var(--panel-muted)}
.strip .v{font:800 28px/1.15 var(--f);color:var(--sun)}
.strip select{width:auto;min-height:44px;padding:9px 12px;font-size:16px;background:#ffffff14;color:#fff;border-color:#ffffff33}
.strip select option{color:#1c2430}
.strip .grow{flex:1 1 100%;font-size:14px;line-height:1.5;color:var(--panel-muted);margin:0}
table.src{border-collapse:collapse;width:100%;font-size:16px}
.tablewrap{overflow-x:auto}
table.src th,table.src td{text-align:left;padding:11px 12px;border-bottom:1px solid var(--line);vertical-align:top}
table.src thead th{font:700 15px/1.3 var(--f);color:var(--muted);border-bottom:2px solid var(--ink)}
table.src td.n{font-weight:600}
.related{display:grid;gap:10px;max-width:720px;margin-top:20px;padding-top:26px;border-top:1px solid var(--line)}
.related a{font-weight:600}
.prose{max-width:720px}
.prose ul{padding-left:1.25em;display:grid;gap:8px}
.faq{display:grid;max-width:740px}
details{border-bottom:1px solid var(--line);padding:16px 2px}
.faq details:first-of-type{border-top:1px solid var(--line)}
summary{cursor:pointer;font-weight:700}
details p{margin:10px 0 0;color:var(--muted)}
@media (prefers-reduced-motion:reduce){.sunpath .paid,.sunpath .mark{transition:none}}