:root{--bg:#f7f8fa;--card:#fff;--card2:#f2f4f7;--ink:#1f2328;--muted:#556070;--line:#e5e7eb;--brand:#2563eb;--brand-ink:#fff;--ok:#059669;color-scheme:light}
/* Dark mode: follow the system by default; a manual choice wins (html[data-theme] has higher priority) */
html[data-theme="dark"]{--bg:#0f1216;--card:#171b21;--card2:#1e242c;--ink:#e8eaed;--muted:#9aa4b2;--line:#2a313a;--brand:#6ea8fe;--brand-ink:#0b0e12;--ok:#34d399;color-scheme:dark}
html[data-theme="light"]{color-scheme:light}
@media (prefers-color-scheme:dark){
  html:not([data-theme="light"]){--bg:#0f1216;--card:#171b21;--card2:#1e242c;--ink:#e8eaed;--muted:#9aa4b2;--line:#2a313a;--brand:#6ea8fe;--brand-ink:#0b0e12;--ok:#34d399;color-scheme:dark}
}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.6 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif}
.site-head{display:flex;justify-content:space-between;align-items:center;gap:16px;padding:14px 20px;background:var(--card);border-bottom:1px solid var(--line)}
.brand{font-weight:700;font-size:18px;color:var(--ink);text-decoration:none}
.brand span{color:var(--muted);font-weight:400}
.site-head nav a{color:var(--brand);text-decoration:none;font-size:14px}
main{max-width:780px;margin:0 auto;padding:28px 20px 60px}
h1{font-size:30px;line-height:1.25;margin:0 0 10px}
h2{font-size:22px;margin:30px 0 12px}
.intro{color:var(--muted);margin:0 0 22px}
/* Direct answer box: sits right under the H1 and answers in 40-60 words. This is the block that wins featured snippets. */
.answer{margin:0 0 16px;padding:14px 16px;background:var(--card2);border-left:3px solid var(--brand);border-radius:0 8px 8px 0;font-size:16.5px;line-height:1.6;color:var(--ink)}
.answer strong{font-weight:700}
/* Key takeaways: 3-5 short bullets with numbers, below the calculator */
.takeaways{margin:26px 0 6px;padding:18px 20px;border:1px solid var(--line);border-radius:12px;background:var(--card)}
.takeaways h2{margin:0 0 10px;font-size:17px}
.takeaways ul{margin:0;padding-left:20px}
.takeaways li{margin:7px 0;line-height:1.55}
.takeaways strong{font-weight:700}
/* Site search: lives in the header, present on every page */
.head-search{position:relative;flex:1 1 190px;min-width:140px;max-width:330px}
.head-search input{width:100%;padding:8px 12px;font-size:14.5px;border:1px solid var(--line);border-radius:8px;background:var(--card);color:var(--ink)}
.head-search input:focus{outline:2px solid var(--brand);outline-offset:1px}
.head-search .search-results,.head-search .search-msg{position:absolute;top:calc(100% + 6px);left:0;right:0;z-index:60;margin:0}
.head-search .search-results{background:var(--card);border:1px solid var(--line);border-radius:10px;overflow:hidden auto;max-height:62vh;box-shadow:0 10px 28px rgba(0,0,0,.14)}
.head-search .search-msg{background:var(--card);border:1px solid var(--line);border-radius:8px;padding:8px 12px;font-size:13px;color:var(--muted)}
@media(max-width:700px){
  .site-head{flex-wrap:wrap}
  .head-search{order:3;flex:1 1 100%;max-width:none;margin-top:8px}
}
/* Site search: pure front end. One JSON index, filter as you type, no backend. */
.site-search{position:relative;margin:0 0 22px}
.site-search input{width:100%;padding:12px 14px;font-size:16px;border:1px solid var(--line);border-radius:10px;background:var(--card);color:var(--ink)}
.site-search input:focus{outline:2px solid var(--brand);outline-offset:1px}
.search-results{list-style:none;margin:8px 0 0;padding:0;border:1px solid var(--line);border-radius:10px;background:var(--card);overflow:hidden}
.search-results li+li{border-top:1px solid var(--line)}
.search-results a{display:flex;justify-content:space-between;gap:12px;align-items:baseline;padding:11px 14px;text-decoration:none;color:var(--ink)}
.search-results a:hover{background:var(--card2)}
.search-results span{font-size:12.5px;color:var(--muted);text-transform:capitalize;white-space:nowrap}
.search-msg{font-size:13.5px;margin:8px 0 0}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
@media print{.site-search{display:none!important}}
.tool-card{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:22px}
/* Desktop two-column card: inputs left, results right, so the answer is on screen.
   Measured: a simple tool shows its result at 816px (still visible) but a mortgage
   calculator pushed it to 1141px, below a 900px fold. A calculator should answer
   without scrolling. */
@media(min-width:901px){
  .tool-card{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:0 26px;align-items:start}
  .tool-card > .fields{grid-column:1}
  .tool-card > .results{grid-column:2;margin-top:0;border-top:0;padding-top:0;border-left:1px dashed var(--line);padding-left:26px}
  .tool-card > .tool-actions{grid-column:1/-1}
}
label{display:block;font-size:14px;font-weight:600;margin:12px 0 4px}
input,select{width:100%;padding:10px 12px;border:1px solid var(--line);border-radius:8px;font-size:15px;background:var(--card);color:var(--ink)}
button{margin-top:16px;padding:11px 20px;border:0;border-radius:8px;background:var(--brand);color:var(--brand-ink);font-size:15px;font-weight:600;cursor:pointer}
button:hover{filter:brightness(.95)}
.results{margin-top:18px;border-top:1px dashed var(--line);padding-top:14px}
.results table{width:100%;border-collapse:collapse;font-size:15px}
.results td{padding:6px 0;border-bottom:1px solid var(--line)}
.results td:last-child{text-align:right;font-variant-numeric:tabular-nums}
.big{font-size:22px;font-weight:700}
.faq details{border-bottom:1px solid var(--line);padding:12px 0}
.faq summary{font-weight:600;cursor:pointer}
.faq p{color:var(--muted);margin:8px 0 0}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:12px;padding:0;list-style:none}
.grid a{display:block;background:var(--card);border:1px solid var(--line);border-radius:10px;padding:14px;text-decoration:none;color:var(--ink)}
.grid a:hover{border-color:var(--brand)}
.grid small{display:block;color:var(--muted);font-weight:400;margin-top:4px}
.site-foot{max-width:780px;margin:0 auto;padding:24px 20px 50px;color:var(--muted);font-size:13px;border-top:1px solid var(--line)}
.crumbs{font-size:13px;color:var(--muted);margin:0 0 14px}
.crumbs a{color:var(--muted);text-decoration:none}
.crumbs a:hover{color:var(--brand);text-decoration:underline}
.byline{font-size:13px;color:var(--muted);margin:-8px 0 20px}
.share{margin:0 0 18px;position:relative}
.share-bottom{margin:30px 0 8px;padding:18px 0 0;border-top:1px solid var(--line)}
.share-lead{font-size:14px;color:var(--muted);margin:0 0 10px}
.share-btn{padding:9px 16px;border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:8px;font-size:14px;font-weight:600;cursor:pointer}
.share-btn:hover{border-color:var(--brand);color:var(--brand)}
.share-menu{display:flex;flex-wrap:wrap;gap:8px;margin-top:10px}
.share-menu a,.share-menu button{padding:8px 13px;border:1px solid var(--line);background:var(--card);border-radius:8px;font-size:13.5px;color:var(--ink);text-decoration:none;cursor:pointer;font-family:inherit}
.share-menu a:hover,.share-menu button:hover{border-color:var(--brand);color:var(--brand)}
.share-msg{font-size:13px;color:var(--ok);margin-left:10px}
.report{margin:0 0 18px}
.report-lead{font-size:14px;color:var(--muted);margin:0 0 10px}
.report-btn{padding:9px 16px;border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:8px;font-size:14px;font-weight:600;cursor:pointer;font-family:inherit}
.report-btn:hover{border-color:var(--brand);color:var(--brand)}
.report-form{display:flex;flex-direction:column;gap:8px;padding:16px;border:1px solid var(--line);border-radius:10px;background:var(--card);max-width:620px}
.report-form[hidden]{display:none}
.report-form label{font-size:13.5px;font-weight:600;color:var(--ink)}
.report-form textarea,.report-form input{padding:9px 11px;border:1px solid var(--line);border-radius:8px;font-size:14px;font-family:inherit;color:var(--ink);width:100%;box-sizing:border-box}
.report-form textarea:focus,.report-form input:focus{outline:2px solid var(--brand);outline-offset:1px}
.report-actions{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-top:2px}
.report-actions button{padding:9px 16px;border-radius:8px;font-size:14px;font-weight:600;cursor:pointer;font-family:inherit;border:1px solid var(--line);background:var(--card);color:var(--ink)}
.report-actions button[type=submit]{background:var(--brand);border-color:var(--brand);color:var(--brand-ink)}
.report-actions button[type=submit]:disabled{opacity:.6;cursor:default}
.report-status{font-size:13px;color:var(--muted)}
.report-alt{font-size:13px;color:var(--muted);margin:0}
.sections h2{margin-top:30px}
.sections h3{margin-top:22px;font-size:17px}
.sections table{width:100%;border-collapse:collapse;font-size:15px;margin:14px 0}
.sections th,.sections td{border:1px solid var(--line);padding:8px 10px;text-align:left}
.sections th{background:var(--card2);font-weight:600}
.sections ul{margin:10px 0 10px 20px}
.sections li{margin:6px 0}
.disclaimer{margin-top:34px;font-size:13px;border-top:1px solid var(--line);padding-top:14px}
.figures{margin:28px 0}
.fig{margin:0 0 24px;text-align:center}
.more{margin-top:34px;border-top:1px solid var(--line);padding-top:18px}
.more-list{list-style:none;padding:0;margin:0;display:grid;grid-template-columns:repeat(auto-fill,minmax(215px,1fr));gap:8px 16px}
.more-list a{font-size:14px;color:var(--brand);text-decoration:none}
.more-list a:hover{text-decoration:underline}
/* Horizontally scrolling cards. Looks like a carousel but every card is in the static HTML, so no JS is needed. */
.rail-wrap{margin:26px 0 8px}
.rail{list-style:none;padding:0 0 10px;margin:0;display:flex;gap:12px;overflow-x:auto;scroll-snap-type:x mandatory;-webkit-overflow-scrolling:touch}
.rail .card{flex:0 0 240px;scroll-snap-align:start}
.rail .card a{display:block;height:100%;background:var(--card);border:1px solid var(--line);border-radius:10px;padding:14px;text-decoration:none;color:var(--ink)}
.rail .card a:hover{border-color:var(--brand)}
.rail .card strong{display:block;font-size:15px;margin-bottom:6px}
.rail .card span{display:block;font-size:13px;color:var(--muted);line-height:1.45}
/* Directory page */
.dir-list{list-style:none;padding:0;margin:0}
.dir-list li{padding:7px 0;border-bottom:1px solid var(--line);font-size:15px}
.dir-list li a{color:var(--brand);text-decoration:none;font-weight:600}
.dir-list li a:hover{text-decoration:underline}
.dir-list li .muted{font-size:13px;margin-left:6px}
/* Cross-links to other categories at the bottom of a category page */
.cats-cross{margin-top:34px;border-top:1px solid var(--line);padding-top:16px}
.cats-cross ul{list-style:none;padding:0;display:flex;flex-wrap:wrap;gap:8px 14px;margin:10px 0 0}
.cats-cross a{font-size:14px;color:var(--brand);text-decoration:none}
.cats-cross a:hover{text-decoration:underline}
.fig svg{max-width:100%;height:auto}
.fig figcaption{font-size:13px;color:var(--muted);margin-top:8px}
/* Ad slot: a fixed min-height stops the ad from shifting content when it loads (CLS is a Core Web Vitals metric) */
.ad-slot{min-height:280px;margin:26px 0;display:flex;align-items:center;justify-content:center;background:var(--card2);border:1px solid var(--line);border-radius:10px;overflow:hidden}
.ad-slot ins{width:100%}
@media(max-width:700px){.ad-slot{min-height:250px;margin:20px 0}}
.foot-links{margin:0 0 12px}
.foot-links a{color:var(--brand);text-decoration:none;margin-right:18px;font-weight:600}
.foot-links a:hover{text-decoration:underline}
.muted{color:var(--muted)}
@media(max-width:700px){
  h1{font-size:26px}
  main{padding:20px 14px 40px}
  /* Let wide tables scroll sideways instead of breaking the layout, but do not force
     nowrap: measured, the mortgage table is 846px wide and 484px of it was cut off
     with no hint that it scrolls. */
  .sections table,.results table{display:block;overflow-x:auto;-webkit-overflow-scrolling:touch;max-width:100%}
  .sections th,.sections td{padding:8px 10px}
  /* Bigger touch targets (>=44px) */
  input,select{padding:12px;font-size:16px;min-height:44px}
  button{min-height:46px;font-size:16px}
  /* Collapsible headings need to be tappable too: measured, FAQ / TOC / "Show the math"
     summaries were only 22.4px tall, under both the 44px touch target and the 24px
     WCAG 2.5.8 floor. */
  summary{padding:11px 0}
  /* Single-column tool list on phones, easier to tap */
  .grid{grid-template-columns:1fr}
  .site-head{padding:10px 14px}
  /* Keep the header on one row. The brand link already goes home, so drop the
     "All tools" text link on phones. Measured: the search box used to wrap to a
     second row and the header grew to 139px, 16.5% of an 844px screen. */
  .site-head nav a{display:none}
  .head-search{order:0;flex:1 1 120px;min-width:104px;max-width:none;margin-top:0}
  .crumbs{font-size:12px}
  .fig svg{width:100%;height:auto}
  .fig{margin-bottom:18px}
  /* Stack the action bar vertically on phones so the buttons are full width */
  .tool-actions{flex-direction:column;align-items:stretch}
  .tool-actions button{width:100%}
}
/* Action bar inside the tool card: copy result, print */
.tool-actions{display:flex;flex-wrap:wrap;align-items:center;gap:8px;margin:18px 0 0;padding-top:14px;border-top:1px solid var(--line)}
.tool-actions button{margin-top:0;padding:8px 14px;border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:8px;font-size:13.5px;font-weight:600;cursor:pointer;font-family:inherit}
.tool-actions button:hover{border-color:var(--brand);color:var(--brand)}
.tool-actions .ta-msg{font-size:13px;color:var(--ok)}
/* Table of contents */
.toc{margin:22px 0 8px;border:1px solid var(--line);border-radius:10px;background:var(--card2);padding:12px 16px;font-size:14px}
.toc summary{font-weight:600;cursor:pointer;font-size:14px}
.toc ol{margin:10px 0 0 18px;padding:0}
.toc li{margin:5px 0}
.toc a{color:var(--brand);text-decoration:none}
.toc a:hover{text-decoration:underline}
@media(min-width:901px){.toc.toc-sticky{position:sticky;top:10px;z-index:5}}
.sections h2,.sections h3{scroll-margin-top:14px}
/* Range sliders (drag to recalculate) on money, term and percentage pages */
input[type=range]{width:100%;padding:0;border:0;background:transparent;height:32px;accent-color:var(--brand);cursor:pointer}
input[type=range]:focus-visible{outline:2px solid var(--brand);outline-offset:2px}
/* Show the math steps */
.steps{margin:14px 0 0;border-top:1px dashed var(--line);padding-top:12px}
.steps summary{font-weight:600;font-size:14px;cursor:pointer;color:var(--brand)}
.steps summary:hover{text-decoration:underline}
.steps p{margin:7px 0;font-size:14px;color:var(--ink);line-height:1.55}
.steps strong{font-variant-numeric:tabular-nums}
@media print{.steps[open] summary{display:none}}
/* Theme toggle button */
.site-head nav{display:flex;align-items:center;gap:12px}
.theme-toggle{margin:0;padding:7px 12px;border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:8px;font-size:13px;font-weight:600;cursor:pointer;font-family:inherit;line-height:1.2}
.theme-toggle:hover{border-color:var(--brand);color:var(--brand)}
/* Print: keep the title, the calculator and the article; drop nav, ads, sharing and the report form */
@media print{
  .site-head,.ad-slot,.share,.report,.toc,.related,.more,.rail-wrap,footer,.crumbs,.byline,.tool-actions,.disclaimer,.cats-cross{display:none!important}
  body{background:#fff!important;color:#000!important;font-size:11.5pt}
  main{max-width:100%!important;padding:0!important}
  .tool-card{border:1px solid #999!important;background:#fff!important;break-inside:avoid}
  .results table,.sections table,.faq details{break-inside:avoid}
  h1{font-size:19pt;margin-bottom:6pt}
  h2{font-size:13.5pt;break-after:avoid}
  a{color:#000!important;text-decoration:none}
  .fig svg{max-width:75%}
  .fig figcaption{font-size:9.5pt}
}