/* HeizkörperPlaner — Technical Blueprint: blueprint blue, white line motifs, mono accents. */
:root {
  --bp: #14356b; --bp-deep: #0d2347; --bp-mid: #1f4b96; --bp-line: #8fa8d6;
  --paper: #f5f8fd; --white: #ffffff; --ink: #16233c; --mut: #5a6b88;
  --hair: #d5e0f0; --amber: #f2a33c; --amber-deep: #c77f1a;
  --sans: "Avenir Next", "Segoe UI", -apple-system, Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, "SF Mono", "Cascadia Mono", Menlo, Consolas, monospace;
  --r: 6px; --sh: 0 2px 14px rgba(13,35,71,.10); --sh-lift: 0 16px 38px rgba(13,35,71,.16);
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body { font-family: var(--sans); color: var(--ink);
  background-color: var(--paper);
  background-image: repeating-linear-gradient(0deg, rgba(31,75,150,.045) 0 1px, transparent 1px 34px),
                    repeating-linear-gradient(90deg, rgba(31,75,150,.045) 0 1px, transparent 1px 34px);
  line-height: 1.7; -webkit-font-smoothing: antialiased; }
.wrap { max-width: 1060px; margin: 0 auto; padding: 0 24px; }
.mono { font-family: var(--mono); }
h1, h2, h3 { line-height: 1.28; letter-spacing: -.01em; color: var(--bp-deep); }
/* header */
header.site { background: var(--bp-deep); border-bottom: 3px solid var(--amber); position: sticky; top: 0; z-index: 50; }
header.site .bar { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 13px 0; flex-wrap: wrap; }
.brand { display: inline-flex; align-items: center; gap: 11px; color: #fff; text-decoration: none; font-weight: 800; font-size: 1.28rem; }
.brand .ruler-ic { width: 38px; height: 38px; border-radius: 8px; background: var(--bp-mid); border: 1.5px solid var(--bp-line);
  display: inline-flex; align-items: center; justify-content: center; }
.brand .ruler-ic svg { width: 22px; height: 22px; stroke: #fff; fill: none; stroke-width: 2; }
.brand .dim { font-family: var(--mono); font-weight: 400; color: var(--amber); font-size: 1.28rem; }
nav.main a { color: #cfe0f7; text-decoration: none; margin-left: 18px; font-size: .9rem; font-weight: 600; }
nav.main a:hover { color: var(--amber); }
/* hero */
.hero { background: linear-gradient(135deg, var(--bp-deep) 0%, var(--bp) 55%, var(--bp-mid) 100%); color: #eaf1fd; padding: 84px 0 76px; position: relative; overflow: hidden; }
.hero::before { content: ""; position: absolute; inset: 0; opacity: .28;
  background-image: repeating-linear-gradient(0deg, rgba(255,255,255,.35) 0 1px, transparent 1px 42px),
                    repeating-linear-gradient(90deg, rgba(255,255,255,.35) 0 1px, transparent 1px 42px); }
.hero::after { content: ""; position: absolute; left: 0; right: 0; bottom: 26px; height: 2px;
  background-image: repeating-linear-gradient(90deg, rgba(255,255,255,.75) 0 22px, transparent 22px 34px); }
.hero .wrap { position: relative; z-index: 1; }
.kicker { display: inline-block; font-family: var(--mono); font-size: .74rem; letter-spacing: .16em; color: var(--amber);
  border: 1.5px dashed rgba(242,163,60,.7); padding: 7px 16px; border-radius: 999px; margin-bottom: 20px; text-transform: uppercase; }
.hero h1 { color: #fff; font-size: 2.9rem; max-width: 700px; margin-bottom: 16px; }
.hero h1 .u { color: var(--amber); text-decoration: underline; text-decoration-thickness: 3px; text-underline-offset: 7px; }
.hero p.lead { color: #c9d9f2; font-size: 1.08rem; max-width: 640px; margin-bottom: 30px; }
.hero-cta { display: flex; gap: 14px; flex-wrap: wrap; }
.btn-amber { display: inline-block; background: var(--amber); color: var(--bp-deep); text-decoration: none; padding: 15px 34px;
  border-radius: var(--r); font-weight: 800; transition: transform .15s, background .15s; }
.btn-amber:hover { transform: translateY(-3px); background: #f7b45e; }
.btn-ghost { display: inline-block; border: 2px solid rgba(255,255,255,.5); color: #fff; text-decoration: none;
  padding: 13px 32px; border-radius: var(--r); font-weight: 700; }
.btn-ghost:hover { border-color: #fff; background: rgba(255,255,255,.08); }
.hero-dim { position: absolute; right: 6%; top: 24px; width: 190px; opacity: .85; z-index: 1; }
/* sections */
section.block { padding: 66px 0; }
.sec-tab { display: inline-block; font-family: var(--mono); font-size: .74rem; letter-spacing: .14em; color: var(--bp-mid);
  background: #fff; border: 1.5px solid var(--bp-line); border-top: 4px solid var(--amber); padding: 8px 18px; border-radius: 4px;
  margin-bottom: 16px; text-transform: uppercase; }
.sec-title { font-size: 2.05rem; margin-bottom: 12px; }
.sec-sub { color: var(--mut); max-width: 720px; margin-bottom: 36px; }
/* tool cards */
.tgrid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 22px; }
.tcard { background: var(--white); border-radius: var(--r); border: 1.5px solid var(--hair); box-shadow: var(--sh);
  text-decoration: none; color: var(--ink); overflow: hidden; transition: transform .16s, box-shadow .16s; display: flex; flex-direction: column; }
.tcard:hover { transform: translateY(-5px); box-shadow: var(--sh-lift); }
.tcard .strip { background: var(--bp); color: #fff; font-family: var(--mono); font-size: .72rem; letter-spacing: .1em;
  padding: 9px 20px; display: flex; justify-content: space-between; align-items: center; }
.tcard .strip svg { width: 20px; height: 20px; stroke: var(--amber); fill: none; stroke-width: 1.8; }
.tcard .tx { padding: 20px 22px 24px; flex: 1; }
.tcard .tx h3 { font-size: 1.16rem; margin-bottom: 8px; }
.tcard .tx p { font-size: .92rem; color: var(--mut); margin-bottom: 12px; }
.tcard .go { font-weight: 800; color: var(--bp-mid); font-size: .9rem; font-family: var(--mono); }
/* prose / article */
article.prose { max-width: 820px; }
article.prose h2 { font-size: 1.6rem; margin: 36px 0 12px; }
article.prose h3 { font-size: 1.14rem; margin: 24px 0 8px; }
article.prose p, article.prose li { margin-bottom: 10px; color: #33445f; }
article.prose ul, article.prose ol { padding-left: 24px; }
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 46px; align-items: center; margin: 50px 0; }
.split.flip > div:first-child { order: 2; }
.split img { width: 100%; border-radius: var(--r); box-shadow: var(--sh-lift); display: block; border: 1.5px solid var(--hair); }
.split h3 { font-size: 1.55rem; margin-bottom: 12px; }
.split p { color: var(--mut); margin-bottom: 12px; }
.split .more { font-weight: 800; color: var(--bp-mid); text-decoration: none; border-bottom: 3px solid var(--amber); }
/* tables */
table.ref { width: 100%; border-collapse: collapse; margin: 14px 0 26px; font-size: .93rem; background: #fff;
  border-radius: var(--r); overflow: hidden; box-shadow: var(--sh); border: 1.5px solid var(--hair); }
table.ref th { background: var(--bp); color: #fff; padding: 12px 14px; text-align: left; font-size: .84rem; font-family: var(--mono); letter-spacing: .03em; }
table.ref td { padding: 11px 14px; border-bottom: 1px solid var(--hair); }
table.ref tr:last-child td { border-bottom: none; }
table.ref tr:nth-child(even) td { background: #eef3fb; }
/* page head */
.crumbs { font-size: .85rem; color: var(--mut); margin: 24px 0 10px; font-family: var(--mono); }
.crumbs a { color: var(--bp-mid); text-decoration: none; font-weight: 700; }
.pagehead { max-width: 800px; margin-bottom: 6px; }
.pagehead h1 { font-size: 2.35rem; margin-bottom: 12px; }
.pagehead h1 .u { color: var(--amber-deep); text-decoration: underline; text-decoration-thickness: 3px; text-underline-offset: 7px; }
.pagehead p { color: var(--mut); font-size: 1.02rem; }
.pagehead .pimg { margin: 26px 0 0; max-width: 660px; }
.pagehead .pimg img { width: 100%; max-height: 300px; object-fit: cover; border-radius: var(--r); box-shadow: var(--sh-lift); border: 1.5px solid var(--hair); }
/* calculator */
.calc { background: #fff; border-radius: var(--r); padding: 34px; margin: 30px 0; box-shadow: var(--sh); border: 1.5px solid var(--hair); max-width: 760px; }
.calc .chead { display: flex; align-items: center; gap: 12px; margin-bottom: 22px; padding-bottom: 16px; border-bottom: 2px dashed var(--bp-line); }
.calc .chead .tick { width: 14px; height: 14px; background: var(--amber); clip-path: polygon(0 0, 100% 0, 100% 100%, 0 100%); }
.calc .chead strong { color: var(--bp-deep); font-family: var(--mono); letter-spacing: .04em; }
.field { margin-bottom: 18px; }
.field label { display: block; font-weight: 700; margin-bottom: 7px; font-size: .93rem; }
.field label .unit { font-family: var(--mono); color: var(--mut); font-weight: 400; font-size: .85rem; }
.field input, .field select { width: 100%; padding: 13px 16px; border: 2px solid var(--hair); border-radius: var(--r);
  font-size: 1rem; font-family: var(--mono); background: #f7faff; color: var(--ink); }
.field input:focus, .field select:focus { outline: none; border-color: var(--bp-mid); background: #fff; }
.field input.invalid { border-color: #c0392b; background: #fdf2f0; }
.field .hint { font-size: .83rem; color: var(--mut); margin-top: 5px; }
.field .error { font-size: .83rem; color: #c0392b; margin-top: 5px; display: none; font-weight: 600; }
.frow { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.btn-row { display: flex; gap: 12px; margin-top: 8px; }
button.calc-btn { background: var(--bp); color: #fff; border: none; padding: 15px 30px; border-radius: var(--r); font-size: 1rem;
  font-weight: 800; cursor: pointer; flex: 1; transition: transform .15s, background .15s; font-family: var(--sans); }
button.calc-btn:hover { transform: translateY(-2px); background: var(--bp-deep); }
button.reset-btn { background: transparent; color: var(--mut); border: 2px solid var(--hair); padding: 15px 26px;
  border-radius: var(--r); cursor: pointer; font-weight: 700; font-family: var(--sans); }
button.reset-btn:hover { border-color: var(--mut); }
.result { display: none; margin-top: 24px; background: var(--bp-deep); border-radius: var(--r); padding: 26px; color: #fff; }
.result.show { display: block; animation: bpIn .3s ease; }
@keyframes bpIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }
.result .big { font-family: var(--mono); font-size: 1.85rem; font-weight: 700; color: var(--amber); }
.result .rrow { display: flex; justify-content: space-between; gap: 12px; padding: 9px 0; border-bottom: 1px dashed rgba(255,255,255,.25);
  font-size: .95rem; font-family: var(--mono); }
.result .rrow:last-child { border-bottom: none; }
.result .rrow span:first-child { color: #b9cdf0; }
.result .note { font-size: .85rem; color: #b9cdf0; margin-top: 10px; }
/* boxes */
.formula { background: #fff; border: 1.5px dashed var(--bp-line); border-radius: var(--r); padding: 20px 24px; margin: 24px 0; font-size: .93rem; }
.formula .flab { font-family: var(--mono); font-size: .74rem; letter-spacing: .12em; color: var(--bp-mid); font-weight: 700; margin-bottom: 8px; text-transform: uppercase; }
.formula code { font-family: var(--mono); background: #eef3fb; padding: 2px 8px; border-radius: 4px; }
.warnbox { background: #fff8ec; border: 2px solid var(--amber); border-radius: var(--r); padding: 18px 22px; margin: 24px 0; font-size: .92rem; color: #6b4a12; }
.warnbox strong { text-transform: uppercase; letter-spacing: .04em; }
.tipbox { background: #eaf1fd; border: 2px solid var(--bp-mid); border-radius: var(--r); padding: 18px 22px; margin: 24px 0; font-size: .92rem; color: #20365f; }
.example { background: #fff; border-radius: var(--r); padding: 20px 24px; margin: 22px 0; box-shadow: var(--sh);
  border-left: 6px solid var(--amber); font-size: .93rem; }
.example .elab { font-family: var(--mono); font-size: .76rem; letter-spacing: .1em; color: var(--amber-deep); font-weight: 700; margin-bottom: 8px; text-transform: uppercase; }
/* faq */
.faq details { background: #fff; border-radius: var(--r); margin-bottom: 10px; padding: 16px 22px; box-shadow: var(--sh); border: 1.5px solid var(--hair); }
.faq summary { font-weight: 800; cursor: pointer; color: var(--bp-deep); }
.faq p { margin-top: 8px; color: var(--mut); font-size: .94rem; }
/* checklist */
.checklist { background: #fff; border-radius: var(--r); border: 1.5px solid var(--hair); box-shadow: var(--sh); margin: 28px 0; max-width: 760px; }
.checklist .progress { padding: 18px 26px; border-bottom: 2px dashed var(--bp-line); font-family: var(--mono); color: var(--bp-mid); font-weight: 700; }
.check-item { display: flex; gap: 16px; padding: 18px 26px; border-bottom: 1px solid var(--hair); cursor: pointer; align-items: flex-start; }
.check-item:last-child { border-bottom: none; }
.check-item input { width: 22px; height: 22px; margin-top: 3px; accent-color: var(--bp); flex-shrink: 0; }
.check-item.done .ctitle { text-decoration: line-through; color: var(--mut); }
.check-item .ctitle { font-weight: 800; color: var(--bp-deep); }
.check-item .cbody { font-size: .9rem; color: var(--mut); }
/* cta + footer */
.cta-band { background: linear-gradient(120deg, var(--bp-deep), var(--bp-mid)); border-radius: 10px; padding: 54px 36px;
  text-align: center; color: #dbe7fa; margin: 60px 0; border-top: 4px solid var(--amber); }
.cta-band h2 { color: #fff; font-size: 2rem; margin-bottom: 10px; }
.cta-band p { margin-bottom: 26px; }
footer.site { background: var(--bp-deep); color: #9fb6da; padding: 54px 0 28px; margin-top: 64px; font-size: .9rem; border-top: 4px solid var(--amber); }
footer.site .fgrid { display: grid; grid-template-columns: 1.7fr 1fr 1fr 1fr; gap: 28px; margin-bottom: 30px; }
footer.site h4 { color: var(--amber); font-size: .8rem; text-transform: uppercase; letter-spacing: .12em; margin-bottom: 12px; font-family: var(--mono); }
footer.site a { color: #dbe7fa; text-decoration: none; display: block; margin-bottom: 8px; }
footer.site a:hover { color: var(--amber); }
footer.site .fbot { border-top: 1px solid rgba(255,255,255,.14); padding-top: 18px; font-size: .82rem; display: flex; justify-content: space-between; gap: 10px; flex-wrap: wrap; }
@media (max-width: 760px) {
  .hero h1 { font-size: 2.1rem; }
  .split, .frow { grid-template-columns: 1fr; }
  footer.site .fgrid { grid-template-columns: 1fr 1fr; }
  .hero-dim { display: none; }
  .calc { padding: 24px 20px; }
}