/* RohrRechner — "Stahl" design: steel blue-grey + safety orange, industrial. Distinct from all previous sites. */
:root {
  --steel: #2e3a46; --steel-deep: #1a222b; --iron: #4a5a6a; --silver: #aebac6;
  --orange: #e8641b; --orange-pale: #fdeadd; --bg: #eef1f4; --paper: #ffffff;
  --ink: #232d38; --mut: #5f6f7f; --line: #d4dbe2; --radius: 8px;
  --sans: -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, "Roboto Mono", Menlo, Consolas, monospace;
  --cond: "Arial Narrow", "Helvetica Neue", sans-serif;
  --shadow: 0 4px 18px rgba(26,34,43,.1); --shadow-lift: 0 16px 38px rgba(26,34,43,.16);
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body { font-family: var(--sans); background: var(--bg); color: var(--ink); line-height: 1.7; -webkit-font-smoothing: antialiased; }
.container { max-width: 1040px; margin: 0 auto; padding: 0 24px; }
h1, h2, h3 { font-weight: 800; line-height: 1.2; color: var(--steel-deep); font-family: var(--cond); text-transform: uppercase; letter-spacing: .02em; }
.rivetdiv { height: 12px; background: repeating-linear-gradient(90deg, var(--iron) 0 10px, transparent 10px 34px); opacity: .45; }
header.site { background: var(--steel-deep); position: sticky; top: 0; z-index: 50; border-bottom: 4px solid var(--orange); }
header.site .bar { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 10px; padding: 14px 0; }
.brand { font-family: var(--cond); font-size: 1.45rem; font-weight: 800; color: #fff; text-decoration: none; display: inline-flex; align-items: center; text-transform: uppercase; letter-spacing: .04em; }
.brand .bolt { width: 38px; height: 38px; background: linear-gradient(135deg, var(--orange), #b34a0e); margin-right: 10px; display: inline-flex; align-items: center; justify-content: center; clip-path: polygon(50% 0, 93% 25%, 93% 75%, 50% 100%, 7% 75%, 7% 25%); }
.brand .bolt svg { width: 18px; height: 18px; fill: #fff; }
.brand em { font-style: normal; color: var(--orange); }
nav.main a { color: #c3ced8; text-decoration: none; margin-left: 20px; font-size: .93rem; font-weight: 700; text-transform: uppercase; font-size: .85rem; letter-spacing: .05em; }
nav.main a:hover { color: var(--orange); }
.hero { position: relative; padding: 96px 0 90px; background: url('../images/hero.webp') center/cover; }
.hero::before { content: ""; position: absolute; inset: 0; background: linear-gradient(100deg, rgba(26,34,43,.92), rgba(26,34,43,.5)); }
.hero .container { position: relative; z-index: 1; }
.hero .stahl { display: inline-block; background: rgba(232,100,27,.18); border: 1px solid rgba(232,100,27,.6); color: #f5b98a; font-size: .78rem; font-weight: 800; letter-spacing: .12em; text-transform: uppercase; padding: 8px 18px; margin-bottom: 18px; }
.hero h1 { color: #fff; font-size: 2.9rem; max-width: 660px; margin-bottom: 16px; }
.hero h1 .or { color: var(--orange); }
.hero p.lead { color: #c3ced8; font-size: 1.12rem; max-width: 620px; margin-bottom: 30px; }
.hero-cta { display: flex; gap: 14px; flex-wrap: wrap; }
.btn-stahl { display: inline-block; background: linear-gradient(135deg, var(--orange), #b34a0e); color: #fff; text-decoration: none; padding: 15px 36px; font-weight: 800; text-transform: uppercase; letter-spacing: .05em; box-shadow: 0 10px 26px rgba(232,100,27,.4); transition: transform .15s; clip-path: polygon(12px 0, 100% 0, calc(100% - 12px) 100%, 0 100%); padding-left: 44px; padding-right: 44px; }
.btn-stahl:hover { transform: translateY(-3px); }
.btn-rohr { display: inline-block; border: 2px solid rgba(255,255,255,.5); color: #fff; text-decoration: none; padding: 13px 34px; font-weight: 700; text-transform: uppercase; letter-spacing: .05em; font-size: .9rem; }
.btn-rohr:hover { background: rgba(255,255,255,.1); }
section.block { padding: 66px 0; }
.sec-pre { color: var(--orange); font-size: .8rem; font-weight: 800; letter-spacing: .14em; text-transform: uppercase; font-family: var(--mono); }
.sec-title { font-size: 2.2rem; margin: 8px 0 12px; }
.sec-sub { color: var(--mut); max-width: 700px; margin-bottom: 36px; font-size: 1.02rem; }
.tgrid { display: grid; grid-template-columns: repeat(auto-fill, minmax(310px, 1fr)); gap: 22px; }
.tcard { background: var(--paper); border-radius: var(--radius); text-decoration: none; color: var(--ink); box-shadow: var(--shadow); transition: transform .16s, box-shadow .16s; display: flex; flex-direction: column; overflow: hidden; border: 1px solid var(--line); border-top: 5px solid var(--iron); }
.tcard:hover { transform: translateY(-6px); box-shadow: var(--shadow-lift); border-top-color: var(--orange); }
.tcard .ph { height: 132px; background-size: cover; background-position: center; border-bottom: 1px solid var(--line); }
.tcard .tx { padding: 20px 24px 24px; flex: 1; }
.tcard .no { font-family: var(--mono); font-size: .72rem; color: var(--orange); letter-spacing: .06em; font-weight: 700; }
.tcard .tx h3 { font-size: 1.2rem; margin: 6px 0 8px; }
.tcard .tx p { font-size: .92rem; color: var(--mut); margin-bottom: 12px; }
.tcard .go { font-weight: 800; color: var(--steel-deep); font-size: .9rem; text-transform: uppercase; letter-spacing: .04em; }
.tcard .go span { color: var(--orange); }
.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(--radius); box-shadow: var(--shadow-lift); display: block; }
.split h3 { font-size: 1.6rem; margin-bottom: 12px; }
.split p { color: var(--mut); margin-bottom: 12px; }
.split .more { font-weight: 800; color: var(--orange); text-decoration: none; border-bottom: 3px solid var(--orange); text-transform: uppercase; font-size: .9rem; letter-spacing: .04em; }
table.ref { width: 100%; border-collapse: collapse; margin: 12px 0 24px; font-size: .93rem; background: var(--paper); border-radius: 8px; overflow: hidden; box-shadow: var(--shadow); }
table.ref th { background: var(--steel-deep); color: var(--orange); padding: 12px 14px; text-align: left; font-size: .84rem; text-transform: uppercase; letter-spacing: .04em; }
table.ref td { padding: 11px 14px; border-bottom: 1px solid var(--line); font-family: var(--mono); font-size: .88rem; }
table.ref tr:last-child td { border-bottom: none; }
table.ref tr:nth-child(even) td { background: #f2f5f7; }
.crumbs { font-size: .85rem; color: var(--mut); margin: 22px 0 8px; font-family: var(--mono); }
.crumbs a { color: var(--orange); text-decoration: none; font-weight: 700; }
.pagehead { max-width: 780px; }
.pagehead h1 { font-size: 2.4rem; margin-bottom: 10px; }
.pagehead h1 .or { color: var(--orange); }
.pagehead p { color: var(--mut); }
.pagehead .pimg { margin: 24px 0 0; max-width: 640px; }
.pagehead .pimg img { width: 100%; max-height: 300px; object-fit: cover; border-radius: var(--radius); box-shadow: var(--shadow-lift); }
.calc { background: var(--paper); border-radius: 10px; padding: 36px; margin: 30px 0; box-shadow: var(--shadow); border: 1px solid var(--line); max-width: 720px; border-left: 6px solid var(--orange); }
.field { margin-bottom: 18px; }
.field label { display: block; font-weight: 700; margin-bottom: 7px; font-size: .94rem; text-transform: uppercase; font-size: .85rem; letter-spacing: .04em; color: var(--steel); }
.field input, .field select { width: 100%; padding: 13px 16px; border: 2px solid var(--line); border-radius: 6px; font-size: 1rem; font-family: var(--mono); background: #f6f8fa; }
.field input:focus, .field select:focus { outline: none; border-color: var(--orange); 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; }
.btn-row { display: flex; gap: 12px; margin-top: 8px; }
button.calc-btn { background: linear-gradient(135deg, var(--orange), #b34a0e); color: #fff; border: none; padding: 15px 30px; font-size: 1rem; font-weight: 800; cursor: pointer; flex: 1; text-transform: uppercase; letter-spacing: .05em; box-shadow: 0 8px 22px rgba(232,100,27,.35); transition: transform .15s; clip-path: polygon(10px 0, 100% 0, calc(100% - 10px) 100%, 0 100%); }
button.calc-btn:hover { transform: translateY(-2px); }
button.reset-btn { background: transparent; color: var(--mut); border: 2px solid var(--line); padding: 15px 26px; cursor: pointer; font-weight: 700; text-transform: uppercase; font-size: .85rem; letter-spacing: .04em; }
button.reset-btn:hover { border-color: var(--mut); }
.result { display: none; margin-top: 26px; background: linear-gradient(135deg, var(--steel-deep), var(--steel)); border-radius: 8px; padding: 28px; color: #fff; border-left: 6px solid var(--orange); }
.result.show { display: block; animation: stahlIn .35s ease; }
.result .big { font-family: var(--mono); font-size: 2rem; font-weight: 700; color: var(--orange); }
.result .rrow { display: flex; justify-content: space-between; padding: 9px 0; border-bottom: 1px solid rgba(255,255,255,.15); font-size: .95rem; font-family: var(--mono); }
.result .rrow:last-child { border-bottom: none; }
.result .rrow span:first-child { color: #aebac6; }
.result .note { font-size: .85rem; color: #aebac6; margin-top: 10px; }
article.prose { margin: 36px 0; max-width: 800px; }
article.prose h1 { font-size: 1.5rem; margin: 34px 0 12px; }
.prose h2 { font-size: 1.5rem; margin: 34px 0 12px; }
article.prose h3 { font-size: 1.1rem; margin: 24px 0 8px; }
article.prose p, article.prose li { margin-bottom: 10px; color: #3a4653; }
article.prose ul, article.prose ol { padding-left: 22px; }
.warnbox { background: var(--orange-pale); border: 2px solid var(--orange); border-radius: var(--radius); padding: 18px 22px; margin: 24px 0; font-size: .92rem; color: #7a3a0e; }
.warnbox strong { text-transform: uppercase; letter-spacing: .04em; }
.tipbox { background: #e8eef3; border: 2px solid var(--iron); border-radius: var(--radius); padding: 18px 22px; margin: 24px 0; font-size: .92rem; color: #2e3a46; }
.example { background: var(--paper); border-radius: var(--radius); padding: 20px 24px; margin: 22px 0; box-shadow: var(--shadow); border-left: 6px solid var(--iron); font-size: .93rem; font-family: var(--mono); }
.faq details { background: var(--paper); border-radius: var(--radius); margin-bottom: 10px; padding: 16px 22px; box-shadow: var(--shadow); border: 1px solid var(--line); }
.faq summary { font-weight: 800; cursor: pointer; }
.faq p { margin-top: 8px; color: var(--mut); font-size: .94rem; }
.cta-band { background: linear-gradient(120deg, var(--steel-deep), var(--steel)); border-radius: 10px; padding: 54px 36px; text-align: center; color: #c3ced8; margin: 60px 0; border-top: 5px solid var(--orange); }
.cta-band h2 { color: #fff; font-size: 2.1rem; margin-bottom: 10px; }
.cta-band h2 .or { color: var(--orange); }
.cta-band p { margin-bottom: 26px; }
footer.site { background: var(--steel-deep); color: #8a99a8; padding: 54px 0 28px; margin-top: 64px; font-size: .9rem; border-top: 4px solid var(--orange); }
footer.site .fgrid { display: grid; grid-template-columns: 1.6fr 1fr 1fr 1fr; gap: 28px; margin-bottom: 28px; }
footer.site h4 { color: var(--orange); font-size: .82rem; text-transform: uppercase; letter-spacing: .1em; margin-bottom: 12px; }
footer.site a { color: #c3ced8; text-decoration: none; display: block; margin-bottom: 8px; }
footer.site a:hover { color: var(--orange); }
footer.site .brand { color: #fff; }
footer.site .bottom { border-top: 1px solid rgba(255,255,255,.14); padding-top: 20px; color: #5f6f7f; font-size: .82rem; font-family: var(--mono); }
@keyframes stahlIn { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: none; } }
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { animation: none !important; transition: none !important; } html { scroll-behavior: auto; } }
@media (max-width: 760px) {
  .hero { padding: 64px 0; } .hero h1 { font-size: 2rem; }
  .split { grid-template-columns: 1fr; gap: 26px; } .split.flip > div:first-child { order: 0; }
  .calc { padding: 26px 22px; } .btn-row { flex-direction: column; }
  nav.main a { margin-left: 14px; } footer.site .fgrid { grid-template-columns: 1fr 1fr; }
  .pagehead h1 { font-size: 1.85rem; }
}