/* ==========================================================================
   Online Calculators — design system
   Concept: precision instrument panel. Graph-paper canvas, brass hardware,
   an LCD-style digital readout as the recurring signature element.
   ========================================================================== */

:root{
  --paper:      #EEF0E9;
  --paper-line: #D7DBCC;
  --panel:      #FFFFFF;
  --ink:        #131B2A;
  --ink-soft:   #46516399;
  --ink-soft-solid: #46516A;
  --brass:      #B9812B;
  --brass-dark: #8F631E;
  --teal:       #2F6F6B;
  --teal-dark:  #204E4B;
  --line:       #CBCFC0;
  --lcd-bg:     #0E1A14;
  --lcd-fg:     #8FE3A0;
  --lcd-fg-dim: #4C7A57;
  --radius-sm:  3px;
  --radius-md:  6px;
  --shadow-card: 0 1px 0 rgba(19,27,42,0.04), 0 8px 24px -12px rgba(19,27,42,0.18);
  --font-display: 'Space Grotesk', 'IBM Plex Sans', sans-serif;
  --font-body:    'IBM Plex Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono:    'IBM Plex Mono', ui-monospace, SFMono-Regular, monospace;
}

*{ box-sizing:border-box; }
html{ scroll-behavior:smooth; }
body{
  margin:0;
  background:
    linear-gradient(var(--paper-line) 1px, transparent 1px) 0 0/100% 28px,
    linear-gradient(90deg, var(--paper-line) 1px, transparent 1px) 0 0/28px 100%,
    var(--paper);
  background-attachment:local;
  color:var(--ink);
  font-family:var(--font-body);
  font-size:16px;
  line-height:1.55;
  -webkit-font-smoothing:antialiased;
}
img{ max-width:100%; display:block; }
a{ color:var(--teal-dark); text-decoration-thickness:1.5px; text-underline-offset:2px; }
a:hover{ color:var(--brass-dark); }
h1,h2,h3,h4{ font-family:var(--font-display); font-weight:700; line-height:1.12; margin:0 0 .5em; letter-spacing:-0.01em; }
p{ margin:0 0 1em; color:var(--ink); }
:focus-visible{ outline:3px solid var(--brass); outline-offset:2px; }
.container{ max-width:1120px; margin:0 auto; padding:0 24px; }
.mono{ font-family:var(--font-mono); }

/* ---------- header ---------- */
.site-header{
  position:sticky; top:0; z-index:40;
  background:rgba(238,240,233,0.92);
  backdrop-filter:blur(6px);
  border-bottom:1px solid var(--line);
}
.site-header .bar{
  display:flex; align-items:center; justify-content:space-between;
  padding:14px 24px; max-width:1120px; margin:0 auto; gap:20px;
}
.brand{ display:flex; align-items:center; gap:10px; font-family:var(--font-display); font-weight:700; font-size:19px; color:var(--ink); }
.brand .dot{
  width:11px; height:11px; border-radius:2px; background:var(--brass);
  box-shadow:3px 3px 0 var(--teal);
}
.brand small{ display:block; font-family:var(--font-mono); font-weight:400; font-size:10px; letter-spacing:.12em; color:var(--ink-soft-solid); text-transform:uppercase; }
.site-nav{ display:flex; gap:22px; font-size:14px; font-weight:500; }
.site-nav a{ color:var(--ink-soft-solid); text-decoration:none; }
.site-nav a:hover{ color:var(--brass-dark); }
.searchbox{ position:relative; }
.searchbox input{
  font-family:var(--font-mono); font-size:13px; padding:8px 12px; width:200px;
  border:1px solid var(--line); border-radius:var(--radius-sm); background:var(--panel);
}
.header-inner-mobile-toggle{ display:none; }

/* ---------- buttons ---------- */
.btn{
  display:inline-flex; align-items:center; gap:8px; font-family:var(--font-display); font-weight:600;
  font-size:14px; padding:11px 20px; border-radius:var(--radius-sm); border:1.5px solid var(--ink);
  background:var(--ink); color:var(--paper); cursor:pointer; text-decoration:none;
  transition:transform .12s ease, box-shadow .12s ease;
}
.btn:hover{ transform:translate(-1px,-1px); box-shadow:3px 3px 0 var(--brass); color:var(--paper); }
.btn.brass{ background:var(--brass); border-color:var(--brass-dark); color:#1c1305; }
.btn.brass:hover{ box-shadow:3px 3px 0 var(--teal); }
.btn.ghost{ background:transparent; color:var(--ink); }

/* ---------- hero ---------- */
.hero{ padding:64px 0 40px; }
.hero-grid{ display:grid; grid-template-columns:1.1fr .9fr; gap:48px; align-items:center; }
.eyebrow{
  font-family:var(--font-mono); font-size:12px; letter-spacing:.14em; text-transform:uppercase;
  color:var(--teal-dark); display:flex; align-items:center; gap:8px; margin-bottom:14px;
}
.eyebrow::before{ content:''; width:18px; height:2px; background:var(--brass); display:inline-block; }
.hero h1{ font-size:clamp(34px,5vw,54px); max-width:14ch; }
.hero .lede{ font-size:18px; color:var(--ink-soft-solid); max-width:46ch; margin-bottom:26px; }
.hero-stats{ display:flex; gap:28px; margin-top:30px; }
.hero-stats div{ font-family:var(--font-mono); }
.hero-stats b{ display:block; font-size:22px; color:var(--ink); }
.hero-stats span{ font-size:12px; color:var(--ink-soft-solid); text-transform:uppercase; letter-spacing:.06em; }

/* ---------- instrument card (mini demo + all calculators) ---------- */
.device{
  background:var(--panel); border:1px solid var(--line); border-radius:var(--radius-md);
  box-shadow:var(--shadow-card); overflow:hidden;
}
.device-head{
  display:flex; align-items:center; justify-content:space-between; padding:14px 18px;
  background:linear-gradient(180deg, #fbfaf5, #f2f1e8); border-bottom:1px solid var(--line);
}
.device-head .label{ font-family:var(--font-mono); font-size:11px; letter-spacing:.1em; text-transform:uppercase; color:var(--ink-soft-solid); }
.device-head .screws{ display:flex; gap:6px; }
.device-head .screws i{ width:6px; height:6px; border-radius:50%; background:var(--line); display:block; border:1px solid #b9beac; }
.device-body{ padding:20px 18px; }
.field{ margin-bottom:14px; }
.field label{ display:block; font-size:12.5px; font-weight:600; color:var(--ink-soft-solid); margin-bottom:5px; }
.field .unit{ font-family:var(--font-mono); color:var(--ink-soft-solid); font-weight:400; }
.field input[type=number], .field input[type=text], .field input[type=date], .field select{
  width:100%; font-family:var(--font-mono); font-size:15px; padding:10px 12px;
  border:1.5px solid var(--line); border-radius:var(--radius-sm); background:#fcfcf9; color:var(--ink);
}
.field input:focus, .field select:focus{ border-color:var(--teal); }
.readout{
  margin-top:6px; background:var(--lcd-bg); border-radius:var(--radius-sm); padding:18px 18px;
  position:relative; overflow:hidden; border:1px solid #050b07;
  box-shadow:inset 0 2px 10px rgba(0,0,0,.5);
}
.readout::after{
  content:''; position:absolute; inset:0;
  background:repeating-linear-gradient(180deg, rgba(255,255,255,0.025) 0 1px, transparent 1px 3px);
  pointer-events:none;
}
.readout .rlabel{ font-family:var(--font-mono); font-size:10.5px; letter-spacing:.14em; text-transform:uppercase; color:var(--lcd-fg-dim); margin-bottom:6px; }
.readout .rvalue{ font-family:var(--font-mono); font-size:clamp(26px,4vw,34px); color:var(--lcd-fg); text-shadow:0 0 10px rgba(143,227,160,.45); word-break:break-word; }
.readout .rnote{ font-family:var(--font-mono); font-size:11.5px; color:var(--lcd-fg-dim); margin-top:6px; }
.calc-actions{ display:flex; gap:10px; margin-top:16px; }

/* ---------- category tags / catalog numbering ---------- */
.cat-tag{
  display:inline-block; font-family:var(--font-mono); font-size:11px; letter-spacing:.08em;
  text-transform:uppercase; padding:3px 8px; border-radius:2px; background:#e4e8dc; color:var(--teal-dark);
  border:1px solid #ccd2bd;
}
.spec-id{ font-family:var(--font-mono); font-size:11px; color:var(--brass-dark); }

/* ---------- grids / cards ---------- */
section{ padding:52px 0; }
.section-head{ display:flex; align-items:baseline; justify-content:space-between; margin-bottom:26px; gap:20px; flex-wrap:wrap; }
.section-head h2{ font-size:28px; }
.section-head .more{ font-family:var(--font-mono); font-size:13px; }

.cat-grid{ display:grid; grid-template-columns:repeat(3,1fr); gap:16px; }
.cat-card{
  display:block; background:var(--panel); border:1px solid var(--line); border-radius:var(--radius-md);
  padding:20px; text-decoration:none; color:var(--ink); box-shadow:var(--shadow-card);
  transition:transform .12s ease;
}
.cat-card:hover{ transform:translateY(-2px); color:var(--ink); }
.cat-card .n{ font-family:var(--font-mono); font-size:12px; color:var(--brass-dark); }
.cat-card h3{ font-size:19px; margin:6px 0 6px; }
.cat-card p{ font-size:13.5px; color:var(--ink-soft-solid); margin:0; }
.cat-card .count{ margin-top:12px; font-family:var(--font-mono); font-size:11.5px; color:var(--teal-dark); }

.calc-grid{ display:grid; grid-template-columns:repeat(4,1fr); gap:12px; }
.calc-card{
  background:var(--panel); border:1px solid var(--line); border-radius:var(--radius-sm);
  padding:14px 16px; text-decoration:none; color:var(--ink); font-size:14px; font-weight:600;
}
.calc-card:hover{ border-color:var(--brass); color:var(--ink); }
.calc-card .spec-id{ display:block; margin-bottom:4px; }

/* ---------- calculator page layout ---------- */
.breadcrumbs{ font-family:var(--font-mono); font-size:12px; color:var(--ink-soft-solid); margin-bottom:18px; }
.breadcrumbs a{ color:var(--ink-soft-solid); }
.calc-layout{ display:grid; grid-template-columns:1fr 380px; gap:40px; align-items:start; }
.calc-main article{ font-size:16px; }
.calc-main h1{ font-size:32px; margin-bottom:10px; }
.calc-main .dek{ font-size:16px; color:var(--ink-soft-solid); margin-bottom:20px; }
.faq{ margin-top:30px; }
.faq-item{ border-top:1px solid var(--line); padding:16px 0; }
.faq-item h3{ font-size:16px; margin-bottom:6px; }
.faq-item p{ font-size:14.5px; color:var(--ink-soft-solid); margin:0; }
.calc-sidebar{ position:sticky; top:90px; }
.ad-slot{
  border:1px dashed var(--line); border-radius:var(--radius-sm); background:#f6f5ec;
  color:var(--ink-soft-solid); font-family:var(--font-mono); font-size:11.5px; text-align:center;
  padding:26px 10px; margin:18px 0; letter-spacing:.06em; text-transform:uppercase;
}
.related{ margin-top:22px; }
.related h4{ font-size:13px; text-transform:uppercase; letter-spacing:.06em; color:var(--ink-soft-solid); margin-bottom:10px; }
.related a{ display:block; font-size:13.5px; padding:8px 0; border-top:1px solid var(--line); color:var(--ink); text-decoration:none; }
.related a:hover{ color:var(--brass-dark); }

/* ---------- footer ---------- */
.site-footer{ border-top:1px solid var(--line); padding:44px 0 30px; margin-top:40px; background:#e9ebe1; }
.footer-grid{ display:grid; grid-template-columns:1.4fr repeat(3,1fr); gap:28px; margin-bottom:26px; }
.footer-grid h4{ font-size:12px; text-transform:uppercase; letter-spacing:.08em; color:var(--ink-soft-solid); margin-bottom:12px; }
.footer-grid a{ display:block; font-size:13.5px; color:var(--ink); text-decoration:none; padding:4px 0; }
.footer-grid a:hover{ color:var(--brass-dark); }
.footer-bottom{ font-family:var(--font-mono); font-size:12px; color:var(--ink-soft-solid); display:flex; justify-content:space-between; flex-wrap:wrap; gap:10px; border-top:1px solid var(--line); padding-top:18px; }

/* ---------- static/legal pages ---------- */
.prose{ max-width:74ch; }
.prose h2{ margin-top:1.6em; font-size:22px; }
.prose ul{ padding-left:1.2em; }
.prose li{ margin-bottom:.4em; }

/* ---------- responsive ---------- */
@media (max-width: 980px){
  .hero-grid{ grid-template-columns:1fr; }
  .cat-grid{ grid-template-columns:repeat(2,1fr); }
  .calc-grid{ grid-template-columns:repeat(2,1fr); }
  .calc-layout{ grid-template-columns:1fr; }
  .calc-sidebar{ position:static; }
  .footer-grid{ grid-template-columns:1fr 1fr; }
  .site-nav{ display:none; }
}
@media (max-width: 560px){
  .cat-grid, .calc-grid{ grid-template-columns:1fr; }
  .footer-grid{ grid-template-columns:1fr; }
  .searchbox input{ width:130px; }
}

@media (prefers-reduced-motion: reduce){
  html{ scroll-behavior:auto; }
  .btn, .cat-card{ transition:none; }
}