/* ==========================================================================
   Industrial Calculators — Design System
   Palette: steel charcoal + safety-orange, spec-sheet / blueprint aesthetic
   Type: Barlow Semi Condensed (display) + Inter (body) + IBM Plex Mono (data)
   ========================================================================== */

:root{
  --ink:        #1E293B;   /* slate-800, matches gurukrupacompressors.in body text */
  --steel-900:  #0F172A;   /* slate-900, matches header/hero bg */
  --steel-700:  #334155;   /* slate-700 */
  --steel-500:  #64748B;   /* slate-500 */
  --steel-300:  #CBD5E1;   /* slate-300 */
  --steel-100:  #F1F5F9;   /* slate-100 */
  --paper:      #F8FAFC;   /* slate-50, matches site body background */
  --panel:      #FFFFFF;
  --line:       #E2E8F0;   /* slate-200 */
  --orange:     #0284C7;   /* industrial-600 (matches the shop site's accent blue) */
  --orange-dark:#0369A1;   /* industrial-700 */
  --green:      #16A34A;   /* green-600, matches the site's WhatsApp/Inquire buttons */
  --green-bg:   #F0FDF4;
  --red:        #DC2626;
  --red-bg:     #FEF2F2;
  --focus:      #0284C7;

  --font-display: ui-sans-serif, system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  --font-body: ui-sans-serif, system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --radius: 10px;
  --container: 1180px;
}

:root.dark{
  --ink:        #F1F5F9;
  --steel-900:  #020617;
  --steel-700:  #CBD5E1;
  --steel-500:  #94A3B8;
  --steel-300:  #475569;
  --steel-100:  #1E293B;
  --paper:      #0F172A;
  --panel:      #1E293B;
  --line:       #334155;
  --orange:     #38BDF8;
  --orange-dark:#0EA5E9;
  --green:      #22C55E;
  --green-bg:   #052e16;
  --red:        #F87171;
  --red-bg:     #450a0a;
}
:root.dark .formula-box{background:#020617;}
:root.dark .parent-bar{color:#0F172A;}

*{box-sizing:border-box;}
html{-webkit-text-size-adjust:100%;}
body{
  margin:0;
  background:var(--paper);
  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(--orange-dark);text-decoration:none;}
a:hover{text-decoration:underline;}
h1,h2,h3,h4{
  font-family:var(--font-display);
  font-weight:600;
  line-height:1.15;
  margin:0 0 .5em;
  color:var(--steel-900);
  letter-spacing:.01em;
}
h1{font-size:clamp(1.9rem,4.2vw,2.7rem);}
h2{font-size:clamp(1.4rem,2.6vw,1.85rem);}
h3{font-size:1.2rem;}
p{margin:0 0 1em;}
ul,ol{margin:0 0 1em;padding-left:1.3em;}
code, .mono{font-family:var(--font-mono);}

:focus-visible{outline:3px solid var(--focus);outline-offset:2px;}

.container{max-width:var(--container);margin:0 auto;padding:0 20px;}
.visually-hidden{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;}

/* ---------- Parent site bar ---------- */
.topbar{background:var(--steel-900);color:var(--steel-300);font-size:.78rem;}
.topbar .container{padding:7px 20px;display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap;}
.topbar a{color:var(--steel-300);}
.topbar a:hover{color:#fff;}
.topbar .tb-left{display:flex;align-items:center;gap:16px;flex-wrap:wrap;}
.topbar .tb-right{display:flex;align-items:center;gap:12px;}
.topbar .tb-social a{font-size:.95rem;}
.theme-toggle{background:var(--steel-700);color:#fff;border:none;width:26px;height:26px;border-radius:6px;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;}
.theme-toggle:hover{background:var(--steel-500);}

/* ---------- Header / Nav ---------- */
.site-header{
  background:var(--panel);
  border-bottom:1px solid var(--line);
  box-shadow:0 1px 3px rgba(15,23,42,.06);
  position:sticky;top:0;z-index:50;
  backdrop-filter:blur(6px);
}
.site-header .container{display:flex;align-items:center;justify-content:space-between;height:64px;gap:16px;}
.logo{
  display:flex;align-items:center;gap:9px;
  font-family:var(--font-display);
  font-weight:700;font-size:1.2rem;color:var(--orange-dark);
  white-space:nowrap;
}
.logo:hover{text-decoration:none;}
.logo .mark{
  width:30px;height:30px;flex:0 0 30px;
  background:var(--orange);
  display:flex;align-items:center;justify-content:center;
  color:#fff;font-weight:800;font-family:var(--font-mono);font-size:.95rem;
  border-radius:8px;
}
.logo .sub{color:var(--steel-500);font-size:.6em;font-weight:500;display:block;letter-spacing:.02em;}
.logo .name-block{display:flex;flex-direction:column;line-height:1.15;}

.main-nav{display:flex;align-items:center;gap:2px;}
.main-nav a{
  color:var(--ink);font-size:.92rem;font-weight:500;
  padding:9px 12px;border-radius:6px;
}
.main-nav a:hover{background:var(--steel-100);text-decoration:none;color:var(--orange-dark);}
.main-nav .home-link{
  background:var(--orange);color:#fff !important;font-weight:600;
}
.main-nav .home-link:hover{background:var(--orange-dark);color:#fff !important;}
.nav-toggle{
  display:none;background:none;border:1px solid var(--steel-300);color:var(--ink);
  width:40px;height:36px;border-radius:8px;cursor:pointer;
}
.nav-toggle svg{pointer-events:none;}

@media (max-width:840px){
  .main-nav{
    position:fixed;top:64px;left:0;right:0;bottom:0;
    background:var(--panel);
    flex-direction:column;align-items:stretch;gap:0;
    padding:8px 20px 40px;overflow-y:auto;
    transform:translateX(100%);transition:transform .2s ease;
  }
  .main-nav.open{transform:translateX(0);}
  .main-nav a{padding:13px 4px;border-bottom:1px solid var(--line);font-size:1.05rem;border-radius:0;}
  .main-nav .home-link{border-radius:6px;margin-top:8px;text-align:center;}
  .nav-toggle{display:block;}
}

/* ---------- Buttons ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  font-family:var(--font-body);font-weight:600;font-size:.95rem;
  padding:11px 20px;border-radius:2px;border:1px solid transparent;
  cursor:pointer;line-height:1.2;
}
.btn-primary{background:var(--orange);color:#fff;}
.btn-primary:hover{background:var(--orange-dark);text-decoration:none;}
.btn-secondary{background:transparent;color:var(--steel-900);border-color:var(--steel-500);}
.btn-secondary:hover{background:var(--steel-100);text-decoration:none;}
.btn-ghost{background:transparent;color:var(--steel-700);border-color:var(--line);}
.btn-ghost:hover{background:var(--steel-100);text-decoration:none;}
.btn:disabled{opacity:.5;cursor:not-allowed;}
.btn-block{width:100%;}

/* ---------- Hero / search ---------- */
.hero{
  background:var(--steel-900);
  color:#fff;
  padding:56px 0 64px;
  position:relative;
  border-bottom:3px solid var(--orange);
}
.hero .eyebrow{color:var(--steel-300);font-size:.85rem;margin-bottom:10px;}
.hero h1{color:#fff;max-width:14ch;}
.hero p.lead{color:var(--steel-100);font-size:1.1rem;max-width:56ch;margin-bottom:28px;}

.search-box{position:relative;max-width:620px;}
.search-box input{
  width:100%;padding:15px 16px 15px 46px;
  font-size:1.05rem;border:none;border-radius:2px;
  background:#fff;color:var(--ink);
}
.search-box input:focus{outline:3px solid var(--orange);}
.search-box .icon{position:absolute;left:15px;top:50%;transform:translateY(-50%);color:var(--steel-500);}
.search-results{
  position:absolute;left:0;right:0;top:calc(100% + 6px);
  background:#fff;color:var(--ink);
  border:1px solid var(--line);border-top:3px solid var(--orange);
  border-radius:2px;max-height:420px;overflow-y:auto;
  box-shadow:0 10px 30px rgba(0,0,0,.25);
  z-index:40;display:none;
}
.search-results.show{display:block;}
.search-results a{
  display:block;padding:11px 16px;border-bottom:1px solid var(--steel-100);color:var(--ink);
}
.search-results a:last-child{border-bottom:none;}
.search-results a:hover, .search-results a.active{background:var(--paper);text-decoration:none;}
.search-results .r-cat{color:var(--steel-500);font-size:.78rem;font-family:var(--font-mono);}
.search-results .r-name{font-weight:600;}
.search-empty{padding:16px;color:var(--steel-500);font-size:.9rem;}
.search-examples{margin-top:12px;font-size:.85rem;color:var(--steel-300);}
.search-examples span{
  display:inline-block;border:1px solid var(--steel-700);color:var(--steel-100);
  padding:3px 9px;border-radius:2px;margin:3px 6px 0 0;
}

/* ---------- Section ---------- */
.section{padding:52px 0;}
.section.alt{background:var(--panel);border-top:1px solid var(--line);border-bottom:1px solid var(--line);}
.section-head{display:flex;align-items:baseline;justify-content:space-between;gap:20px;margin-bottom:24px;flex-wrap:wrap;}
.section-head h2{margin:0;}
.section-head .see-all{font-size:.9rem;font-weight:600;white-space:nowrap;}
.intro-text{max-width:74ch;color:var(--steel-700);}

/* ---------- Cards ---------- */
.grid{display:grid;gap:16px;}
.grid-4{grid-template-columns:repeat(4,1fr);}
.grid-3{grid-template-columns:repeat(3,1fr);}
.grid-2{grid-template-columns:repeat(2,1fr);}
@media (max-width:920px){.grid-4{grid-template-columns:repeat(2,1fr);} .grid-3{grid-template-columns:repeat(2,1fr);}}
@media (max-width:560px){.grid-4,.grid-3,.grid-2{grid-template-columns:1fr;}}

.calc-card{
  background:var(--panel);border:1px solid var(--line);border-left:3px solid var(--steel-300);
  padding:18px 18px 16px;border-radius:var(--radius);
  display:flex;flex-direction:column;gap:8px;
  transition:border-color .15s ease;
}
.calc-card:hover{border-left-color:var(--orange);}
.calc-card .cat-tag{
  font-family:var(--font-mono);font-size:.7rem;text-transform:uppercase;letter-spacing:.06em;
  color:var(--orange-dark);
}
.calc-card h3{font-size:1.05rem;margin:0;}
.calc-card h3 a{color:var(--steel-900);}
.calc-card h3 a:hover{color:var(--orange-dark);text-decoration:none;}
.calc-card p{font-size:.88rem;color:var(--steel-500);margin:0;flex:1;}
.calc-card .open-link{font-size:.85rem;font-weight:600;margin-top:4px;}

.category-card{
  background:var(--panel);border:1px solid var(--line);padding:20px;border-radius:var(--radius);
  display:flex;flex-direction:column;gap:6px;
}
.category-card .count{font-family:var(--font-mono);color:var(--steel-500);font-size:.82rem;}
.category-card h3{margin:0;font-size:1.15rem;}
.category-card h3 a{color:var(--steel-900);}
.category-card p{color:var(--steel-500);font-size:.87rem;margin:0;}

/* ---------- Breadcrumb ---------- */
.breadcrumb{font-size:.82rem;color:var(--steel-500);padding:14px 0;}
.breadcrumb a{color:var(--steel-500);}
.breadcrumb a:hover{color:var(--orange-dark);}
.breadcrumb .sep{margin:0 6px;}

/* ---------- Calculator page ---------- */
.calc-page-head{background:var(--panel);border-bottom:1px solid var(--line);padding-bottom:8px;}
.calc-page-head .cat-tag{
  font-family:var(--font-mono);font-size:.75rem;text-transform:uppercase;letter-spacing:.06em;color:var(--orange-dark);
}
.calc-page-head .short-desc{color:var(--steel-700);font-size:1.05rem;max-width:70ch;}

.calc-layout{display:grid;grid-template-columns:minmax(0,1fr) 300px;gap:32px;align-items:start;}
@media (max-width:920px){.calc-layout{grid-template-columns:1fr;}}

.calc-tool{
  background:var(--panel);border:1px solid var(--line);border-top:4px solid var(--orange);
  border-radius:var(--radius);padding:22px 22px 24px;
}
.calc-tool h2{font-size:1.15rem;margin-bottom:16px;}
.field{margin-bottom:16px;}
.field label{display:block;font-size:.88rem;font-weight:600;color:var(--steel-900);margin-bottom:5px;}
.field .field-row{display:flex;gap:8px;}
.field input[type=number], .field select{
  width:100%;padding:11px 12px;font-size:1rem;border:1px solid var(--steel-300);
  border-radius:2px;background:#fff;color:var(--ink);font-family:var(--font-mono);
}
.field select{font-family:var(--font-body);}
.field input:focus, .field select:focus{border-color:var(--focus);outline:2px solid var(--focus);outline-offset:-1px;}
.field .unit-select{max-width:110px;flex:0 0 auto;font-family:var(--font-body);}
.field .hint{font-size:.78rem;color:var(--steel-500);margin-top:4px;}
.field .err{font-size:.8rem;color:var(--red);margin-top:4px;display:none;}
.field.has-error input, .field.has-error select{border-color:var(--red);}
.field.has-error .err{display:block;}

.calc-actions{display:flex;gap:10px;margin-top:20px;}

.result-box{
  margin-top:22px;padding:18px;background:var(--green-bg);border:1px solid #bfe0d1;
  border-radius:var(--radius);display:none;
}
.result-box.show{display:block;}
.result-box.is-error{background:var(--red-bg);border-color:#e6b7b1;}
.result-box .r-label{font-size:.8rem;text-transform:uppercase;letter-spacing:.05em;color:var(--steel-700);font-family:var(--font-mono);}
.result-box .r-value{font-family:var(--font-mono);font-size:2rem;font-weight:700;color:var(--green);margin:4px 0 8px;word-break:break-word;}
.result-box.is-error .r-value{color:var(--red);font-size:1.1rem;font-weight:600;font-family:var(--font-body);}
.result-box .r-breakdown{font-size:.87rem;color:var(--steel-700);border-top:1px dashed #bfe0d1;padding-top:10px;margin-top:8px;}
.result-box .r-breakdown div{display:flex;justify-content:space-between;padding:3px 0;font-family:var(--font-mono);font-size:.85rem;}
.result-actions{margin-top:12px;display:flex;gap:8px;}
.copy-toast{font-size:.8rem;color:var(--green);margin-left:6px;display:none;}
.copy-toast.show{display:inline;}

.side-panel{display:flex;flex-direction:column;gap:16px;}
.side-box{background:var(--panel);border:1px solid var(--line);padding:16px 18px;border-radius:var(--radius);}
.side-box h3{font-size:.95rem;text-transform:uppercase;letter-spacing:.04em;color:var(--steel-700);margin-bottom:10px;}
.side-box ul{list-style:none;padding:0;margin:0;}
.side-box li{border-bottom:1px solid var(--steel-100);}
.side-box li:last-child{border-bottom:none;}
.side-box li a{display:block;padding:8px 0;font-size:.92rem;color:var(--ink);}
.side-box li a:hover{color:var(--orange-dark);text-decoration:none;}
.ad-slot{
  border:1px dashed var(--steel-300);color:var(--steel-500);font-size:.78rem;
  text-align:center;padding:14px 8px;border-radius:var(--radius);background:var(--steel-100);
}

.content-block{max-width:76ch;margin:0 auto;}
.content-block h2{margin-top:2.2em;border-top:1px solid var(--line);padding-top:1.1em;}
.content-block h2:first-child{border-top:none;padding-top:0;margin-top:0;}
.formula-box{
  background:var(--steel-900);color:#fff;padding:18px 20px;border-radius:var(--radius);
  font-family:var(--font-mono);font-size:1.15rem;overflow-x:auto;margin:14px 0;
}
.var-list{list-style:none;padding:0;margin:0 0 1em;}
.var-list li{
  display:grid;grid-template-columns:70px 1fr;gap:12px;padding:7px 0;border-bottom:1px solid var(--steel-100);font-size:.92rem;
}
.var-list .sym{font-family:var(--font-mono);font-weight:700;color:var(--orange-dark);}
.example-box{background:var(--panel);border:1px solid var(--line);border-left:3px solid var(--green);padding:16px 18px;border-radius:var(--radius);margin:14px 0;}
.assumption-list li, .mistake-list li{margin-bottom:.5em;}
.faq-item{border-bottom:1px solid var(--line);padding:14px 0;}
.faq-item:last-child{border-bottom:none;}
.faq-item h3{font-size:1rem;margin-bottom:6px;}
.faq-item p{color:var(--steel-700);margin:0;font-size:.94rem;}
.disclaimer-note{
  font-size:.85rem;color:var(--steel-500);background:var(--steel-100);
  padding:14px 16px;border-radius:var(--radius);margin-top:30px;
}

/* ---------- Filter bar (All Calculators) ---------- */
.filter-bar{
  display:flex;gap:10px;flex-wrap:wrap;align-items:center;
  background:var(--panel);border:1px solid var(--line);padding:14px 16px;border-radius:var(--radius);margin-bottom:22px;
}
.filter-bar select, .filter-bar input[type=search]{
  padding:9px 11px;border:1px solid var(--steel-300);border-radius:2px;font-size:.92rem;background:#fff;
}
.filter-bar input[type=search]{flex:1;min-width:180px;}
.filter-count{font-size:.85rem;color:var(--steel-500);margin-bottom:14px;}

/* ---------- FAQ home ---------- */
.faq-home .faq-item h3{cursor:pointer;}

/* ---------- Footer ---------- */
.site-footer{background:var(--steel-900);color:var(--steel-300);padding:44px 0 26px;margin-top:40px;}
.footer-grid{display:grid;grid-template-columns:1.4fr repeat(3,1fr);gap:28px;margin-bottom:28px;}
@media (max-width:760px){.footer-grid{grid-template-columns:1fr 1fr;}}
.site-footer h4{color:#fff;font-size:.85rem;text-transform:uppercase;letter-spacing:.05em;margin-bottom:12px;font-family:var(--font-body);font-weight:700;}
.site-footer ul{list-style:none;padding:0;margin:0;}
.site-footer li{margin-bottom:7px;}
.site-footer a{color:var(--steel-300);font-size:.9rem;}
.site-footer a:hover{color:#fff;}
.site-footer .brand-desc{font-size:.88rem;color:var(--steel-300);max-width:38ch;}
.footer-bottom{border-top:1px solid var(--steel-700);padding-top:18px;font-size:.82rem;color:var(--steel-500);display:flex;justify-content:space-between;flex-wrap:wrap;gap:8px;}
.footer-bottom .tb-social{display:flex;gap:12px;font-size:1rem;}
.footer-bottom .tb-social a{color:var(--steel-300);}
.footer-bottom .tb-social a:hover{color:#fff;}

/* ---------- Misc pages ---------- */
.page-hero{background:var(--steel-900);color:#fff;padding:40px 0;border-bottom:3px solid var(--orange);}
.page-hero h1{color:#fff;}
.legal-body{max-width:76ch;padding:40px 0 60px;}
.legal-body h2{margin-top:1.8em;}
.contact-form{max-width:560px;}
.contact-form .field input, .contact-form .field textarea{
  width:100%;padding:11px 12px;border:1px solid var(--steel-300);border-radius:2px;font-family:var(--font-body);font-size:.95rem;
}
.contact-form textarea{resize:vertical;min-height:120px;}
.form-note{font-size:.85rem;background:var(--steel-100);border-radius:var(--radius);padding:12px 14px;color:var(--steel-700);margin-bottom:18px;}
.notfound{text-align:center;padding:90px 0;}
.notfound .code{font-family:var(--font-mono);font-size:4.5rem;color:var(--orange);font-weight:700;}