/* ==========================================================================
   TOOLHUB — Core Design System
   Palette: deep navy ink + signal gold + precision teal
   Type: Sora (display) / Inter (body) / JetBrains Mono (numeric readouts)
   ========================================================================== */

:root{
  /* ---- Color tokens (light mode) ---- */
  --ink-950:#0B1120;
  --ink-900:#111A2E;
  --ink-800:#1A2540;
  --paper-50:#F7F8FC;
  --paper-100:#EEF1F8;
  --paper-200:#E3E7F2;
  --indigo-600:#3B4CCA;
  --indigo-500:#4C5FE0;
  --indigo-100:#E7E9FB;
  --gold-500:#E8A94C;
  --gold-400:#F0BE72;
  --teal-500:#2BB3A3;
  --teal-100:#DCF5F1;
  --coral-500:#E1543F;
  --slate-700:#334055;
  --slate-500:#6B7280;
  --slate-300:#B7BFCC;

  --bg:var(--paper-50);
  --bg-elevated:#FFFFFF;
  --bg-sunken:var(--paper-100);
  --text-primary:var(--ink-950);
  --text-secondary:var(--slate-700);
  --text-muted:var(--slate-500);
  --border:var(--paper-200);
  --border-strong:var(--slate-300);
  --brand:var(--indigo-600);
  --accent:var(--gold-500);
  --positive:var(--teal-500);
  --negative:var(--coral-500);
  --readout-bg:var(--ink-950);
  --readout-text:var(--gold-400);
  --card-glass: rgba(255,255,255,0.6);
  --shadow-sm: 0 1px 2px rgba(17,26,46,0.06);
  --shadow-md: 0 6px 20px rgba(17,26,46,0.08);
  --shadow-lg: 0 20px 48px rgba(17,26,46,0.14);
  --radius-sm:10px;
  --radius-md:16px;
  --radius-lg:24px;
  --font-display:'Sora',system-ui,sans-serif;
  --font-body:'Inter',system-ui,sans-serif;
  --font-mono:'JetBrains Mono',ui-monospace,Menlo,Consolas,monospace;
  --header-h:72px;
}

[data-theme="dark"]{
  --bg:var(--ink-950);
  --bg-elevated:var(--ink-900);
  --bg-sunken:var(--ink-800);
  --text-primary:#F3F5FB;
  --text-secondary:#C4CBDB;
  --text-muted:#8791A8;
  --border:#232F4A;
  --border-strong:#324063;
  --card-glass: rgba(26,37,64,0.55);
  --readout-bg:#050810;
  --readout-text:var(--gold-400);
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
  --shadow-md: 0 6px 20px rgba(0,0,0,0.35);
  --shadow-lg: 0 20px 48px rgba(0,0,0,0.5);
}

*,*::before,*::after{box-sizing:border-box;margin:0;padding:0;}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%;}
body{
  font-family:var(--font-body);
  background:var(--bg);
  color:var(--text-primary);
  line-height:1.6;
  font-size:16px;
  transition:background .25s ease,color .25s ease;
  min-height:100vh;
}
img{max-width:100%;display:block;}
a{color:inherit;text-decoration:none;}
button{font:inherit;cursor:pointer;border:none;background:none;color:inherit;}
input,select,textarea{font:inherit;color:inherit;}
ul{list-style:none;}
h1,h2,h3,h4{font-family:var(--font-display);line-height:1.2;letter-spacing:-0.01em;}
.container{max-width:1240px;margin:0 auto;padding:0 24px;}
:focus-visible{outline:2px solid var(--indigo-500);outline-offset:3px;border-radius:4px;}
@media (prefers-reduced-motion: reduce){*{animation:none!important;transition:none!important;}}

/* ---- Skip link ---- */
.skip-link{position:absolute;left:-999px;top:0;background:var(--brand);color:#fff;padding:10px 16px;border-radius:0 0 8px 0;z-index:999;}
.skip-link:focus{left:0;}

/* ==========================================================================
   HEADER
   ========================================================================== */
.site-header{
  position:sticky;top:0;z-index:100;
  height:var(--header-h);
  display:flex;align-items:center;
  background:var(--card-glass);
  backdrop-filter:blur(14px) saturate(140%);
  -webkit-backdrop-filter:blur(14px) saturate(140%);
  border-bottom:1px solid var(--border);
}
.site-header .container{display:flex;align-items:center;gap:28px;}
.brand{display:flex;align-items:center;gap:10px;font-family:var(--font-display);font-weight:700;font-size:1.25rem;flex-shrink:0;}
.brand-mark{width:34px;height:34px;border-radius:9px;background:linear-gradient(135deg,var(--indigo-600),var(--teal-500));display:flex;align-items:center;justify-content:center;color:#fff;font-family:var(--font-mono);font-size:.85rem;font-weight:700;box-shadow:var(--shadow-sm);}
.main-nav{display:flex;align-items:center;gap:4px;flex:1;}
.main-nav>ul{display:flex;gap:2px;}
.nav-link{padding:10px 14px;border-radius:999px;font-size:.925rem;font-weight:500;color:var(--text-secondary);transition:background .15s,color .15s;white-space:nowrap;}
.nav-link:hover{background:var(--bg-sunken);color:var(--text-primary);}
.header-actions{display:flex;align-items:center;gap:10px;margin-left:auto;}

.header-search{position:relative;}
.header-search input{
  width:230px;padding:9px 14px 9px 38px;border-radius:999px;border:1px solid var(--border);
  background:var(--bg-elevated);color:var(--text-primary);font-size:.875rem;transition:width .2s,border-color .2s;
}
.header-search input:focus{width:280px;border-color:var(--brand);}
.header-search svg{position:absolute;left:13px;top:50%;transform:translateY(-50%);width:16px;height:16px;stroke:var(--text-muted);}
.search-results{position:absolute;top:calc(100% + 8px);left:0;right:0;background:var(--bg-elevated);border:1px solid var(--border);border-radius:var(--radius-sm);box-shadow:var(--shadow-lg);max-height:340px;overflow-y:auto;display:none;z-index:50;}
.search-results.open{display:block;}
.search-results a{display:block;padding:10px 14px;font-size:.875rem;border-bottom:1px solid var(--border);}
.search-results a:last-child{border-bottom:none;}
.search-results a:hover{background:var(--bg-sunken);}
.search-results .sr-cat{color:var(--text-muted);font-size:.75rem;}
.search-empty{padding:14px;font-size:.85rem;color:var(--text-muted);}

.icon-btn{width:38px;height:38px;border-radius:999px;display:flex;align-items:center;justify-content:center;background:var(--bg-sunken);color:var(--text-secondary);flex-shrink:0;transition:background .15s;}
.icon-btn:hover{background:var(--border);}
.icon-btn svg{width:18px;height:18px;}
#theme-toggle .sun{display:none;}
[data-theme="dark"] #theme-toggle .moon{display:none;}
[data-theme="dark"] #theme-toggle .sun{display:block;}
.menu-toggle{display:none;}

/* ==========================================================================
   HERO
   ========================================================================== */
.hero{padding:76px 0 64px;position:relative;overflow:hidden;}
.hero::before{
  content:"";position:absolute;inset:-20% -10% auto -10%;height:520px;
  background:radial-gradient(60% 60% at 30% 20%, rgba(59,76,202,.16), transparent 70%),
             radial-gradient(50% 50% at 80% 10%, rgba(232,169,76,.14), transparent 70%);
  pointer-events:none;z-index:0;
}
.hero .container{position:relative;z-index:1;display:grid;grid-template-columns:1.05fr .95fr;gap:56px;align-items:center;}
.eyebrow{display:inline-flex;align-items:center;gap:8px;font-family:var(--font-mono);font-size:.75rem;letter-spacing:.08em;text-transform:uppercase;color:var(--brand);background:var(--indigo-100);padding:6px 12px;border-radius:999px;margin-bottom:18px;}
[data-theme="dark"] .eyebrow{background:rgba(76,95,224,.16);}
.hero h1{font-size:clamp(2.1rem,4.2vw,3.4rem);font-weight:700;margin-bottom:18px;}
.hero h1 .accent{color:var(--brand);}
.hero p.lead{font-size:1.1rem;color:var(--text-secondary);max-width:52ch;margin-bottom:30px;}
.hero-search{display:flex;gap:10px;max-width:520px;margin-bottom:18px;}
.hero-search input{flex:1;padding:15px 18px;border-radius:var(--radius-sm);border:1px solid var(--border-strong);background:var(--bg-elevated);font-size:1rem;}
.hero-search button{padding:0 24px;border-radius:var(--radius-sm);background:var(--brand);color:#fff;font-weight:600;box-shadow:var(--shadow-sm);}
.hero-tags{display:flex;flex-wrap:wrap;gap:8px;}
.hero-tags a{font-size:.8rem;padding:6px 12px;border-radius:999px;border:1px solid var(--border);color:var(--text-muted);transition:border-color .15s,color .15s;}
.hero-tags a:hover{border-color:var(--brand);color:var(--brand);}

/* ---- Signature: live readout demo panel ---- */
.readout-demo{background:var(--readout-bg);border-radius:var(--radius-lg);padding:28px;box-shadow:var(--shadow-lg);position:relative;border:1px solid rgba(232,169,76,.25);}
.readout-demo::before{content:"";position:absolute;inset:0;border-radius:var(--radius-lg);background:radial-gradient(120% 100% at 100% 0%, rgba(232,169,76,.12), transparent 60%);pointer-events:none;}
.readout-demo .rd-label{font-family:var(--font-mono);font-size:.7rem;letter-spacing:.1em;text-transform:uppercase;color:#8791A8;margin-bottom:6px;}
.readout-demo .rd-title{color:#F3F5FB;font-family:var(--font-display);font-size:1.05rem;font-weight:600;margin-bottom:22px;}
.rd-row{display:flex;justify-content:space-between;align-items:baseline;padding:10px 0;border-bottom:1px dashed rgba(135,145,168,.25);}
.rd-row span:first-child{color:#8791A8;font-size:.85rem;}
.rd-row .rd-value{font-family:var(--font-mono);color:var(--readout-text);font-size:1.05rem;font-variant-numeric:tabular-nums;}
.rd-result{margin-top:20px;padding-top:16px;}
.rd-result .rd-big{font-family:var(--font-mono);font-size:2.4rem;color:var(--readout-text);font-variant-numeric:tabular-nums;text-shadow:0 0 24px rgba(232,169,76,.35);}
.rd-result span:first-child{color:#C4CBDB;font-size:.9rem;}
.readout-demo input[type=range]{width:100%;margin-top:22px;accent-color:var(--gold-500);}

/* ==========================================================================
   SECTIONS / CARDS
   ========================================================================== */
.section{padding:56px 0;}
.section-head{display:flex;align-items:flex-end;justify-content:space-between;gap:20px;margin-bottom:30px;}
.section-head h2{font-size:clamp(1.5rem,2.6vw,2rem);}
.section-head p{color:var(--text-muted);margin-top:6px;}
.section-head .see-all{font-size:.875rem;font-weight:600;color:var(--brand);white-space:nowrap;display:flex;align-items:center;gap:6px;}

.cat-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:18px;}
.cat-card{
  background:var(--bg-elevated);border:1px solid var(--border);border-radius:var(--radius-md);
  padding:22px;transition:transform .2s,box-shadow .2s,border-color .2s;position:relative;overflow:hidden;
}
.cat-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-md);border-color:var(--border-strong);}
.cat-card .cat-icon{width:44px;height:44px;border-radius:12px;display:flex;align-items:center;justify-content:center;margin-bottom:16px;font-size:1.3rem;}
.cat-card h3{font-size:1.05rem;margin-bottom:6px;}
.cat-card p{font-size:.85rem;color:var(--text-muted);margin-bottom:10px;}
.cat-card .cat-count{font-family:var(--font-mono);font-size:.75rem;color:var(--brand);}

.tool-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px;}
.tool-card{
  background:var(--bg-elevated);border:1px solid var(--border);border-radius:var(--radius-md);
  padding:18px;display:flex;flex-direction:column;gap:10px;transition:transform .18s,box-shadow .18s,border-color .18s;
}
.tool-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-md);border-color:var(--border-strong);}
.tool-card .tc-top{display:flex;align-items:center;gap:10px;}
.tool-card .tc-icon{width:36px;height:36px;border-radius:10px;background:var(--indigo-100);color:var(--brand);display:flex;align-items:center;justify-content:center;font-size:1rem;flex-shrink:0;}
[data-theme="dark"] .tool-card .tc-icon{background:rgba(76,95,224,.18);}
.tool-card h3{font-size:.95rem;}
.tool-card .tc-desc{font-size:.8rem;color:var(--text-muted);flex:1;}
.tool-card .tc-badge{align-self:flex-start;font-size:.68rem;font-family:var(--font-mono);text-transform:uppercase;letter-spacing:.05em;padding:3px 8px;border-radius:6px;background:var(--teal-100);color:var(--teal-500);}
[data-theme="dark"] .tool-card .tc-badge{background:rgba(43,179,163,.16);}

.pill-row{display:flex;flex-wrap:wrap;gap:10px;margin-bottom:34px;}
.pill{padding:8px 16px;border-radius:999px;border:1px solid var(--border);font-size:.85rem;font-weight:500;color:var(--text-secondary);}
.pill.active{background:var(--brand);color:#fff;border-color:var(--brand);}

.why-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px;}
.why-card{padding:24px;border-radius:var(--radius-md);background:var(--bg-elevated);border:1px solid var(--border);}
.why-card .wc-num{font-family:var(--font-mono);color:var(--accent);font-size:.85rem;margin-bottom:10px;}
.why-card h3{font-size:1.05rem;margin-bottom:8px;}
.why-card p{font-size:.875rem;color:var(--text-muted);}

.faq-list{max-width:820px;}
.faq-item{border-bottom:1px solid var(--border);}
.faq-q{width:100%;display:flex;justify-content:space-between;align-items:center;padding:18px 4px;text-align:left;font-weight:600;font-size:.98rem;}
.faq-q svg{width:18px;height:18px;flex-shrink:0;transition:transform .2s;color:var(--text-muted);}
.faq-item.open .faq-q svg{transform:rotate(45deg);}
.faq-a{max-height:0;overflow:hidden;transition:max-height .25s ease;font-size:.9rem;color:var(--text-secondary);}
.faq-item.open .faq-a{max-height:400px;padding-bottom:18px;}

.newsletter{background:linear-gradient(135deg,var(--ink-950),var(--ink-800));border-radius:var(--radius-lg);padding:48px;display:flex;justify-content:space-between;align-items:center;gap:30px;color:#fff;flex-wrap:wrap;}
.newsletter h2{color:#fff;font-size:1.6rem;margin-bottom:8px;}
.newsletter p{color:#B7C0D8;}
.newsletter-form{display:flex;gap:10px;}
.newsletter-form input{padding:13px 16px;border-radius:var(--radius-sm);border:none;min-width:240px;}
.newsletter-form button{padding:13px 22px;border-radius:var(--radius-sm);background:var(--accent);color:var(--ink-950);font-weight:700;}

/* ==========================================================================
   BREADCRUMBS / PAGE HEADER
   ========================================================================== */
.breadcrumb{font-size:.8rem;color:var(--text-muted);padding:18px 0;display:flex;gap:6px;flex-wrap:wrap;}
.breadcrumb a{color:var(--text-muted);}
.breadcrumb a:hover{color:var(--brand);}
.breadcrumb .sep{opacity:.5;}
.breadcrumb .current{color:var(--text-primary);font-weight:500;}

.page-head{padding:8px 0 36px;border-bottom:1px solid var(--border);margin-bottom:40px;}
.page-head h1{font-size:clamp(1.7rem,3vw,2.3rem);margin-bottom:10px;}
.page-head p{color:var(--text-secondary);max-width:70ch;}

/* ==========================================================================
   CALCULATOR LAYOUT
   ========================================================================== */
.calc-layout{display:grid;grid-template-columns:1.05fr .95fr;gap:32px;align-items:start;margin-bottom:56px;}
.calc-card{background:var(--bg-elevated);border:1px solid var(--border);border-radius:var(--radius-lg);padding:28px;box-shadow:var(--shadow-sm);}
.calc-card h2{font-size:1.2rem;margin-bottom:20px;}
.field{margin-bottom:20px;}
.field label{display:flex;justify-content:space-between;font-size:.85rem;font-weight:600;margin-bottom:8px;color:var(--text-secondary);}
.field label .unit{font-weight:400;color:var(--text-muted);font-family:var(--font-mono);}
.field input[type=text],.field input[type=number],.field select{
  width:100%;padding:12px 14px;border-radius:var(--radius-sm);border:1px solid var(--border-strong);
  background:var(--bg);color:var(--text-primary);font-size:1rem;font-family:var(--font-mono);
}
.field input:focus,.field select:focus{border-color:var(--brand);}
.field input[type=range]{width:100%;accent-color:var(--brand);margin-top:6px;}
.range-row{display:flex;justify-content:space-between;font-family:var(--font-mono);font-size:.75rem;color:var(--text-muted);margin-top:4px;}
.field-group{display:grid;grid-template-columns:1fr 1fr;gap:14px;}
.toggle-row{display:flex;gap:8px;margin-bottom:20px;background:var(--bg-sunken);padding:4px;border-radius:999px;}
.toggle-row button{flex:1;padding:9px;border-radius:999px;font-size:.85rem;font-weight:600;color:var(--text-muted);}
.toggle-row button.active{background:var(--bg-elevated);color:var(--brand);box-shadow:var(--shadow-sm);}
.calc-actions{display:flex;gap:10px;margin-top:8px;}
.btn{padding:12px 20px;border-radius:var(--radius-sm);font-weight:600;font-size:.9rem;display:inline-flex;align-items:center;gap:8px;}
.btn-primary{background:var(--brand);color:#fff;}
.btn-ghost{background:var(--bg-sunken);color:var(--text-secondary);}
.btn-ghost:hover{background:var(--border);}
.btn svg{width:16px;height:16px;}

.result-card{background:var(--readout-bg);border-radius:var(--radius-lg);padding:28px;color:#fff;position:sticky;top:calc(var(--header-h) + 20px);}
.result-card .rc-label{font-family:var(--font-mono);font-size:.7rem;letter-spacing:.1em;text-transform:uppercase;color:#8791A8;margin-bottom:16px;}
.result-card .rc-main{margin-bottom:20px;}
.result-card .rc-main .rc-tag{font-size:.85rem;color:#C4CBDB;}
.result-card .rc-main .rc-value{font-family:var(--font-mono);font-size:2.6rem;color:var(--readout-text);font-variant-numeric:tabular-nums;text-shadow:0 0 24px rgba(232,169,76,.3);word-break:break-word;}
.result-card .rc-row{display:flex;justify-content:space-between;padding:11px 0;border-bottom:1px dashed rgba(135,145,168,.25);font-size:.875rem;}
.result-card .rc-row span:first-child{color:#8791A8;}
.result-card .rc-row span:last-child{font-family:var(--font-mono);color:#F3F5FB;font-variant-numeric:tabular-nums;}
.result-card canvas{max-width:100%;margin-top:18px;}
.result-actions{display:flex;gap:8px;margin-top:20px;}
.result-actions button{flex:1;padding:10px;border-radius:var(--radius-sm);background:rgba(255,255,255,.08);color:#fff;font-size:.8rem;font-weight:600;display:flex;align-items:center;justify-content:center;gap:6px;}
.result-actions button:hover{background:rgba(255,255,255,.14);}
.result-actions svg{width:14px;height:14px;}

.ad-slot{background:var(--bg-sunken);border:1px dashed var(--border-strong);border-radius:var(--radius-sm);display:flex;align-items:center;justify-content:center;color:var(--text-muted);font-size:.75rem;font-family:var(--font-mono);text-transform:uppercase;letter-spacing:.05em;margin:32px 0;}
.ad-slot.leaderboard{min-height:90px;}
.ad-slot.rectangle{min-height:250px;max-width:336px;margin-left:auto;margin-right:auto;}
.ad-slot.inline{min-height:100px;}

/* ---- Article / SEO content ---- */
.article{max-width:820px;}
.article h2{font-size:1.4rem;margin:36px 0 14px;}
.article h3{font-size:1.1rem;margin:24px 0 10px;}
.article p{color:var(--text-secondary);margin-bottom:14px;}
.article ul,.article ol{color:var(--text-secondary);margin:0 0 14px 22px;}
.article li{margin-bottom:6px;}
.article table{width:100%;border-collapse:collapse;margin:16px 0;font-size:.9rem;}
.article th,.article td{padding:10px 12px;border:1px solid var(--border);text-align:left;}
.article th{background:var(--bg-sunken);font-family:var(--font-mono);font-size:.75rem;text-transform:uppercase;letter-spacing:.04em;}
.formula-box{background:var(--bg-sunken);border-left:3px solid var(--accent);border-radius:0 var(--radius-sm) var(--radius-sm) 0;padding:16px 20px;font-family:var(--font-mono);font-size:.95rem;margin:16px 0;overflow-x:auto;}

.related-tools{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;margin-top:20px;}
.related-tools a{padding:14px 16px;border:1px solid var(--border);border-radius:var(--radius-sm);font-size:.875rem;font-weight:500;display:flex;justify-content:space-between;align-items:center;background:var(--bg-elevated);}
.related-tools a:hover{border-color:var(--brand);color:var(--brand);}

/* ==========================================================================
   FOOTER
   ========================================================================== */
.site-footer{background:var(--ink-950);color:#C4CBDB;margin-top:60px;padding:56px 0 24px;}
.footer-grid{display:grid;grid-template-columns:1.4fr repeat(4,1fr);gap:32px;padding-bottom:36px;border-bottom:1px solid #1E2A47;}
.footer-brand p{font-size:.875rem;color:#8791A8;margin:14px 0 18px;max-width:32ch;}
.footer-col h4{color:#fff;font-size:.85rem;margin-bottom:14px;text-transform:uppercase;letter-spacing:.04em;}
.footer-col ul li{margin-bottom:9px;}
.footer-col a{font-size:.875rem;color:#8791A8;}
.footer-col a:hover{color:#fff;}
.footer-bottom{display:flex;justify-content:space-between;align-items:center;padding-top:22px;font-size:.8rem;color:#6B7A99;flex-wrap:wrap;gap:12px;}
.social-row{display:flex;gap:10px;}
.social-row a{width:34px;height:34px;border-radius:999px;background:#1A2540;display:flex;align-items:center;justify-content:center;}
.social-row svg{width:16px;height:16px;}

/* ==========================================================================
   404
   ========================================================================== */
.error-page{min-height:60vh;display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;padding:80px 24px;}
.error-page .code{font-family:var(--font-mono);font-size:5rem;color:var(--accent);}

/* ==========================================================================
   RESPONSIVE
   ========================================================================== */
@media (max-width:1024px){
  .cat-grid{grid-template-columns:repeat(2,1fr);}
  .tool-grid{grid-template-columns:repeat(2,1fr);}
  .why-grid{grid-template-columns:1fr;}
  .hero .container{grid-template-columns:1fr;}
  .calc-layout{grid-template-columns:1fr;}
  .result-card{position:static;}
  .footer-grid{grid-template-columns:repeat(3,1fr);}
  .related-tools{grid-template-columns:1fr 1fr;}
}
@media (max-width:768px){
  .main-nav{display:none;}
  .menu-toggle{display:flex;}
  .header-search input{width:150px;}
  .footer-grid{grid-template-columns:repeat(2,1fr);}
  .field-group{grid-template-columns:1fr;}
}
@media (max-width:480px){
  .cat-grid,.tool-grid{grid-template-columns:1fr;}
  .footer-grid{grid-template-columns:1fr 1fr;}
  .newsletter{flex-direction:column;align-items:flex-start;}
  .related-tools{grid-template-columns:1fr;}
  .container{padding:0 16px;}
}