/* CalcKit — shared stylesheet (vanilla, no frameworks) */
:root{
  --bg:#f0fdf6; --card:#ffffff; --text:#052e22; --muted:#5f7a6e;
  --accent:#059669; --accent-dark:#047857; --accent-soft:#d1fae5;
  --border:#d3e8dd; --input:#ffffff; --shadow:0 2px 12px rgba(6,95,70,.08);
  --good:#15803d; --warn:#b45309; --bad:#b91c1c; --radius:14px;
}
[data-theme="dark"]{
  --bg:#06110d; --card:#0c1f17; --text:#e9f7f0; --muted:#8fa89b;
  --accent:#34d399; --accent-dark:#6ee7b7; --accent-soft:#0e2a20;
  --border:#1c3a2d; --input:#0a1a13; --shadow:0 2px 12px rgba(0,0,0,.4);
  --good:#4ade80; --warn:#fbbf24; --bad:#f87171;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Inter,Helvetica,Arial,sans-serif;background:var(--bg);color:var(--text);line-height:1.6}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
img{max-width:100%}
.container{max-width:1120px;margin:0 auto;padding:0 16px}

/* Header */
.site-header{background:var(--card);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:50}
.header-inner{display:flex;align-items:center;gap:12px;height:62px}
.logo{display:flex;align-items:center;gap:9px;font-weight:800;font-size:1.35rem;color:var(--text)}
.logo:hover{text-decoration:none}
.logo-img{width:34px;height:34px;border-radius:10px;display:block}
.header-spacer{flex:1}
.icon-btn{background:var(--accent-soft);border:1px solid var(--border);color:var(--text);border-radius:10px;width:40px;height:40px;font-size:1.15rem;cursor:pointer;display:flex;align-items:center;justify-content:center}
.icon-btn:hover{filter:brightness(.95)}
.hamburger{display:none}

/* Nav */
.main-nav{background:var(--card);border-bottom:1px solid var(--border)}
.nav-links{display:flex;gap:4px;overflow-x:auto;padding:10px 16px;max-width:1120px;margin:0 auto;scrollbar-width:thin}
.nav-links a{white-space:nowrap;padding:7px 13px;border-radius:999px;font-size:.88rem;color:var(--muted);font-weight:600}
.nav-links a:hover{background:var(--accent-soft);color:var(--accent);text-decoration:none}
.nav-links a.active{background:var(--accent);color:#fff}
.drawer{position:fixed;top:0;left:-300px;width:280px;height:100%;background:var(--card);z-index:100;transition:left .25s ease;overflow-y:auto;border-right:1px solid var(--border);padding:18px}
.drawer.open{left:0}
.drawer h3{margin:0 0 10px;font-size:1rem}
.drawer a{display:block;padding:9px 6px;border-bottom:1px solid var(--border);color:var(--text);font-size:.93rem}
.scrim{position:fixed;inset:0;background:rgba(0,0,0,.45);z-index:90;display:none}
.scrim.show{display:block}

/* Hero */
.hero{background:linear-gradient(135deg,#065f46 0%,#10b981 100%);color:#fff;padding:44px 0 40px;text-align:center}
.hero h1{margin:0 0 8px;font-size:2rem;line-height:1.25}
.hero p{margin:0 auto 20px;max-width:640px;opacity:.93;font-size:1.02rem}
.search-wrap{max-width:560px;margin:0 auto;position:relative}
.search-wrap input{width:100%;padding:14px 18px 14px 46px;border-radius:999px;border:none;font-size:1rem;box-shadow:0 6px 24px rgba(0,0,0,.22)}
.search-wrap .s-icon{position:absolute;left:17px;top:50%;transform:translateY(-50%);font-size:1.15rem}

/* Sections & grid */
.section{padding:30px 0 6px}
.section h2{font-size:1.35rem;margin:0 0 4px}
.section .sub{color:var(--muted);margin:0 0 16px;font-size:.95rem}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:14px}
.card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:18px;box-shadow:var(--shadow);display:flex;gap:13px;align-items:flex-start;transition:transform .12s ease}
.card:hover{transform:translateY(-2px);text-decoration:none}
.card .emoji{font-size:1.9rem;line-height:1}
.card h3{margin:0 0 4px;font-size:1.02rem;color:var(--text)}
.card p{margin:0;font-size:.86rem;color:var(--muted)}
.cat-tag{display:inline-block;font-size:.7rem;font-weight:700;text-transform:uppercase;letter-spacing:.5px;color:var(--accent);background:var(--accent-soft);border-radius:6px;padding:2px 8px;margin-top:8px}
.pop-row{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:12px}
.pop-card{background:var(--card);border:1px solid var(--border);border-left:4px solid var(--accent);border-radius:12px;padding:14px 16px;box-shadow:var(--shadow);display:flex;align-items:center;gap:12px}
.pop-card:hover{text-decoration:none;transform:translateY(-2px)}
.pop-num{font-size:1.5rem;font-weight:800;color:var(--accent);min-width:34px}
.pop-card h3{margin:0;font-size:.98rem;color:var(--text)}
.hidden{display:none!important}

/* Calculator box */
.calc-hero{padding:34px 0 10px;text-align:center}
.calc-hero h1{margin:0 0 8px;font-size:1.7rem}
.calc-hero p{color:var(--muted);max-width:680px;margin:0 auto}
.breadcrumb{font-size:.85rem;color:var(--muted);margin:14px 0 0;text-align:center}
.breadcrumb a{color:var(--muted)}
.calc-box{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:24px;margin:18px auto;max-width:640px}
.field{margin-bottom:15px}
.field label{display:block;font-weight:600;margin-bottom:6px;font-size:.94rem}
.field input,.field select{width:100%;padding:11px 13px;border:1.5px solid var(--border);border-radius:10px;font-size:1rem;background:var(--input);color:var(--text)}
.field input:focus,.field select:focus{outline:none;border-color:var(--accent)}
.field .hint{font-size:.82rem;color:var(--muted);margin-top:4px}
.row2{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.btn{display:inline-block;background:var(--accent);color:#fff;border:none;border-radius:10px;padding:13px 26px;font-size:1rem;font-weight:700;cursor:pointer;width:100%}
.btn:hover{background:var(--accent-dark)}
.btn-ghost{background:transparent;color:var(--accent);border:1.5px solid var(--accent);width:auto;padding:9px 18px;font-size:.9rem}
.result{display:none;margin-top:20px;background:var(--accent-soft);border:1px solid var(--border);border-radius:12px;padding:18px}
.result.show{display:block;animation:fadeIn .25s ease}
@keyframes fadeIn{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}
.result .big{font-size:2rem;font-weight:800;color:var(--accent);margin:4px 0 10px}
.result table{width:100%;border-collapse:collapse;font-size:.93rem}
.result td{padding:7px 4px;border-top:1px solid var(--border)}
.result td:last-child{text-align:right;font-weight:600}
.badge{display:inline-block;padding:3px 12px;border-radius:999px;font-size:.82rem;font-weight:700}
.badge.good{background:#dcfce7;color:var(--good)}
.badge.warn{background:#fef3c7;color:var(--warn)}
.badge.bad{background:#fee2e2;color:var(--bad)}
[data-theme="dark"] .badge.good{background:#14532d}[data-theme="dark"] .badge.warn{background:#713f12}[data-theme="dark"] .badge.bad{background:#7f1d1d}
.error{color:var(--bad);font-size:.9rem;margin-top:8px;display:none}

/* Scientific keypad */
.sci-display{width:100%;padding:14px;font-size:1.35rem;text-align:right;border:1.5px solid var(--border);border-radius:10px;background:var(--input);color:var(--text);margin-bottom:12px;font-family:ui-monospace,Menlo,monospace}
.sci-keys{display:grid;grid-template-columns:repeat(5,1fr);gap:8px}
.sci-keys button{padding:13px 4px;font-size:1rem;border-radius:10px;border:1px solid var(--border);background:var(--input);color:var(--text);cursor:pointer;font-weight:600}
.sci-keys button:hover{background:var(--accent-soft)}
.sci-keys button.op{background:var(--accent-soft);color:var(--accent)}
.sci-keys button.eq{background:var(--accent);color:#fff}

/* Share + related */
.share-row{display:flex;gap:10px;flex-wrap:wrap;justify-content:center;margin:8px auto 4px;max-width:640px}
.share-row .btn-ghost{width:auto}
.related{max-width:680px;margin:26px auto}
.related h2{font-size:1.15rem}
.related ul{list-style:none;padding:0;display:flex;flex-wrap:wrap;gap:10px}
.related li a{background:var(--card);border:1px solid var(--border);border-radius:999px;padding:8px 16px;font-size:.9rem;display:inline-block}

/* Guide + FAQ */
.guide{max-width:720px;margin:26px auto;background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:24px;box-shadow:var(--shadow)}
.guide h2{font-size:1.25rem;margin-top:0}
.faq{max-width:720px;margin:0 auto 30px}
.faq h2{font-size:1.25rem}
.faq details{background:var(--card);border:1px solid var(--border);border-radius:10px;margin-bottom:10px;padding:14px 16px}
.faq summary{font-weight:700;cursor:pointer;font-size:.97rem}
.faq details p{margin:8px 0 2px;color:var(--muted);font-size:.94rem}

/* Recent strip */
.recent-strip{max-width:1120px;margin:0 auto;padding:6px 16px}
.recent-inner{background:var(--card);border:1px solid var(--border);border-radius:12px;padding:12px 16px;margin-top:18px}
.recent-inner h3{margin:0 0 8px;font-size:.95rem;color:var(--muted)}
.recent-inner ul{list-style:none;margin:0;padding:0;display:flex;gap:10px;overflow-x:auto}
.recent-inner li{white-space:nowrap;background:var(--accent-soft);border-radius:8px;padding:6px 12px;font-size:.85rem}

/* Ad slots */
.ad-slot{background:repeating-linear-gradient(45deg,transparent,transparent 12px,rgba(120,120,120,.06) 12px,rgba(120,120,120,.06) 24px);border:1px dashed var(--border);border-radius:10px;color:var(--muted);font-size:.8rem;text-align:center;padding:14px;margin:18px auto;max-width:728px}
.ad-leaderboard{min-height:90px;display:flex;align-items:center;justify-content:center}

/* Footer */
footer{background:var(--card);border-top:1px solid var(--border);margin-top:40px;padding:30px 0 20px}
.foot-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:20px;margin-bottom:20px}
.foot-grid h4{margin:0 0 10px;font-size:.95rem}
.foot-grid a{display:block;color:var(--muted);font-size:.88rem;padding:3px 0}
.foot-bottom{text-align:center;color:var(--muted);font-size:.82rem;border-top:1px solid var(--border);padding-top:16px}

/* Static pages */
.static-page{max-width:760px;margin:0 auto;padding:30px 16px}
.static-page h1{font-size:1.8rem}
.static-page h2{font-size:1.2rem;margin-top:28px}

@media(max-width:720px){
  .hamburger{display:flex}
  .main-nav{display:none}
  .hero h1{font-size:1.55rem}
  .row2{grid-template-columns:1fr}
  .sci-keys{grid-template-columns:repeat(4,1fr)}
  .calc-box{padding:18px}
}