/* ═══ FONTS ═══ */
@font-face{font-family:'Phudu';src:url('https://kth-electric.com/wp-content/fonts/DT-Phudu/DTPhudu-Bold.woff') format('woff');font-weight:700;font-display:swap}
@font-face{font-family:'Ganh';src:url('https://kth-electric.com/wp-content/fonts/Ganh/Ganh%20Type-Regular.otf') format('opentype');font-weight:400;font-display:swap}

:root{
  --bg:#f0f2f5;--card:#fff;--border:#e2e8f0;--text:#1e293b;
  --primary:#0f7c78;--primary-dk:#084c4a;--primary-lt:#ccfbf1;
  --accent:#d97706;--accent-lt:#fef3c7;
  --good:#16a34a;--danger:#dc2626;
  --radius:16px;--shadow:0 8px 32px rgba(15,124,120,.10);
  --font-h:'Phudu',sans-serif;--font-b:'Ganh','Segoe UI',sans-serif;
}
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:var(--font-b);background:var(--bg);color:var(--text);line-height:1.6;-webkit-font-smoothing:antialiased}
h1,h2,h3,h4,.brand{font-family:var(--font-h)}

.container{max-width:1100px;margin:0 auto;padding:0 clamp(12px,3vw,24px)}

/* ═══ HEADER ═══ */
.site-header{background:#fff;padding:12px 0;box-shadow:0 2px 8px rgba(0,0,0,.05);position:sticky;top:0;z-index:100}
.site-header .container{display:flex;justify-content:space-between;align-items:center}
.logo{font-family:var(--font-h);font-size:1.4rem;font-weight:700;color:var(--primary);text-decoration:none;display:flex;align-items:center;gap:8px}
.logo span{color:#333}
.header-nav{display:flex;gap:clamp(10px,2vw,20px);flex-wrap:wrap}
.header-nav a{text-decoration:none;color:#64748b;font-weight:600;font-size:.88rem;transition:color .2s;white-space:nowrap}
.header-nav a:hover{color:var(--primary)}

/* ═══ HERO ═══ */
.hero{background:linear-gradient(135deg,var(--primary),var(--primary-dk));color:#fff;padding:clamp(36px,6vw,64px) 0 clamp(56px,8vw,80px);text-align:center;position:relative;overflow:hidden}
.hero::before{content:'';position:absolute;inset:0;background:url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' stroke='%23ffffff' stroke-opacity='.06' stroke-width='1'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/svg%3E") repeat}
.hero h1{font-size:clamp(1.7rem,4vw,2.5rem);margin-bottom:8px;position:relative;z-index:2}
.hero h1 em{font-style:normal;color:var(--accent-lt)}
.hero p{font-size:clamp(.9rem,1.8vw,1.1rem);opacity:.9;max-width:520px;margin:0 auto;position:relative;z-index:2}
.hero .badge{display:inline-flex;align-items:center;gap:6px;margin-top:12px;font-size:.85rem;background:rgba(0,0,0,.15);padding:5px 14px;border-radius:50px;border:1px solid rgba(255,255,255,.12);position:relative;z-index:2}
.hero .badge .stars{color:#fbbf24;letter-spacing:1px}

/* ═══ CONVERTER ═══ */
.converter-wrap{margin-top:-44px;position:relative;z-index:10;max-width:760px;margin-left:auto;margin-right:auto}
.converter-card{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);border:1px solid var(--border);padding:clamp(20px,4vw,32px);margin-bottom:24px}

/* Tabs */
.cat-tabs{display:flex;gap:6px;flex-wrap:wrap;margin-bottom:20px;padding-bottom:16px;border-bottom:2px solid var(--border)}
.cat-tab{padding:8px 14px;border:2px solid transparent;border-radius:10px;background:#f1f5f9;color:#64748b;font-weight:700;font-size:.8rem;cursor:pointer;transition:.2s;font-family:var(--font-b);white-space:nowrap}
.cat-tab:hover{background:#e2e8f0}
.cat-tab.active{background:var(--primary-lt);color:var(--primary);border-color:var(--primary)}
.cat-tab i{margin-right:4px}

/* Input Area */
.convert-area{display:grid;grid-template-columns:1fr auto 1fr;gap:12px;align-items:start;margin-bottom:16px}
.field{display:flex;flex-direction:column;gap:6px}
.field label{font-weight:600;color:#475569;font-size:.82rem}
.field input[type="number"],.field input[type="text"]{padding:12px;border:2px solid var(--border);border-radius:10px;font-size:1.15rem;font-family:var(--font-b);outline:none;transition:.2s;background:#fff;text-align:center;font-weight:700;color:var(--primary-dk);width:100%}
.field input:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(15,124,120,.1)}
.field select{padding:10px 30px 10px 10px;border:2px solid var(--border);border-radius:10px;font-size:.9rem;font-family:var(--font-b);outline:none;background:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23475569' d='M6 8L1 3h10z'/%3E%3C/svg%3E") no-repeat right 10px center #fff;appearance:none;-webkit-appearance:none;cursor:pointer;transition:.2s;width:100%}
.field select:focus{border-color:var(--primary)}
.swap-btn{width:44px;height:44px;border-radius:50%;border:2px solid var(--primary);background:#fff;color:var(--primary);font-size:1.1rem;cursor:pointer;transition:.3s;display:flex;align-items:center;justify-content:center;align-self:center;margin-top:24px}
.swap-btn:hover{background:var(--primary);color:#fff;transform:rotate(180deg)}

/* Result */
.result-display{background:linear-gradient(135deg,var(--primary-lt),#ecfdf5);border:2px solid #a7f3d0;border-radius:12px;padding:20px;text-align:center;margin-bottom:16px;opacity:0;transform:translateY(8px);transition:.4s}
.result-display.show{opacity:1;transform:translateY(0)}
.rd-eq{font-size:clamp(1rem,2.5vw,1.2rem);color:var(--primary-dk);font-weight:700;line-height:1.5}
.rd-eq .num{color:var(--accent);font-size:clamp(1.2rem,3vw,1.5rem)}
.rd-formula{font-size:.82rem;color:#64748b;margin-top:8px}

/* Action Buttons Row */
.action-row{display:flex;gap:8px;justify-content:center;flex-wrap:wrap;margin-bottom:16px}
.act-btn{display:inline-flex;align-items:center;gap:6px;padding:8px 16px;border:1px solid var(--border);border-radius:8px;background:#fff;color:#64748b;font-size:.82rem;font-weight:600;cursor:pointer;font-family:var(--font-b);transition:.2s}
.act-btn:hover{background:var(--primary-lt);color:var(--primary);border-color:var(--primary)}
.act-btn.copied{background:#dcfce7;color:var(--good);border-color:#86efac}

/* All Units Table */
.all-units-section{margin-bottom:16px}
.all-units-toggle{display:flex;align-items:center;justify-content:space-between;padding:12px 16px;background:#f8fafc;border:1px solid var(--border);border-radius:10px;cursor:pointer;font-weight:700;color:var(--primary);font-size:.9rem;transition:.2s}
.all-units-toggle:hover{background:var(--primary-lt)}
.all-units-toggle i.arrow{transition:transform .3s}
.all-units-toggle.open i.arrow{transform:rotate(180deg)}
.all-units-table{display:none;margin-top:8px;border:1px solid var(--border);border-radius:10px;overflow:hidden}
.all-units-table.show{display:block}
.aut-row{display:grid;grid-template-columns:2fr 1fr;padding:10px 16px;font-size:.85rem;border-bottom:1px solid var(--border);transition:background .1s}
.aut-row:last-child{border-bottom:none}
.aut-row:hover{background:#f0fdfa}
.aut-row:nth-child(even){background:#f8fafc}
.aut-row:nth-child(even):hover{background:#f0fdfa}
.aut-name{color:#475569}
.aut-val{font-weight:700;color:var(--primary-dk);text-align:right}

/* Quick Refs */
.quick-refs{display:grid;grid-template-columns:repeat(auto-fill,minmax(180px,1fr));gap:8px;margin-top:16px}
.qr-chip{display:flex;justify-content:space-between;padding:10px 14px;background:#f8fafc;border:1px solid var(--border);border-radius:10px;font-size:.85rem;cursor:pointer;transition:.15s}
.qr-chip:hover{background:var(--primary-lt);border-color:var(--primary)}
.qr-chip .qr-from{color:#64748b}
.qr-chip .qr-to{font-weight:700;color:var(--primary-dk)}

/* Favorites */
.fav-section{max-width:760px;margin:0 auto 20px}
.fav-section h3{font-size:.95rem;color:var(--primary);margin-bottom:10px;display:flex;align-items:center;gap:8px}
.fav-list{display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:8px}
.fav-item{display:flex;justify-content:space-between;align-items:center;padding:10px 14px;background:var(--card);border:1px solid var(--border);border-radius:10px;font-size:.85rem;cursor:pointer;transition:.15s}
.fav-item:hover{background:var(--primary-lt);border-color:var(--primary)}
.fav-item .fav-text{font-weight:600;color:var(--primary-dk)}
.fav-item .fav-del{color:#94a3b8;border:none;background:none;cursor:pointer;font-size:.9rem;padding:2px 6px;border-radius:4px;transition:.2s}
.fav-item .fav-del:hover{color:var(--danger);background:#fee2e2}

/* History */
.history-section{max-width:760px;margin:0 auto 24px}
.history-section h3{font-size:.95rem;color:var(--primary);margin-bottom:10px;display:flex;align-items:center;justify-content:space-between}
.history-list{display:flex;flex-direction:column;gap:6px}
.history-item{display:flex;justify-content:space-between;align-items:center;padding:10px 16px;background:var(--card);border:1px solid var(--border);border-radius:10px;font-size:.85rem;cursor:pointer;transition:.15s}
.history-item:hover{background:var(--primary-lt)}
.hi-val{font-weight:700;color:var(--primary-dk)}
.hi-meta{color:#94a3b8;font-size:.78rem;display:flex;align-items:center;gap:8px}
.btn-clear{background:none;border:none;color:#94a3b8;cursor:pointer;font-size:.82rem;font-family:var(--font-b);transition:.2s}
.btn-clear:hover{color:var(--danger)}

/* Conversion Table (popular) */
.pop-table{max-width:760px;margin:0 auto 24px}
.pop-table h3{font-size:1rem;color:var(--primary);margin-bottom:12px}
.pop-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(160px,1fr));gap:8px}
.pop-card{background:var(--card);border:1px solid var(--border);border-radius:10px;padding:14px;text-align:center;cursor:pointer;transition:.2s}
.pop-card:hover{box-shadow:var(--shadow);transform:translateY(-2px)}
.pop-card .pc-val{font-size:1.1rem;font-weight:700;color:var(--accent)}
.pop-card .pc-label{font-size:.78rem;color:#64748b;margin-top:4px}

/* ═══ CONTENT ═══ */
.content-area{max-width:800px;margin:0 auto clamp(24px,4vw,40px)}
.content-area h2{font-size:clamp(1.2rem,3vw,1.6rem);margin:clamp(20px,3vw,36px) 0 12px;color:#333}
.content-area p{margin-bottom:12px;color:#475569}
.content-area ul{padding-left:20px;margin-bottom:16px}
.content-area li{margin-bottom:6px;color:#475569}
.faq-item{background:var(--card);border:1px solid var(--border);border-radius:12px;padding:18px;margin-bottom:10px}
.faq-item h4{margin:0 0 6px;color:var(--primary);font-size:1rem}
.faq-item p{margin:0;font-size:.92rem}

/* Related */
.related-section{margin:clamp(30px,5vw,50px) auto;max-width:1000px}
.related-section h2{text-align:center;color:var(--primary);margin-bottom:20px}
.related-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:14px}
.related-card{background:var(--card);border:1px solid var(--border);padding:20px;border-radius:var(--radius);text-align:center;text-decoration:none;color:inherit;transition:.3s;display:block}
.related-card:hover{transform:translateY(-3px);box-shadow:var(--shadow)}
.related-card i{font-size:2rem;margin-bottom:10px;display:block}
.related-card h3{font-size:.95rem;margin-bottom:4px}
.related-card p{color:#64748b;font-size:.82rem;margin:0}

/* Footer */
.site-footer{background:#fff;padding:18px 0;text-align:center;border-top:1px solid #eee;font-size:.88rem;color:#64748b}
.footer-links{margin-top:10px;display:flex;justify-content:center;gap:14px;flex-wrap:wrap}
.footer-links a{color:#64748b;text-decoration:none;transition:.2s}
.footer-links a:hover{color:var(--primary)}

/* Toast */
.toast{position:fixed;bottom:24px;left:50%;transform:translateX(-50%) translateY(60px);background:var(--primary-dk);color:#fff;padding:10px 24px;border-radius:10px;font-size:.88rem;font-weight:600;z-index:999;opacity:0;transition:.3s;pointer-events:none}
.toast.show{opacity:1;transform:translateX(-50%) translateY(0)}

/* ═══ RESPONSIVE ═══ */
@media(max-width:640px){
  .convert-area{grid-template-columns:1fr;gap:8px}
  .swap-btn{margin:0 auto;transform:rotate(90deg)}
  .swap-btn:hover{transform:rotate(270deg)}
  .cat-tabs{gap:4px}
  .cat-tab{padding:6px 10px;font-size:.76rem}
  .header-nav{display:none}
  .quick-refs{grid-template-columns:1fr 1fr}
  .pop-grid{grid-template-columns:1fr 1fr}
  .fav-list{grid-template-columns:1fr}
  .action-row{flex-direction:column;align-items:stretch}
  .act-btn{justify-content:center}
}
@media print{
  .site-header,.hero,.cat-tabs,.swap-btn,.action-row,.history-section,.fav-section,.related-section,.site-footer,.quick-refs{display:none!important}
  .converter-card{box-shadow:none;border:2px solid #333}
  .result-display{border:2px solid #333;background:#fff!important;opacity:1!important;transform:none!important}
}