:root{
  --primary:#0b5cab;
  --primary-dk:#08457d;
  --accent:#e8a33d;
  --bg:#f2f5f9;
  --card:#ffffff;
  --line:#d9e1ec;
  --text:#1c2733;
  --muted:#5c6b7a;
  --ok:#1e8e5a;
  --warn:#c77d0a;
  --danger:#c0392b;
  --radius:10px;
  --shadow:0 2px 8px rgba(12,60,110,.08);
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  font-family:"Segoe UI",system-ui,-apple-system,"Helvetica Neue",Arial,"Microsoft YaHei","PingFang SC",sans-serif;
  background:var(--bg);color:var(--text);line-height:1.5;
  -webkit-font-smoothing:antialiased;
}
a{color:var(--primary);text-decoration:none}
a:hover{text-decoration:underline}

/* ===== Top bar ===== */
.topbar{
  background:linear-gradient(90deg,var(--primary) 0%,var(--primary-dk) 100%);
  color:#fff;position:sticky;top:0;z-index:50;box-shadow:0 2px 10px rgba(0,0,0,.18);
}
.topbar-inner{
  max-width:1200px;margin:0 auto;padding:10px 16px;display:flex;align-items:center;gap:14px;flex-wrap:wrap;
}
.brand{display:flex;align-items:center;gap:10px;font-weight:700;font-size:18px}
.brand .logo{
  width:34px;height:34px;border-radius:8px;background:#fff;display:flex;align-items:center;justify-content:center;
  font-size:19px;color:var(--primary);flex:0 0 auto;
}
.brand small{display:block;font-weight:400;font-size:11px;opacity:.85}
.topbar-actions{margin-left:auto;display:flex;align-items:center;gap:10px;flex-wrap:wrap}
.btn{
  display:inline-flex;align-items:center;gap:6px;border:none;cursor:pointer;
  padding:8px 14px;border-radius:8px;font-size:13.5px;font-weight:600;transition:.15s;
}
.btn-sm{padding:6px 10px;font-size:12.5px}
.btn-home{background:#fff;color:var(--primary)}
.btn-home:hover{background:#eaf2fb}
.btn-mail{background:rgba(255,255,255,.14);color:#fff;border:1px solid rgba(255,255,255,.35)}
.btn-mail:hover{background:rgba(255,255,255,.26)}
.lang-picker{position:relative}
.lang-btn{
  background:rgba(255,255,255,.14);color:#fff;border:1px solid rgba(255,255,255,.35);
  padding:7px 12px;border-radius:8px;cursor:pointer;font-size:13px;display:inline-flex;align-items:center;gap:6px;font-weight:600;
}
.lang-btn:hover{background:rgba(255,255,255,.26)}
.lang-menu{
  position:absolute;right:0;top:calc(100% + 6px);background:#fff;color:var(--text);
  border:1px solid var(--line);border-radius:10px;box-shadow:0 8px 24px rgba(0,0,0,.16);
  min-width:190px;padding:6px;display:none;z-index:60;
}
.lang-menu.open{display:block}
.lang-opt{
  display:flex;justify-content:space-between;gap:10px;width:100%;text-align:left;border:none;background:none;
  padding:8px 10px;border-radius:7px;cursor:pointer;font-size:13.5px;
}
.lang-opt:hover{background:#eef4fb}
.lang-opt.active{background:var(--primary);color:#fff;font-weight:600}

/* ===== Layout ===== */
.wrap{max-width:1200px;margin:0 auto;padding:24px 16px 60px}
.page-head{margin-bottom:22px}
.page-head h1{margin:0 0 4px;font-size:24px;color:var(--primary-dk)}
.page-head p{margin:0;color:var(--muted);font-size:14px;max-width:900px}
.tools-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:18px}
.card{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow);padding:20px;
}
.tool-card{cursor:pointer;transition:.18s;display:flex;flex-direction:column;gap:8px;color:inherit}
.tool-card:hover{transform:translateY(-3px);box-shadow:0 8px 22px rgba(12,60,110,.14);text-decoration:none}
.tool-card h3{margin:0;font-size:17px;color:var(--primary-dk);display:flex;align-items:center;gap:8px}
.tool-card p{margin:0;font-size:13.5px;color:var(--muted);flex:1}
.tool-card .go{align-self:flex-start;color:var(--primary);font-weight:600;font-size:13px}

/* ===== Tool layout ===== */
.tool-grid{display:grid;grid-template-columns:340px 1fr;gap:20px;align-items:start}
@media(max-width:900px){.tool-grid{grid-template-columns:1fr}}
.panel-title{
  display:flex;align-items:center;gap:8px;margin:0 0 14px;font-size:15px;color:var(--primary-dk);
  border-bottom:2px solid var(--line);padding-bottom:8px;
}
label{display:block;font-size:12.5px;font-weight:600;color:var(--muted);margin:10px 0 4px}
input[type=number],input[type=text],select{
  width:100%;padding:8px 10px;border:1px solid var(--line);border-radius:8px;font-size:14px;
  background:#fff;color:var(--text);outline:none;transition:.12s;
}
input:focus,select:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(11,92,171,.15)}
input:disabled,select:disabled{background:#eef1f5;color:var(--muted)}
.row2{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.row2lab{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.row3{display:grid;grid-template-columns:1fr 1fr 1fr;gap:12px}
.hint{font-size:11.5px;color:var(--muted);margin-top:3px}
.btn-primary{background:var(--primary);color:#fff}
.btn-primary:hover{background:var(--primary-dk)}
.btn-ghost{background:#eef3f9;color:var(--primary-dk);border:1px solid var(--line)}
.btn-accent{background:var(--accent);color:#3a2c08}
.btn-danger{background:#fdecea;color:var(--danger);border:1px solid #f3c6c0}
.btn-row{display:flex;gap:10px;margin-top:16px;flex-wrap:wrap}
.actions{display:flex;gap:10px;margin-top:18px;flex-wrap:wrap}

.results .ok-row{color:var(--ok);font-weight:700}
.results .warn-row{color:var(--danger);font-weight:700}

/* ===== Tables ===== */
.table-wrap{overflow-x:auto;margin-top:6px}
table.tbl{width:100%;border-collapse:collapse;font-size:13px}
.tbl th{
  background:var(--primary);color:#fff;padding:8px 9px;text-align:left;font-weight:600;
  position:sticky;top:0;white-space:nowrap;
}
.tbl td{border-bottom:1px solid var(--line);padding:7px 9px;white-space:nowrap}
.tbl tr:nth-child(even) td{background:#f7fafd}
.tbl tr:hover td{background:#eef4fb}
.tbl .num{text-align:right}
.tbl .hd{background:#eaf1f8;font-weight:700;color:var(--primary-dk)}
.tbl input{width:110px}

.spec-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:12px}
.spec-item{background:#f6f9fc;border:1px solid var(--line);border-radius:10px;padding:12px}
.spec-item .k{font-size:11.5px;color:var(--muted)}
.spec-item .v{font-size:19px;font-weight:700;color:var(--primary-dk)}

.result-box{
  background:linear-gradient(180deg,#f0f7ff,#e6f0fb);border:1px solid #c6dcf2;border-radius:10px;padding:16px;margin-top:12px;
}
.result-box.big .big{font-size:30px;font-weight:800;color:var(--primary)}

.note{
  font-size:12px;color:var(--muted);background:#fdf6ea;border:1px solid #f0dfc0;border-radius:8px;padding:10px 12px;margin-top:14px;
}

.tabs{display:flex;gap:4px;border-bottom:2px solid var(--line);margin-bottom:16px;flex-wrap:wrap}
.tab{padding:9px 16px;font-size:13.5px;font-weight:600;color:var(--muted);cursor:pointer;border:none;background:none;border-bottom:3px solid transparent}
.tab.active{color:var(--primary);border-bottom-color:var(--primary)}

footer{text-align:center;color:var(--muted);font-size:12px;padding:20px;border-top:1px solid var(--line);margin-top:20px}
footer a{color:var(--primary)}

.calc-algo{
  background:var(--card);border:1px solid var(--line);border-radius:8px;padding:14px 16px;margin-top:16px;font-size:12.5px;color:var(--muted);
}
.calc-algo h4{margin:0 0 8px;color:var(--primary-dk);font-size:13px}