/* ===== EngTool - Professional Engineering Tools ===== */
:root{
  --bg:#0f1b2d;
  --bg-soft:#16263c;
  --panel:#1b2c44;
  --panel-2:#213350;
  --line:#2c4060;
  --line-soft:#263952;
  --text:#e8eef5;
  --text-dim:#9fb2c9;
  --text-faint:#6e829e;
  --accent:#3da9ff;
  --accent-2:#ffb03d;
  --good:#37c16b;
  --warn:#ffb03d;
  --bad:#ff5c6a;
  --radius:12px;
  --shadow:0 8px 24px rgba(0,0,0,.35);
  font-size:16px;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  background:var(--bg);
  background-image:radial-gradient(1200px 500px at 80% -10%, rgba(61,169,255,.10), transparent 60%),
                   radial-gradient(900px 400px at -10% 0%, rgba(255,176,61,.06), transparent 55%);
  color:var(--text);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,"Noto Sans","PingFang SC","Microsoft YaHei",sans-serif;
  line-height:1.5;
  min-height:100vh;
  display:flex;flex-direction:column;
}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}

/* ===== Top bar ===== */
.topbar{
  background:linear-gradient(180deg, #122338, #0e1b2c);
  border-bottom:1px solid var(--line);
  position:sticky;top:0;z-index:50;
}
.topbar-inner{
  max-width:1200px;margin:0 auto;padding:.6rem 1rem;
  display:flex;align-items:center;gap:.8rem;flex-wrap:wrap;
}
.brand{display:flex;align-items:center;gap:.55rem;font-weight:800;font-size:1.15rem;letter-spacing:.2px;min-width:0;flex:1 1 auto}
.brand > span{min-width:0;max-width:760px}
.brand .logo{
  width:34px;height:34px;border-radius:8px;flex:none;
  background:linear-gradient(135deg,var(--accent),#2479c9);
  display:grid;place-items:center;color:#fff;font-size:1.1rem;
  box-shadow:inset 0 1px 0 rgba(255,255,255,.25);
}
.brand small{display:block;font-weight:500;font-size:.68rem;color:var(--text-faint);letter-spacing:.2px;line-height:1.35;margin-top:2px;max-width:760px}
.actions{margin-left:auto;display:flex;align-items:center;gap:.55rem;flex-wrap:wrap}
.btn{
  display:inline-flex;align-items:center;gap:.4rem;
  border:1px solid var(--line);background:var(--panel-2);color:var(--text);
  padding:.42rem .7rem;border-radius:8px;font-size:.85rem;cursor:pointer;
  transition:background .15s,border-color .15s,transform .05s;white-space:nowrap;
}
.btn:hover{background:#2a3f60;border-color:var(--accent);text-decoration:none}
.btn:active{transform:translateY(1px)}
.btn.primary{background:linear-gradient(135deg,var(--accent),#2479c9);border-color:transparent;color:#fff}
.btn.primary:hover{filter:brightness(1.08)}
.btn.ghost{background:transparent}
.btn svg{width:15px;height:15px;flex:none}
.lang-wrap{display:flex;align-items:center;gap:.3rem}
.lang-wrap svg{color:var(--text-faint)}
select.lang{
  background:var(--bg-soft);color:var(--text);border:1px solid var(--line);
  border-radius:8px;padding:.42rem .4rem;font-size:.85rem;cursor:pointer;
}
select.lang:focus{outline:none;border-color:var(--accent)}

/* main navigation row — Windows-style menu bar (no horizontal scrollbar) */
.mainnav{width:100%;display:flex;align-items:center;gap:.2rem;padding:.12rem 0 .14rem;overflow:visible}
@media (max-width:760px){
  .mainnav{flex-wrap:wrap;gap:.2rem .3rem}
}
.navlink{
  color:var(--text-dim);padding:.32rem .62rem;border-radius:7px;font-size:.84rem;
  white-space:nowrap;border:1px solid transparent;flex:none;
}
.navlink:hover{color:var(--text);background:var(--panel-2);text-decoration:none;border-color:var(--line)}
.navlink.on{color:#fff;background:var(--panel-2);border-color:var(--accent)}

/* ===== Grouped dropdown menu (Windows-style app menu bar) ===== */
.menu-item{position:relative;flex:none}
.menubtn{
  font:inherit;color:var(--text-dim);background:none;border:1px solid transparent;
  padding:.3rem .6rem;border-radius:7px;font-size:.84rem;white-space:nowrap;
  display:inline-flex;align-items:center;gap:.4rem;cursor:pointer;flex:none;
}
.menubtn:hover{color:var(--text);background:var(--panel-2);border-color:var(--line)}
.menubtn.on{color:#fff;background:var(--panel-2);border-color:var(--accent)}
.menubtn .caret{width:0;height:0;border-left:4px solid transparent;border-right:4px solid transparent;border-top:5px solid currentColor;display:inline-block;opacity:.75}
.dropdown{
  display:none;position:absolute;top:calc(100% + 7px);left:0;min-width:216px;z-index:70;
  background:var(--panel);border:1px solid var(--line);border-radius:10px;
  box-shadow:0 10px 30px rgba(0,0,0,.22);padding:.35rem;
}
/* right-most groups open leftward so they never overflow the viewport */
.menu-item:nth-last-child(-n+2)>.dropdown{left:auto;right:0}
.menu-item:hover>.dropdown,.menu-item.open>.dropdown{display:block}
.dropdown ul{list-style:none;margin:0;padding:0}
.dropdown li{margin:0}
.dropdown .drop-link{
  display:flex;align-items:center;gap:.5rem;padding:.46rem .7rem;border-radius:6px;
  color:var(--text-dim);font-size:.87rem;white-space:nowrap;
}
.dropdown .drop-link:hover{background:var(--panel-2);color:var(--text);text-decoration:none}
.dropdown .drop-link.on{color:#fff;background:var(--panel-2);box-shadow:inset 3px 0 0 var(--accent);font-weight:600}

/* ===== Home hero ===== */
.hero{max-width:1200px;margin:0 auto;width:100%;padding:2.4rem 1rem 1.4rem}
.hero h1{font-size:2.1rem;margin:.2rem 0 .4rem;line-height:1.15}
.hero .sub{color:var(--text-dim);font-size:1.02rem;max-width:820px;margin:0}
.badges{display:flex;gap:.5rem;flex-wrap:wrap;margin-top:1rem}
.badge{font-size:.72rem;padding:.28rem .6rem;border-radius:20px;background:var(--panel-2);border:1px solid var(--line);color:var(--text-dim);letter-spacing:.2px}
.badge b{color:var(--accent)}

/* ===== Cards grid ===== */
.grid{max-width:1200px;margin:0 auto;width:100%;padding:1rem 1rem 2.5rem;display:grid;gap:1rem;grid-template-columns:repeat(auto-fill,minmax(300px,1fr))}
.card{
  background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);
  padding:1.15rem 1.2rem;color:var(--text);box-shadow:var(--shadow);
  display:flex;flex-direction:column;transition:transform .12s,border-color .12s;
  position:relative;overflow:hidden;
}
.card:hover{transform:translateY(-3px);border-color:var(--accent);text-decoration:none}
.card .ic{font-size:1.5rem;margin-bottom:.5rem;display:flex;align-items:center;gap:.5rem;color:var(--accent)}
.card h3{margin:0 0 .35rem;font-size:1.05rem;color:#fff}
.card p{margin:0 0 .5rem;color:var(--text-dim);font-size:.9rem;flex:1}
.card .tag{font-size:.72rem;color:var(--accent-2);font-weight:600;letter-spacing:.3px;text-transform:uppercase}

/* ===== Page layout ===== */
.wrap{max-width:1200px;margin:0 auto;width:100%;padding:1.6rem 1rem 3rem;flex:1}
.pagehead{margin-bottom:1.4rem}
.pagehead h1{font-size:1.7rem;margin:0 0 .3rem}
.pagehead p{color:var(--text-dim);margin:0;max-width:820px}
.breadcrumb{font-size:.82rem;color:var(--text-faint);margin-bottom:.6rem}
.breadcrumb a{color:var(--text-faint)}
.breadcrumb a:hover{color:var(--accent)}

.panel{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);padding:1.2rem;margin-bottom:1.2rem}
.panel h2{margin:0 0 .8rem;font-size:1.12rem;color:#fff;display:flex;align-items:center;gap:.5rem}
.panel h2 .dot{width:9px;height:9px;border-radius:50%;background:var(--accent);flex:none}

/* form controls */
label{display:block;font-size:.83rem;color:var(--text-dim);margin-bottom:.3rem}
.field{margin-bottom:.85rem}
.inputs{display:grid;gap:.85rem;grid-template-columns:repeat(auto-fit,minmax(180px,1fr))}
input[type=number],input[type=text],select.inp{
  width:100%;background:var(--bg-soft);border:1px solid var(--line);color:var(--text);
  border-radius:8px;padding:.55rem .6rem;font-size:.95rem;
}
input:focus,select.inp:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 2px rgba(61,169,255,.18)}
input:disabled{opacity:.45}
.unit{font-size:.72rem;color:var(--text-faint)}
.hint{font-size:.78rem;color:var(--text-faint);margin-top:.2rem}
.radio-row{display:flex;gap:1rem;flex-wrap:wrap;align-items:center}
.radio-row label{display:flex;align-items:center;gap:.35rem;font-size:.9rem;color:var(--text);margin:0;cursor:pointer}
.radio-row input{accent-color:var(--accent)}

.check-row{display:flex;align-items:center;gap:.45rem;font-size:.9rem;color:var(--text);cursor:pointer;margin-bottom:.5rem}
.check-row input{accent-color:var(--accent);width:16px;height:16px}

.btn-row{display:flex;gap:.6rem;margin-top:.4rem;flex-wrap:wrap}
.btn-row .btn{font-size:.92rem;padding:.55rem 1rem}

/* results */
.result{
  background:#0f2138;border:1px solid #2c4a70;border-left:4px solid var(--accent);
  border-radius:10px;padding:1rem 1.1rem;margin-top:1rem;
}
.result.hidden{display:none}
.result .big{font-size:1.05rem;margin:.1rem 0}
.result .big b{font-size:1.45rem;color:var(--accent)}
.result .line{display:flex;justify-content:space-between;gap:1rem;padding:.28rem 0;border-bottom:1px dashed #24405f}
.result .line:last-child{border-bottom:none}
.result .line span{color:var(--text-dim)}
.result .line b{color:var(--text);font-weight:600}
.tag-s{padding:.18rem .5rem;border-radius:6px;font-size:.78rem;font-weight:700}
.tag-ok{background:rgba(55,193,107,.15);color:var(--good)}
.tag-no{background:rgba(255,92,106,.15);color:var(--bad)}
.tag-hi{background:rgba(255,176,61,.15);color:var(--warn)}

/* tables */
.tbl-scroll{overflow-x:auto;border:1px solid var(--line);border-radius:10px;background:var(--panel)}
table.tbl{width:100%;border-collapse:collapse;font-size:.88rem;min-width:520px}
table.tbl th,table.tbl td{padding:.5rem .65rem;text-align:right;border-bottom:1px solid var(--line-soft);white-space:nowrap}
table.tbl th:first-child,table.tbl td:first-child{text-align:left}
table.tbl thead th{
  background:var(--panel-2);color:var(--text-dim);font-weight:600;font-size:.78rem;
  text-transform:uppercase;letter-spacing:.3px;position:sticky;top:0;z-index:2;
}
table.tbl tbody tr:nth-child(even){background:rgba(255,255,255,.02)}
table.tbl tbody tr:hover{background:rgba(61,169,255,.06)}
table.tbl td.mono{font-variant-numeric:tabular-nums}
table.tbl td.hilite{color:var(--accent);font-weight:700}
.tbl-note{font-size:.78rem;color:var(--text-faint);margin-top:.5rem}

/* tabs */
.tabs{display:flex;gap:.4rem;flex-wrap:wrap;margin-bottom:1rem}
.tab{
  border:1px solid var(--line);background:var(--panel);color:var(--text-dim);
  padding:.5rem .85rem;border-radius:9px;cursor:pointer;font-size:.88rem;
}
.tab:hover{color:var(--text);border-color:var(--accent)}
.tab.active{background:linear-gradient(135deg,var(--accent),#2479c9);color:#fff;border-color:transparent;font-weight:600}
.tabpane{display:none}
.tabpane.active{display:block}

/* search */
.searchbar{display:flex;gap:.6rem;margin-bottom:1rem;flex-wrap:wrap}
.searchbar input{flex:1;min-width:200px}

/* footer */
footer{
  margin-top:auto;border-top:1px solid var(--line);background:#0d1929;
  padding:1.8rem 1rem 2rem;text-align:center;
}
footer .f-inner{max-width:1200px;margin:0 auto}
footer .links{display:flex;gap:1.2rem;justify-content:center;flex-wrap:wrap;margin-bottom:.7rem;font-size:.88rem}
footer p{color:var(--text-faint);font-size:.8rem;margin:.2rem 0}

/* responsive */
@media(max-width:640px){
  .hero{padding-top:1.4rem}
  .hero h1{font-size:1.5rem}
  .topbar-inner{padding:.5rem .7rem}
  :root{font-size:15px}
}