/* Modbus Lab — shared stylesheet
   Tokens follow the Fairland / Nebular Eva design system.
   Light, high-contrast, mono for all hex. No external font or asset requests. */

:root{
  --primary:#3366FF;
  --primary-hover:#2749d6;
  --primary-soft:#EAF0FF;
  --success:#00D68F;
  --success-soft:#E3FBF3;
  --warning:#FFAA00;
  --warning-soft:#FFF6E0;
  --danger:#FF3D71;
  --danger-soft:#FFE9EF;
  --bg:#F7F9FC;
  --card:#FFFFFF;
  --border:#E4E9F2;
  --border-strong:#C5CEE0;
  --text:#222B45;
  --ink:#2E3A59;
  --muted:#8F9BB3;
  --code-bg:#1B2333;
  --code-fg:#E6ECF7;
  --mono:ui-monospace,"SF Mono","JetBrains Mono","Cascadia Code","Consolas","Liberation Mono",monospace;
  --sans:-apple-system,BlinkMacSystemFont,"Segoe UI",Inter,"Helvetica Neue",Arial,"Noto Sans SC","Microsoft YaHei",sans-serif;
  --radius:12px;
  --shadow:0 1px 2px rgba(34,43,69,.06),0 4px 16px rgba(34,43,69,.05);
}

*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{
  margin:0;background:var(--bg);color:var(--text);
  font:400 16px/1.65 var(--sans);
  -webkit-font-smoothing:antialiased;
}
a{color:var(--primary);text-decoration:none}
a:hover{text-decoration:underline}
h1,h2,h3,h4{color:var(--text);line-height:1.25;margin:0 0 .5em;font-weight:700;letter-spacing:-.01em}
h1{font-size:34px}
h2{font-size:23px;margin-top:1.6em}
h3{font-size:18px;margin-top:1.3em}
p{margin:0 0 1em}
ul,ol{margin:0 0 1em;padding-left:1.35em}
li{margin:.35em 0}
code,kbd,pre{font-family:var(--mono)}
code{background:#EEF2FA;border:1px solid var(--border);border-radius:5px;padding:.05em .35em;font-size:.9em;color:#1B2333;white-space:nowrap}
pre{background:var(--code-bg);color:var(--code-fg);padding:14px 16px;border-radius:10px;overflow-x:auto;font-size:13.5px;line-height:1.7;margin:0 0 1em}
pre code{background:none;border:0;padding:0;color:inherit;white-space:pre}
hr{border:0;border-top:1px solid var(--border);margin:2em 0}
strong{font-weight:700;color:var(--ink)}

/* ── language switch ───────────────────────────────── */
html[data-lang="en"] .zh{display:none!important}
html[data-lang="zh"] .en{display:none!important}

/* ── header ────────────────────────────────────────── */
.site-header{
  position:sticky;top:0;z-index:50;background:rgba(255,255,255,.92);
  backdrop-filter:saturate(180%) blur(8px);
  border-bottom:1px solid var(--border);
}
.site-header .inner{
  max-width:1180px;margin:0 auto;padding:0 20px;height:62px;
  display:flex;align-items:center;gap:8px;
}
.brand{display:flex;align-items:center;gap:9px;font-weight:800;font-size:17px;color:var(--text);letter-spacing:-.02em}
.brand:hover{text-decoration:none}
.brand .mark{
  width:30px;height:30px;border-radius:8px;flex:0 0 auto;
  background:linear-gradient(135deg,var(--primary),#00C2FF);
  color:#fff;font:800 13px/30px var(--mono);text-align:center;letter-spacing:-.5px;
}
.brand small{display:block;font:500 11px/1.2 var(--sans);color:var(--muted);letter-spacing:0}
.nav{display:flex;align-items:center;gap:2px;margin-left:auto;flex-wrap:wrap}
.nav a{
  color:var(--ink);font-size:14.5px;font-weight:500;padding:7px 11px;border-radius:8px;
}
.nav a:hover{background:#F0F4FC;text-decoration:none}
.nav a.active{color:var(--primary);background:var(--primary-soft);font-weight:600}
.lang-btn{
  margin-left:6px;border:1px solid var(--border-strong);background:#fff;color:var(--ink);
  font:600 13px/1 var(--sans);padding:7px 10px;border-radius:8px;cursor:pointer;min-width:52px;
}
.lang-btn:hover{border-color:var(--primary);color:var(--primary)}

/* ── layout ────────────────────────────────────────── */
.wrap{max-width:1180px;margin:0 auto;padding:0 20px}
.page{padding:34px 0 64px}
.narrow{max-width:860px}
.lede{font-size:17.5px;color:#4A5875;max-width:760px}
.crumb{font-size:13px;color:var(--muted);margin-bottom:10px}
.crumb a{color:var(--muted)}
.crumb a:hover{color:var(--primary)}

/* ── cards ─────────────────────────────────────────── */
.card{
  background:var(--card);border:1px solid var(--border);border-radius:var(--radius);
  box-shadow:var(--shadow);padding:20px;margin:0 0 20px;
}
.card h2:first-child,.card h3:first-child{margin-top:0}
.card-head{display:flex;align-items:center;gap:10px;margin-bottom:14px;flex-wrap:wrap}
.card-head h2,.card-head h3{margin:0;font-size:17px}
.card-head .spacer{margin-left:auto}

.grid{display:grid;gap:18px}
.grid > *{min-width:0}
.grid.two{grid-template-columns:1fr 1fr}
.grid.three{grid-template-columns:repeat(3,1fr)}
.grid.four{grid-template-columns:repeat(4,1fr)}
@media (max-width:900px){.grid.two,.grid.three,.grid.four{grid-template-columns:1fr}}

/* ── home cards ────────────────────────────────────── */
.hero{padding:46px 0 10px}
.hero h1{font-size:40px;max-width:820px}
.hero .lede{font-size:18px}
.tool-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin:26px 0 10px}
@media (max-width:900px){.tool-grid{grid-template-columns:1fr}}
.tool-card{
  display:block;background:#fff;border:1px solid var(--border);border-radius:var(--radius);
  padding:18px;color:var(--text);box-shadow:var(--shadow);transition:border-color .15s,transform .15s;
}
.tool-card:hover{text-decoration:none;border-color:var(--primary);transform:translateY(-1px)}
.tool-card .tc-top{display:flex;align-items:center;gap:9px;margin-bottom:6px}
.tool-card .tc-icon{
  width:30px;height:30px;border-radius:8px;background:var(--primary-soft);color:var(--primary);
  font:700 14px/30px var(--mono);text-align:center;flex:0 0 auto;
}
.tool-card h3{margin:0;font-size:16px}
.tool-card p{margin:0;font-size:14px;color:#5A6785;line-height:1.55}

/* ── forms ─────────────────────────────────────────── */
.field{display:flex;flex-direction:column;gap:6px;min-width:0}
.field label{font-size:12.5px;font-weight:700;color:var(--muted);text-transform:uppercase;letter-spacing:.05em}
input[type=text],input[type=number],select,textarea{
  width:100%;border:2px solid var(--border);background:#fff;color:var(--text);
  border-radius:9px;padding:9px 11px;font:500 15px/1.4 var(--sans);outline:none;
  transition:border-color .12s,box-shadow .12s;
}
input:focus,select:focus,textarea:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(51,102,255,.13)}
textarea{font-family:var(--mono);font-size:14px;resize:vertical;min-height:84px}
select{cursor:pointer}
.mono-input{font-family:var(--mono);letter-spacing:.04em}
.form-row{display:grid;gap:12px;grid-template-columns:repeat(auto-fit,minmax(140px,1fr))}
.hint{font-size:12.5px;color:var(--muted);line-height:1.45}
.hint code{font-size:12px}

/* ── buttons ───────────────────────────────────────── */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:6px;
  border:1px solid transparent;border-radius:9px;cursor:pointer;
  font:700 13px/1 var(--sans);letter-spacing:.03em;text-transform:uppercase;
  padding:10px 15px;transition:background .12s,border-color .12s,color .12s;
  background:var(--primary);color:#fff;
}
.btn:hover{background:var(--primary-hover)}
.btn.ghost{background:#fff;color:var(--ink);border-color:var(--border-strong)}
.btn.ghost:hover{border-color:var(--primary);color:var(--primary);background:#fff}
.btn.sm{padding:7px 11px;font-size:12px}
.btn.success{background:var(--success);color:#04352A}
.btn.danger{background:var(--danger)}
.btn:disabled{opacity:.45;cursor:not-allowed}
.btn-row{display:flex;gap:8px;flex-wrap:wrap;align-items:center}

/* ── code output ───────────────────────────────────── */
.out{
  position:relative;background:var(--code-bg);color:var(--code-fg);border-radius:10px;
  padding:14px 52px 14px 16px;font-family:var(--mono);font-size:16px;line-height:1.75;
  word-break:break-all;min-height:52px;
}
.out .copy{
  position:absolute;top:8px;right:8px;background:rgba(255,255,255,.12);color:#DCE5F5;border:0;
  border-radius:6px;padding:5px 8px;font:600 11px/1 var(--sans);cursor:pointer;text-transform:uppercase;letter-spacing:.05em;
}
.out .copy:hover{background:rgba(255,255,255,.22)}
.out.tiny{font-size:14px;padding:10px 44px 10px 12px}
.bytes{display:flex;flex-wrap:wrap;gap:4px;margin:0}
.byte{
  font-family:var(--mono);font-size:14px;line-height:1;padding:6px 7px;border-radius:5px;
  background:#EEF2FA;border:1px solid var(--border);color:#1B2333;
}
.byte.crc{background:#FFF1D6;border-color:#F7CE7B}
.byte.hdr{background:#E4F6FF;border-color:#A9DDF5}
.byte.err{background:var(--danger-soft);border-color:#FFB3C6}

/* ── badges / status ───────────────────────────────── */
.badge{
  display:inline-flex;align-items:center;gap:5px;border-radius:999px;padding:4px 10px;
  font:700 12px/1 var(--sans);letter-spacing:.02em;border:1px solid transparent;white-space:nowrap;
}
.badge.ok{background:var(--success-soft);color:#00875C;border-color:#A8EBD7}
.badge.warn{background:var(--warning-soft);color:#9A6200;border-color:#F7D79B}
.badge.err{background:var(--danger-soft);color:#C2003C;border-color:#FFB9CB}
.badge.info{background:var(--primary-soft);color:#1E4BD8;border-color:#BBD0FF}
.badge.muted{background:#EEF2FA;color:#5A6785;border-color:var(--border)}

/* ── tables ────────────────────────────────────────── */
.table-wrap{overflow-x:auto;border:1px solid var(--border);border-radius:10px;background:#fff}
table{border-collapse:collapse;width:100%;font-size:14px}
th,td{padding:9px 12px;text-align:left;border-bottom:1px solid var(--border);vertical-align:top}
th{background:#F5F8FE;font-size:12.5px;text-transform:uppercase;letter-spacing:.04em;color:var(--muted);font-weight:700;white-space:nowrap}
tbody tr:last-child td{border-bottom:0}
tbody tr:hover{background:#FAFCFF}
td.mono,th.mono{font-family:var(--mono);font-size:13px;white-space:nowrap}
.num{text-align:right;font-variant-numeric:tabular-nums}

/* ── callouts ──────────────────────────────────────── */
.note{
  border-left:3px solid var(--primary);background:#F2F6FF;border-radius:0 9px 9px 0;
  padding:12px 15px;margin:0 0 1em;font-size:14.5px;color:#31405E;
}
.note.warn{border-color:var(--warning);background:var(--warning-soft);color:#6B4A00}
.note.ok{border-color:var(--success);background:var(--success-soft);color:#04543F}
.note.err{border-color:var(--danger);background:var(--danger-soft);color:#7A0026}
.note p:last-child{margin-bottom:0}

/* ── tabs ──────────────────────────────────────────── */
.tabs{display:flex;gap:4px;border-bottom:1px solid var(--border);margin:0 0 16px;flex-wrap:wrap}
.tab{
  border:0;background:none;cursor:pointer;padding:9px 13px;border-radius:8px 8px 0 0;
  font:600 14px/1 var(--sans);color:var(--muted);border-bottom:2px solid transparent;margin-bottom:-1px;
}
.tab:hover{color:var(--ink);background:#F5F8FE}
.tab.active{color:var(--primary);border-bottom-color:var(--primary);background:#fff}

/* ── faq ───────────────────────────────────────────── */
details.faq{
  border:1px solid var(--border);background:#fff;border-radius:10px;
  padding:0 16px;margin:0 0 8px;box-shadow:var(--shadow);
}
details.faq summary{
  cursor:pointer;padding:13px 0;font-weight:600;font-size:15px;color:var(--ink);
  list-style:none;display:flex;gap:9px;align-items:baseline;
}
details.faq summary::-webkit-details-marker{display:none}
details.faq summary::before{content:'+';color:var(--muted);font-family:var(--mono);font-weight:700}
details.faq[open] summary::before{content:'–'}
details.faq p{margin:0 0 14px 18px;font-size:14.5px;color:#4A5875}

/* ── misc ──────────────────────────────────────────── */
.kv{display:grid;grid-template-columns:auto 1fr;gap:6px 16px;font-size:14.5px;margin:0}
.kv dt{color:var(--muted);font-weight:600}
.kv dd{margin:0;font-family:var(--mono);font-size:14px}
.section-title{display:flex;align-items:baseline;gap:10px;margin:34px 0 12px}
.section-title h2{margin:0;font-size:21px}
.section-title .sub{font-size:13px;color:var(--muted)}
.footer{border-top:1px solid var(--border);margin-top:40px;padding:26px 0 40px;background:#fff}
.footer .inner{max-width:1180px;margin:0 auto;padding:0 20px;display:flex;gap:18px;flex-wrap:wrap;font-size:13.5px;color:var(--muted)}
.footer a{color:var(--ink)}
.footer .spacer{margin-left:auto}
.toast{
  position:fixed;left:50%;bottom:26px;transform:translate(-50%,20px);opacity:0;pointer-events:none;
  background:var(--ink);color:#fff;padding:10px 18px;border-radius:999px;font-size:13.5px;font-weight:600;
  transition:opacity .18s,transform .18s;z-index:100;
}
.toast.show{opacity:1;transform:translate(-50%,0)}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}

@media (max-width:760px){
  h1{font-size:28px}
  .hero h1{font-size:30px}
  .hero{padding:30px 0 6px}
  .page{padding:22px 0 48px}
  .card{padding:16px}
  .out{font-size:14px}
  .site-header .inner{height:auto;padding:10px 16px;flex-wrap:wrap;gap:6px}
  .nav{order:3;width:100%;margin-left:0;flex-wrap:wrap;gap:0;padding-bottom:2px}
  .nav a{padding:6px 9px;font-size:13.5px;white-space:nowrap}
  .lang-btn{order:2;margin-left:auto}
  th,td{padding:8px 9px;font-size:13px}
}