:root{
  color-scheme:light;
  --bg:#f3f6f7;
  --panel:#ffffff;
  --panel-2:#eef3f4;
  --line:#d5dfe2;
  --ink:#10222b;
  --ink-soft:#3b525c;
  --muted:#6a7f88;
  --accent:#0e8f80;
  --accent-ink:#ffffff;
  --net:#0e8f80;
  --net-bg:#d6f1ec;
  --host:#7a5bc7;
  --host-bg:#ebe4fa;
  --bad:#c4382b;
  --hit:#fff5d6;
  --mono:ui-monospace,"Cascadia Mono","Cascadia Code",Consolas,"SF Mono",Menlo,monospace;
  --ui:system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
}
@media (prefers-color-scheme:dark){
  :root:not([data-theme="light"]){
    color-scheme:dark;
    --bg:#0c151b;
    --panel:#121f27;
    --panel-2:#182a33;
    --line:#263b46;
    --ink:#e4eef1;
    --ink-soft:#b3c5cc;
    --muted:#7f97a1;
    --accent:#2bb5a3;
    --accent-ink:#06201c;
    --net:#3fcab7;
    --net-bg:#123a37;
    --host:#a98cf0;
    --host-bg:#2a2344;
    --bad:#ff7b6b;
    --hit:#3a3212;
  }
}
:root[data-theme="dark"]{
  color-scheme:dark;
  --bg:#0c151b;--panel:#121f27;--panel-2:#182a33;--line:#263b46;--ink:#e4eef1;--ink-soft:#b3c5cc;
  --muted:#7f97a1;--accent:#2bb5a3;--accent-ink:#06201c;--net:#3fcab7;--net-bg:#123a37;
  --host:#a98cf0;--host-bg:#2a2344;--bad:#ff7b6b;--hit:#3a3212;
}

*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font:15px/1.5 var(--ui);padding:0 16px 56px}
[hidden]{display:none!important}
button,input,select{font:inherit;color:inherit}
code{font-family:var(--mono);font-size:.92em}
:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
.wrap{max-width:1100px;margin:0 auto}
.muted{color:var(--muted)}

/* header */
.top{display:flex;flex-wrap:wrap;align-items:flex-end;justify-content:space-between;gap:10px 32px;padding:32px 0 20px}
.mark{display:flex;align-items:center;gap:12px}
.mark img{border-radius:8px}
h1{font-size:clamp(24px,3.6vw,32px);line-height:1.1;margin:0;letter-spacing:-.01em}
.tag{margin:0;max-width:52ch;color:var(--ink-soft)}
h2{font-size:15px;margin:0;letter-spacing:.01em}

/* cards */
.card{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:18px 20px;margin-bottom:16px;min-width:0}
.card-head{display:flex;flex-wrap:wrap;align-items:baseline;justify-content:space-between;gap:6px 16px;margin-bottom:14px}
.lbl{display:block;font-size:12px;font-weight:700;letter-spacing:.1em;text-transform:uppercase;color:var(--muted);margin-bottom:8px}
.hint{margin:8px 0 0;font-size:13px;color:var(--muted)}
.err{margin:8px 0 0;font-size:14px;color:var(--bad);font-weight:600}

/* entry */
.entry-row{display:flex;gap:10px;align-items:stretch}
#addr{flex:1;min-width:0;font:600 clamp(18px,3vw,24px)/1.2 var(--mono);padding:12px 14px;border:1px solid var(--line);border-radius:10px;background:var(--panel-2)}
#addr[aria-invalid="true"]{border-color:var(--bad)}
.fam{display:grid;place-items:center;padding:0 14px;border-radius:10px;background:var(--accent);color:var(--accent-ink);font-weight:700;font-size:14px}
.slider{margin-top:18px}
.slider output{font-family:var(--mono);color:var(--ink);font-size:14px;letter-spacing:0;text-transform:none;margin-left:6px}
.slider-row{display:flex;align-items:center;gap:10px}
.slider-row input{flex:1;min-width:0;accent-color:var(--accent)}
.step{width:34px;height:34px;border-radius:8px;border:1px solid var(--line);background:var(--panel-2);cursor:pointer;font-size:18px;line-height:1}
.step:hover{border-color:var(--accent)}

/* results */
.results{display:grid;grid-template-columns:minmax(0,1.1fr) minmax(0,1fr);gap:16px}
.results .card{margin-bottom:16px}
@media (max-width:860px){.results{grid-template-columns:minmax(0,1fr);gap:0}}
.badge{font-size:12.5px;font-weight:600;padding:3px 10px;border-radius:999px;background:var(--net-bg);color:var(--net)}
.badge.pub{background:var(--host-bg);color:var(--host)}

.kv{display:grid;grid-template-columns:auto minmax(0,1fr);margin:0}
.kv dt{color:var(--muted);font-size:13.5px;padding:7px 14px 7px 0;border-top:1px solid var(--line)}
.kv dd{margin:0;padding:4px 0;border-top:1px solid var(--line);display:flex;align-items:center;gap:6px;min-width:0}
.kv dt:first-of-type,.kv dd:first-of-type{border-top:0}
.kv .v{font-family:var(--mono);font-size:14px;overflow-wrap:anywhere;flex:1;min-width:0}
.kv .v small{font-family:var(--ui);color:var(--muted);font-size:12.5px;margin-left:6px}
.copy{flex:none;border:1px solid transparent;background:none;border-radius:6px;padding:3px 6px;cursor:pointer;color:var(--muted);font-size:12px}
.copy:hover{border-color:var(--line);color:var(--ink)}

/* bits */
.legend{font-size:12.5px;color:var(--muted);display:flex;align-items:center;gap:6px}
.sw{display:inline-block;width:10px;height:10px;border-radius:2px;margin-left:6px}
.sw.net{background:var(--net)}.sw.host{background:var(--host)}
.bits{display:grid;gap:12px}
.bitrow .lbl{margin-bottom:4px}
.bitrow .line{display:flex;flex-wrap:wrap;gap:4px 8px;font:13px/1 var(--mono)}
.bitrow .grp{display:flex}
.bitrow .grp span{display:inline-block;width:1.25ch;text-align:center;padding:4px 0;border-radius:2px}
.bitrow .grp.nib span{width:auto;padding:4px 2px}
.bitrow .n{background:var(--net-bg);color:var(--net)}
.bitrow .h{background:var(--host-bg);color:var(--host)}
.bitrow .s{background:linear-gradient(90deg,var(--net-bg) 50%,var(--host-bg) 50%);color:var(--ink)}
.bitrow .dot{align-self:end;color:var(--muted);padding:0 1px}

/* split + vlsm */
.split-ctl{display:flex;flex-wrap:wrap;align-items:center;gap:8px 12px;margin-bottom:10px}
.split-ctl strong{font-family:var(--mono)}
select,.vlsm-rows input{padding:7px 10px;border:1px solid var(--line);border-radius:8px;background:var(--panel-2)}
.hit{margin:0 0 10px;font-size:14px;color:var(--ink-soft)}
.hit:empty{display:none}
.hit.bad{color:var(--bad);font-weight:600}
.hit code{background:var(--panel-2);padding:1px 5px;border-radius:4px}
.tbl-wrap{overflow-x:auto;border:1px solid var(--line);border-radius:8px;max-height:560px;overflow-y:auto}
.tbl-wrap:has(table:empty){display:none}
.tbl{width:100%;border-collapse:collapse;font-size:13.5px}
.tbl th{position:sticky;top:0;background:var(--panel-2);text-align:left;font-weight:600;color:var(--ink-soft);padding:8px 12px;white-space:nowrap;border-bottom:1px solid var(--line)}
.tbl td{padding:6px 12px;border-top:1px solid var(--line);font-family:var(--mono);white-space:nowrap}
.tbl tr:first-child td{border-top:0}
.tbl td.t{font-family:var(--ui)}
.tbl td.num,.tbl th.num{text-align:right}
.tbl tr.here td{background:var(--hit)}
.tbl tr.cur td{background:var(--net-bg)}
.btn{margin-top:12px;padding:8px 14px;border-radius:8px;border:1px solid var(--accent);background:var(--accent);color:var(--accent-ink);font-weight:600;cursor:pointer}
.btn.ghost{background:none;color:var(--ink);border-color:var(--line)}
.btn:hover{filter:brightness(1.08)}
.vlsm-rows{display:grid;gap:8px}
.vrow{display:grid;grid-template-columns:minmax(0,1fr) 130px 34px;gap:8px;align-items:center}
.vrow input{min-width:0;width:100%}
.vrow .num{font-family:var(--mono)}
.vrow .rm{width:34px;height:34px;border-radius:8px;border:1px solid var(--line);background:none;cursor:pointer;color:var(--muted)}
.vrow .rm:hover{color:var(--bad);border-color:var(--bad)}
.vhead{font-size:12px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:var(--muted)}
.vlsm-actions{display:flex;gap:8px;margin-bottom:12px}

/* reference */
details summary{cursor:pointer;list-style:none;display:flex;align-items:center;gap:8px}
details summary::-webkit-details-marker{display:none}
details summary::before{content:"▸";color:var(--muted);transition:transform .15s}
details[open] summary::before{transform:rotate(90deg)}
details[open] summary{margin-bottom:14px}
.ref td button{font:inherit;background:none;border:0;padding:0;color:var(--accent);cursor:pointer;text-decoration:underline;text-underline-offset:2px}

.foot{color:var(--muted);font-size:13px;text-align:center;margin-top:24px}

.toast{position:fixed;left:50%;bottom:24px;transform:translate(-50%,20px);opacity:0;pointer-events:none;
  background:var(--ink);color:var(--bg);padding:8px 14px;border-radius:8px;font-size:14px;transition:opacity .15s,transform .15s}
.toast.on{opacity:1;transform:translate(-50%,0)}

@media (max-width:520px){
  .card{padding:16px 14px}
  .kv{grid-template-columns:minmax(0,1fr)}
  .kv dt{padding-bottom:0}
  .kv dd{border-top:0;padding-top:2px}
  .vrow{grid-template-columns:minmax(0,1fr) 96px 34px}
}
@media (prefers-reduced-motion:reduce){*{transition:none!important}}
.offscreen{position:fixed;left:-9999px;top:0}