:root{
  --paper:#F6F8FB; --grid:#DCE6F0; --line:#A9C0D6; --ink:#1E3D9F; --ink-soft:rgba(30,61,159,.13);
  --hatch:rgba(30,61,159,.32); --red:#C6352E; --red-soft:rgba(198,53,46,.16); --red-hatch:rgba(198,53,46,.35);
  --pencil:#5C6574; --text:#1B2332; --card:#FFFFFF; --on-ink:#FFFFFF;
  --serif:"Noto Serif Georgian","Sylfaen",Georgia,serif;
  --sans:"Noto Sans Georgian","Sylfaen","DejaVu Sans",system-ui,sans-serif;
}
@media (prefers-color-scheme:dark){
  :root:not([data-theme="light"]){
    --paper:#141B26; --grid:#1E2A3C; --line:#35496A; --ink:#93B1FF; --ink-soft:rgba(147,177,255,.15);
    --hatch:rgba(147,177,255,.38); --red:#FF7A6B; --red-soft:rgba(255,122,107,.18); --red-hatch:rgba(255,122,107,.4);
    --pencil:#9AA6B8; --text:#E5EBF4; --card:#1A2331; --on-ink:#0F1520;
  }
}
:root[data-theme="dark"]{
  --paper:#141B26; --grid:#1E2A3C; --line:#35496A; --ink:#93B1FF; --ink-soft:rgba(147,177,255,.15);
  --hatch:rgba(147,177,255,.38); --red:#FF7A6B; --red-soft:rgba(255,122,107,.18); --red-hatch:rgba(255,122,107,.4);
  --pencil:#9AA6B8; --text:#E5EBF4; --card:#1A2331; --on-ink:#0F1520;
}
*{box-sizing:border-box}
html,body{margin:0}
body{
  background-color:var(--paper);
  background-image:linear-gradient(var(--grid) 1px,transparent 1px),linear-gradient(90deg,var(--grid) 1px,transparent 1px);
  background-size:22px 22px;
  color:var(--text); font-family:var(--sans); font-size:16px; line-height:1.55;
  min-height:100vh; overflow-x:hidden;
}
body::before{ /* notebook margin line */
  content:""; position:fixed; top:0; bottom:0; left:max(12px, calc(50vw - 478px));
  width:2px; background:var(--red); opacity:.45; pointer-events:none;
}
.wrap{max-width:980px; margin:0 auto; padding:28px 16px 64px 34px; position:relative}
h1{font-family:var(--serif); font-weight:800; color:var(--ink); font-size:clamp(40px,8vw,72px); line-height:1.05; margin:8px 0 4px; letter-spacing:-.01em}
.squiggle{display:block; width:min(340px,70%); height:14px; color:var(--red); margin-bottom:14px}
h2{font-family:var(--serif); font-weight:600; font-size:22px; margin:0 0 4px; color:var(--text)}
p{margin:0 0 10px; max-width:62ch}
.muted{color:var(--pencil)}
button{font:inherit}
.btn{
  appearance:none; border:1.5px solid var(--ink); background:var(--card); color:var(--ink);
  padding:8px 16px; border-radius:6px; cursor:pointer; font-weight:600; line-height:1.3;
}
.btn:hover{background:var(--ink-soft)}
.btn.primary{background:var(--ink); color:var(--on-ink)}
.btn.primary:hover{filter:brightness(1.08)}
.btn:disabled{opacity:.45; cursor:not-allowed}
.btn:focus-visible,.seg label:focus-within,input:focus-visible,.cell:focus-visible,.dock-ship:focus-visible,summary:focus-visible{outline:2px solid var(--red); outline-offset:2px}
.linkish{appearance:none; background:none; border:0; color:var(--ink); text-decoration:underline; cursor:pointer; padding:0; font-weight:600}
input[type=text]{
  font:inherit; padding:8px 10px; border:1.5px solid var(--line); border-radius:6px; background:var(--card); color:var(--text); width:170px;
}
.row{display:flex; flex-wrap:wrap; gap:10px; align-items:center}
.screen{display:none}
body[data-screen="home"] #home, body[data-screen="place"] #place, body[data-screen="pass"] #pass, body[data-screen="battle"] #battle{display:block}

/* home */
.mode{padding:22px 0 20px; border-top:1px solid var(--line)}
.mode:last-of-type{border-bottom:1px solid var(--line)}
.seg{display:inline-flex; border:1.5px solid var(--ink); border-radius:6px; overflow:hidden}
.seg input{position:absolute; opacity:0; pointer-events:none}
.seg label{padding:7px 14px; cursor:pointer; color:var(--ink); font-weight:600; background:var(--card)}
.seg label + label{border-left:1.5px solid var(--ink)}

.seg label.on{background:var(--ink); color:var(--on-ink)}
.err{color:var(--red); font-weight:600; min-height:1.5em; margin-top:6px}
details{margin-top:22px; max-width:62ch}
summary{cursor:pointer; font-family:var(--serif); font-weight:600; font-size:18px; color:var(--ink)}
details ul{padding-left:20px; margin:10px 0 0}
details li{margin-bottom:4px}

/* boards */
.board{display:grid; grid-template-columns:calc(var(--cell)*.8) repeat(10,var(--cell)); width:max-content; user-select:none; -webkit-user-select:none; touch-action:manipulation}
.lab{display:grid; place-items:center; font-size:calc(var(--cell)*.42); color:var(--pencil); height:calc(var(--cell)*.8)}
.lab.side{height:var(--cell)}
.cell{
  position:relative; width:var(--cell); height:var(--cell); padding:0; margin:0;
  border:0; border-right:1px solid var(--line); border-bottom:1px solid var(--line);
  background:transparent; color:inherit; border-radius:0; display:block; appearance:none;
}
.board .cell{background-color:color-mix(in srgb, var(--card) 70%, transparent)}
.cell.fl{border-left:2px solid var(--ink)} .cell.ft{border-top:2px solid var(--ink)}
.cell.fr{border-right:2px solid var(--ink)} .cell.fb{border-bottom:2px solid var(--ink)}
button.cell{cursor:pointer}
button.cell.shoot:hover{background-color:var(--ink-soft)}
.cell.ship{
  --edge:var(--ink);
  background-image:repeating-linear-gradient(135deg,var(--h,var(--hatch)) 0 1.5px,transparent 1.5px 5px);
  box-shadow:inset calc(var(--l,0)*3px) 0 0 var(--edge), inset calc(var(--r,0)*-3px) 0 0 var(--edge),
             inset 0 calc(var(--t,0)*3px) 0 var(--edge), inset 0 calc(var(--b,0)*-3px) 0 var(--edge);
}
.cell.ship.sunkship{--edge:var(--red); --h:var(--red-hatch)}
.cell.ship.ghost{opacity:.55}
.cell.hit::before,.cell.hit::after{
  content:""; position:absolute; left:17%; right:17%; top:calc(50% - 1.25px); height:2.5px;
  background:var(--red); border-radius:2px; transform:rotate(45deg);
}
.cell.hit::after{transform:rotate(-45deg)}
.cell.miss::after,.cell.auto::after{
  content:""; position:absolute; inset:0; margin:auto; width:22%; height:22%; border-radius:50%; background:var(--ink);
}
.cell.auto::after{opacity:.35; width:16%; height:16%}
.cell.pend::after{content:"?"; position:absolute; inset:0; display:grid; place-items:center; color:var(--pencil); font-weight:700; font-size:calc(var(--cell)*.5)}
.cell.pv-ok{background-color:var(--ink-soft)}
.cell.pv-bad{background-color:var(--red-soft)}
.cell.last{z-index:1; animation:ping .75s ease-out 1}
@keyframes ping{0%{outline:2px solid var(--red); outline-offset:0} 100%{outline:2px solid transparent; outline-offset:8px}}
@media (prefers-reduced-motion:reduce){.cell.last{animation:none; outline:2px solid var(--red); outline-offset:-2px}}

/* placement */
#place .board{--cell:clamp(26px, calc((100vw - 76px)/11), 40px)}
.place-grid{display:flex; flex-wrap:wrap; gap:28px; align-items:flex-start; margin-top:14px}
.dock{display:flex; flex-direction:column; gap:10px; min-width:220px}
.dock-ships{display:flex; flex-wrap:wrap; gap:10px; max-width:280px}
.dock-ship{
  appearance:none; border:1.5px solid transparent; background:transparent; padding:4px; border-radius:6px; cursor:pointer; display:flex;
}
.dock-ship.sel{border-color:var(--red)}
.dock-ship i{
  width:22px; height:22px; display:block; border:2px solid var(--ink); margin-left:-2px;
  background-image:repeating-linear-gradient(135deg,var(--hatch) 0 1.5px,transparent 1.5px 5px);
}
.dock-ship i:first-child{margin-left:0}
.note{background:var(--card); border-left:3px solid var(--red); padding:10px 14px; margin:12px 0; max-width:62ch}
.code{font-family:var(--serif); font-weight:800; color:var(--ink); font-size:26px; letter-spacing:.12em}

/* battle */
.status{font-family:var(--serif); font-weight:600; color:var(--ink); font-size:clamp(20px,3.2vw,26px); margin:6px 0 2px; min-height:1.4em}
.sub{color:var(--pencil); min-height:1.5em}
.arena{display:flex; flex-wrap:wrap; gap:26px 36px; align-items:flex-start; margin-top:16px}
.arena .target .board{--cell:clamp(26px, calc((100vw - 76px)/11), 38px)}
.arena .own .board{--cell:clamp(17px, calc((100vw - 76px)/16), 25px)}
.boardtitle{font-weight:600; margin:0 0 6px}
.tally{display:flex; flex-wrap:wrap; gap:6px 10px; margin-top:10px; max-width:calc(var(--cell)*10.8)}
.tship{display:flex; position:relative}
.tship i{width:10px; height:10px; border:1.5px solid var(--ink); margin-left:-1.5px; display:block}
.tship i:first-child{margin-left:0}
.tship.sunk i{border-color:var(--red); opacity:.7}
.tship.sunk::after{content:""; position:absolute; left:-3px; right:-3px; top:calc(50% - 1px); height:2px; background:var(--red)}
.overbar{display:none; margin-top:14px}
.overbar.show{display:flex}
.topline{display:flex; justify-content:space-between; align-items:center; gap:12px; flex-wrap:wrap}
#pass .passbox{margin-top:12vh}
@media (max-width:560px){ .wrap{padding-left:30px} .arena{gap:22px} }

/* identity + leaderboard */
.who{display:flex; flex-wrap:wrap; gap:10px; align-items:center; margin:6px 0 18px}
.who b{color:var(--ink)}
.boards{display:flex; flex-wrap:wrap; gap:18px 40px; margin-top:6px}
.lb{border-collapse:collapse; min-width:260px; font-variant-numeric:tabular-nums}
.lb caption{text-align:left; font-weight:600; padding-bottom:6px}
.lb th,.lb td{padding:5px 12px 5px 0; text-align:left; border-bottom:1px solid var(--line)}
.lb th{font-weight:600; color:var(--pencil); font-size:14px}
.lb td.num,.lb th.num{text-align:right; padding-right:0; padding-left:12px}
.lb tr.me td{color:var(--ink); font-weight:700}
.back{display:inline-block; margin-bottom:6px; color:var(--pencil)}