/* Packet Routing (computer-science/packet-routing.php). The page chrome is the one-screen layout in
   /css/resource.css and the drawings' line style is net-draw.css. Here: the stage (the status chips, the
   network, the destination's buffer), and beside it the controls, what's happening, the routing table and
   the packet. On a laptop or desktop it fits one window, the side panels scrolling inside themselves if they
   must; on a phone it stacks. Theme tokens only. */
.rp-main{gap:10px}
.pr-grid{flex:1;min-height:0;display:grid;grid-template-columns:minmax(0,1fr) clamp(270px,30vw,380px);grid-template-rows:auto minmax(0,1fr) auto;grid-template-areas:"stage controls" "stage log" "stage table";gap:10px}
.pr-stage{grid-area:stage;display:flex;flex-direction:column;min-height:0;min-width:0;overflow:hidden}
.pr-controls{grid-area:controls}.pr-log{grid-area:log}.pr-table{grid-area:table}
.pr-bottom{flex:none;display:grid;grid-template-columns:minmax(0,1fr) minmax(250px,330px);border-top:1px solid var(--line)}

/* ---------- the status chips ---------- */
.pr-status{flex:none;display:flex;flex-wrap:wrap;align-items:center;gap:6px;padding:7px 12px;border-bottom:1px solid var(--line);background:var(--panel-2);border-radius:6px 6px 0 0}
.chip{font:11.5px/1.3 var(--font-mono);letter-spacing:.03em;border:1px solid var(--line);border-radius:3px;padding:3px 8px;color:var(--ink-soft);background:var(--panel);white-space:nowrap}
.chip b{color:var(--ink);font-weight:600}
#chipPreset{border-color:var(--accent);color:var(--accent);font-weight:600}
#chipConv.busy{border-color:var(--warn);color:var(--warn)}
#chipConv.busy b{color:var(--warn)}
.chip.tick{margin-left:auto}

/* ---------- the network ---------- */
.pr-scene{position:relative;flex:1;min-height:220px;background:var(--panel)}
.pr-scene > svg{position:absolute;inset:0;width:100%;height:100%;display:block}
#moveSvg{pointer-events:none}
#moveSvg .pr-pk{pointer-events:auto}
.pr-route{fill:none;stroke:var(--accent-tint);stroke-width:16;stroke-linecap:round;stroke-linejoin:round}
.pr-link{cursor:pointer}
.pr-link:focus{outline:none}
.pr-hit{stroke:transparent;stroke-width:22}
.pr-wire{stroke:var(--ink-soft);stroke-width:2.2;stroke-linecap:round}
.pr-cost{fill:var(--panel);stroke:var(--ink-soft);stroke-width:1.4}
.pr-cost-t{font-family:var(--font-mono);font-weight:700;fill:var(--ink)}
.pr-cross{fill:none;stroke:var(--bad);stroke-width:3;stroke-linecap:round;display:none}
.pr-link:hover .pr-wire,.pr-link:focus-visible .pr-wire{stroke:var(--accent);stroke-width:3.2}
.pr-link:focus-visible .pr-cost{stroke:var(--focus);stroke-width:2.5}
.pr-link[data-state="down"] .pr-wire{stroke:var(--bad);stroke-dasharray:6 6;opacity:.75}
.pr-link[data-state="down"] .pr-cost{display:none}
.pr-link[data-state="down"] .pr-cross{display:inline}
.pr-link[data-state="busy"] .pr-wire{stroke:var(--warn);stroke-width:4.5}
.pr-link[data-state="busy"] .pr-cost{stroke:var(--warn);fill:var(--warn-tint);stroke-width:2}
.pr-link[data-state="busy"] .pr-cost-t{fill:var(--warn)}
.pr-lan line{stroke:var(--ink-soft);stroke-width:2.2;stroke-dasharray:2 4;stroke-linecap:round}
.pr-router{cursor:pointer}
.pr-router:focus{outline:none}
.pr-router:focus-visible .pr-rbody,.pr-router:hover .pr-rbody{stroke:var(--accent)}
.pr-router.is-pinned .pr-rbody{fill:var(--accent-tint)}
.pr-router[data-state="down"] .pr-rbody{fill:var(--bad-tint);stroke:var(--bad)}
.pr-router[data-state="down"] .pr-cross{display:inline}
.pr-router[data-state="down"] .pr-rname{fill:var(--bad)}
.pr-rname{fill:var(--ink)}
.pr-net{font:600 10.5px var(--font-mono);fill:var(--muted)}
.pr-ip{font:10.5px var(--font-mono);fill:var(--ink-soft)}
.pr-ip,.pr-net{paint-order:stroke;stroke:var(--panel);stroke-width:3px;stroke-linejoin:round}
.pr-ring{fill:none;stroke:var(--accent);stroke-width:2;stroke-dasharray:4 4;opacity:.8}

/* packets and routing updates */
.pr-pk rect{fill:var(--accent);stroke:var(--panel);stroke-width:1.5}
.pr-pk text{fill:var(--on-accent);font-weight:700}
.pr-pk.is-resent rect{stroke:var(--ink);stroke-dasharray:3 2}
.pr-pk.k-req rect{fill:var(--accent-b)}
.pr-pk.k-icmp rect{fill:var(--warn)}
.pr-pk.k-icmp text{fill:var(--panel)}
.pr-pk.is-queued{opacity:.9}
.pr-pk.is-dropped rect{fill:var(--bad);opacity:.85}
.pr-pk.is-dropped text{fill:var(--panel);text-decoration:line-through}
.pr-pk.is-focus rect{stroke:var(--ink);stroke-width:2.6;stroke-dasharray:none}
.pr-dv rect{fill:var(--hint-tint);stroke:var(--hint);stroke-width:1.4}
.pr-dv path{stroke:var(--hint);stroke-width:1.3;fill:none}

/* the changes menu */
.pr-pop{position:absolute;z-index:3;display:flex;flex-wrap:wrap;align-items:center;gap:6px 6px;max-width:280px;padding:8px 30px 8px 10px;background:var(--panel);border:1px solid var(--line-strong);border-radius:6px;box-shadow:var(--shadow);font-size:13px}
.pr-pop b{color:var(--ink)}
.pr-pop span{color:var(--muted);font:11.5px var(--font-mono);flex:1 1 auto}
.pr-pop .btn{min-height:32px}
.pr-pop-x{position:absolute;top:3px;right:4px;width:26px;height:26px;border:0;background:transparent;color:var(--muted);font-size:18px;line-height:1;cursor:pointer;border-radius:4px}
.pr-pop-x:hover{color:var(--ink);background:var(--panel-2)}
.pr-hint{position:absolute;right:10px;bottom:6px;margin:0;font:11px var(--font-mono);color:var(--muted);pointer-events:none}

/* ---------- the destination's buffer ---------- */
.pr-buffer{padding:6px 12px 7px;display:grid;gap:4px;align-content:start;min-width:0}
.pr-brow{display:grid;grid-template-columns:72px minmax(0,1fr);align-items:center;gap:8px;min-height:24px}
.pr-blab{font:600 10px var(--font-mono);letter-spacing:.08em;text-transform:uppercase;color:var(--muted)}
.pr-boxes{display:flex;flex-wrap:wrap;gap:4px}
.pr-box{display:inline-flex;align-items:center;justify-content:center;min-width:24px;height:22px;padding:0 5px;border-radius:4px;background:var(--accent);color:var(--on-accent);font:700 12px var(--font-mono)}
.pr-box.late{background:var(--warn);color:var(--panel)}
.pr-box.resent{box-shadow:inset 0 0 0 2px var(--ink)}
.pr-box.slot{background:var(--panel-2);color:var(--muted);border:1px dashed var(--line-strong)}
.pr-box.slot.have{background:var(--ok-tint);color:var(--ok);border:1px solid var(--ok)}
.pr-box.slot.gap{border-color:var(--warn);color:var(--warn)}
.pr-box.slot.asked{border:1.5px solid var(--bad);color:var(--bad);background:var(--bad-tint)}
.pr-empty{font:12px var(--font-mono);color:var(--muted);font-style:italic}
.pr-msg{font:600 14px/1.3 var(--font-mono);letter-spacing:.04em;overflow-wrap:anywhere}
.pr-msg .have{color:var(--ink)}
.pr-msg .miss{color:var(--line-strong)}
.pr-msg.done .have{color:var(--ok)}

/* ---------- the side: controls, what's happening, the table, the packet ---------- */
.pr-controls{display:flex;flex-wrap:wrap;align-items:center;gap:8px;padding:8px 10px}
.pr-controls .btn{flex:1 1 0;min-width:0;padding-left:8px;padding-right:8px}
.pr-slider{flex:1 1 100%;display:flex;align-items:center;gap:7px;font:11px var(--font-mono);letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.pr-slider input[type=range]{flex:1;min-width:0;accent-color:var(--accent)}
.pr-slider output{color:var(--ink);min-width:36px;font-variant-numeric:tabular-nums}

.pr-log{min-height:0;display:flex;flex-direction:column;overflow:hidden}
.pr-log h2{flex:none;padding:10px 14px 6px;border-bottom:1px solid var(--line)}
.pr-events{flex:1;min-height:0;overflow:auto;margin:0;padding:6px 14px 10px;list-style:none;font-size:13.5px;line-height:1.45;color:var(--ink-soft)}
.pr-tick{padding:4px 0 6px;opacity:.6}
.pr-tick.is-now{opacity:1}
.pr-tick + .pr-tick{border-top:1px dashed var(--line)}
.pr-tno{font:600 10.5px var(--font-mono);letter-spacing:.06em;text-transform:uppercase;color:var(--accent)}
.pr-tick ul{margin:2px 0 0;padding-left:16px}
.pr-tick li{margin-bottom:3px}
.pr-tick b{color:var(--ink)}
.pr-tick .ev-change,.pr-tick .ev-lost,.pr-tick .ev-ttl{color:var(--bad)}
.pr-tick .ev-change b,.pr-tick .ev-ttl b{color:var(--bad)}
.pr-tick .ev-table,.pr-tick .ev-dv,.pr-tick .ev-converged{color:var(--hint)}
.pr-tick .ev-done{color:var(--ok)}

.pr-table{padding:9px 12px 10px}
.pr-packet{padding:6px 12px 7px;border-left:1px solid var(--line);min-width:0}
.pr-table h2,.pr-packet h2{margin-bottom:6px}
.pr-rt{width:100%;border-collapse:collapse;font-size:12.5px}
.pr-rt th{font:600 10px/1.2 var(--font-mono);letter-spacing:.05em;text-transform:uppercase;color:var(--muted);text-align:left;padding:3px 6px;border-bottom:1px solid var(--line);background:none}
.pr-rt td{padding:3px 6px;border-bottom:1px solid var(--line);color:var(--ink);font-family:var(--font-mono);font-size:12px;white-space:nowrap}
.pr-rt td:first-child{font-family:var(--font-body);font-size:12.5px;white-space:normal}
.pr-rt .pfx{color:var(--muted);font:10.5px var(--font-mono)}
.pr-rt tr.is-match td{background:var(--accent-tint);box-shadow:inset 0 1px 0 var(--accent),inset 0 -1px 0 var(--accent)}
.pr-rt tr.is-new td{animation:pr-flash 1.4s ease-out}
.pr-rt tr.is-new td:nth-child(2),.pr-rt tr.is-new td:nth-child(3){color:var(--hint);font-weight:700}
.pr-rt tr.is-none td:nth-child(2),.pr-rt tr.is-none td:nth-child(3){color:var(--bad)}
@keyframes pr-flash{from{background:var(--hint-tint)}}

.pr-pkt{display:grid;grid-template-columns:1fr auto auto;border:1.5px solid var(--ink-soft);border-radius:5px;overflow:hidden;font-size:12px}
.pr-part{padding:4px 7px;min-width:0}
.pr-part .lab{display:block;font:600 9.5px var(--font-mono);letter-spacing:.07em;text-transform:uppercase;color:var(--muted)}
.pr-part.hdr{grid-column:1/-1;background:var(--accent-tint);border-bottom:1px solid var(--line)}
.pr-part.pay{grid-column:1/3;border-right:1px solid var(--line)}
.pr-part.trl{background:var(--panel-2)}
.pr-part dl{margin:2px 0 0;display:grid;grid-template-columns:1fr 1fr;gap:1px 10px}
.pr-part dl div{display:flex;justify-content:space-between;gap:6px;min-width:0}
.pr-part dt{color:var(--ink-soft);font-size:11px}
.pr-part dd{margin:0;font-family:var(--font-mono);color:var(--ink);font-weight:600;white-space:nowrap}
.pr-part dd.low{color:var(--bad)}
.pr-part code{font:600 12.5px var(--font-mono);color:var(--ink)}
.pr-where{margin:5px 0 0;font-size:12.5px;line-height:1.4;color:var(--ink-soft)}
.pr-where b{color:var(--ink)}
.pr-none{margin:0;font-size:13px;color:var(--muted)}

/* the Explanation */
.objective h4{margin:18px 0 8px;font:700 15px/1.2 var(--font-display);color:var(--accent-deep)}
.mis div{border-left:3px solid var(--bad);padding:2px 0 2px 11px;margin-bottom:8px}
.mis b{display:block;color:var(--ink)}
details.qa{border-top:1px dashed var(--line);padding:6px 0}
details.qa summary{cursor:pointer;color:var(--ink);font-weight:600}
details.qa p{margin:6px 0 0}

/* short laptop screens: tighter */
@media (min-width:901px) and (max-height:700px){
  .pr-controls{padding:6px 10px;gap:6px}
  .pr-controls .btn{padding-top:6px;padding-bottom:6px}
  .pr-table{padding:6px 10px 7px}
  .pr-rt td,.pr-rt th{padding-top:2px;padding-bottom:2px}
  .pr-where{display:none}
  .pr-buffer{padding:4px 12px 5px;gap:2px}
  .pr-brow{min-height:22px}
  .pr-box{height:20px}
  .pr-hint{display:none}
  .pr-scene{min-height:150px}
  .pr-status{flex-wrap:nowrap;overflow:hidden;padding-top:5px;padding-bottom:5px}
  #chipPreset{display:none}
  .pr-part{padding-top:2px;padding-bottom:2px}
}
/* ---------- smaller screens: everything stacks, and the page scrolls ---------- */
@media (max-width:900px){
  .pr-grid{grid-template-columns:1fr;grid-template-rows:none;grid-template-areas:"stage" "controls" "log" "table"}
  .pr-scene{flex:none;height:440px}
  .pr-events{max-height:300px}
}
@media (max-width:640px){
  .pr-scene{height:640px}
  .pr-hint{display:none}
  .rp-titlebar .seg-toggle button{padding-left:8px;padding-right:8px;font-size:12.5px}
  .pr-bottom{grid-template-columns:1fr}
  .pr-packet{border-left:0;border-top:1px solid var(--line)}
  .chip.tick{margin-left:0}
  .pr-controls .btn{min-height:42px}
  .pr-slider input[type=range]{height:32px}
  .pr-pop .btn{min-height:40px}
  .pr-pop-x{width:36px;height:36px}
  .pr-hint{left:10px;right:auto}
}
@media (prefers-reduced-motion:reduce){.pr-rt tr.is-new td{animation:none}}