:root {
  --bg: #05060a;
  --panel: #0f1526;
  --panel-2: #151d33;
  --line: rgba(255, 255, 255, 0.1);
  --text: #f5f6f7;
  --muted: rgba(245, 246, 247, 0.62);
  --accent: #5b8cff;
  --start: #2fd07a;
  --end: #ff5a7a;
  --wall: #33405e;
  --visited: #24407e;
  --frontier: #3a63c2;
  --path: #ffc24b;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(1200px 600px at 15% -10%, rgba(91, 140, 255, 0.14), transparent 60%),
    radial-gradient(1000px 500px at 110% 10%, rgba(255, 90, 122, 0.1), transparent 55%),
    var(--bg);
  color: var(--text);
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

.wrap {
  max-width: 980px;
  margin: 0 auto;
  padding: 24px 20px 48px;
}

.head { text-align: center; margin-bottom: 22px; }
.head h1 {
  margin: 0 0 8px;
  font-size: clamp(1.7rem, 4vw, 2.4rem);
  letter-spacing: -0.02em;
}
.head p { margin: 0 auto; max-width: 60ch; color: var(--muted); line-height: 1.55; }

.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: space-between;
  align-items: center;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 12px;
  margin-bottom: 14px;
}

.modes { display: flex; gap: 6px; flex-wrap: wrap; }
.mode {
  border: 1px solid var(--line);
  background: var(--panel-2);
  color: var(--muted);
  padding: 8px 14px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: color .15s, border-color .15s, background .15s;
}
.mode:hover { color: var(--text); }
.mode.is-active { color: #fff; border-color: var(--accent); background: rgba(91, 140, 255, 0.18); }

.actions { display: flex; gap: 8px; flex-wrap: wrap; }
.btn {
  border: 1px solid var(--line);
  background: var(--panel-2);
  color: var(--text);
  padding: 9px 16px;
  border-radius: 10px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: transform .1s, background .15s, border-color .15s;
}
.btn:hover { background: #1c2743; }
.btn:active { transform: translateY(1px); }
.btnPrimary { background: var(--accent); border-color: transparent; color: #fff; }
.btnPrimary:hover { background: #6f9bff; }
.btn:disabled { opacity: .5; cursor: not-allowed; }

.stats {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  align-items: center;
  margin-bottom: 14px;
  font-size: 13px;
  color: var(--muted);
}
.stat b { color: var(--text); font-size: 15px; margin-right: 4px; }
.stat.msg { margin-left: auto; color: var(--accent); font-weight: 600; }

.board {
  display: grid;
  gap: 2px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 2px;
  overflow: hidden;
  touch-action: none;
  user-select: none;
}

.cell {
  aspect-ratio: 1 / 1;
  background: var(--panel-2);
  border-radius: 3px;
  cursor: pointer;
  transition: background .12s ease, transform .12s ease;
}
.cell:hover { background: #1e294a; }
.cell.wall { background: var(--wall); }
.cell.visited { background: var(--visited); animation: pop .25s ease; }
.cell.frontier { background: var(--frontier); }
.cell.path { background: var(--path); animation: pop .2s ease; }
.cell.start { background: var(--start); box-shadow: inset 0 0 0 2px rgba(255,255,255,.35); }
.cell.end { background: var(--end); box-shadow: inset 0 0 0 2px rgba(255,255,255,.35); }

@keyframes pop {
  0% { transform: scale(.55); }
  100% { transform: scale(1); }
}

.legend {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  padding: 16px 4px 0;
  margin: 0;
  font-size: 13px;
  color: var(--muted);
}
.legend li { display: flex; align-items: center; gap: 7px; }
.dot { width: 14px; height: 14px; border-radius: 4px; display: inline-block; }
.dot-start { background: var(--start); }
.dot-end { background: var(--end); }
.dot-wall { background: var(--wall); }
.dot-visited { background: var(--visited); }
.dot-path { background: var(--path); }

@media (max-width: 620px) {
  .toolbar { flex-direction: column; align-items: stretch; }
  .actions { justify-content: space-between; }
  .stat.msg { margin-left: 0; width: 100%; }
}