:root {
  --wall: #2f4858;
  --bench: #c9d9dc;
  --paper: #f4fafa;
  --sample: #2e9e5b;
  --danger: #d62f3a;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  background: var(--bench);
  color: var(--wall);
  font-family: "Trebuchet MS", "Segoe UI", sans-serif;
}

.lab {
  width: min(100%, 680px);
  padding: 16px;
}

h1 {
  margin: 0 0 10px;
  font-size: clamp(1.4rem, 4vw, 2rem);
  letter-spacing: 0.02em;
}

.hud {
  display: flex;
  justify-content: space-between;
  padding: 8px 14px;
  margin-bottom: 10px;
  background: var(--paper);
  border: 3px solid var(--wall);
  font-size: 1.1rem;
}

.hud b { font-size: 1.3rem; }
#score { color: var(--sample); }

.arena {
  position: relative;
  border: 6px solid var(--wall);
  background: var(--paper);
}

canvas {
  display: block;
  width: 100%;
  height: auto;
}

.overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 20px;
  text-align: center;
  background: rgba(244, 250, 250, 0.93);
}

.overlay[hidden] { display: none; }

.overlay h2 { margin: 0; font-size: 1.8rem; }
.overlay p { margin: 0; max-width: 34ch; line-height: 1.4; }

button {
  margin-top: 6px;
  padding: 10px 26px;
  font: inherit;
  font-weight: bold;
  color: var(--paper);
  background: var(--wall);
  border: 3px solid var(--wall);
  cursor: pointer;
}

button:hover { background: var(--sample); border-color: var(--sample); }
button:focus-visible { outline: 3px solid var(--danger); outline-offset: 2px; }

.hint { margin: 10px 0 0; font-size: 0.9rem; opacity: 0.8; }