:root {
  --bg: #f6f5f0;
  --ink: #111;
  --ink-soft: #444;
  --paper: #fff;
  --accent: #d33;
  --shadow: 0 2px 0 var(--ink);
  --font-display: "Outfit", "Noto Sans TC", system-ui, sans-serif;
  --font-body: "Noto Sans TC", system-ui, sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  min-height: 100vh;
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background-image:
    radial-gradient(circle at 20% 20%, rgba(0, 0, 0, 0.04) 0 1px, transparent 2px),
    radial-gradient(circle at 80% 60%, rgba(0, 0, 0, 0.04) 0 1px, transparent 2px);
  background-size: 24px 24px;
}

#game-shell {
  position: relative;
  width: min(960px, 100%);
  background: var(--paper);
  border: 2px solid var(--ink);
  box-shadow: 6px 6px 0 var(--ink);
  overflow: hidden;
}

#hud {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 16px;
  border-bottom: 2px solid var(--ink);
  font-family: var(--font-display);
  letter-spacing: 0.08em;
  background: var(--paper);
}

.hud-item {
  display: flex;
  align-items: baseline;
  gap: 8px;
}

.hud-label {
  font-size: 12px;
  color: var(--ink-soft);
}

#hud-distance,
#hud-best {
  font-size: 22px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.hud-unit {
  font-size: 12px;
  color: var(--ink-soft);
}

#game-canvas {
  display: block;
  width: 100%;
  height: auto;
  background: var(--paper);
  image-rendering: pixelated;
}

.overlay {
  position: absolute;
  inset: 0;
  top: 49px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 18px;
  padding: 24px;
  background: rgba(246, 245, 240, 0.92);
  text-align: center;
  backdrop-filter: blur(2px);
  transition: opacity 200ms ease;
}

.overlay[hidden] {
  display: none;
}

.overlay h1 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(40px, 6vw, 64px);
  letter-spacing: 0.08em;
  border-bottom: 4px solid var(--ink);
  padding-bottom: 6px;
}

.overlay p {
  margin: 0;
  font-size: 16px;
  color: var(--ink-soft);
}

.overlay-controls {
  display: grid;
  gap: 4px;
  font-size: 14px;
  color: var(--ink-soft);
}

.overlay-controls kbd {
  display: inline-block;
  padding: 1px 8px;
  border: 1.5px solid var(--ink);
  border-radius: 4px;
  font-family: var(--font-display);
  font-size: 12px;
  background: var(--paper);
  box-shadow: 2px 2px 0 var(--ink);
  margin: 0 2px;
}

#overlay-action {
  margin-top: 6px;
  padding: 10px 28px;
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 700;
  letter-spacing: 0.12em;
  background: var(--ink);
  color: var(--paper);
  border: 2px solid var(--ink);
  cursor: pointer;
  box-shadow: 4px 4px 0 var(--ink);
  transition: transform 80ms ease, box-shadow 80ms ease;
}

#overlay-action:hover {
  transform: translate(-2px, -2px);
  box-shadow: 6px 6px 0 var(--ink);
}

#overlay-action:active {
  transform: translate(2px, 2px);
  box-shadow: 0 0 0 var(--ink);
}

.overlay-gameover h1 {
  color: var(--accent);
  border-bottom-color: var(--accent);
}