:root {
  --bg: #030712;
  --panel: rgba(7, 15, 29, 0.82);
  --line: rgba(130, 245, 255, 0.2);
  --ink: #ecf9ff;
  --muted: rgba(236, 249, 255, 0.72);
  --cyan: #82f5ff;
  --pink: #ff6ec7;
  --gold: #ffd86b;
  --danger: #ff7a90;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  font-family: "IBM Plex Mono", monospace;
  overflow-x: hidden;
  background:
    radial-gradient(circle at 12% 18%, rgba(130,245,255,0.18), transparent 24%),
    radial-gradient(circle at 88% 18%, rgba(255,110,199,0.16), transparent 24%),
    linear-gradient(180deg, #07101f 0%, #02050d 100%);
}
.shell {
  width: min(1180px, calc(100vw - 24px));
  margin: 0 auto;
  padding: 20px 0 32px;
}
.hero, .arena-card, .panel, .stats div {
  border: 1px solid var(--line);
  background: var(--panel);
  box-shadow: 0 18px 60px rgba(0,0,0,0.35), inset 0 0 24px rgba(130,245,255,0.04);
  backdrop-filter: blur(10px);
}
.hero {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  padding: 24px;
  border-radius: 28px;
}
.eyebrow, .panel-kicker {
  margin: 0 0 10px;
  color: var(--cyan);
  font-size: 12px;
  letter-spacing: 0.28em;
}
h1, h2, .upgrade-btn strong {
  margin: 0;
  font-family: "Syne", sans-serif;
}
h1 {
  font-size: clamp(38px, 8vw, 76px);
  line-height: 0.94;
  max-width: 8ch;
}
.subtitle {
  max-width: 58ch;
  margin: 14px 0 0;
  line-height: 1.7;
  color: var(--muted);
}
.stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(110px, 1fr));
  gap: 12px;
  min-width: min(100%, 320px);
}
.stats div {
  padding: 14px 16px;
  border-radius: 18px;
  text-align: center;
}
.stats span {
  display: block;
  font-size: 11px;
  color: var(--muted);
}
.stats strong {
  display: block;
  margin-top: 8px;
  font-size: clamp(24px, 5vw, 34px);
  color: var(--gold);
}
.top-actions {
  margin: 16px 0;
}
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  border-radius: 999px;
  text-decoration: none;
  color: var(--ink);
  border: 1px solid var(--line);
  background: rgba(255,255,255,0.04);
}
.arena-card {
  position: relative;
  overflow: hidden;
  border-radius: 28px;
  display: grid;
  place-items: center;
}
.upgrade-hud {
  position: absolute;
  top: 12px;
  right: 12px;
  z-index: 2;
  display: grid;
  gap: 8px;
  width: min(260px, calc(100% - 24px));
  max-height: calc(100% - 24px);
  overflow: auto;
  padding: 10px;
  border-radius: 18px;
  border: 1px solid rgba(130, 245, 255, 0.16);
  background: rgba(3, 8, 18, 0.62);
  backdrop-filter: blur(10px);
  pointer-events: none;
}
.upgrade-meter {
  display: grid;
  gap: 5px;
}
.upgrade-meter-head {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  font-size: 10px;
  color: var(--muted);
}
.upgrade-meter-head strong {
  font-size: 11px;
  color: var(--ink);
}
.upgrade-meter-bars {
  display: grid;
  grid-template-columns: repeat(var(--segments, 4), minmax(0, 1fr));
  gap: 4px;
}
.upgrade-meter-bars span {
  height: 6px;
  border-radius: 999px;
  background: rgba(255,255,255,0.12);
  border: 1px solid rgba(130, 245, 255, 0.12);
}
.upgrade-meter-bars span.is-filled {
  background: linear-gradient(90deg, var(--cyan), var(--gold));
  border-color: rgba(255, 216, 107, 0.5);
}
canvas {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  max-width: 100%;
  touch-action: none;
  background: linear-gradient(180deg, rgba(10, 19, 35, 0.92), rgba(3, 6, 14, 0.98));
}
.overlay {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 20px;
  background: rgba(1, 4, 10, 0.48);
  touch-action: manipulation;
}
.overlay.hidden,
.hidden { display: none; }
.panel {
  width: min(560px, 100%);
  max-height: min(100%, calc(100dvh - 40px));
  overflow: auto;
  border-radius: 24px;
  padding: 26px;
  text-align: center;
}
.panel h2 {
  font-size: clamp(28px, 6vw, 42px);
  line-height: 1;
}
.panel p {
  color: var(--muted);
  line-height: 1.65;
}
.panel-meta {
  display: grid;
  gap: 10px;
  margin-top: 14px;
}
.panel-note,
.scoreboard {
  text-align: left;
  border: 1px solid rgba(130,245,255,0.12);
  border-radius: 16px;
  background: rgba(255,255,255,0.04);
  padding: 12px 14px;
}
.panel-note strong,
.scoreboard strong {
  display: block;
  margin-bottom: 6px;
  color: var(--gold);
}
.scoreboard ol {
  margin: 6px 0 0 18px;
  padding: 0;
  color: var(--muted);
}
.scoreboard li + li {
  margin-top: 4px;
}
button {
  border: 0;
  border-radius: 999px;
  font: inherit;
}
#start-btn,
.upgrade-btn,
.burst-btn {
  cursor: pointer;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
}
#start-btn,
.burst-btn {
  padding: 14px 22px;
  background: linear-gradient(90deg, var(--cyan), var(--pink));
  color: #041018;
  font-weight: 700;
  box-shadow: 0 10px 26px rgba(255,110,199,0.2);
}
.burst-btn.is-cooling {
  background: linear-gradient(90deg, rgba(130,245,255,0.38), rgba(255,110,199,0.4));
  color: rgba(4,16,24,0.82);
  box-shadow: none;
}
.upgrade-list {
  display: grid;
  gap: 12px;
  margin: 18px 0 20px;
  max-height: min(46dvh, 420px);
  overflow: auto;
}
.upgrade-btn {
  width: 100%;
  text-align: left;
  padding: 16px 18px;
  border: 1px solid var(--line);
  background: rgba(255,255,255,0.04);
  color: var(--ink);
}
.upgrade-btn.is-difficulty strong {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
}
.badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 5px 10px;
  border-radius: 999px;
  font-size: 11px;
  letter-spacing: 0.08em;
  background: rgba(130,245,255,0.12);
  color: var(--cyan);
}
.upgrade-btn strong {
  display: block;
  font-size: 22px;
}
.upgrade-btn span {
  display: block;
  margin-top: 6px;
  color: var(--muted);
  overflow-wrap: anywhere;
}
.touch-ui {
  position: absolute;
  inset: auto 0 16px 0;
  display: flex;
  justify-content: space-between;
  align-items: end;
  padding: 0 16px;
  pointer-events: none;
}
.joystick,
.burst-btn {
  pointer-events: auto;
}
.joystick {
  position: relative;
  width: 112px;
  height: 112px;
  border-radius: 50%;
  border: 1px solid rgba(255,255,255,0.15);
  background: rgba(255,255,255,0.06);
}
.joystick-knob {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: linear-gradient(180deg, rgba(255,255,255,0.8), rgba(130,245,255,0.35));
  transform: translate(-50%, -50%);
  box-shadow: 0 8px 16px rgba(0,0,0,0.25);
}
.burst-btn {
  min-width: 112px;
  min-height: 112px;
  font-weight: 700;
}
.tips {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 24px;
  align-items: center;
  color: var(--muted);
  margin: 16px 2px 0;
}
.tips div { display: flex; align-items: center; gap: 8px; }
kbd {
  min-width: 42px;
  padding: 6px 10px;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: rgba(255,255,255,0.05);
  text-align: center;
}
@media (max-width: 920px) {
  .hero {
    flex-direction: column;
  }
}
@media (max-width: 720px) {
  .shell {
    width: min(1180px, calc(100vw - 12px));
    padding-bottom: max(18px, env(safe-area-inset-bottom));
  }
  .hero, .panel {
    padding: 18px;
  }
  .arena-card {
    min-height: calc(100dvh - 170px);
    padding: 10px 10px 122px;
    align-items: start;
  }
  canvas {
    width: min(100%, calc((100dvh - 240px) * 9 / 16));
    max-height: calc(100dvh - 240px);
    aspect-ratio: 9 / 16;
    margin: 0 auto;
  }
  .overlay {
    align-items: stretch;
    padding: 10px;
  }
  .panel {
    width: min(100%, 460px);
    max-height: calc(100dvh - 32px);
    margin: auto;
  }
  .upgrade-hud {
    top: 8px;
    right: 8px;
    left: 8px;
    width: auto;
    gap: 6px;
    padding: 8px;
    max-height: min(26dvh, 190px);
  }
  .upgrade-meter-head {
    font-size: 9px;
  }
  .upgrade-meter-head strong {
    font-size: 10px;
  }
  .upgrade-meter-bars span {
    height: 5px;
  }
  .panel h2 {
    font-size: clamp(24px, 7vw, 34px);
  }
  .panel p,
  .panel-note,
  .scoreboard,
  .upgrade-btn span {
    font-size: 13px;
    line-height: 1.5;
  }
  .upgrade-btn {
    padding: 14px;
  }
  .upgrade-btn strong {
    font-size: 18px;
  }
  #start-btn {
    width: 100%;
    justify-content: center;
  }
  .touch-ui {
    inset: auto 0 10px 0;
    padding: 0 10px;
  }
  .joystick,
  .burst-btn {
    width: 92px;
    height: 92px;
    min-width: 92px;
    min-height: 92px;
  }
  .joystick-knob {
    width: 40px;
    height: 40px;
  }
  .tips {
    font-size: 13px;
  }
}