:root {
  --ink: #14203a;
  --panel: rgba(255, 255, 255, 0.88);
  --line: rgba(20, 32, 58, 0.18);
  --accent: #0fa3b1;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  font-family: "IBM Plex Sans", sans-serif;
  background:
    radial-gradient(circle at 86% 12%, rgba(15, 163, 177, 0.25), transparent 30%),
    radial-gradient(circle at 11% 24%, rgba(255, 140, 107, 0.24), transparent 35%),
    linear-gradient(135deg, #eef9ff, #f8f2ff 45%, #fff8ef);
}

.shell {
  width: min(1240px, 94vw);
  margin: 0 auto;
  padding: 2rem 0 2.4rem;
}

header h1 {
  margin: 0.2rem 0 0;
  font-family: "Archivo", sans-serif;
  font-size: clamp(2rem, 5vw, 3.2rem);
}

.kicker {
  margin: 0;
  text-transform: uppercase;
  letter-spacing: 0.16em;
  font-size: 0.8rem;
  color: #3b6381;
}

.layout {
  margin-top: 1rem;
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 1rem;
}

.arena-wrap {
  position: relative;
  border: 2px solid var(--line);
  border-radius: 18px;
  overflow: hidden;
  box-shadow: 0 16px 42px rgba(20, 32, 58, 0.2);
  background: #0d172b;
}

#arena {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
}

.overlay {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  text-align: center;
  background: rgba(13, 23, 43, 0.68);
  color: #fff;
}

.overlay[hidden] {
  display: none !important;
}

.panel {
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--panel);
  box-shadow: 0 16px 42px rgba(20, 32, 58, 0.12);
  padding: 1rem;
  display: grid;
  gap: 0.6rem;
  align-content: start;
}

button,
input {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 0.62rem 0.72rem;
  font: inherit;
}

button {
  cursor: pointer;
  font-weight: 700;
  background: #fff;
}

button:hover:enabled {
  background: #f3fcff;
}

button:disabled {
  opacity: 0.55;
}

#startBtn {
  background: var(--accent);
  color: #fff;
  border-color: transparent;
}

.stats {
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
  padding: 0.6rem;
}

.stats p {
  margin: 0.35rem 0;
  display: flex;
  justify-content: space-between;
}

.meta {
  margin: 0;
  font-size: 0.86rem;
  color: #4b5b74;
}

kbd {
  border: 1px solid rgba(20, 32, 58, 0.28);
  border-radius: 6px;
  padding: 0.1rem 0.3rem;
  background: #fff;
}

@media (max-width: 980px) {
  .layout {
    grid-template-columns: 1fr;
  }
}