:root {
  --bg: #f0f3f7;
  --card: #ffffff;
  --accent: #2563eb;
  --text: #0f172a;
}
* {
  box-sizing: border-box;
}
html,
body {
  height: 100%;
}
body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI",
    Roboto, "Helvetica Neue", Arial;
  background: var(--bg);
  color: var(--text);
}
.container {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 24px;
  padding: 24px;
}
.centered {
  display: flex;
  align-items: center;
  justify-content: center;
}
.cta {
  appearance: none;
  border: 0;
  background: var(--accent);
  color: white;
  padding: 12px 24px;
  font-size: 18px;
  border-radius: 8px;
  cursor: pointer;
}
.box {
  width: 260px;
  height: 260px;
  border-radius: 12px;
  background: linear-gradient(135deg, #e2e8f0, #cbd5e1);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 6px 20px rgba(15, 23, 42, 0.08);
}
.hidden {
  display: none;
}
.result {
  margin-top: 18px;
  font-size: 18px;
}

#game {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 20px;
}

#againBtn {
  align-self: center;
}
.notes {
  opacity: 0.9;
  max-width: 640px;
  text-align: center;
  font-size: 14px;
}
h1 {
  margin: 0 0 8px 0;
}
button:focus {
  outline: 3px solid rgba(37, 99, 235, 0.2);
}