:root {
  color-scheme: light;
  --bg: #f7f8fb;
  --surface: #ffffff;
  --text: #141821;
  --muted: #5a6475;
  --border: #d7dce5;
  --button-bg: #141821;
  --button-text: #ffffff;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0f1218;
  --surface: #181d27;
  --text: #f3f5f8;
  --muted: #a6b0c2;
  --border: #2a3345;
  --button-bg: #f3f5f8;
  --button-text: #0f1218;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: radial-gradient(circle at top left, #fdfefe 0%, var(--bg) 60%);
  color: var(--text);
}

:root[data-theme="dark"] body {
  background: radial-gradient(circle at top left, #202838 0%, var(--bg) 60%);
}

.page {
  width: min(520px, 100%);
  padding: 28px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--surface);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
}

h1 {
  margin: 0 0 8px;
  font-size: clamp(1.6rem, 5vw, 2rem);
}

p {
  margin: 0 0 20px;
  color: var(--muted);
}

#theme-toggle {
  border: 0;
  border-radius: 999px;
  padding: 10px 16px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  background: var(--button-bg);
  color: var(--button-text);
  transition: transform 120ms ease;
}

#theme-toggle:hover {
  transform: translateY(-1px);
}