/* THEME VARIABLES */
:root {
  --bg: #ffffff;
  --text: #1e293b;
  --card-bg: #f1f5f9;
  --accent: #7c3aed;
}

html[data-theme="dark"] {
  --bg: #002252;
  --text: #e2e8f0;
  --card-bg: #1e293b;
  --accent: #c084fc;
}

html, body {
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, system-ui, sans-serif;
  margin: 0;
  transition: background 0.3s ease, color 0.3s ease;
}

/* CARD */
.card {
  width: min(700px, 92%);
  margin: 40px auto;
  background: var(--card-bg);
  padding: 22px;
  border-radius: 14px;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
  transition: background 0.3s ease;
}

.head {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.lead {
  margin-top: -10px;
  font-size: 14px;
  opacity: 0.8;
}

/* TOGGLE BUTTON */
.theme-btn {
  background: var(--accent);
  border: none;
  color: white;
  font-size: 22px;
  border-radius: 50%;
  width: 44px;
  height: 44px;
  cursor: pointer;
  box-shadow: 0 4px 14px rgba(124, 58, 237, 0.4);
  transition: transform 0.2s ease;
}

.theme-btn:hover {
  transform: scale(1.1);
}

.small {
  font-size: 13px;
  opacity: 0.8;
}