:root {
  --bg-color: #111;
  --text-color: #fff;
  --header-bg: #222;
  --button-bg: #333;
  --button-hover: #555;
  --panel-bg: #1a1a1a;
  --accent: #00c6ff;
}

body {
  font-family: Arial, sans-serif;
  background: var(--bg-color);
  color: var(--text-color);
  margin: 0;
  text-align: center;
}
header {
  background: var(--header-bg);
  padding: 1em;
  position: sticky;
  top: 0;
}
nav button, #theme-selector, #back-button {
  background: var(--button-bg);
  color: var(--text-color);
  border: none;
  border-radius: 6px;
  padding: 8px 12px;
  cursor: pointer;
  margin: 0 5px;
  transition: background 0.2s;
}
nav button:hover, #theme-selector:hover, #back-button:hover {
  background: var(--button-hover);
}
iframe {
  border: none;
  max-width: 90vw;
  height: 600px;
  border-radius: 12px;
  box-shadow: 0 0 15px rgba(0,0,0,0.2);
}
