body {
  font-family: system-ui, sans-serif;
  background: #111;
  color: #fff;
  margin: 0;
  padding: 16px;
}

h1 {
  text-align: center;
}

ul {
  list-style: none;
  padding: 0;
}

li {
  padding: 12px;
  margin-bottom: 8px;
  background: #222;
  border-radius: 8px;
  cursor: pointer;
}

li:hover {
  background: #333;
}

iframe {
  width: 100%;
  aspect-ratio: 16 / 9;
  margin-top: 12px;
}

button {
  margin-top: 8px;
}

.notice {
  font-size: 14px;
  opacity: 0.9;
  margin-top: 24px;
}

/* 🔧 FIX: Notice lists should NOT look clickable */
.notice ul {
  list-style: disc;
  padding-left: 20px;
}

.notice li {
  background: none;
  padding: 4px 0;
  margin-bottom: 4px;
  cursor: default;
}

.notice li:hover {
  background: none;
}

.hidden {
  display: none;
}

#player {
  background: #000;
  padding-bottom: 8px;
}

#youtube-player {
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
}

.module {
  margin-bottom: 24px;
}

.module-header {
  font-weight: bold;
  pointer-events: none;
  margin-bottom: 6px;
  opacity: 0.8;
}

.lesson-active {
  background: #eaeaea;
  color: #000;
  font-weight: bold;
}

/* 🔗 Link styling */
a {
  color: #4ea1ff;
  text-decoration: none;
  font-weight: 500;
}

a:hover {
  text-decoration: underline;
}