/* ===== Base layout ===== */
body {
  margin: 0;
  font-family: Arial, sans-serif;
  display: flex;
  height: 100vh;
  transition: background-color 0.3s, color 0.3s;
}

#content {
  flex: 1;
  padding: 20px;
  overflow-y: auto;
}

/* ===== Sidebar ===== */
#sidebar {
  width: 250px;
  background-color: #f5f5f5;
  border-right: 1px solid #ddd;
  overflow-y: auto;
  transition: width 0.3s;
}

#sidebar.collapsed {
  width: 60px;
}

/* ===== Sidebar buttons (toggle + mode) ===== */
.toggle-btn,
.mode-btn {
  display: flex;
  align-items: center;
  justify-content: flex-start;
  padding: 10px;
  cursor: pointer;
  background-color: #ddd;
  font-size: 16px;
  line-height: 1;
  white-space: nowrap;
  overflow: hidden;
  transition: background-color 0.3s, color 0.3s;
}

.toggle-btn:hover,
.mode-btn:hover {
  background-color: #ccc;
}

.toggle-btn .toggle-text {
  margin-left: 10px;
}

.mode-btn .mode-text {
  margin-left: 8px;
}

/* ===== Lecture list ===== */
#sidebar ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

#sidebar ul li {
  padding: 10px;
  cursor: pointer;
  transition: background-color 0.2s;
}

#sidebar ul li:hover {
  background-color: #eee;
}

/* ===== Collapsed sidebar behavior ===== */
#sidebar.collapsed .toggle-btn,
#sidebar.collapsed .mode-btn {
  justify-content: center;
}

#sidebar.collapsed .toggle-text,
#sidebar.collapsed .mode-text,
#sidebar.collapsed #lecture-list {
  display: none;
}

/* ===== Dark mode ===== */
body.dark-mode {
  background-color: #121212;
  color: #e0e0e0;
}

body.dark-mode #sidebar {
  background-color: #1e1e1e;
  border-right: 1px solid #333;
}

body.dark-mode #sidebar .toggle-btn,
body.dark-mode #sidebar .mode-btn {
  background-color: #2a2a2a;
  color: #e0e0e0;
}

body.dark-mode #sidebar .toggle-btn:hover,
body.dark-mode #sidebar .mode-btn:hover {
  background-color: #3a3a3a;
}

body.dark-mode #sidebar ul li {
  color: #e0e0e0;
}

body.dark-mode #sidebar ul li:hover {
  background-color: #2f2f2f;
}