#sidebar {
  width: var(--sidebar-width); min-width: var(--sidebar-width);
  background: var(--card-bg); border-right: 1px solid var(--border-color);
  transition: width var(--transition), min-width var(--transition), transform var(--transition);
  overflow: hidden; flex-shrink: 0;
}
#sidebar.collapsed { width: 0; min-width: 0; }
.sidebar-inner { width: 240px; padding: 16px 0; overflow-y: auto; height: 100%; }
.sidebar-section { margin-bottom: 20px; }
.sidebar-title { font-size: 0.72rem; font-weight: 700; text-transform: uppercase; letter-spacing: 1px; color: #999; padding: 0 16px 8px; }
.sidebar-nav a {
  display: flex; align-items: center; gap: 10px;
  padding: 10px 16px; color: var(--text-color); font-size: 0.88rem;
  border-radius: 6px; margin: 1px 8px;
  transition: background var(--transition), color var(--transition), padding-left var(--transition);
  position: relative;
}
.sidebar-nav a:hover { background: var(--hover-color); color: var(--accent-color); padding-left: 20px; text-decoration: none; }
.sidebar-nav a.active { background: var(--hover-color); color: var(--accent-color); font-weight: 600; }
.sidebar-nav a.active::before {
  content: ''; position: absolute; left: 0; top: 4px; bottom: 4px;
  width: 3px; background: var(--accent-color); border-radius: 0 3px 3px 0;
}
.sidebar-nav a .emoji { font-size: 1rem; }
body[data-page="music"]   { --accent-color: #9c27b0; }
body[data-page="gaming"]  { --accent-color: #4CAF50; }
body[data-page="sports"]  { --accent-color: #ff5722; }
body[data-page="science"] { --accent-color: #00bcd4; }
body[data-page="history"] { --accent-color: #795548; }
body[data-page="art"]     { --accent-color: #e91e63; }
@media (max-width: 1024px) {
  #sidebar {
    position: fixed; left: 0; top: 120px;
    height: calc(100vh - 120px); z-index: 900;
    transform: translateX(-100%);
    width: 240px !important; min-width: 240px !important;
  }
  #sidebar.open { transform: translateX(0); box-shadow: 4px 0 20px rgba(0,0,0,0.15); }
}