body {
  margin: 0;
  font-family: sans-serif;
}
header {
  background: #eee;
  padding: 10px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
header img {
  height: 50px;
}
#container {
  display: flex;
  height: calc(100vh - 70px);
}
#sidebar {
  width: 200px;
  background: #f8f8f8;
  padding: 10px;
  overflow-y: auto;
}
#sidebar ul {
  list-style: none;
  padding: 0;
}
#sidebar li {
  padding: 5px;
  cursor: pointer;
}
#sidebar li.selected {
  background: #cce5ff;
}
#main {
  flex: 1;
  padding: 10px;
  position: relative;
}
#photos {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}
#photos img {
  width: 200px;
  height: 200px;
  object-fit: cover;
}
#notice {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: #666;
  display: none;
}