.content {
  height: 30px;
  display: flex;
  align-items: center;
  padding: 0px 10px;
}
.tool_icon {
  height: 20px;
  width: 20px;
  background-size: 100%;
  background-repeat: no-repeat;
  background-position: center;
  margin-right: 10px;
}
.tool_icon:hover {
  cursor: pointer;
}
.emoji {
  background-image: url('../../image/emoji_black.png');
}
.emoji:hover {
  background-image: url('../../image/emoji_light.png');
}
.file {
  background-image: url('../../image/file_black.png');
}
.file:hover {
  background-image: url('../../image/file_light.png');
}
.pic {
  background-image: url('../../image/pic_black.png');
}
.pic:hover {
  background-image: url('../../image/pic_light.png');
}