chatwork.css

#_logo {
  background-image: url(https://slack.global.ssl.fastly.net/22317/img/landing_slack_logo_white.png);
  background-size: contain;
  background-repeat: no-repeat;
  height: 28px;
  width: 88px;
}
#_logo img {
  display: none;
}
.sideContent {
  background: none;
}
.sideContentHl {
  background: none;
}
.chatTimeLine {
  background-image: url(https://pbs.twimg.com/media/BtyqcduCMAAnVRH.png:large);
  background-size: cover;
}
.chatTimeLineMessage .chatTimeLineMessageInner {
  border: none;
}
.chatTimeLineMessageMention {
  background: none;
  border: 2px solid red;
}
.dateContent {
  background: none;
}