$bg: #1c1c1c;

html, body {
  margin: 0;
  padding: 0;
  background: #1c1c1c;
  color: white;
}

body {
  height: 100vh;
  display: flex;
}

#root {
  height: 100vh;
  width: 100vw;
  display: flex;
}

.sidebar {
  flex: 0 0 15vw;
}

.main {
  flex: 1 1 auto;
}

.sidebar, .main {
  display: flex;
  flex-direction: column;

  div:nth-child(2) { // Room list & Chat
    flex: 1 1 auto;
    overflow-y: auto;
  }
}

.filter {
  background: red;
}

.list {
  background: purple
}

.info {
  background: lime;
}

.chat {
  background: blue;
}