client/src/index.scss

:root {
  --main-color: #1F1F1F;
  --secondary-color: white;
  --third-color: #8b8b8b;
  --main-text-color: #3e5869;
  --secondary-text-color: #b0c7d6;
  --send-message-form: #F5F5F5;
}

html, body {
  height: 100%;
  margin: 0;
  padding: 0;
  font-family: 'Open Sans', sans-serif;
  font-weight: 200;
  color: #3e5869;
}

#root {
  height: 100%;
}

.app {
  display: grid;
  height: 100%;
  grid-template-columns: 320px 1fr;
  grid-template-rows: 40px 50px 1fr 1fr 92px;
  grid-template-areas:
      "h m"
      "n m"
      "r m"
      "r m"
      "r m";
}

.messenger {
  grid-area: m;
  display: grid;
  grid-template-rows: 73px 1fr 72px;
  grid-template-areas:
      "h"
      "m"
      "i";
}

.MuiContainer-root {
  padding-bottom: 32px;
}

.login {
  background-color: var(--main-color);
}

.header-section {
  grid-area: h;
}

.main-search {
  grid-area: n;
}

.rooms-list {
  grid-area: r;
}

.conversation-header {
  grid-area: h;
}

.message-list {
  grid-area: m;
  position: relative;
}

.message-list-inner {
  max-height: 100%;
  position: absolute;
  overflow-y: auto;
  width: 100%;
  bottom: 0;
  padding: 24px;
}

.send-message-form {
  grid-area: i;
}

/* REST OF CSS */

.header-section {
  background-color: var(--main-color);

}

.simple-menu {
  color: var(--send-message-form);
}

.main-search-input {
  padding: 8px;
  background-color: var(--secondary-color);
  width: 100%;
}

.rooms-list {
  overflow-y: scroll;
}
.rooms-list .MuiListItemText-primary,
.rooms-list .MuiListItemText-secondary
{
  overflow: hidden;
  text-overflow: ellipsis;
}

.list-placeholder {
  margin: 32px auto;
  width: 256px;
  text-align: center;
}

.list-placeholder .subtitle {
  color:#a0a0a0;
}

.message {
  margin: 15px 0;
}

.message .message-username {
  font-size: 11px;
  font-weight: bold;
  color: var(--secondary-color);
  opacity: 0.9;
  margin-bottom: 6px;
}
.message .message-text {
  background: var(--third-color);
  color: var(--secondary-color);
  display: inline;
  padding: 8px 16px;
  border-radius: 16px;
}

.send-message-card {
  border-radius: 8px;
  margin: 16px;
}

.help-text {
  position: absolute;
  top: 10px;
}