App.css

* {
  box-sizing: border-box;
}

html, body {
  height: 100%;
}

#root {
  display: flex;
  align-items: center;
  justify-content: center;
  background: #f8f8f8;
  height: 100%;
}

.container {
  display: flex;
  flex-direction: column;
  width: 540px;
  height: 680px;
  background: white;
  border-radius: 16px;
  box-shadow: 0 2px 16px rgba(0, 0, 0, 0.0);
}

.messages {
  flex: 1;
  position: relative;
}

.messages-scroller {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  display: flex;
  flex-direction: column;
  padding: 16px;
  overflow-y: scroll;
}

.message {
  align-self: flex-start;
  margin-top: 4px;
  padding: 8px 12px;
  max-width: 240px;
  background: #f1f0f0;
  border-radius: 16px;
  font-size: 14px;
}

.message.me {
  align-self: flex-end;
  background: #f19e38;
  color: white;
}

.chat-bar {
  height: 64px;
  border-top: 1px solid #ddd;
}

.chat-bar form {
  height: 100%;
  padding: 16px;
}

.chat-bar form input {
  width: 100%;
  height: 32px;
  padding: 8px 16px;
  border: 1px solid #ddd;
  border-radius: 16px;
  outline: none;
}

.chat-bar form input:focus {
  border: 1px solid #f19e38;
}