style.css

//Note that we'll be using several !important tags in this file to override Bootstrap styles at some places for a unified and modern look which is completely usual.

body {
      background: #001a3f !important; //dark bg default, change it according to your needs.
    }
    .container {
      max-width: 100%;
    }
    #chatbox {
      display: flex;
      flex-direction: column;
    }
    .assistant-message {
      align-self: flex-start;
      background-color: #ffffff1a;
      color: #fff;
      padding: 10px;
      overflow: auto;
      border-radius: 0px 25px 25px 25px;
    }
    .user-message {
      align-self: flex-end;
      background-color: #ffffff1a;
      color: #fff;
      padding: 10px 10px 0px 10px;
      overflow: auto;
      border-radius: 25px 0px 25px 25px;
      margin: 10px 0;
    }
    .typing-indicator {
      align-self: center;
      background-color: #ffffff1a;
      color: #fff;
      padding: 10px;
      overflow: auto;
      border-radius: 15px 15px 15px 15px;
    }
    .typing-indicator::after {
      content: "";
      animation: typing 1s infinite;
    }
    .form-control {
    display: block;
    width: 100%;
    padding: 15px 20px;
    font-size: 1rem;
    font-weight: 400;
    line-height: 1.5;
    color: #212529;
    background-color: transparent !important;
    background-clip: padding-box;
    border: 0px solid red !important;
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    border-radius: 0.375rem;
    transition: border-color .15s ease-in-out,box-shadow .15s ease-in-out;
}
.form-control:focus {
    color: white !important;
    background-color: transparent !important;
    border-color: transparent;
    outline: 0 !important;
    box-shadow: none !important;
}
    @keyframes typing {
      0% {content: "Typing";}
      25% {content: "Typing.";}
      50% {content: "Typing..";}
      75% {content: "Typing...";}
    }