style.css

.chat {
    width: 500px;
    height: 90%;
    position: fixed;
    overflow: scroll;
}

.actions {
    position: fixed;
    bottom: 0;
    display: block;
    width: 100%;
}

.actions input {
    height: 30px;
    display: block;
    width: 100%;
    outline: 0;
    border-top: 0;
    border-left: 0;
    border-right: 0;
}

.messages div {
    max-width: 60%;
    display: block;
    margin: 5px;
    padding: 10px;
    border-radius: 7px;
}

.messages .bot {
    text-align: left;
    margin-right: auto;
    background: lightblue;
}

.messages .self {
    text-align: right;
    margin-left: auto;
    background: #DDD
}

body {
    font-family: Arial, Helvetica, sans-serif;
}

* {
    box-sizing: border-box;
}


/* Button used to open the chat form - fixed at the bottom of the page */

.open-button {
    background-color: #555;
    color: white;
    padding: 16px 20px;
    border: none;
    cursor: pointer;
    opacity: 0.8;
    position: fixed;
    bottom: 23px;
    right: 28px;
    width: 280px;
}


/* The popup chat - hidden by default */

.chat-popup {
    display: none;
    position: fixed;
    bottom: 0;
    right: 15px;
    border: 3px solid #f1f1f1;
    z-index: 9;
}


/* Add styles to the form container */

.form-container {
    max-width: 520px;
    padding: 10px;
    background-color: white;
}


/* Full-width textarea */

.form-container textarea {
    width: 100%;
    padding: 15px;
    margin: 5px 0 22px 0;
    border: none;
    background: #f1f1f1;
    resize: none;
    min-height: 200px;
}


/* When the textarea gets focus, do something */

.form-container textarea:focus {
    background-color: #ddd;
    outline: none;
}


/* Set a style for the submit/send button */

.form-container .btn {
    background-color: #4CAF50;
    color: white;
    padding: 16px 20px;
    border: none;
    cursor: pointer;
    width: 100%;
    margin-bottom: 10px;
    opacity: 0.8;
}


/* Add a red background color to the cancel button */

.form-container .cancel {
    background-color: red;
}


/* Add some hover effects to buttons */

.form-container .btn:hover,
.open-button:hover {
    opacity: 1;
}