style.css

*{
    margin: 0;
    padding: 0;
}

body{
    background-image: linear-gradient(white, blue);
    height: 97vh;
}

.logo img{
    width: 50px;
    height: 50px;
    margin: auto;
    margin-top: 20px;
    align-items: center;
    display: flex;
}

.head h1{
    font-size: 24px;
    margin: auto;
    margin-top: 15px;
    margin-bottom: 15px;
    text-align: center;
}

.container{
    max-width: 900px;
    height: 500px;
    border-radius: 25px;
    margin: auto;
    border: 2px solid black;
    overflow: auto;
    scroll-behavior: smooth;
}

.message{
    margin: 10px;
    padding: 10px;
}

.container .left{
    border: 2px solid black;
    border-radius: 20px;
    font-size: 20px;
    padding: 8px 30px;
    float: left;
    clear: both;
    display: inline;
    position: relative;
}

.container .mid{
    color: black;
    font-weight: 900;
    font-size: 20px;
    opacity: .6;
    border-radius: 20px;
    display: flex;
    margin: auto;
    width: 90%;
    padding: 5px 20px;
    justify-content: center;
}

.container .right{
    background-color: rgb(103, 103, 241);
    border: 2px solid black;
    border-radius: 20px;
    float: right;
    font-size: 20px;
    padding: 8px 30px;
    color: white;
    clear: both;
}

.send{
    display: flex;
    width: 100%;
    /* margin: auto; */
    margin-top: 5px;
    justify-content: center;
}

.send .box .input{
    width: 50vw;
    font-size: large;
    padding: 6px 11px;
    display: flex;
    background-color: white;
    border-left: 2px solid black;
    border-top: 2px solid black;
    border-bottom: 2px solid black;
    border-top-left-radius: 10px;
    border-bottom-left-radius: 10px;
    margin: auto;
}

.send .btn{
    width: 50px;
    border-right: 2px solid black;
    border-top: 2px solid black;
    border-bottom: 2px solid black;
    border-top-right-radius: 10px;
    border-bottom-right-radius: 10px;
    background-color: rgb(93, 93, 250);
    color: white;
    justify-content: center;
    align-items: center;
    font-size: 14px;
}

.send .btn:hover{
    background-color: rgb(61, 61, 224);
    color: white;
    cursor: pointer;
}