style.css

*{
    margin:0px;
    padding:0px;
    scroll-behavior: smooth;
    text-align: center;
    font-size: 18px;
    box-sizing: border-box;
}
header{
    color: azure;
}
.header_title{
    text-align: center;
    font-size:xxx-large;
}
body{
    display:block;
    background-image: url("https://media.istockphoto.com/vectors/abstract-vector-background-for-use-in-design-vector-id183954960?k=20&m=183954960&s=612x612&w=0&h=n_Z933ml0u6ZKZJ3KOxKl2tSqNv_N9L1vheVVdBX_5Q=") ;
    background-repeat: no-repeat;
    background-size: 100vw 100vh;
}
.img1{
    height:100vh;
    width: 100vw;
}
.img_logo{
    max-height: 40px;
    max-width: 40px;
    margin-top: 20px;
}
.container {
    background-color:none;
    margin: 0 auto;
    max-width: 400px;
    border-radius: 10px;
    margin-top: 80px;
}
#screen {
    margin: 4px auto;
    width: 100%;
    max-width: 400px;
    height: 4rem;
    text-align: center;
    padding: 5px;
    border: 1px solid black;
    background-color: white;
    border-radius: 10px;
    overflow-x: scroll;
    overflow-y: visible;
    -ms-overflow-style: none;
    scrollbar-width: none;
}
#screen::-webkit-scrollbar {
    display: none;
}

#input, #result {
    margin: auto;
    width: 100%;
    height: 3rem;
    max-width: 768px;
    text-align: left;
    border: none;
}

#input {
    font-size: 20px;
    padding-top: 16px;
    margin-top: -13px;
    word-spacing: 0.07em;
}

#result {
    font-size: 25px;
}

#memory {
    position: absolute;
    font-size: 18px;
    top: 12px;
    right: 14px;
}

button, .bottom-buttons {
    width: 100%;
    height: 3rem;
    border: none;
    border-radius: 10px;
}

button:hover, .bottom-buttons {
    cursor: pointer;
    background-color: #a87861a9;
}

.table {
    margin: auto;
    width: 99%;
    max-width: 768px;
}

td {
    width: 100rem;
    margin:100px;
}

#equals {
    height: 6rem;
    background-color: #3b62e3;
    color: white;
    font-weight: bold;
}

.white {
    font-weight: bold;
    background-color: white;
}

.white:hover {
    background-color: #f0f0f0;
}

.more {
    background-color: #c7c7c7;
}

.more:hover {
    background-color: #bdbbbb;
}

.light {
    background-color: #d9d9d9;
}

.light:hover {
    background-color: #d2d2d2;
}

#equals:hover {
    background-color: #3b4ce3;
}

#topside, #downside {
    height: 5px;
}