h1 {
    color: green;
    text-align: center;
}
html {
    background-color: black;
}
.calculator {
    width: 300px;
    background-color: gray;
    position: relative;
    left: 40%;
}
.panel{
    background-color: gold;
    color: black;
    height: 70px;
    width: 280px;
    margin-bottom: 5px;
    border-radius: 5px;
    position: relative;
    left: 10px;
    top: 3px;
    font-size: 20px;
    
}
button{
    width: 70px;
    height: 70px;
    position:relative;

}
.buttons {
    width: 300px;
    height: 355px;
    background-color: darkgreen;
    border-radius: 10px;    
}
.action {
    background-color: blue;
}