body, html { 
    background-color: rgb(1, 48, 48);
    height: 100%; 
    margin: 0; display: 
    flex; justify-content: 
    center; align-items: center; 
}
.main {
    background-color: gray;
    border: 2px solid rgb(0, 0, 0);
    flex-direction: column;
    border-radius: 10px;
    display: flex;
    gap: 2.5px;
    width: 270px;
    height: 400px;
    margin: 0 auto;
    padding: 5px;
}

.layer {
    background-color: rgb(120, 120, 120);
    display: flex;
    flex-direction: row;
    flex: 1;
    gap: 2.5px;
}
.sub {
    display: flex;
    flex: 1;
    justify-content: center;
    align-items: center;
    border-radius: 5px;
    color: white;
    font-size: 20px;
}
.screen{    
    box-sizing: border-box;
    display: flex;
    align-items: center;
    flex-direction: row-reverse;
    font-family: monospace;
    border: 2px solid rgb(66, 9, 9);
    border-radius: 8px;
    font-size: 44px;
    margin-bottom: 15px;
}

.number {
    background-color: rgb(49, 32, 32);
}
.operate {
    background-color: rgb(59, 42, 42);
}
.one>.sub,.equals,.dot {
    background-color: rgb(33, 46, 46);
}
footer {
    background-color: rgb(6, 53, 53);
    position: fixed;
    right: 0;
    left: 0;
    bottom: 0;
    text-align: center;
    height: 20px;
    font-family: monospace;
    font-size: 18px;
}
footer>a {
    text-decoration: none;
    color: rgb(51, 51, 158);
}