style.css

body {
    font: 400 16px/1.3 Roboto,Trebuchet MS,Helvetica,Arial,sans-serif;
    justify-content: center;
    background-size:contain;
    
    display: block;
    background-image:url('https://wallpaperset.com/w/full/3/2/5/480582.jpg')
    
}


.bordered-text {
   
    
    -webkit-text-stroke: 0.25px white;
  
  
  }

header {
    
    background: linear-gradient(to right, #ebeff254, hsla(232, 80%, 67%, 0.177));
    color: #1a1884;
    padding: 28px;
    text-align: center;
}


#space{
    display: block;
    height: 60px;
    padding: 60px;
}

#pad{
    padding-left: 60px;
    padding-right: 60px;
    
}
#res {
    display: block;
    font-size: 28px;
    height: 40px;
    background: linear-gradient(to right, #ffffffb7,#3e68d395);;
    border: 2px solid rgb(196, 187, 187);
    box-sizing: border-box;
}

#btns {
    display: block;
    overflow: hidden;

}

#btns button {
    display: block;
    float: left;
    width: 25%;
    height: 50px;
    font-size: 25px;
    background: rgba(0, 0, 0, 0.636);
    color: rgb(245, 235, 235);
}

#btns #btn0,
#btns #btn1 {
    background-color: rgba(102, 197, 231, 0.84);
    color: rgb(3, 35, 35);
}


#btns #btnClr,
#btns #btnEql {
    background-color: rgba(7, 102, 100, 0.875);
    color: rgb(255, 255, 255);
}

footer {

    background: linear-gradient(to right, #ebeff22d, #687aee4a);
    color: #01000a;
    padding:5px;
    
    transition: all;
}




  button:hover{
    border-color:#cfe6eb;
    color: white;
    box-shadow: 0 0.5em 0.5em #57bfd9;
    
    transform : translateY(-0.25em);
  }