style.css

#secdiv{
   width: 300px;
   border: 2px solid black;
   border-radius: 10%;
   display: flex;
   margin-top: 30px;
   background-color: rgb(56, 51, 51);
   border-bottom: 3px solid rgb(112, 104, 104);
   border-left: 2px solid white;
   border-right: 1px solid rgb(0, 247, 255);
   margin-left: auto;
   margin-right: auto;
}

body{
    background-color: rgb(0, 0, 0);    
}
#firstdiv {
    position: static;
    height:50px ;
    width: 300px;
    border-left: 2px solid rgb(53, 50, 50);
    border-bottom: 2px solid rgb(150, 143, 143);
    border-top: 2px solid white;
    border-right: 1px solid brown;
    border-radius: 10%;
    background-color: black;
    color:red;
    margin: auto;


}
.thdiv{
    width: 20%;
    margin: auto;
    
}
h1{
    font-family: Orbitron,'Courier New', Courier, monospace;
    text-align: center;
}
h2{
    text-align: center;
    width: 80%;
    border-left: 2px solid rgb(196, 185, 185);
    margin-left: 10%;
    border-radius: 10%;
    color: rgb(4, 141, 72);
    background-color: black;
    font-family: Orbitron,'Courier New', Courier, monospace;
    border-bottom: 1px solid rgb(48, 156, 160);
}
h2:hover{
    color:  rgb(0, 255, 128);
    border-bottom: 1px solid  rgb(0, 255, 128) ;
    border-left: 2px solid white;
}
#equal{
    border: 2px solid black;
}
.CAL{
    border-color: transparent;
    background-color: transparent;
    color: rgb(255, 255, 255);
}
.CAL:hover{
    border-color: transparent;
    color: white;
}
#display{
    
    padding: 5px;
    width: 100%;
    font-size: 25px;
    margin-top: 4%;
    text-align: center;
}