*{
    margin: 0;
    padding: 0;
}

body{
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    background-color: black;
}
h1{
    font-weight: bold;
   text-align: center;
   font-size: 50px;
   color:hsl(35, 100%, 65%);
   transition-timing-function: ease-in-out;
}
h1:hover{
    color:hsl(35, 100%, 75%);
    scale: 1.1;
}

#display{
    width: 100%;
    padding: 25px;
    font-size: 5rem;
    text-align: left;
    color: white;
    background-color:hsl(0, 0%, 30%); 
}
.container{
    font-family: Arial, Helvetica, sans-serif;
    background-color: black;
    border-radius: 50px;
    max-width: 500px;
    overflow: hidden;
    border: 1px solid whitesmoke;
}
#keys{
    display: grid;
    grid-template-columns: repeat(4,1fr);
    gap:10px;
    padding: 25px;
}

button{
    position: relative;
    top: 15px;
    width: 100px;
    height: 100px;
    border-radius: 50px;
    border: none;
    color: white;
    background-color:hsl(0, 0%, 30%);
    font-size: 3rem;
    font-weight: bold;
    cursor: pointer;
}
button:hover{
    background-color:hsl(0, 0%, 40%);
}
button:active{
    background-color:hsl(0, 0%, 50%);
}

.operator-btn{
    background-color:hsl(35, 100%, 55%);
}
.operaotr-btn:hover{
    background-color:hsl(35, 100%, 65%);
}
.operator-btn:active{
    background-color:hsl(35, 100%, 75%);
}

@media only screen and (max-width: 600px) {
    .container{
        width: 100%;
        min-width:200px;
        height: 800px;
    }
    button{
       
        width: 100%;
    
    }
    #display{
     
        font-size: 4rem;
    }
    
}