*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    text-decoration: none;
    list-style: none;
}
body{
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
    background-color: #dddddd;
}
#calculator{
    font-family: 'Gill Sans', 'Gill Sans MT', Calibri, 'Trebuchet MS', sans-serif;
    background-color: rgb(97, 97, 97);
    border-radius: 30px;
    max-width: 500px;
    overflow: hidden;
    box-shadow: 10px 10px 10px 1px gray;
}

#display{
    width: 100%;
    padding: 20px;
    font-size: 5rem;
    text-align: left;
    border: none;
    background-color: rgb(77, 76, 76);
    color: white;
    box-shadow: inset 10px 10px 50px 1px black;
}

#keys{
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    padding: 25px;
}

button{
    width: 100px;
    height: 100px;
    border-radius: 20px;
    border: none;
    background-color: rgb(46, 46, 46);
    color: white;
    font-size: 2rem;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.1s linear;
}
button:hover{
    transform: translateY(-5px);
    background-color: rgb(78, 78, 78);
    box-shadow: 10px 10px 10px 1px rgb(49, 49, 49);
}
button:active{
    transform: translateY(5px);
    background-color: rgb(102, 102, 102);
    box-shadow: none;
}

.operator-btn{
    color: rgb(88, 88, 88);
    background-color: lightblue
}
.operator-btn:hover{
    background-color: rgb(134, 204, 228);
}
.operator-btn:active{
    background-color: rgb(109, 193, 221);
}