body{
    background: hwb(204 88% 4%);
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

h2{
    color: #f5f1f0;
    margin-bottom: 15px;
}

button{
    border-radius: 8px;
    border: none;
    padding: 15px;
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
}

.keys{
    display: grid;
    grid-template-columns: repeat(4,68px);
    gap: 10px;
}

.calculator{
    font-family: Arial, Helvetica, sans-serif;
    text-align: center;
    background: hsl(0, 0%, 15%);
    border-radius: 15px;
    width: 300px;
    padding: 20px;
}

#display{
    width: 93%;
    background: hsl(0, 0%, 30%);
    padding: 10px;
    text-align: right;
    margin-bottom: 15px;
    font-size: 3rem;
    color: white;
    overflow: hidden;
    border-radius: 8px;
    border-color: rgb(240, 228, 228);
}

button:hover{
    background: hsl(0, 0%, 40%);
}

button:active{
    background: hsl(0, 0%, 60%);
}

.operator-btn{
    background: hsl(35, 100%, 75%);
}

.operator-btn:hover{
    background: hsl(35, 100%, 45%);
}

.operator-btn:active{
    background: hsl(35, 100%, 65%);
}

.equal-btn{
    width: 145px;
    border-radius: 10px;
    background-color: green;
}

.equal-btn:hover{
    background-color: rgb(213, 19, 19);
}

.equal-btn:active{
    background-color: rgb(255, 19, 19);
}