*{
    margin:0;
    padding: 0;
    box-sizing: border-box;
}
.buttons{
    margin: 10px;
    display:flex;
    justify-content: center;
}
button{
    display: block;
    font-size: 1.5em;
    border: 2px solid black;
    background: white;
    box-shadow: 0 0 3px black;
    border-radius: 10px;
    padding: 10px;
    cursor: pointer;
}
.resultado h1{
    opacity: 0;
    transition: 0.3;
}
.container{
    margin: 20px auto;
    display: grid;
    max-width: 300px;
    grid-template-columns: 1fr 1fr 1fr;
    grid-template-rows: 100px 100px 100px;
}
.container div{
    border-left: 3px solid black;
    border-bottom: 3px solid black;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 6em;
    font-family: monospace;
}
.container div:nth-child(1),
.container div:nth-child(4),
.container div:nth-child(7){
    border-left: none;
}
.container div:nth-child(7),
.container div:nth-child(8),
.container div:nth-child(9){
    border-bottom: none;
}
h1{
    text-align: center;
    font-family: 'Calibri';
    font-size: 3em;
}