* {
    box-sizing: border-box;
}

body {
    font-family: 'Courier New', Courier, monospace;
}

.largura-padrao {
    width: 200px;
}

[x-calculadora] {
    display: flex;
    flex-direction: column;
    align-items: center;
    border: solid black 2px;
    padding: 20px;
    width: 240px;
    
}

[x-display] {
    border: solid black 2px;
    height: 30px;
    margin-bottom: 10px;
    padding-right: 2px;
    text-align: right;
    align-content: center;
}

[x-botoes] {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-content: center;
    border: solid 2px black;

    user-select: none;
    -webkit-user-select: none; /* Para navegadores WebKit/Blink (Chrome, Safari, Edge) */
    -moz-user-select: none; /* Para o Firefox */
    -ms-user-select: none; /* Para o Internet Explorer */
    
}

[x-botao] {
    border: solid 2px black;
    padding: 15px;
    border-radius: 5px;
    margin: 2px;
}

.numero {
    color: black;
    background-color: lightgray;
}

.numero:hover {
    background-color: #555;
}

.operacao {
    background-color: lightgreen;
}

.operacao:hover {
    background-color: green;
}

.limpar {
    background-color: lightsalmon;
}

.limpar:hover {
    background-color: brown;
}

.numero:active, .operacao:active, .limpar:active {
    color: black;
    box-shadow: 3px 3px 3px #444 ;
}