* {
    margin: 0;
    padding: 0;
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
}

body {
    background-image: url('pay-937884_640.jpg');
    background-size: cover;
}

.calculatorName {
    font-size: 2rem;
    text-transform: uppercase;
    text-align: center;
    border-radius: 10px;
    width: 400px;
    margin: 10px auto;
    padding: 20px;
    background-color: white;
}

.calculator {
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-align: start;
    -ms-flex-align: start;
    align-items: flex-start;
    -webkit-box-pack: space-evenly;
    -ms-flex-pack: space-evenly;
    justify-content: space-evenly;
    -ms-flex-wrap: wrap;
    flex-wrap: wrap;
    width: 90%;
    max-width: 400px;
    height: 90vh;
    max-height: 700px;
    margin-top: 10px;
    position: relative;
    left: 50%;
    top: 30px;
    -webkit-transform: translateX(-50%);
    -ms-transform: translateX(-50%);
    transform: translateX(-50%);
    border-radius: 10px;
    background-color: #fff;
    -webkit-box-shadow: 0 0 4px 4px black;
    box-shadow: 0 0 4px 4px black;
    background-color: rgb(1, 79, 19);
}

.calculator__display {
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-pack: end;
    -ms-flex-pack: end;
    justify-content: flex-end;
    -webkit-box-align: center;
    -ms-flex-align: center;
    align-items: center;
    padding: 10px;
    /* -ms-flex-preferred-size: 400px;
    flex-basis: 400px; */
    /* I had to force width in spite of flex basis because of the display, on the phone was too long */
    width: 400px;
    height: 15%;
    margin-top: 5px;
    margin-left: auto;
    margin-right: auto;
    background-color: cadetblue;
    border: 2px solid silver;
    border-radius: 10px;
    background-color: #000;
    color: #fff;
    font-size: 2rem;
    text-align: right;
}

.calculator__btn {
    display: block;
    -ms-flex-preferred-size: 32%;
    flex-basis: 32%;
    height: 11%;
    cursor: pointer;
    border: 3px solid silver;
    border-radius: 10px;
    font-size: 2.5rem;
    background-color: #35509D;
    -webkit-transform: scale(0.9);
    -ms-transform: scale(0.9);
    transform: scale(0.9);
    color: #fff;
}

.calculator__btn--hide {
    opacity: 0;
    font-size: 0.1rem;
}

.calculator__btn:hover {
    -webkit-transform: scale(0.95);
    -ms-transform: scale(0.95);
    transform: scale(0.95);
}

@media(min-width:1024px) {
    body {
        background-image: url('pay-937884_1920.jpg');
    }
}