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

body {
    height: 100vh;
    width: 100vw;
    display: grid;
    justify-content: center;
    align-items: center;
    background-color: #6b4040e7;
}

div {
    background: linear-gradient(191.34deg, #17181a -4.95%, #17181a 103.74%);
    width: 375px;
    height: 568px;
    border-radius: 35px;
    padding: 20px;
    display: grid;
    grid-template-columns: repeat(4, 1fr) ;
    grid-template-rows: repeat(7, 1fr);
}

input {
    font-size: 48px;
    background-color: #17181a;
    border: none;
    outline: none;
    text-align: right;
    padding-top: 50px;
    color: #ffffff;
    grid-row: 1/3;
    grid-column: 1/5;
}

button {
    font-size: 24px;
    border: none;
    margin: 7px;
    border-radius: 10px;
    cursor: pointer;
    color: #ffffff;
}

button:hover {
    opacity: 0.7;
}

.black-button {
    background: #303136;
}

.blue-button {
    background: #005db2;
}

.equal {
    background: #1991ff;
    grid-row: 6/8;
    grid-column: 4/5;
}

.gray-button {
    background: #616161;
}

.zero {
    grid-column: 1/3;
}