* {
    box-sizing: border-box;
}

body {
    font-family: sans-serif;
}

.flex-container-coloumn {
    display: flex;
    flex-direction: column;
    max-width: 800px;
    margin: 0 auto;
    text-align: right;
}

.flex-container-row {
    display: flex;
}

.button {
    flex-basis: 25%;
    font-size: 1.5em;
    text-align: center;
    padding: 40px;
    border: 1px solid black;
    background: -webkit-linear-gradient(top, #d2d2d2, #ddd);
    cursor: pointer;
}

.double {
    flex-basis: 50%;
}

.display {
    color: white;
    width: 100%;
    padding: 10px 20px;
    background-color: #333333;
    border: 1px solid black;
    font-size: 2em;
 }

 .operator, .negative, .equals {
    background: orange;
 }

 .card {
    box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2);
    border-radius: 5px;
    padding: 30px;
    margin-top: 20px;
 }

 .button:hover {
     font-weight: bold;
 }

 .history {
     width: 80%;
     margin: 30px auto 0 auto;
     overflow: scroll;
 }

 table {
     border-collapse: collapse;
     border-spacing: 0;
     width: 100%;
     border: 1px solid #ddd;
 }

 th, td {
     text-align: center;
     padding: 16px;
 }

 th {
     background-color: orange;
     color: white;
 }

 tr:nth-child(even) {
     background-color: #d2d2d2;
 }

 @media screen and (max-width: 513px) {
     .button {
         padding: 10px;
     }

     .history {
         width: 100%;
     }
 }