body, html {
                height: 100%;
            }

            body {
                font-family: monospace;
                font-weight: bold;
                font-size: 20px;
                margin: 0;
                overflow: hidden;
                background-color: #222
            }

            body, #box {
                display: flex;
                align-items: center;
                justify-content: center;
            }

            #box {
                color: #aaa;
                height: 20em;
                width: 30em;
                max-width: 80%;
                max-height: 80%;
                background-color: #333;
                border-radius: 0.4em;
                border: 2px solid #555;
                position: relative;
                flex-direction: column;
                transition-duration: 0.2s;
                overflow: hidden
            }

            #box:hover, #box[drag] {
                border-color: #38f;
                color: #ddd
            }

            #input {
                cursor: pointer;
                position: absolute;
                left: 0;
                top: 0;
                width: 100%;
                height: 100%;
                opacity: 0
            }

            #display {
                width: 100%;
                height: 100%
            }

            select, button {
                padding: 0.6em 0.4em;
                margin: 0.5em;
                width: 15em;
                max-width: 100%;
                font-family: monospace;
                font-weight: bold;
                font-size: 16px;
                background-color: #444;
                color: #aaa;
                border-radius: 0.4em;
                border: 1px solid #555;
                cursor: pointer;
                transition-duration: 0.2s
            }

            select:hover, button:hover {
                background-color: #666;
                color: #ddd
            }