<!doctype html>
<html lang="en">
    <head>
        <meta charset="utf-8" />
        <meta name="viewport" content="width=device-width, initial-scale=1" />
        <title>write</title>
        <style>
        body {
            background-color: #EEE;
            margin: 0;
            font-size: 16px;
            font-family: Charter, 'Bitstream Charter', 'Sitka Text', Cambria, serif;
            font-weight: normal;
            overflow: hidden;
        }

        textarea {
            box-sizing: border-box;
            width: 100%;
            height: 100vh;
            font-size: 1.5em;
            border: none;
            margin: 0;
            padding: 1em max(calc(50vw - 15em), 1em);
            font-family: inherit;
            overflow: scroll;
            color: #333;
            resize: none;
        }

        textarea:focus {
            outline: none;
        }

        button {
            position: absolute;
            right: 0;
            bottom: 0;
        }

        body:fullscreen button {
            display: none;
        }

        @media print {
            button {
                display: none;
            }
        }
        </style>
    </head>
    <body>
        <textarea autofocus placeholder="Start typing..."></textarea>
        <button>go fullscreen</button>
        <script>
            document.querySelector('button').addEventListener('click', () => {
                if (!document.fullscreenElement) {
                    document.body.requestFullscreen();
                }
            });
        </script>
    </body>
</html>