!DOCTYPE html
html lang=en
head
    meta charset=UTF-8
    meta http-equiv=X-UA-Compatible content=IE=edge
    meta name=viewport content=width=device-width, initial-scale=1.0
    titleHello Worldtitle
    style
        body {
            display flex;
            justify-content center;
            align-items center;
            height 100vh;
            margin 0;
            font-family Arial, sans-serif;
            background-color #f0f0f0;
        }
        h1 {
            color #333;
        }
    style
head
body
    h1Hello, World!h1
body
html