body, h1 {
    margin: 0;
}
html {
    font-size: 100%;
    box-sizing: border-box;
    font-family: Arial, Helvetica, sans-serif;
    line-height: 1.5;
}
*, *::before, *::after {
    box-sizing: inherit;
}
img {
    max-width: 100%;
}