Background Paper Effect

Use SVG filters and CSS gradients to create a grainy background effect.

https://css-tricks.com/grainy-gradients/

Create pattern with SVG filter.

https://css-tricks.com/creating-patterns-with-svg-filters/

Paper texture effect.

<div></div>

<svg>
    <filter id='roughpaper'>
        <feTurbulence type="fractalNoise" baseFrequency='0.04 0.06' result='noise' numOctaves="3" />
        <feDiffuseLighting in='noise' lighting-color='#FEFEF9' surfaceScale='1'>
            <feDistantLight azimuth='65' elevation='69' />
        </feDiffuseLighting>
    </filter>
</svg>

html, body {
    width: 100%;
    height: 100%;
    display: flex;
} 

svg {
    width: 0;
    height: 0;
}

div {
    margin: auto;
    width: 650px;
    height: 500px;
    filter: url(#roughpaper);
}