With the background set at 100% width, it will fill the text area left to right, but the full background image won’t show if the text is not long enough. You can add hard breaks to add “length” to the content. HOWEVER, note that this length may vary on different devices as the width of the content changes. (Narrower content will take more length to display.) Be careful not to add content at the bottom of the hard breaks, since there’s no way to gauge where this content will appear in relation to the background.
If the content is too long for the background, try choosing a different background size. “Cover” cover the full available space, but may cut out parts of the background. “Contain” will display the full background image, but may not show the background behind all parts of the content. Just find the one which works best for your needs.
