Keynote for Mac: Change the background of Keynote slides
You can change the background color or image of individual slides in a presentation, or change the background of a master slide to apply the change to all slides that use the master.
In the Format sidebar, click the disclosure triangle next to Background, then choose one of the following:
A color designed to match your theme: Click the color well next to Background, then select a color.
Any color: Click the pop-up menu and choose Color Fill, then click the color wheel to open the Colors window, where you can choose any color.
A two-color gradient fill: Click the pop-up menu and choose Gradient Fill, then choose colors. The left side of the color well shows colors that match the theme; the color wheel opens the Colors window, where you can choose any color.
A custom gradient: Click the pop-up menu and choose Advanced Gradient Fill, then click the color stops below the slider to choose colors. You can slide the color stops and use the other controls to change the blend, angle, and direction of the gradient.
An image: Click the pop-up menu and choose Image Fill, or choose Advanced Image Fill if you want to add a tint to the image. Click Choose, navigate to your photos, then double-click an image to add it. To change how the image fills the background, click the pop-up menu above the Choose button, then choose an option:
Original Size: Places the image without altering the image’s original dimensions. To resize the image, drag the Scale slider.
Stretch: Resizes the image to fit the slide’s dimensions, which might change the image’s proportions.
Tile: Repeats the image on the slide. To resize the image, drag the Scale slider.
Scale to Fill: Makes the image larger or smaller to leave no space around the image.
Scale to Fit: Resizes the image to fit the slide’s dimensions, but maintains the image’s proportions.
If you chose Advanced Image Fill, click the color well or color wheel to select a tint color. Adding a tint makes the image more transparent.