Open Online Store → Themes → Customize → Theme settings. These controls apply across Compose; an individual section or block can also have its own layout and color controls.
Branding
Upload your Logo image, Inverse logo, and Favicon. The inverse logo provides an alternative for dark or transparent header backgrounds. Preview both header backgrounds and check that each logo remains readable.
Typography
Choose the Body, Subheading, Heading, and Accent fonts. Adjust paragraph and heading sizes and line heights, then preview long headings and mobile text. Reduce heading sizes on mobile controls the smaller mobile heading treatment.
Layout
Set Page width, Page margin, shared corner radii, and border widths. Under Layout → Cards, use Card gap and Layout gap for their shared spacing defaults. Section padding controls the space around a section, rather than the space between its cards.
Products
Configure the New product label's publication window and position. Enable or disable Quick add separately for desktop and mobile. Preview the result on a collection page with single-variant, multi-variant, and sold-out products. Product information comes from Shopify admin; edit the product itself to change its title, price, inventory, or images.
Colors
Create and adjust color schemes, then assign the appropriate Color scheme in each section or block that supports it. Check text, buttons, and links against their backgrounds, especially when content overlays an image or video.
Social media
Enter complete profile URLs under Accounts. Use a Social links block where you want those profiles displayed, such as the footer, and test each link. Under Sharing options, choose which services are offered by supported sharing blocks.
Save and preview
Save your changes and check desktop and mobile previews. Global changes can affect several pages at once; use a duplicate theme when trying a substantial design change.