Your application automatically gets Lightning Design System styles and design tokens if it extends force:slds. This method is the easiest way to stay up to date and consistent with Lightning Design System enhancements.
To extend force:slds:
<aura:application extends="force:slds"> <!-- customize your application here --> </aura:application>
When you extend force:slds, the version of Lightning Design System styles are automatically updated whenever the CSS changes. If you want to use a specific Lightning Design System version, download the version and add it to your org as a static resource.
To download the latest version of Lightning Design System, generate and download it.
We recommend that you name the Lightning Design System archive static resource using the name format SLDS###, where ### is the Lightning Design System version number (for example, SLDS203). This lets you have multiple versions of the Lightning Design System installed, and manage version usage in your components.
<aura:component> <ltng:require styles="{!$Resource.SLDS203 + '/assets/styles/lightning-design-system-ltng.css'}"/> </aura:component>