Starting with version 3.2 of the ArcGIS API for JavaScript, developers must include an additional Cascading Style Sheet (CSS) file: esri.css.
The URL for this file is:
// versions 3.11 and forward
<link rel="stylesheet" href="https://js.arcgis.com/API-VERSION/esri/css/esri.css&...
The esri.css file does not include the CSS for various Dojo widgets or themes like tundra or claro; those files must be included separately. Exceptions are the Grid and RangeSlider, which are used by widgets in the API. Grid styles must be explicitly included.
For instance, this CSS file would be i...