polygon - Changing categorized style color simultaneously in QGIS

I work with this polygon: and i need that all features will be with border line only without fil colors. I seek for a way to do it simultaneously to all the categorized features, and not treat every

QGIS:Becoming a GIS Power User

Part II A: More Symbology – The Geospatial Humanities

Massachusetts Institute of Technology Department of Urban Studies

Advanced QGIS (Full Course Material)

polygon - Same symbology and color for all attributes of layer in

Part II A: More Symbology – The Geospatial Humanities

1.8. QGIS visualization for vectors — GIS4Schools documentation

4.3. Lesson: Classification — QGIS Documentation documentation

Symbolising data - QGIS Tutorial

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QGIS IeQGIS

style - QGIS ordering categorized styling doesn't work

Symbolising data - QGIS Tutorial

Merge two or more polygons, points or polyline of Shapefile