You can create a file using a simple text editor for custom css and name it using this format: templatefolder-custom.css (e.g., rt_kirigami-custom.css or gantry-custom.css). For this issue add this to the custom CSS filebody .logo-block #rt-logo {margin: 0 auto;}
More Info here:
www.gantry-framework.org/documentation/j...custom_stylesheet.md
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