fix: variables dropdown wrong color on mouse hover (#1286)

Author: alexbarros

src/ydata_profiling/report/structure/report.py

@@ -377,7 +377,7 @@ def get_report_structure(config: Settings, summary: dict) -> Root:
                     anchor_id="variables-dropdown",
                     id="variables-dropdown",
                     is_row=True,
-                    classes=["btn", "btn-secondary", "dropdown-toggle"],
+                    classes=["dropdown-toggle"],
                     items=list(summary["variables"]),
                     item=Container(
                         render_variables_section(config, summary),