My project has two dependencies: packageA and packageB. The packageA has dependency of postcss@7.x while the other one packageB has postcss@8.x.
When I used npm install the postcss installed in the first layer in node_modules would be postcss@8.x.
But when I used yarn, some problem popped up. The postcss installed at the first layer became postcss@7.x.
Actually postcss@8.x installed at first layer node_modules totally met my expectation but yarn did not. What make that difference happen ? How could I fix this when the project has to use yarn.