Syntax Error: SassError: Expected selector Error Syntax Error: Expected selector

Today, when I was writing the Vue project, I encountered this error when writing the style:

Because I wrote the scoped attribute in the < style > tag when I wrote the style, the style I wrote could not be passed to the child component, so I wrote a /deep/ to use style penetration to make the child component match the style, but it failed, reported the error in the image.

Later, I found that there was something wrong with /deep/ written by me.

If less is used to preprocess CSS, using /deep/ can accomplish style penetration;

However, the SCSS I use preprocesses CSS, so instead of using /deep/, I should use ::v-deep, so I solved the problem by replacing /deep/ with ::v-deep.