How does vue.js vue-router control sub-reason elements

who is proficient in vue, teach me how to control the elements of child routing.
case is: two links title 1, title 2, click to display content 1, content 2; then, content 1 has two links: title 11, title 22, click title 11 to add a border to him, display content 11; click title 22 title 11 border to disappear title 22 plus border to display content 22; click on the element in content 22 to change the color of the word; finally, click on the content in content 2 to change the background color.

Mar.01,2021
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b30ac9-2b585.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b30ac9-2b585.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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