Why do CSS styles of different Drupal 7 pages overlap each other?

Question

CMS

There are two pages: main and example.com/page.
The master page template has a styles.css file specified, the page page has a page.css file
But when the master page is loaded, the styles from page.css are applied to the styles of the master page!
Why is this and how to fix it?
PS All styles are connected via .info file.

Answer 1

style priorities:
seodon.ru/css/priority-stilej.php
most likely page.css is included later styles.css