[ADD] some fixes & improvements of main

main/static/main/main.css

main/templates/main/blocks/homepage_carousel_block.html

main/templates/main/blocks/news_block.html

main/templates/main/blocks/regions_block.html

main/templates/main/blocks/twitter_block.html

main/templates/main/includes/form_button.html

main/templates/main/includes/href_button.html

main/templates/main/includes/href_button_secondary.html

main/templates/main/includes/newsletter_section.html

main/templates/main/includes/plain_button.html

main/templates/main/includes/twitter_widget.html

main/templates/main/main_articles_page.html