fix responsive styling

src/components/thread/Pagination.jsx

src/components/thread/Post.jsx

src/styles/profile/Profile.css

src/styles/thread/Form.css

src/styles/thread/ListThreads.css

src/styles/thread/Post.css

src/styles/thread/PreviewThread.css

src/styles/thread/Thread.css

src/styles/topic/Topic.css

src/styles/topic/TopicList.css

src/styles/utility/Button.css

src/styles/utility/Navbar.css