What is the issue : When you navigate to http://localhost/students, you will see list of students as shown below 
Click on any student name. For example when you click on Mark, you will see mark details and the URL in the address bar is http://localhost/students/1
At this point if you refresh the page by pressing CTRL + F5 or CTRL + R, the student details disappear and the page will be renedered as shown below. 
To see the errors, launch the Browser Developer Tools by pressing F12. 
To fix this issue all you have to do is place the <base href="/"> element just below the<title> element in the head section of index.html page.