Check existing website for a simple inconsistency among common browsers

I have a site made in .NET and ASPX, located here temporarily: [login to view URL] If you open the site in Firefox, Chrome and Edge or Internet Explorer, it behaves differently in all of them. In Firefox, an ugly border of every single big cell is shown. In Chrome, there is no border at all. In MS Edge and IE, it shows only a delimiter between "articles" on the site. This project is just to tell me what needs to be changed, in either HTML code or CSS to show a smaller horizontal line (not a line accross like right now, but some what smaller) dividing articles of different dates, for example, in the picture shown below I want a horizontal line only on top of the 8/18/2017; right now you see two lines, the line under "Read More" needs to be removed. The change has to behave exactly the same on those browsers plus Safari. You can get existing HTML and CSS directly from the site. As a bonus, if you show me how to put some extra code that will hide/show one section of this site with a click of the button, using JS or what not, without calling the server again, extra bonus payment will be considered. This is a very fast and simple project, if you know what you are doing you should get this done within minutes. Please message me directly your solution and if correct, the project is yours. Only then I will tell you what the real project is so you can bid appropriately, so consider this a quick paid test so you can get the bigger project. First comes first served, so please be quick!