How to add a drop down menu - css

Question

Using just CSS can somebody please show me how to add a drop down menu on the Big Cartel Neat theme.
Need help on adding subheading to the main heading for example...
About The Brand (hover mouse and subheadings appear)
Brands Philosophy
About the Founder
About Us
header .sections {
display: -webkit-flex;
display: -ms-flexbox;
display: flex;
-ms-flex-align: center;
-webkit-align-items: center;
align-items: center;
-ms-flex-pack: center;
-webkit-justify-content: center;
justify-content: center;
padding: 0 32px;
position: relative;
width: 50%;
z-index: 97;
}
header .sections .navigation {
display: -webkit-flex;
display: -ms-flexbox;
display: flex;
-ms-flex-align: center;
-webkit-align-items: center;
align-items: center;
list-style: none;
margin: 0;
padding: 0;
}
header .sections .navigation li {
display: block;
margin: 0 16px;
}
header .sections .navigation li a {
padding: 4px 0;
text-align: center;

Answer 1

I'm new to CSS also, but I'll try my best to help. This is what you can do.
#heading:hover .subheadings{
display: block
}
Basically, your #heading id (You'll probably only have 1, so you should use id.) is the "About The Brand" text. When you add hover, you can make something happen when the mouse hovers over the main heading. In this case, you can add the class .subheadings right after it and display it as a block element (The 3 subheadings will be stacked on top of each other). This will cause the subheadings to appear after you hover over the main heading. Basically, it's like an if then statement in Python.
I hope this explanation helps! Good luck :)