My div ID is not styling - what am I doing wrong? - html

Question

Question 1: css doesn't style div id
In my html file I've created a div id for a top bar (with text + social links). In the related css file I've created the corresponding style
#topbar {
height: 40px;
width: 100%;
background-color: #383433;
margin: auto;
overflow: hidden;
}
#topbar p {
color: white;
}
<div id="topbar">
<p>Text text text</p>
</div>
The text becomes white, but the height, background color etc. isn't coming through. Am I overlooking something?
Question 2: can I style an image as part of a div id?
Html:
<div id="scroller">
<img src="images/scroller-1.jpg">
</div>
When I add:
#scroller {
max-width: 100%;
height: auto;
}
The image doesn't get responsive / resized.
If I add:
#scroller img {
max-width: 100%;
height: auto;
}
It works.
So elements part of a div-id don't inherit the parent-style?

Answer 1

First of all: If you have two questions, its better to post them seperated. It is cleaner this way.
To question 1: It is working actually. You can run your pasted code snippet. Likely, some other style is overwriting it. Since we cant know which one it is, the only advice i can give you is to write !important behind your css code like this:
height: 40px !important;
This way, nothing can overwrite it except styles that also have an !important tag.
To question 2:
So elements part of a div-id don't inherit the parent-style?
Well, it depends. You can set the font-color of a div then the headlines and p tags in this div will have the same color unless you specify it otherwise like
#scroller{
color:blue;
}
#scroller p{
color:red;
}
Images dont inherit from divs. They are by default always the full image size so you have to specifiy their size seperately if it should be the full width at all times.
If it was helpful to you, pls mark the answer as accepted :)