Question in html property and css


i am nearly finishing my course but suck at 92% now
could you please ans my question?

Q1:I don’t quite sure what pix mean. For example, every time I write px, I have to refresh it to see the result how should i understand px to get better sense of it?

Q2: I am not so sure what clear property mean, as I don’t see much differce after refreshing

Q3: I don’t quite understand what rel mean? Is it considered as a name of the link of href

Q4: in previous lesson, we learn div as a tool to group things and class= sth is considered as a name of selector, but div class"row" mean the same thing ? Also, I am not so sure the meaning of col-md-4 mean as well.


Px stands for pixels which is a measure of size

Rel stands for related

Is a class in bootstrap

You see div is as you say to group things then you add a class so that you can select the class and style it .. So you think of the class as a name so when you want to style it you use the name (your class)

It is so that none of the div's overlap or touch each other


thank you for your fast reply

so how should i interpret rel="stylesheet" href="main.css" ?

so it mean all div group in learn-more would not touch each other? but what clear : both mean mean? i dont know what both here mean ?


also, class="row" here mean i create a class of row or there is already a class of row and i just call it out?

sorry that i have learnt c++ and java before, class here got me a bit confused.


learn more about the clear element her- click here
For more information on links (href &rel definition) click here
HTML & CSS Glossary

It depends if you need to add another one to your HTML or you need to style it,
But if I'm not mistaken in this lesson you need to style it so you will select it in your CSS

.row {


Hope this clears up all your questions

Did you learn HTML and CSS before this course ?


thanks for reply
i didnt learn any html before, i am a computer science student and for programming just learnt c++ and java.


okay I suggest you do the course here on CodeCademy HTML and CSS and then come back to this course then only will you understand everything..