@PervasiveRichesLLC
Why do you feel it necessary to be a condescending to a new user asking for help???
@jvtecheto
What you've posted is not valid markup.
<h1>promo.jumbotron {</h1>
border-radius: 30px; padding: 40px; /background-color: rgba(255,255,255,0.75);/ }
First, the correct way to post anything code-related in this forum is by prefacing and postfacing the code with the tilda character `
Example: border-radius: 30px;
padding: 40px;
The tilda will make your code appear as code should.
Second, there are a number of errors in what you posted. <h1>
is an HTML tag, not a CSS rule. You can't stick an open bracket { inside an HTML tag. And you can't style the class promo.jumbotron
by enclosing it in heading tags. There is no need for the slash / before and after the background color rule. I'm not sure if you actually typed these characters, or they somehow appeared when you attempted to copy and paste your code into the forum. You need to understand the difference between HTML and CSS in order to use Bootstrap Studio. The program does not allow you to directly edit the HTML on the page. That is what the components are for. You place the components on the page to "build" your HTML, and then style them either through the visual interface, or by writing code directly in the Styles panel.
Now, if you're trying to style the Jumbotron component, the correct way to do this is to drag it on to your page and then select it in the Overview panel (lower left) then go to the Style panel (center right) and click the Create button, which will create a new CSS class in your custom stylesheet for that component. This will override the standard Bootstrap CSS. Then you can write your new CSS rules (if you like to write your CSS directly.)
Alternatively, you can select the Jumbotron component and go the the Look & Feel tab in the panel at the upper right, and there you will be able to change the background color simply by clicking on the swatch and it will open a floating window where you can use either Hex or rgb (or rgba) to choose your color. The transparency is adjusted by using the slider below the color slider (it will automatically change the rgb to rgba when you move the slider.) This will apply the new background color as an inline style unless you select Create CSS Block from the dropdown menu at the top of the Look & Feel tab. You can also affect the background color of Bootstrap components by clicking the Option tab next to the Look & Feel tab, scrolling to Decorations and changing the background by applying a difference class through the dropdown menu.
There a number of different ways to accomplish the same goal in the this program. I would recommend that if you have no previous experience with coding websites from scratch that before you try to jump in and start building a site, watch the three tutorial videos and follow along with them, building the sample sites that are created in the videos. This will give you a pretty good working knowledge of how the program itself functions. You should also read through all the written tutorials, and as PervasiveRichesLLC pointed out, W3 Schools is a good starting point for learning Bootstrap, along with Bootstrap's own website.
Although Bootstrap Studio is built around the concept of "dragging and dropping" components to build a website, and it does include a few good starter templates, it's really not a great program for a total novice to just throw together a website. It is actually a far more powerful program that is capable of building almost any kind of site you can imagine, and to really get the most out of it, you do need a fairly good understanding of (at the very least) how Cascading Style Sheets work, and a general knowledge of how HTML and CSS combine to create a web page.
There are other programs out there that are less complicated and more (pardon the phrase) "idiot-proof" where they won't really let you do anything that will "break" the website (eg. Wix, Weebly, Mobirise.) That's not the case with BSS. If you write improper CSS, you can completely mess up your site and not understand how or why (though you can always delete the code to get back to the raw component.)
Hopefully this gets you pointed in the right direction.