Hi Everyone! Welcome to the 6th and final post in the HTML series. If you have just stumbled onto this post, use the links below to catch up on the series.
CSS with Style
This post picks up where post 4 left off with CSS. To review, CSS can be written in 3 ways. As a Spotfire developer, you care about 2 of them.
- In a separate CSS file — only applicable to building web pages
- Inside an HTML tag using the style attribute (see post Containers and Style Attributes).
- Inside a style tag
Now, folks new to HTML will generally start with the style attribute, but using CSS inside a style tag is where you can achieve beauty and efficiency in Text Areas. This method allows you to create a reusable CSS template for all DXPs, and formatting will be a thing of the past. It’s magical! Furthermore, CSS opens up formatting for pieces of the application that have no GUI. In other words, the only way to format it is with CSS.
In order to tackle this subject, it will be broken down into 4 parts.
- Example of CSS in a style tag
- Explanation of the basic syntax and rules
- Other syntax and rules
- Explanation of how to decipher the “Spotfire” elements
Let’s start off with an example so you have a frame of reference. Download this Ruths.ai template NFL Expectancy Win Calculator. (Note: The button says subscriber-only, but click it anyway. It will take you to a different website. You might have to create an account, but the template is free.). Go to the Expected Wins Page. In the Pythagorean Win Expectancy Text Area, right-click and select Edit HTML to see the code… A LOT of code. Scroll down in the sample template to make sure you know where the end is. I’ve taken a small screenshot below. This was all written by Lucas Wood of Ruths.ai.
In this example, the code is controlling the appearance of the entire template. It can be copied and pasted into other DXPs to achieve the same look and feel. Next, let’s look at the rules and structure for writing this type of code.
It’s very simple syntax that consists of a selector and a declaration block. The declaration block uses property-value pairs where the property and value are separated by a colon and multiple property-value pairs are separated by semi-colons. The declaration block itself is wrapped in squiggly braces.
Now, selectors are important. They find HTML elements and format all elements of that type on a page (or in our case, in a Text Area or DXP file). This is the efficiency I have been talking about. CSS formats everything with one block of code so you don’t have to format individual elements (like buttons) or add attributes to all HTML tags to format them.
There are many different types of CSS selectors, and you should definitely review them at W3Schools . Here is a simple example of an element selector. The “p” references the <p> tag, and the selector is selecting all of the <p> tagged content and formatting it.
Here is an example of a class selector from the Ruths.ai template. The selector is looking for the .sf-element-page-tab class. It will select all page tabs and change the border and padding accordingly.
Now that you know the basic syntax, let’s look at some specific code in the template that might not yet make sense. For example, you may be wondering what @import and !important are doing.
Other Rules & Syntax
CSS also utilizes “at-rules”. The “@import” is an example of an “at-rule”. At-rules are special instructions that control how styles are applied. In the case of this example, @import is pulling in a Google font. Other examples include @media, @font-face.
Each line of CSS in the template has “!important” at the end of it. “!important” establishes priority. It is telling SPotfire this code takes precedence over any other formatting that might be in the template, such as formatting in HTML tags or formatting from the set theme. The exclamation mark is called a delimiter token, and “important” is a keyword.
You may also have noticed that a line can be commented out with a forward slash and an asterisk.
Okay, that was a lot of talk about syntax. However, there is still more to learn. Next, we are going to talk about how to decipher the classes used by Spotfire. For example, if we want to change the active page tab color, how do we know to write “.sf-element-page-tab.sfpc-active”?
CSS for Spotfire
To figure this out, you can use the Developer Tools that accompany the browser to inspect the underlying HTML and CSS that creates the DXP in the web player. In Chrome, DevTools are accessible by pressing F12. So, open a DXP in the web player, press F12, click the button that looks like this and click on the Elements tab . Now, you can mouse around the page and hover over various pieces of the DXP. When you hover, you will see the name of the element as shown in a few examples below. I realize these screenshots aren’t the best. I actually tried to make a video, but when you move and hover, stuff is constantly flashing on the screen. It was painful to watch.
I know this is turning out to be quite a long post, but just hold on. I’m about to wrap it up. There are just a few more things to note. First, in order to have CSS apply to an entire DXP, you need to have the <style> tag and accompanying CSS in at least one Text Area on each page. With that said, be careful when you edit. You might drive yourself crazy trying to figure out why the CSS isn’t doing what you want when there are conflicting pieces of code on different pages.
Well, that wraps it up. Thanks for sticking with me to the end. Clearly, there is much more to learn about CSS than one blog post can handle, but this will get you started.