Skip to main content

CSS inheritance sequence

    Starting today, I will also write about a few things CSS apart from Google Maps Javascript API and Jquery Mobile. I will cover some really interesting things in CSS and keep updating this blog as and when I learn something new and think its worth sharing with you all.

    Today we will look at a very common mostly known thing in CSS - the inheritance sequence of CSS. Most of you reading this post must be aware that there are 3 ways in which you can include CSS into your web application.

  • External Stylesheet
  • Internal Stylesheet
  • Inline Styles

External Style Sheet
    An external style sheet is ideal when you are writing a style that would be applied across multiple pages. The external style sheet gives the developer lot of control over the look and feel of the entire website or web application. The external style sheet is included using the the "link" tag which is included in the head section.

<link rel="stylesheet" href="styles/default.css" />

Internal Style Sheet
    An internal style sheet is used usually when a single document has unique style. The internal styles are written as part of the "style" tag which is again included in the "head" section.

<style>
    p{
        font-size: 20px;
        color: #a123bb;
    }
</style>

Inline Style
    An inline style loses many of the advantages of style sheets by mixing the content with the presentation. Inline styles should generally be avoided and be used when absolutely necessary and unavoidable!

<p style="font-size: 20px; color: #a123bb;"></p>

    As we know and/or have learned from experience, that these styles cascade into one, let's say a "virtual" style sheet which gets applied on the entire web site/application. This cascade follows the following sequence to override each other and create one final style sheet. Number #4 in the following list has the highest priority in the cascade.
  1. Browser default styles
  2. External style sheet
  3. Internal style sheet
  4. Inline styles
    So an inline styles has the highest priority, meaning that it will override a style defined inside the "head" tag, or in an external style sheet or the default browser styles. However, there are a few cases where this sequence of cascade can change!

Case #1: Usage of the !important keyword
    In case there is the "!important" keyword associated with an of the styles, then that style would get applied irrespective of whether it is part of the internal or the external style sheet.

Case #2: Javascript
    When styles are applied through javascript, these styles will override all styles included as part of the internal or external style sheet or even the inline styles.

Case #3: Sequence of inclusion of stylesheets
    If the link to the external style sheet is placed after the internal style sheet in the "head" tag, the external style sheet will override the internal stye sheet!

    Hope you have enjoyed this post and learned a few new things. Do let me know in case you want me to include a topic as part of the blog and I would be happy to write about it! Till then keep reading and keep sharing.

Labels:

Comments

Post a Comment

Please leave your comments here...

Recommended for You

Playing with the markers and info window bubbles...

    In the last few posts, we have seen some marker examples and some information window examples. Now, lets do something interesting combining these two things. Just writing that "This is an info window" in the information bubble is not very interesting! And I know this...Have gone through the same phase!     So, today we will do something interesting! We will display the latitude- longitude co-ordinates of the point that the user clicks on the map! Doing this is not at all complex! Copy paste the following code and you will see for yourself a map coming to life!     The output of the above code looks as seen in the result section above! If you have any queries regarding the above code please comment on the blog post or feel free to contact me at my mail ID .
3 comments
Read more

Fusion Table - Heat Map Layer

    In continuation with the previous example on Fusion Table, we will have a look at another Fusion Table layer example. Today's point of discussion is heat map! What is a heat map? A heat map is geographical representation of data where the values taken by a variable in two-dimensional map are represented as colors. Higher the value of the variable, that place on the map would be represented with a deeper color.     This example is very much similar to the previous one, just for one minor change! Let us have a look at the code.     I have just used a readily available Google Fusion Table for this example. Any anomalies in the data is not my responsibility! Copy the above code in an html file and open it in your browser! You will see the fusion table heat map layer in action! The only change in this code from the previous one is that, the heatmap property of the fusion table layer is made true! The output of the above code looks as s...
Post a Comment
Read more

Where on Google Map was Osama bin Laden?

                It took years of intelligence gathering and months of following leads and planning an attack for the US to track down the world’s most wanted criminal – Osama bin Laden to a compound in the normally quite city of Abottabad in Pakistan. Since the night when US President Barack Obama announced the terrorist’s death, the Internet has been buzzing with attempts by people all around the globe to pin- point the exact location of the compound on a map.                 Bin Laden's compound had been pinned in multiple different locations on Google Maps and Google Earth by users of Google's Map Marker web app, in various spots across Abbottabad. However, none were accurate and exact. Thanks to photos and diagrams released by the U.S. Dept. of Defense on Monday, Osama bin Laden’s Hideout Compound is now embedded in Google Maps and ...
1 comment
Read more

Google Street View Image API

    Street View is one of most used feature of the Google Maps and why not? You can actually see any part of the world as if you are visiting the place at that very moment. And now with the Google Street View Image API, you don't even need to carry a camera with you to the places you visit. You can take-in all the scenic beauty without even bothering about clicking a single picture. You can come back from your vacation and get a few images using the Google Street View Image API and show those images to your friends and relatives. Create an album of high definition images and go ahead and share it on Facebook for your friends to have a look.     Using the Google Street View Image API is very simple and anybody can make use of it without any programming knowledge required. I will walk you through the entire process of effectively using the Google Street View Image API. So if you are set, let's go on an amazing ride across the globe with the Google Street Views. ...
1 comment
Read more

Where does Google get it's live traffic data from?

Referring to a post that I wrote earlier, Google’s - Live traffic Layer , ever wondered how Google collected this data? I was wondering the other day, how Google received live data to display it on their maps as a layer! I looked up the web and found something very interesting and am sharing the same with you all. As we all know, the traffic layer is available most accurately in several states in USA. Most major metro areas in the US have sensors embedded in their highways. These sensors track real time traffic data. Easy to miss at high speeds (hopefully anyway, traffic permitting), more commonly noticed may be the similar sensors that often exist at many busy intersections that help the traffic lights most efficiently let the most amount of people through. The information from these tracking sensors is reported back to the Department of Transportation (DOT). The DOT uses this data to update some of the digital signs that report traffic conditions in many metro areas. They als...
17 comments
Read more