If you are into Tumblr trends, then you might as well be asking how to display hidden messages or text in Tumblr Posts.  When you highlight a regular piece of text it blocks most part of the text revealing a phrase of your choice.  Some may wonder if it should be by default, well, if it were, it wouldn’t be so funny .

Hidden Messages in Tumblr Posts.

1. Go to Customize >>> Advanced.  Once there insert the following code in Add Custom CSS; After that save and close.


p::selection { background:#000;color:#000; }
p::-moz-selection { background:#000;color:#000; }
p span::selection { background:#fff;color:#000; }
p span::-moz-selection { background:#fff;color:#000; }


2. Now, let’s create a post where you can display your hidden message.  Choose a Text Post and write/paste your text.  After that click on the tiny HTML button on the edition screen, this should make the html edition screen pop up.
3. Each part of the text that you want to display when being highlighted, meaning all the text that you want to be part of the hidden message should be surrounded by <span></span>, the rest of the text is surrounded by only a couple of <p></p> tags:


<p> TEXT TEXT TEXT TEXT TEXT
TEXT TEXT <span>HIDDEN TEXT</span>
TEXT TEXT TEXT <span>HIDDEN TEXT</span></p>


4. After click update on the screen and publish your post.  Here is an example of hidden message in a Tumblr Post.

Even when your Tumblr Theme has the following tag included in the html:

{CustomCSS}

You don’t have absolute control over your Tumblr Theme .CSS file, despite being able to add your own touch to the theme through either Customize >> Advanced option or just dropping some inline CSS within the same html tumblr file (which is not advisable by today’s css standards). It turns out to be that there always is a .CSS file stored in Tumblr itself that belongs to any particular theme.

How to Find, Download and Edit your Tumblr Theme .CSS file

1. Go to Customize >>> Theme >>> Use Custom HTML
2. Once there, you will have to find the following line <link rel=”stylesheet” href=”http: ……. that ends with /style.css” .  In this example it would be




<link rel=”stylesheet” href=”http://static.tumblr.com/h1xxjdl/CZ4Y1eqj/style.css” type=”text/css” media=”screen”>

3. Copy the whole .css url and then paste it in a new window (press enter ). You will now be able to see the full .css belonging to your tumblr theme.
4. You can download the .css file by right clicking and “Save Page As..” a Cascading Style Sheet document or just copying the entire code from the screen.
5. The Web Developer Toolbar for Firefox (check here for Firefox Tumblr login issues) is great way to test and preview the changes you want to make to the .css file in real time. Now Edit the Tumblr .CSS file with any web editor you know, such as Dreamweaver.   If you modify any of the images used, remember to save them because you will now have to upload them to tumblr.
6. Use the Tumblr static file uploader to save the images and js files FIRST.  Now paste the images url in the proper place within the .css file you are editing (remember to save it with the same name it had before).  Finally, upload your custom Tumblr .CSS file through this same place.  You now have the path to your new .CSS file !, copy it and replace the old .css url with the new one.  Click save in the top right corner of the screen and that’s it.  Just use this storage service for files related to your theme, nothing else unless you want your account to get banned.

UPDATE: This is how you edit fonts on Tumblr using the .css file.

Putting or changing a background image or picture in your Tumblr theme is actually easy. However, the coding and changes to the html Tumblr theme to make it look exactly the way you want can get extremely annoying, depending on the skin you are actually using for your Tumblr layout. For example, it may not be enough just to insert the url of your image, but you will have to edit, change or delete other background colors that could be covering your image background.

Let’s get started, here is How to Put a background image in your Tumblr Theme the right way and Size:

1. First of all, login into your Tumblr account and visit your very own Tumblr site.  Once there you will see in the top right corner a button that says Customize, click on it please.
2. Now, in this new page, click on Theme on the top navigation bar and then click on Custom HTML at the bottom of the menu that has just dropped down (if you don’t see it you will have to close some bars in your browser theme to give it enough space to see the option Custom HTML.
3. Copy the whole code you see here and paste it in a notepad and save it, this will be a lifesaver to go back to where we start in case you don’t remember the steps you’ve done.
4. Now this is where it gets fun, we need to alter the inline css to include the image you want as the background of your Tumblr Theme.  First of all, find the following code in your theme:  <style type=”text/css”>
5. Now, after that code you should find this code “body {” and inside the body tag there should be the background: line.  It is here that we need to insert the url of the image you want to use for the layout.
6. For example, in my Tumblr the background line looks something like this:
   background: {color:Background} url(‘{image:Background}’) top left fixed repeat;
   Now replace the {image:Background} with the URL of your image (if you have it in your computer upload it to Tumblr first ), and change the top left fixed repeat for top left fixed no-repeat.
7. Click on Update Preview and verify the image is actually showing up as you want, if it does click on the SAVE BUTTON on the top right corner of your screen and that’s it.
8. Is that it?, well I don’t really think so, because there are several other variables that could make your image not fit into the background, the image might be too small and then the rest of the background goes black, fixed body width, other background colors that may be hovering over your background, browser size, and image height as well, but these steps are the very first to change the background image in your Tumblr.

Important Note:  I believe that the single most important thing to know here is if the body tag has a fixed width or not, if it does, just edit your image to fit that size, if it doesn’t I recommend going for a image width bigger than 1600pixels (it depends on the screen resolution you are using actually) and a height bigger than 700pixels. Beyond this, there are many other ways to make your image blend with your background, specially if it was crafted in an editor, but for photos I guess that the major tip I can give.

Please post your questions here and I’ll help you fully customize the image into your current theme.

Tumblr has a really extensive documentation on how to customize your Tumblr theme html if you want to read it.