Easy-to-follow video tutorials help you learn software, creative, and business skills.Become a member

Working with units of measurement

From: Dreamweaver CS5 Essential Training

Video: Working with units of measurement

When working with either typography or layout, it is crucially important that you understand the different units of measurement that CSS allows you to use, and when you would use one over the other. When you discuss units of measurement in CSS, there are two general categories: Absolute and Relative. Absolute, which can also be referred to as fixed units, delineate a fixed size, one that does not change based on any other factors. Relative units of measurement look for either a parent element or the user agent itself for a base value to begin with.

Working with units of measurement

When working with either typography or layout, it is crucially important that you understand the different units of measurement that CSS allows you to use, and when you would use one over the other. When you discuss units of measurement in CSS, there are two general categories: Absolute and Relative. Absolute, which can also be referred to as fixed units, delineate a fixed size, one that does not change based on any other factors. Relative units of measurement look for either a parent element or the user agent itself for a base value to begin with.

With those two categories in mind, let's take a look at the options available to you when specifying sizes in your styles. So here we have measurement.htm opened up, and we're just going to go through a couple of these units of measurement. Let's talk about points first. Now points are units of measurement that are designed for print. They are, in fact, 1/72 of an inch. So what does that translate to on the screen? Now that's a very good question. You need to know the resolution the monitor is set to, as well as the operating system, to answer that one.

Avoid using points for onscreen font measurement and restrict its use to print stylesheets where it belongs. Now what about inches and centimeters? Well, again, they're just what you think they are. They're useful for other media types, but really probably shouldn't be used for onscreen media. Let's move on, and talk about Relative units of measurement. What about ems? Well, ems are, hands down, the most popular relative measurement for onscreen sizing. An em is best described as being the equivalent of the size of a capital M for that particular font.

An ex is equal to the x- height of that specific font. The size of the font can change dramatically as font-families are substituted. So it should be used with care. Now percentages, values are pretty straightforward. A percent value sizes the text to the percentage of its inherited or default value. Now pixels, they're based on the current resolution of the viewing device. Because it relies on the resolution of the user agent, pixels are sometimes referred to as a relative unit.

Now in truth, setting units to pixels fixes them at that size. There are several reasons to avoid using pixels for font measurement. Internet Explorer, prior to Version 7, did not allow the onscreen resizing of pixel-based font sizing. So users of earlier versions of Internet Explorer will not be able to change their font size based on their own viewing preferences if you use pixels. Also, pixel sizes that might look good on a monitor might be far too large for the mobile environment. Pixel-based font sizes don't scale too well between environments.

It's best to avoid using pixels for font sizing when possible. Now most browsers do start with the default font size. And for the majority of browsers that default font size is 16 pixels. We're going to do a really quick exercise where we take advantage of our browser's default font size and compare a relative unit of measurement with a fixed unit of measure. So I'm going to scroll down to the bottom of this page, and I can see that I have one paragraph that says, "Make this paragraph 16 pixels tall," and then there's another paragraph right below that that says, "Make this one 16 pixels tall too, please." Now both of these are paragraphs that have classes applied to them.

You'll notice that the first paragraph says . The second one is , so we have classes resize and resize2, okay. I'm going to go over to my CSS Styles panel, and I'm going to go scroll down until I find those two selectors, and . The first one, I'm going to go ahead and add a property to that. And I'm going to add the font size property. So font-size, again you can get that through the pulldown menu if you'd like. If I hit Tab, I get to go over and set the unit of measurement here.

So for the first one, I'm going to go ahead and set that to pixels. So I'm just going to type in 16 pixels. Okay, mission accomplished. Hey! Nothing really changed here. Hm, okay. Well, I'm going to go down to , add a property there. And again, I'm going to do font-size, and here, instead of 16 pixels, I'm going to type in 1em. No change. Interesting. Okay. Let's preview this in our browser and see if we have any change, or if we notice the difference between the pixels, which are on top, and the em, which is on the bottom.

So we're going to go ahead and Save that and Preview that in my browser, and I'm using Firefox, but feel free to use any browser you want with this. Now if I scroll down, you can see you can't really tell a difference between the two of them. The top one is being sized using pixels. The bottom one is being sized using ems. So you might say, "Well, okay. So then what's the big deal?" Why do we even care which one we're using? Well, the reason that they're both the same size is because my browser is currently set to a default font-size of 16 pixels. So the 1em that the second paragraph is doing is sizing to one times or 100% of that size, which equates to 16 pixels.

Well, let's take a look at what happens if your user changes that within your browser. So I'm going to go up to Tools, and if you're in a different browser, you might find this in a different location, but for Firefox, I'm going to go to Tools and choose Options. And if I click on the Content tab, notice that I have a Default Font and a Default Size, and sure enough, there it is set to 16 pixels. Now if I change that, let's say I go down to say 14, if I click OK, notice that now we can see the difference. The font up top that is sized as 16 pixels remains 16 pixels, whereas the one on the bottom changes to reflect the new browser settings.

So because it says 14 pixels, now 1em is equal to 14 pixels. So that relative unit of measurement is very handy for users that might have set different preferences for their browsers. They're still going to get everything scaled to the relative size that you need it. So let's say somebody has a vision disorder, goes in their Options and cranks that up to say around 18 pixels. Well, they can read your text just fine, whereas if you'd set it explicitly at 16 pixels that would override the browser, and we would force them to look at a size that they don't really want to look at.

So as a general rule ems are the preferred unit of measurement for online type. As always, there are exceptions to this rule. Older versions of Internet Explorer seemed to have problems with font- size values that are defined strictly as ems. As a workaround, most designers will size the body selector using a percentage value and then define all other measurements in ems. This seems to fix those IE-specific problems. Now since font size is by and large inherited, meaning if you apply a font-size to a parent tag, all the tags inside of it gets the same size, it makes sense to carefully plan a sizing strategy for your site, pick a unit of measurement, and take care to stay consistent throughout your site.

Show transcript

This video is part of

Image for Dreamweaver CS5 Essential Training
Dreamweaver CS5 Essential Training

135 video lessons · 89071 viewers

James Williamson
Author

 
Expand all | Collapse all
  1. 2m 57s
    1. Welcome
      1m 8s
    2. Using the exercise files
      1m 49s
  2. 7m 50s
    1. What is Dreamweaver?
      3m 16s
    2. Learning web design
      2m 22s
    3. Current web standards
      2m 12s
  3. 43m 9s
    1. The Welcome screen
      4m 5s
    2. Windows and Mac interface differences
      2m 23s
    3. The Application toolbar
      4m 7s
    4. The Document toolbar
      4m 40s
    5. Arranging panels
      8m 19s
    6. Managing workspaces
      7m 32s
    7. The Properties Inspector
      5m 54s
    8. The Insert panel
      6m 9s
  4. 25m 45s
    1. Basic site structure
      3m 11s
    2. File naming conventions
      1m 49s
    3. Defining a new site
      4m 35s
    4. Managing sites
      4m 51s
    5. Managing files and folders
      6m 36s
    6. Working with browsers
      4m 43s
  5. 27m 21s
    1. Creating new documents
      5m 16s
    2. New document preferences
      3m 6s
    3. Setting accessibility preferences
      4m 56s
    4. Working with starter pages
      3m 46s
    5. Managing starter pages
      10m 17s
  6. 30m 2s
    1. Basic tag structure
      2m 15s
    2. Adding structure to text
      8m 20s
    3. Creating lists
      9m 59s
    4. Getting text into Dreamweaver
      5m 59s
    5. Importing Word documents
      3m 29s
  7. 1h 17m
    1. Understanding style sheets
      2m 16s
    2. The anatomy of a CSS rule
      1m 48s
    3. Setting CSS preferences
      6m 36s
    4. The CSS Styles panel
      10m 2s
    5. Controlling CSS through the Properties Inspector
      5m 14s
    6. Using the Code Navigator
      7m 21s
    7. Using CSS Enable
      6m 45s
    8. Understanding element selectors
      8m 11s
    9. Understanding class selectors
      8m 49s
    10. Understanding ID selectors
      5m 59s
    11. Understanding descendant selectors
      6m 51s
    12. Attaching external style sheets
      7m 44s
  8. 1h 47m
    1. Working with units of measurement
      7m 11s
    2. Declaring font families
      9m 39s
    3. Controlling font sizing
      9m 9s
    4. Controlling weight and style
      8m 0s
    5. Controlling line height
      8m 29s
    6. Controlling vertical spacing with margins
      12m 3s
    7. Controlling spacing with padding
      5m 39s
    8. Aligning text
      8m 26s
    9. Transforming text
      5m 36s
    10. Writing global styles
      15m 42s
    11. Writing targeted styles
      17m 37s
  9. 1h 32m
    1. Understanding image types
      5m 3s
    2. Managing assets in Dreamweaver
      12m 51s
    3. Setting image accessibility preferences
      4m 20s
    4. Setting external image editing preferences
      3m 52s
    5. Placing images on the page
      7m 37s
    6. Photoshop integration
      5m 54s
    7. Modifying Smart Objects
      5m 51s
    8. Alternate Photoshop workflows
      8m 8s
    9. Modifying image properties
      11m 14s
    10. Styling images with CSS
      7m 11s
    11. Using background graphics
      9m 3s
    12. Positioning background graphics
      11m 6s
  10. 55m 16s
    1. Link basics
      3m 37s
    2. Setting site linking preferences
      2m 14s
    3. Creating links in Dreamweaver
      11m 1s
    4. Absolute links
      5m 8s
    5. Using named anchors
      11m 19s
    6. Linking to named anchors in external files
      2m 44s
    7. Creating an email link
      5m 24s
    8. Creating CSS-based rollovers
      13m 49s
  11. 1h 34m
    1. CSS structuring basics
      2m 56s
    2. The Box Model
      13m 21s
    3. Understanding floats
      6m 53s
    4. Clearing and containing floats
      8m 56s
    5. Using relative positioning
      4m 8s
    6. Using absolute positioning
      7m 18s
    7. Creating structure with div tags
      12m 7s
    8. Styling basic structure
      10m 34s
    9. Creating a two-column layout
      10m 37s
    10. Using Live View and CSS Inspect
      7m 51s
    11. Using Browser Lab
      9m 39s
  12. 56m 22s
    1. Reviewing table structure
      7m 41s
    2. Importing tabular data
      5m 13s
    3. Creating accessible tables
      9m 56s
    4. Using thead and tbody tags
      4m 0s
    5. Basic table styling
      8m 45s
    6. Styling table headers
      7m 52s
    7. Styling column groups
      4m 22s
    8. Creating custom table borders
      5m 1s
    9. Styling table captions
      3m 32s
  13. 1h 43m
    1. How forms work
      3m 0s
    2. Reviewing form design
      3m 2s
    3. Creating accessible forms
      7m 33s
    4. Setting form properties
      4m 6s
    5. The fieldset and legend tags
      4m 32s
    6. Inserting text fields
      5m 58s
    7. Inserting list menu items
      5m 26s
    8. Inserting checkboxes
      7m 50s
    9. Inserting radio button groups
      6m 22s
    10. Inserting text areas
      4m 12s
    11. Inserting submit buttons
      3m 37s
    12. Basic form styling
      12m 0s
    13. Form element styling
      8m 52s
    14. Styling form layout
      11m 49s
    15. Adding form interactivity
      2m 47s
    16. Using Spry validation widgets
      12m 49s
  14. 1h 23m
    1. Planning for templates
      10m 51s
    2. Creating a new template
      10m 37s
    3. Using editable attributes
      13m 43s
    4. Creating optional regions
      6m 23s
    5. Creating new pages from a template
      9m 17s
    6. Applying templates to existing pages
      6m 9s
    7. Working with nested templates
      7m 56s
    8. Working with repeating regions
      12m 58s
    9. Modifying templates
      5m 41s
  15. 40m 14s
    1. Behaviors overview
      3m 47s
    2. Hiding and showing elements
      9m 18s
    3. Spry overview
      4m 4s
    4. Using Spry widgets
      11m 36s
    5. Adding Spry effects
      3m 6s
    6. Using the Widget Browser
      8m 23s
  16. 28m 18s
    1. Inserting Flash files
      5m 4s
    2. Setting properties for Flash
      6m 27s
    3. Dreamweaver and Flash integration
      6m 6s
    4. Encoding Flash video
      6m 10s
    5. Adding Flash video
      4m 31s
  17. 45m 28s
    1. Running site-wide reports
      6m 33s
    2. Checking for broken links
      5m 41s
    3. Checking for browser compatibility
      8m 3s
    4. Adding remote servers
      8m 0s
    5. Uploading files
      7m 20s
    6. Managing remote sites
      9m 51s
  18. 34s
    1. Goodbye
      34s

Start learning today

Get unlimited access to all courses for just $25/month.

Become a member
Sometimes @lynda teaches me how to use a program and sometimes Lynda.com changes my life forever. @JosefShutter
@lynda lynda.com is an absolute life saver when it comes to learning todays software. Definitely recommend it! #higherlearning @Michael_Caraway
@lynda The best thing online! Your database of courses is great! To the mark and very helpful. Thanks! @ru22more
Got to create something yesterday I never thought I could do. #thanks @lynda @Ngventurella
I really do love @lynda as a learning platform. Never stop learning and developing, it’s probably our greatest gift as a species! @soundslikedavid
@lynda just subscribed to lynda.com all I can say its brilliant join now trust me @ButchSamurai
@lynda is an awesome resource. The membership is priceless if you take advantage of it. @diabetic_techie
One of the best decision I made this year. Buy a 1yr subscription to @lynda @cybercaptive
guys lynda.com (@lynda) is the best. So far I’ve learned Java, principles of OO programming, and now learning about MS project @lucasmitchell
Signed back up to @lynda dot com. I’ve missed it!! Proper geeking out right now! #timetolearn #geek @JayGodbold
Share a link to this course

What are exercise files?

Exercise files are the same files the author uses in the course. Save time by downloading the author's files instead of setting up your own files, and learn by following along with the instructor.

Can I take this course without the exercise files?

Yes! If you decide you would like the exercise files later, you can upgrade to a premium account any time.

Become a member Download sample files See plans and pricing

Please wait... please wait ...
Upgrade to get access to exercise files.

Exercise files video

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.


Exercise files

Exercise files video

How to use exercise files.

For additional information on downloading and using exercise files, watch our instructional video or read the instructions in the FAQ.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

Join now "Already a member? Log in

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.


Mark all as unwatched Cancel

Congratulations

You have completed Dreamweaver CS5 Essential Training.

Return to your organization's learning portal to continue training, or close this page.


OK
Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Get started

Already a member?

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Get started

Already a member?

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

Get started

Already a Premium member?

Exercise files video

How to use exercise files.

Ask a question

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

Continue to classic layout Stay on new layout
Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Control your viewing experience

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

Are you sure you want to delete this note?

No

Your file was successfully uploaded.

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked
Terms and conditions of use

We've updated our terms and conditions (now called terms of service).Go
Review and accept our updated terms of service.