In Firefox, the vertical scrollbar disappears when content fits inside the viewport. This makes several layout types shift position, typically by 10 to 20 pixels.
You can make the vertical scrollbar visible all the time. Read the instructions below:
Always Visible Scrollbar
like Internet Explorer.
1. Open the HTML Editor/ Text Editor or Notepad
2. Copy & Paste following code snippet
overflow-y: scroll !important;
3. Save this file with name userContent.css in following path
C:\Documents and Settings\[Windows Login Name]\Application Data\Mozilla\Firefox\Profiles\[profile name (random string of 8 letters, a dot (.) followed by some more letters)]\chrome\
4. Restart Firefox
To keep all of these machines straight, each machine on the Internet is assigned a unique address called an IP address. IP stands for Internet protocol, and these addresses are 32-bit numbers, normally expressed as four “octets” in a “dotted decimal number.” A typical IP address looks like this:
The four numbers in an IP address are called octets because they can have values between 0 and 255, which is 2^8 possibilities per octet.
Every machine on the Internet has a unique IP address. A server has a static IP address that does not change very often. A home machine that is dialing up through a modem often has an IP address that is assigned by the ISP when the machine dials in. That IP address is unique for that session — it may be different the next time the machine dials in. This way, an ISP only needs one IP address for each modem it supports, rather than for each customer.
If you are working on a Windows machine, you can view a lot of the Internet information for your machine, including your current IP address and hostname, with the command WINIPCFG.EXE (IPCONFIG.EXE for Windows 2000/XP). On a UNIX machine, type nslookup at the command prompt, along with a machine name, like www.howstuffworks.com — e.g. “nslookup www.howstuffworks.com” — to display the IP address of the machine, and you can use the command hostname to learn the name of your machine.
As far as the Internet’s machines are concerned, an IP address is all you need to talk to a server. For example, in your browser, you can type the URL http://18.104.22.168 and arrive at the machine that contains the Web server for HowStuffWorks. On some servers, the IP address alone is not sufficient, but on most large servers it is — keep reading for details.