Notice that nasty gray background behind our Light Box? This is occurring because IE6 does not natively support the PNG-24 format. As a result, rather than displaying transparency, it instead
renders an ugly gray background.
Luckily, there are a handful of solutions:
Unit PNG Fix
• Download: http://labs.unitinteractive.com/unitpngfix.php.

To target a specific version of IE, we use conditional statements within the head tags of our HTML document. Add the following code to each page:
<!--[if lt IE 8]>
<script src=”http://ie7-js.googlecode.com/svn/version/2.0(beta3)/IE8.js” type=”ext/javascript”></script>
<![endif]-->
<!--[if lte IE 6]>
<link rel=”stylesheet” type=”text/css” href=”css/ie6.css” />
<![endif]-->

It’s important because it forces the element to have a rectangular shape. This means that the content of the element cannot flow around other boxes, which will often cause major layout issues with your website.

css+div中，position有四个属性值：
relative,absolute,static,fixed

Fahrner’s Image Replacement Technique
This technique is named after Todd Fahrner (a user interface technology consultant). To achieve our desired effect, we must perform the following:
1. Measure the width and height of the image, using the ruler tool in Photoshop.
2. Set the background property to our image’s URL.
3. Set the width and height values equal to what we just measured.

  Create a new CSS file called “reset.css” and save it in a new CSS folder within
your project root.
  Save your file, import it into your test document, and reload your browser.
  As we’ll be using this file in all of our projects, be sure to make a copy and store it in a “web dev folder”, or something similar for later use.

Grabbing the logo in Photoshop.
It’s the only way that you’ll remember the following steps.
1. You’ll see that the logo is split into two layers. Click in the small square icon within the first layer. You’ll immediately see the marching ants.
2. While still holding Command/Ctrl, press and hold the Shift key, and click inside of the square icon of the next layer.
3. While still holding Command/Ctrl and Shift, press the letter “C” to copy the layers.

工程引用AutoCAD 2006 Type Library

　　JVM是基于堆栈的虚拟机。JVM为每个新创建的线程都分配一个堆栈。也就是说，对于一个Java程序来说，它的运行就是通过对堆栈的操作来完成的。堆栈以帧为单位保存线程的状态。JVM对堆栈只进行两种操作：以帧为单位的压栈和出栈操作。
　　我们知道，某个线程正在执行的方法称为此线程的当前方法。我们可能不知道，当前方法使用的帧称为当前帧。当线程激活一个Java方法，JVM就会在线程的Java堆栈里新压入一个帧。这个帧自然成为了当前帧。在此方法执行期间，这个帧将用来保存参数，局部变量，中间计算过程和其他数据。这个帧在这里和编译原理中的活动纪录的概念是差不多的。
　　从Java的这种分配机制来看，堆栈又可以这样理解：堆栈（Stack）是操作系统在建立某个进程时或者线程（在支持多线程的操作系统中是线程）为这个线程建立的存储区域，该区域具有先进后出的特性。