CSS HTML 布局 相对定位
除了body以外，最外层的width:80%和height:80%都设置了百分比为什么没有占屏幕的80%呢？
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312"><style type="text/css"> .div1{ width:80%; height:80%; background:blue; border:1px solid black; } .test{ width:80%; height:80%; background:red; border:1px solid yellow; } </style><title>流体定位布局2</title></head><body><div class="div1"> this is a test <div class="test"> this is a second test </div> aaaa </div></body></html><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312"><style type="text/css"> .div1{ width:80%; height:500px; background:blue; border:1px solid black; } .test{ width:80%; height:80%; background:red; border:1px solid yellow; } </style><title>流体定位布局2</title></head><body><div class="div1"> this is a test <div class="test"> this is a second test </div> aaaa </div></body></html><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312"><style type="text/css"> .div1{ width:500px; height:80%; background:blue; border:1px solid black; } .test{ width:80%; height:80%; background:red; border:1px solid yellow; } </style><title>流体定位布局2</title></head><body><div class="div1"> this is a test <div class="test"> this is a second test </div> aaaa </div></body></html> 可能原因：
1.没有给body定义宽度和高度，无法得到是谁的80%.
2.非标准html不识别百分比，标准的是xhtml.
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