Causes and solutions for the problem "incomplete display of frameset page in IE7"

When I first discovered the problem of "incomplete display of ieframeset page", I thought it was due to the compatibility problem of the IE 7 browser and did not find a solution to the problem. However, when the Internet Explorer 7 is used, many users may find that the drop-down list is incomplete. With the increasing popularity of Internet Explorer 7, more users may encounter the same problem. Therefore, this problem must be solved. How can this problem be solved? What is the problem?
After searching for a few days, check whether the JSP is wrong, but the result is not found. After the IE 7 browser was installed, I reproduced it locally. Some drop-down boxes still show missing content. I suddenly found that some page drop-down boxes are complete, while some pages are missing, what are the differences between pages? I carefully compared the complete display drop-down box and the missing display drop-down box page, and found that the difference lies in the part of the page declaration "<! Doctype HTML public "-// W3C // dtd html 4.01 transitional // en" "http://www.w3.org/TR/html4/loose.dtd"> ", isn't IE7 support this label, or is the tag outdated in the IE 7 browser? After I deleted the tag, I verified it. The problem is that.

I collected some information about CSS compatibility between IE6 and IE7 on the Internet.
JSP doctype declaration description:
Html
Public
"-// W3C // DTD
HTML 4.01 transitional // en "http://www.w3.org/TR/html4/loose.dtd">
(1) (2) (3) (4) (5) (6) (7) (8)

[Top element] [availability] "[registration] // [Organization] // [type] [label] // [language]" "[url]">
(1) (2) (3) (4) (5) (6) (7) (8)

(1) Top element: the top-level element declared in DTD, such as HTML.
(2) Availability: indicates whether the identifier is a public or system resource, such as a local file or URL.
(3) Registration: indicates whether the organization is registered as an ISO member. + indicates that the Organization has been registered as an ISO member.-indicates that the Organization is not registered. W3C is not registered, so use -.
(4) Organization: For HTML and XHTML, the organization identifier for maintaining the DTD, W3C.
(5) type: Public text class, the type of the referenced object, which is DTD for HTML and XHTML.
(6) label: Public text description, the unique Name Description of the referenced content. The label can contain a version number (4.01) and a defintion (three types of definition: frameset, strict, transitional, which is described below ).
(7) language: language code.
(8) URL: the URL that references the DTD.
There are many differences in the details of HTML and CSS processing by various browsers. In order to keep the W3C standard closer, the HTML and CSS standards are constantly evolving, therefore, there will be inconsistency in details processing between different versions of the same browser. Now, the browser uses the doctype declaration to determine which mode to use to process HTML and CSS. The standard mode (standard mode, strict mode) and quirks mode (compatible mode compliant mode) are usually mentioned ). The standard mode means that the browser should be as close as possible to the current W3C standard, and supports the current version of HTML, XHTML, and CSS specifications. The compatible mode means that the browser should be processed in the previous version, to be compatible with earlier web applications. In addition, although the main browsers currently support both modes, there are differences. For example, in addition to the two modes above, Firefox also has an almost standards mode.
The following are the DTD of HTML 4.01, which are strict, transitional, and frameset.

IE 6 CSS enhancement and IE 7 CSS compatibility
References: Cascading Style Sheet compatibility in Internet Explorer 7. CSS enhancements in Internet Explorer 6
Three types of definition in label: frameset, which supports frameset documents and transitional. It supports all elements except frameset and strict, and does not support elements and attributes that W3C is about to remove. This description is a bit confusing and cannot correspond to standard standards mode or quirks mode. For specific definitions, refer to W3C standards.

The following table is useful:
Label definition URL present URL not present
No! Doctype present off
HTML (no version present) off
HTML 2.0 off
HTML 3.0 off
HTML 3.2 off
HTML 4.0 no definition present on
HTML 4.0 frameset on off
HTML 4.0 transitional on off
HTML 4.0 strict on
XHTML on
XML on
Unrecognized! Doctype on

In this example, on indicates strict mode (standards mode) and off indicates compliant mode (quirks mode ). URL present/URL not present indicates whether the URL of the DTD document is declared in doctype; definition is null or no definition present indicates that definition is not defined. IE 6 supports switching between the two modes. In strict mode, ie should be consistent with W3C standards, while in compliant mode, ie will be compatible with earlier ie versions. You can use this table to check several doctype types in Table 1. IE 7 only supports the filter: progid: DXImageTransform. Microsoft. Alpha filter in strict mode. It is strange that IE 7 supports filter: alpha (opacity = 60) and compliant mode only in strict mode, this statement is intended for versions earlier than IE 5.5.
There are two important differences under strict mode:
A) Calculation of box height and width

In the CSS standard, width and height indicate the width and height of the content in the image, while IE will include padding and border when calculating the width and height.