Explain almost standard, full standard and quirks mode

In web development, browsers use different modes to render web pages based on the DOCTYPE declaration at the beginning of an HTML document. These modes are known as quirks mode, almost standards mode, and full standards mode (also referred to as no-quirks mode). Each mode affects how web pages are displayed and can influence the compatibility and appearance of websites across different browsers and versions.

Quirks Mode

Quirks mode is a legacy rendering mode that emulates the non-standard behavior of older browsers like Internet Explorer 5 and Netscape Navigator 4. This mode is triggered when a DOCTYPE declaration is missing or incomplete. In quirks mode, browsers mimic historical browser behaviors that are often not compliant with current web standards. For example, quirks mode may incorrectly interpret box model dimensions, leading to differences in how elements are sized and positioned on the page[1][2].

Almost Standards Mode

Almost standards mode is a slight variation of full standards mode. It provides a high level of standards compliance but includes a small number of quirks specifically related to the rendering of certain elements. The primary difference lies in the vertical sizing of table cells and the handling of images inside table cells, which are rendered similarly to how they would be in quirks mode. This mode is typically triggered by using a DOCTYPE that almost triggers full standards mode but includes minor historical artifacts[1].

Full Standards Mode (No-Quirks Mode)

Full standards mode, also kn...