To foster talents with both moral integrity and professional competence for Chinese-style modernization efforts, the ideological and political theories teaching in all courses (IPTTIAC), aimed at holistic development and character cultivation, has been widely implemented across educational institutions in our country. However, many teachers still face uncertainties and challenges in practice. Therefore, using empirical research methods, this paper takes a "residential area design" class as a case study to illustrate the specific practice and research by the author before, during, and after the class. Among these, pre-class problem research and curriculum design are crucial for delivering a high-quality IPTTIAC. By engaging in pre-class literature review and analysis, teachers not only prepare themselves but also proactively identify potential issues to formulate strategies and plans. Meticulous curriculum design involves clarifying key knowledge points, delving deep into relevant ideological and political elements, and effectively managing the allocation of time for each section. Furthermore, it is essential to emphasize the seamless integration of ideological and political elements with knowledge points, the logical sequence of various ideological and political elements, the concept of seamless teaching, and the use of appropriate teaching methods to prevent negative student experiences. The objective is to achieve a simultaneous and collaborative effectiveness in knowledge transmission, skill development, and value guidance. The classroom is the main battlefield for practicing ideological and political education in the curriculum, and teachers need to organically combine curriculum design with on-site performance, classroom organization, and observation of speech and behavior. Post class surveys and follow-up visits can help teachers improve in summarizing. The innovation of this paper resides in two aspects: firstly, it systematically introduces the actions that teachers should undertake before, during, and after class, which holds significant value for educators in general; secondly, it constructs the design logic of a seamless curriculum-based ideological and political education, which includes: clarifying the content and knowledge points → excavating the underlying ideological and political elements → elevating to the middle level ideological and political elements → elevating to the high-level ideological and political elements.