Critical CSS? Not So Fast!

Critical CSS is a theoretically good technique to optimize initial rendering but is often fragile and costly to implement in practice. It works best when CSS is the biggest blocking resource and should be considered from the project outset rather than retrofitted. Success depends on various factors including the proper handling of other render-blocking resources. Missteps in implementation or subsequent changes can negate its benefits, making it essential to carefully assess and maintain any critical CSS strategies.