vindication

（非難・汚名・嫌疑・疑惑を晴らす）申し開き;（物事が正当であるとする）立証,証明,（名誉・要求の）擁護,支持;（権利の）主張.
That's a vindication of the large amount of hard work that O'Reilly design team put into redesigning pages so they were XHTML and CSS.