Hypothesis Testing: Null Hypothesis v.s Alternative Hypothesis

Hello! I have a quick question: Say in your H1 hypothesis you said that a certain attribute would increase -- say, customer engagement -- if you remodeled the front page of your website. If your H0 hypothesis states nothing will happen, and your A/B test results in your customer engagement decreasing, then what does that mean? Does it mean the the null hypothesis is right, or the alternative hypothesis? Apologies if similar questions have already been asked, I haven't been in the Q&A section before, so I'm a bit unsure.