I think that's just a mistake. It almost makes me wonder if they used a computer to add the kana, because while 入らない certainly can be read as はいらない in other contexts, it would never be read that way in the example given in that box (デザインが気に入らない).
In older Japanese texts (pre-WWII), I have seen はいる/入る written as 這入る, but that is not used today.
There are many compound words in which 入 is read as い(り), but probably the most common one is 入口. I was told that it can also be read as はいりぐち, but I don't recall ever hearing a native say that.