1329893 - two CSS targets are active in iframe page after hiding and showing it

Status: UNCONFIRMED

Description

[douman]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:50.0) Gecko/20100101 Firefox/50.0
Build ID: 20161208153507

Steps to reproduce:

1. Open https://doumanash.github.io/#Waifu 
2. Choose next picture with right arrow link (will not reproduce otherwise)
3. Using navigation menu change current target (hash). Except for CV which will go to another page.
4. Go back to #Waifu target.
5. Choose next picture with right arrow link.

Details of HTML layout:
- There is bunch of divs that each has some unique id.
- There is one div without any ID that will act as default
- Both main page and iframe page relies on the same CSS target selector trick

You can find CSS rules that control it here (Stylus pre-processor):
https://github.com/DoumanAsh/DoumanAsh.github.io/blob/generator/app/styles/common.styl#L109-L138

Screenshot of bug: http://i.imgur.com/wNUGobK.png
Screenshot of normal behavior: http://i.imgur.com/X4JRyaV.png


Actual results:

Two targets will become visible due to CSS rule
div.sub_page.flex:target {
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
}


Expected results:

Only one hash target can be active at the time