Good catch. I created 2 upstream tickets last week for this issue. I'll link those and double check that it's the same issue when I get back to my laptop later today.

Confirmed on phone that mobile web has same issue for those sections on https://fr.m.wikipedia.org/wiki/Liste_de_sondages_sur_l%27élection_présidentielle_française_de_2017

So yeah I'll update the upstream tickets and this one when I'm back on laptop.

Again, good catch!

Looks like the Graphs extension generates images bigger than the viewport (mw-graph)
In interim, in lieu of a fix apps could hide these classes...

.mw-graph { display: none; }

or quickly add the noresize class to the graph extension...

@Jdlrobson hey do you recall if we had a ticket for this same issue happening with some wide math formulas? I'm seeing it on enwiki > Lagrangian_point

^ https://phabricator.wikimedia.org/T161405#3270680 that.
Who maintains Graph extension these days?

In interim, in lieu of a fix apps could hide these classes...

.mw-graph { display: none; }

@Jdlrobson Unfortunately every horizontal line div in the graph repeats the following:

style="width:750px; height:1px; background-color:#666; margin-top: 12px; margin-left: 28px; position:absolute; z-index:-1;"

So we still get funkiness even with .mw-graph { display: none; }:

Just add the noresize class to the elements mw-graph instead. Although that really should be done inside the Graph extension.

Also the graph adds a min-width:750px
This would need to be overridden. That's not mobile friendly at all.

Oh wait. I see that the grid lines are done by spitting out the following HTML which has no class:

<div style="width:750px; height:1px; background-color:#666; margin-top: 12px; margin-left: 28px; position:absolute; z-index:-1;"></div>

oh dear.. that's not going to work is it..
A fix is definitely needed in the graph extension. These need to be wrapped my mw-graph as well.