CSS font-size wrecking placement - html

Question

I have two elements that are fairly unrelated, the .menu, and the .content_selection_button. The only thing that ties them together is that they are both inside <li> elements in the same <ul>, other than that they share nothing. Yet, for some reason when I change the font-size of a .content_selection_button it affects the vertical placement of the menu. I had a similar problem here. Why is font-size ruining my placement, and how can I stop it?
JSFIDDLE
Font Size 10
Font Size 25
Menu CSS
.menu {
display: inline-block;
background-color:lightblue;
margin: 1px;
padding: 2px;
box-sizing: border-box;
border-radius:5px;
}
Content Selection Button CSS
.content_selection_button{
font-size: 10px;
box-sizing: border-box;
border-radius:5px;
}
HTML
<ul class="t_inject_container">
<li class="t_inject_row">
<ul class="menu">
<li id="LI_4">
<button class="add_button t_intect_button">
+
</button>
</li>
<li>
<button class="minimize_button t_intect_button">
m
</button>
</li>
</ul>
</li>
<li>
<ul class="content_selection_container">
<li>
<form name="search_form" class="search_form">
<input type="text" name="search_input" class="search_bar" />
<input type="submit" value="🔍" class="search_button" name="search_button" />
</form>
</li>
<li id="LI_14">
<button class="content_selection_button">
My Timeline
</button>
</li>
<li>
<button class="content_selection_button">
relevent
</button>
</li>
<li>
<button class="content_selection_button">
mentions
</button>
</li>
</ul>
</li>
</ul>

Answer 1

I hinted that playing with bottom vertical alignment of the inline-block elements could fix the alignment issues. This could be avoided by simplyfing the UI by reworking the mark-up and CSS.
[ELEMENT] {
vertical-align: text-bottom;
}

Answer 2

You've main parent element's with height 150px with LI inside 25% height. so that comes around 37.5px. The height wont increase due to the increase in font size, but it will affect the calculated line height, the line-height will increase pushing the text below a central axis of the button.