CSS / HTML - stray dash appearing on hover - html

Question

I have a section on a site containing logos for product partners. There's around 28 logos in all - 10 of them are links to separate product pages. When I hover over them there's a stray dash that appears in the bottom right-hand corner and I cannot find where this is coming from and it's sending me crazy. It appears on all the linked logo images except the last one - again I can't see the difference with this one. This is what I mean -
Logo with dash appearing
Without dash
It looks like a stray dash from a page of code but I can't see anything -
partners.php
<div class="row">
<div id="partnerimages" class="col-md">
<a href="<?php the_permalink(76); ?>" id="adia">
<?php if( get_field('axe_img') ): ?>
<img src="<?php the_field('axe_img'); ?>" />
<?php endif; ?>
</a>
<?php if( get_field('beachrotana_img') ): ?>
<img src="<?php the_field('beachrotana_img'); ?>" />
<?php endif; ?>
<a href="<?php the_permalink(78); ?>" id="adia">
<?php if( get_field('bloom_img') ): ?>
<img src="<?php the_field('bloom_img'); ?>" />
<?php endif; ?>
</a>
<a href="<?php the_permalink(80); ?>" id="adia">
<?php if( get_field('bodytree_img') ): ?>
<img src="<?php the_field('bodytree_img'); ?>" />
<?php endif; ?>
</a>
<a href="<?php the_permalink(82); ?>" id="adia">
<?php if( get_field('certo_img') ): ?>
<img src="<?php the_field('certo_img'); ?>" />
<?php endif; ?>
</a>
<?php if( get_field('daphne_img') ): ?>
<img src="<?php the_field('daphne_img'); ?>" />
<?php endif; ?>
<?php if( get_field('ecolab_img') ): ?>
<img src="<?php the_field('ecolab_img'); ?>" />
<?php endif; ?>
<a href="<?php the_permalink(84); ?>" id="adia">
<?php if( get_field('fish_img') ): ?>
<img src="<?php the_field('fish_img'); ?>" />
<?php endif; ?>
</a>
<?php if( get_field('fsw_img') ): ?>
<img src="<?php the_field('fsw_img'); ?>" />
<?php endif; ?>
<?php if( get_field('gloss_img') ): ?>
<img src="<?php the_field('gloss_img'); ?>" />
<?php endif; ?>
<a href="<?php the_permalink(86); ?>" id="adia">
<?php if( get_field('guy_img') ): ?>
<img src="<?php the_field('guy_img'); ?>" />
<?php endif; ?>
</a>
<?php if( get_field('happiness_img') ): ?>
<img src="<?php the_field('happiness_img'); ?>" />
<?php endif; ?>
<?php if( get_field('herbal_img') ): ?>
<img src="<?php the_field('herbal_img'); ?>" />
<?php endif; ?>
<?php if( get_field('ignite_img') ): ?>
<img src="<?php the_field('ignite_img'); ?>" />
<?php endif; ?>
<?php if( get_field('js_img') ): ?>
<img src="<?php the_field('js_img'); ?>" />
<?php endif; ?>
<?php if( get_field('khalidya_img') ): ?>
<img src="<?php the_field('khalidya_img'); ?>" />
<?php endif; ?>
<a href="<?php the_permalink(88); ?>" id="adia">
<?php if( get_field('lucky_img') ): ?>
<img src="<?php the_field('lucky_img'); ?>" />
<?php endif; ?>
</a>
<a href="<?php the_permalink(90); ?>" id="adia">
<?php if( get_field('lux_img') ): ?>
<img src="<?php the_field('lux_img'); ?>" />
<?php endif; ?>
</a>
<?php if( get_field('madiso_img') ): ?>
<img src="<?php the_field('madiso_img'); ?>" />
<?php endif; ?>
<?php if( get_field('maria_img') ): ?>
<img src="<?php the_field('maria_img'); ?>" />
<?php endif; ?>
<?php if( get_field('prca_img') ): ?>
<img src="<?php the_field('prca_img'); ?>" />
<?php endif; ?>
<?php if( get_field('qcomm_img') ): ?>
<img src="<?php the_field('qcomm_img'); ?>" />
<?php endif; ?>
<?php if( get_field('radwater_img') ): ?>
<img src="<?php the_field('radwater_img'); ?>" />
<?php endif; ?>
<?php if( get_field('radmedia_img') ): ?>
<img src="<?php the_field('radmedia_img'); ?>" />
<?php endif; ?>
<a href="<?php the_permalink(92); ?>" id="adia">
<?php if( get_field('shangri_img') ): ?>
<img src="<?php the_field('shangri_img'); ?>" />
<?php endif; ?>
</a>
<?php if( get_field('sofrank_img') ): ?>
<img src="<?php the_field('sofrank_img'); ?>" />
<?php endif; ?>
<a href="<?php the_permalink(94); ?>" id="adia">
<?php if( get_field('tips_img') ): ?>
<img src="<?php the_field('tips_img'); ?>" />
<?php endif; ?>
</a>
<a href="<?php the_permalink(96); ?>" id="adia">
<?php if( get_field('xbd_img') ): ?>
<img src="<?php the_field('xbd_img'); ?>" />
<?php endif; ?>
</a>
</div>
</div>
If it's not from the text editor where else could it be? I've checked the pages and the ACF's. Can anyone assist / see anything I can't?

Answer 1

In HTML, white space is "normalized". This means that multiple white space characters in a row will be compacted down to a single white space character. But, it also means that other non-printable characters are converted to space characters, including carriage returns.
So, if you write a hyperlink like this:
Some content
There only content of the a element is the text and all of that text is what will be clickable and, if underlining is applied, all the text will be underlined.
But, in your case your code basically works out to be like this:
<a href="somePath">
<img src="somePath"></a>
Which puts a carriage return inside the opening and closing a element and that carriage return gets converted to a space and that space is now part of the content of the element. If underlining gets applied, that space will get underlined.
So, you can just re-work your HTML structure to not include carriage returns in your code or you can turn off underlining for links with the following CSS:
a { text-decoration:none; }

Answer 2

This will solve the problem for sure:
#partnerimages a:hover {text-decoration:none!important;}
You are seeing an underline, not a dash.