[Theme: Helsinki] Very annoying styling problem

I’ve been trying to change the colour of the header font through my style.css for a while now, with no success.

I’ve opened the website, and inspected the element, and tried to find the element in the parent’s style.css, but the parent’s style.css is blank! It has nothing in apart from the declaration at the beginning.

I’ve found another file called style.min.css that has all of the styling for the pages, including #headline .logo a (which is the element I want to modify).

When I try and add styling rules for #headline .logo a, in my style.css, nothing happens. Might it be that style.min.css is being called after style.css and therefore overwriting my rules?

How can I overcome this, and modify the colour of #headline .logo a?

My current style.css (that changes the header background colour correctly, but does’t modify the text colour):

/*
Theme Name:     helsinki-child
Description:    Helsinki child theme
Author:         TEST
Template:       helsinki

(optional values you can add: Theme URI, Author URI, Version, License, License URI, Tags, Text Domain)
*/

aside#headline {
	background:red;
	/*background:#1d1f21;*/
	font: white;
}

#headline .logo a {
    color: yellow;
    text-decoration: none
}

I’ve located the style.min.css in tefltest.byethost7.com/htdocs/wp-content/themes/helsinki/assets/css/style.min.css, but I don’t know what to do with it.

Can anyone suggest a solution please?

Thanks