Child theme typography issues

Hiya!

I´m working on a child theme of Twentyeleven, but only some of my changes comes through, and I can´t figure out what I´m doing wrong. I´ve read the documentation (and some threads here) but can´t find my problem solved.

I have installed WP on XAMPP on my computer, created a new directory with a style.css in it, and I have managed to change background colours, menu bar colours and such, so I know the theme css works.

The most important changes I want to make are font/size/color on h1, h2 and h3, and the color of the line above the header image. I have tried this (for instance. I´ve tried a lot…):

.singular .entry-title {
color: #000;
font-size: 36px;
font-weight: bold;
line-height: 48px;
}`

and changed the color, size, and even added a row with font-family (I don´t want to use the inherited helvetica that´s in the body css), but nothing works.

For the line, I have found this:

#branding {
border-top: 2px solid #992700;
padding-bottom: 10px;
position: relative;
z-index: 9999;
}

but my red color does not show up.

The funny thing is, that if I try the exact same tricks in the Firefox Firebug code, the changes applies to the page. So what am I doing wrong in my little style.css?!

I´m half good at css, but no expert, and I don´t know any php, just so you know my level…

Best
/Nina