I was a newbie like you a month ago. Here are snippets I’ve picked up over the last month that are specific to this theme. It may give you a springboard from which you can research bigger CSS questions elsewhere.
/*
Theme Name: customizr-child
Template: customizr
*/
@import url("../customizr/style.css");
/* Get rid of menu border */
.navbar .navbar-inner {
-webkit-box-shadow: 0px 0px 0px;
-moz-box-shadow: 0px 0px 0px;
box-shadow: 0px 0px 0px;
}
/* Get rid of menu background */
.navbar .navbar-inner {
-webkit-box-shadow: 0px 0px 0px;
-moz-box-shadow: 0px 0px 0px;
box-shadow: 0px 0px 0px;
background:none
}
/* Take bold of tagline in navbar */
.navbar-wrapper .navbar h2 {
font-weight: 400;
/*font-size: 20px;*/
}
/* Play with carousel */
/*make the nav drop down on hover*/
ul.nav li.dropdown:hover > ul.dropdown-menu{
display: block;
margin: 0;
}
/* Change navbar padding: 2nd and 4th for horiz padding */
/* and change font size in menu */
.navbar .nav > li > a {
padding: 5px 16px 5px 16px;
font-size: 16px;
}
/* Change font size of first letters in menu */
.navbar .nav > li > a:first-letter {
font-size: 16px;
}
/* Get rid of post dates etc */
body.single .entry-meta {
display: none
}
/* Get rid of page icons */
.format-icon:before {
speak: none;
text-transform: none;
-webkit-font-smoothing: antialiased;
padding-right: 10px;
opacity: 0.2;
position: relative;
top: 8px;
display: none;
font: normal normal 1.2em/1 'entypo';
}
/* Change icon on status
article.format-status .format-icon:before {
content: "\26A1"; */
}
/* Change page title text size */
.entry-title {
font-size: 30px;
}
/* Change h2 text size */
h2 {
font-size: 25px;
}
/* Change h3 text size */
h3 {
font-size: 18px;
}
/* make the fancybox arrows show, even when not hovering */
#fancybox-left span {
left: 20px;
}
#fancybox-right span {
left: auto;
right: 20px;
}
It took me a while to begin to understand how to use Firebug (Safari’s inspector is good too) and point to the elements I wanted to change. I still haven’t completely grasped it, but seeing code snippets from others on this specific theme’s layout helped.
Good luck!
p.s. On the colours: I’m presuming you’ve gone into Customize’it! and chosen the skin you want as a first step.