Anwer AR

No, but !important is something we can use to override any css predefined value.. it makes higher priority.

If your theme has builtin options for customizing menu as Vladff said then its very easy, you just have to adjust settings.. i hope it does.
but if there is no options for customizing menu height as you want, then yes you have add new values (height,width etc ) in you css file.

Hey Rob, Ahisma is not in wordpress directory. its a third party theme and found here
https://ahren.org/code/ahimsa
and i think its not following wordpress code standards.
if you want to modify your theme then its up to you but if you just want a three column theme for your blog then there’s a lot of good themes in wordpress theme directory.you can install them for your blog.
here is the link of three column wordpress themes
Three column themes
and if you cant choice anyone from there i will suggest you to take a loot at This theme.

and let us know if you have found one for your blog?

You have to put CSS into your theme Stylesheet.css file. and what type of template you wanna create? wordpress has built in page and posts templates.. see that in codex,and if you want custom template for you theme, let us know?

Oh, ok… do you have some basic knowledge of PHP? if yes then you can modify your sidebars.. or if you don’t want to play with PHP and just want to hide the sidebar from post and page, you can do that by css..?

maybe the below code will help you.

is_singular()
is_single()

id sidebar.php add this and check.

if(!is_single){
    if(function_exists('dynamic_sidebar')){
       dynamic_sidebar('your_sidebar');
       }
}

and for both page and posts.

if(!is_single && !is_page){
sidebar goes here
}

if its just the matter of background color then i think custom css class will help to do that.
use a custom class like

<div class="blank-page">

blank template code goes here......

</div>

.blank-page {background-color : green;}

can you please give more detail? and post the page link here.

Yes, You Can do that, modify your css file. and use

line-height : desired value;

property to control the height of your menu. and there maybe other things like padding, margin etc. so modify their values also as you need.

Modify your CSS and add !important after every value that you want to style, like

h1, h2, h3, h4, h5, h6 {
font-weight: bold!important;
text-transform: none!important;
}

.container .ten.columns {
width: 100%!important;
}
.container .ten.columns {
width: 100%!important;
}

or copy the above code and paste it into your stylesheet. hope it will solve the issue.

Sorry brother. Any theme with the named “Ahimsa” is not found in wordpress theme directcory. and wordpress default themes are twentyten,twentythirteen & twentyfourteen etc and that comes with wordpress installation.
can you post the link of that theme here. so i will see.

Oh, there was mistake..sorry.
i mean the page should go vertically down when dropdown menu is active(for better user experience. now rest of the page flow to right side when menu opens.

There is no header navigation in your current theme? if it does than try to use it instead of using plugins… and for responsive design you can use CSS and especially media quires(that you already applying).
and yes the menu is not bad, its nice. but the page goes vertically when menu is active.

Thanks CrouchingBruin. this was very helpful. i can use it in future.

Ah ok.
is that theme is in WordPress theme directory? or if you have downloaded that theme from external sites? give me the theme name if its there. i will see if i can do something.
or if you want to try than look at your functions.php file and find the below code.
wp_enqueue_style();
if that function dosent exist in functions.php than open up header.php and loot into head section of theme. maybe that theme is loading stylesheet manually.if yes look for this.
<link rel="stylesheet" href=".........">
and post the result in both case so we will go further.