html css layout with header two columns and footer

Question

I am trying to create a head area that is 100px in height and spans 100% in width. I need 2 columns with the left one being 250px wide and 100% in height down to the footer. The right column should be 100% of the remaining page width and 100% in height to the footer. The footer should be at the bottom of the page and 100px in height and 100% in width. Even if there is no content in the 2 columns, I need them to stretch down to the footer and have the footer visible without scrolling down to it.

Here is what I have so far.

<div id="top"><p>Lorem ipsum dolor sit amet</p></div>
<div id="left"><p>Lorem ipsum dolor sit amet</p></div>
<div id="right"><p>Lorem ipsum dolor sit amet</p></div>
<div id="bot"><p>Lorem ipsum dolor sit amet</p></div>

body, html {
    height: 100%;
}
body {
    margin: 0px;
}
p {
    margin: 0px;
}
#top {
    height: 100px;
    background-color: #F4F4F4;
}
#left {
    width: 250px;
    height: 100%;
    background-color: #878787;
    float: left;
    margin-bottom: -100px;
}
#right {
    background-color: #323232;
    height: 100%;
    margin-bottom: -100px;
}
#bot {
    clear: right;
    height: 100px;
    background-color: #DCDCDC;
    margin-top: -100px;
    z-index: 100;
    position: relative;
}

Here is another example with a table

<table height="100%" width="100%" cellspacing="0" cellpadding="0" border="0" class="" id="">
	<tr>
		<td colspan="2" style="background-color: powderblue; height: 100px;">Header</td>
	</tr>
	<tr>
		<td style="background-color: gray; width: 350px;">Left Col</td>
		<td style="background-color: DarkSeaGreen">Right Col</td>
	</tr>
	<tr>
		<td colspan="2"  style="background-color: tomato; height: 100px;">Footer</td>
	</tr>
</table>

Answer 1

Here is a simple CSS-grid solution (I used 50px instead of 100px so we can see it in the reduced snippet)

html {
    height: 100%;
}
p {
    margin: 0px;
}
body {
  min-height:100%;
  margin:0;
  display:grid;
  grid-template-rows:50px 1fr 50px;
  grid-template-columns:250px 1fr;
  grid-template-areas:
    "top top"
    "left right"
    "bot bot";
}

#top {
    grid-area:top;
    background: linear-gradient(#F4F4F4,blue);
}
#left {
    grid-area:left;
    background: linear-gradient(#878787,red);
}
#right {
    grid-area:right;
    background: linear-gradient(#323232,green);
}
#bot {
    grid-area:bot;
    background: linear-gradient(#DCDCDC,purple);
}

<div id="top"><p>Lorem ipsum dolor sit amet</p></div>
<div id="left"><p>Lorem ipsum dolor sit amet</p></div>
<div id="right"><p>Lorem ipsum dolor sit amet</p></div>
<div id="bot"><p>Lorem ipsum dolor sit amet</p></div>

And here is with flexbox:

body, html {
    height: 100%;
}
p {
    margin: 0px;
}
body {
  margin:0;
  display:flex;
  flex-wrap:wrap;
}

#top,#bot {
    height:50px;
    width:100%;
    background: linear-gradient(#F4F4F4,blue);
}
#left {
    width:250px;
    min-height:calc(100% - 2 * 50px);
    background: linear-gradient(#878787,red);
}
#right {
    flex:1;
    min-height:calc(100% - 2 * 50px);
    background: linear-gradient(#323232,green);
}

<div id="top"><p>Lorem ipsum dolor sit amet</p></div>
<div id="left"><p>Lorem ipsum dolor sit amet</p></div>
<div id="right"><p>Lorem ipsum dolor sit amet</p></div>
<div id="bot"><p>Lorem ipsum dolor sit amet</p></div>