I want to set the height of iframe to expand to the rest of available space (ie windowsHeight - menuHeight - footerHeight), as used in contentFrame, which does not work for me. It works when height is set to specific pixels.The width:100% works. Because the app is a legacy app, it should be compatible with IE 10/11, Chrome, and Firefox.

index.htm 

```
<body>
<iframe name="menuFrame" src="menu.htm" frameborder="1" style="height:40px; width: 100%;">
</iframe>
<iframe name="contentFrame" src="content.htm" frameborder="1" style="height:100%; width: 100%;">
</iframe>
<iframe name="footerFrame" src="footer.htm" frameborder="1" style="height:15px; width: 100%;">
</iframe>
</body>

```

menu.htm

```
<body>
menu
</body>

```

content.htm

```
<body style="border: solid 1 black;height: 100%;">
content
</body>

```

footer.htm 

```
<body>
footer
</body> 

```

**Update**
Thanks all for your help. I tested LGSon's only, which is easier for me to understand.