There are several considerations:
1) All iPads' browsers think that their screen resolution is 768x1024.
In your original media query you have min-width: 1224px
which will never match any iPad.
2) SASS expressions are executed regardless of whether they are wrapped into media queries or not. SASS knows nothing about which resolution the resulting CSS will be viewed at, so this code:
@media #{$ipad-landscape} {
$paragraph-font-size: emCalc(12px);
}
is senseless and is equivalent to just $paragraph-font-size: emCalc(12px);
.
You have to put some CSS declarations inside media queries so that they will be evaluated by a browser.
3) I don't own an iPad so i can't test, but your last media query @media only screen and (min-width: 1000px) and (-webkit-min-device-pixel-ratio: 2)
looks solid to me. It should match in landscape only.