Replacing svg warp-knitting images with png to deal with improper layering

background.html

@@ -531,8 +531,11 @@ fast production. The supply of yarn is very similar to that of warp
 threads in a weaving loom.
 
 <figure id="fig-circular-knitting">
+<!--
 <img src="./figures/warp-knitting.svg" class="h300">
 <img src="./figures/warp-knitting-side.svg" class="h300">
+-->
+<img src="./figures/warp-knitting.png">
 <figcaption>
 <a>Figure 13</a>: An example of swaying illustrating the movement of the yarn guides in
 a Raschel warp knitting machine: the general movement from the front of