Code Blocks in Postachio

My final CSS (which is linked from this blog):

/** this is for the markdown stuff **/
:not(pre) > code[class*="language-"], pre[class*="language-"] {
border: 1px solid gray;
border-radius: 5px;
background-color: #ffffe0;

/** non-markdown background and border **/
div[style*="box-sizing: border-box;"] {
background-color: #ffffe0;
border: 1px solid gray;
border-radius: 5px;

/** non-markdown indention **/
div[style*="box-sizing: border-box;"] div {
margin: 0px;
padding: 5px !important;
overflow: auto;
white-space: pre-wrap;

/** non-markdown line-height consistency **/
div[style*="box-sizing: border-box;"] div,
div[style*="box-sizing: border-box;"] div span,
div[style*="box-sizing: border-box;"] div span {
line-height: 15px;
font-size: 14px;
font-family: Monaco, Menlo, Consolas, monospace;

div.posts div.item .post-content p,
div.posts div.item .post-content div,
.post-content div {
line-height: 1em !important;
margin-top: .25em;
margin-bottom: .25em;
padding-top: 0px;
padding-bottom: 0px;

.post-content div div {
margin: 1px !important;
padding: 1px !important;

/** markdown **/
.post-content p {
background-color: white;
line-height: 1em !important;
margin-top: .5em !important;
margin-bottom: 1em !important;
padding: 0px;

div.posts h3, h3 {
position: relative;
padding: 0 0 12.5px 0;
margin: 0;
font-size: 1.55rem;
font-family: 'Roboto';
font-weight: 300;
color: #0e3029;

Which works with this solution in Evernote and this other solution using Markdown in Postachio (make sure to use languages like language-swift for your code blocks to activate Prism).

Also note Elliot's solution here, which attacks this whole problem from another side.