Bundle CSS with Hugo's Sass feature (#705)

* migrate bootstrap and flags to bundle

* migrated main.css

* migrate navbar.css and plyr

* migrated mulish font and darkreader

* migrated static/css/sections stylesheets

* migrated list page and sidebar styles

* migrated search.html ( nothing to add )

* migration single page styles

* remove duplicated style tags

* migrate notes.  Deleted unused css in static

* migrate 404 css to bundle

* migrate katex styles

* migrate embedpdf styles

* migrated katex css

---------

Co-authored-by: Aaron Qian <aaron@yeet.io>

layouts/shortcodes/embed-pdf.html

@@ -23,46 +23,3 @@
       <canvas class="pdf-canvas"></canvas>
   </div>
 </div>
-
-<!-- Finally, make the canvas more beautiful -->
-<style>
-.pdf-viewer canvas {
-  border: 1px solid black;
-  direction: ltr;
-  width: 100%;
-  height: auto;
-  display: none;
-}
-
-.pdf-viewer  .paginator {
-  display: none;
-  text-align: center;
-  margin-bottom: 10px;
-}
-
-.pdf-viewer .loading-wrapper {
-  display: none;
-  justify-content: center;
-  align-items: center;
-  width: 100%;
-  height: 350px;
-}
-
-.pdf-viewer .loading {
-  display: inline-block;
-  width: 50px;
-  height: 50px;
-  border: 3px solid #d2d0d0;;
-  border-radius: 50%;
-  border-top-color: #383838;
-  animation: spin 1s ease-in-out infinite;
-  -webkit-animation: spin 1s ease-in-out infinite;
-}
-
-@keyframes spin {
-  to { -webkit-transform: rotate(360deg); }
-}
-@-webkit-keyframes spin {
-  to { -webkit-transform: rotate(360deg); }
-}
-</style>