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>

assets/styles/sections/recent-posts.scss

@@ -0,0 +1,95 @@
+.recent-posts-section {
+  .container {
+    padding-top: 1rem;
+  }
+  
+  h1 > span{
+    margin-top: -55px;  /* Size of fixed header */
+    padding-bottom:55px; 
+    display: block; 
+  }
+  
+  .card {
+    height: 100%;
+    min-height: 100%;
+  }
+  
+  .card .card-footer span {
+    font-size: 10pt;
+    color: #6c757d !important;
+    padding-top: 5px;
+  }
+  
+  .card .card-footer {
+    background: #fff;
+    margin-top: auto;
+  }
+  
+  .post-card-link {
+    text-decoration: none;
+  }
+  
+  .post-summary {
+    overflow: hidden;
+    text-overflow: ellipsis;
+    display: -webkit-box;
+    /* line-height: 24px;     fallback */
+    max-height: 144px; /* fallback */
+    -webkit-line-clamp: 5; /* number of lines to show */
+    -webkit-box-orient: vertical;
+  }
+  
+  /* ============= Device specific fixes ======= */
+  
+  /* Large screens such as TV */
+  @media only screen and (min-width: 1824px) {
+  }
+  
+  /* Extra large devices (large desktops, 1200px and up) */
+  
+  @media (max-width: 1400px) {
+  }
+  
+  @media (max-width: 1200px) {
+  }
+  
+  /* IPad Pro */
+  @media (max-width: 1024px) {
+  }
+  
+  /*  Large devices (desktops, 992px and up) */
+  
+  @media (max-width: 992px) {
+  }
+  
+  /* Medium devices (tablets, 768px and up) */
+  
+  @media only screen and (max-width: 768px) {
+    .container {
+      max-width: 100%;
+    }
+    .post-card {
+      width: 50%;
+    }
+  }
+  
+  /* Small devices (landscape phones, 576px and up) */
+  
+  @media only screen and (max-width: 576px) {
+    .post-card {
+      width: 100%;
+    }
+  }
+  
+  /* iPhoneX, iPhone 6,7,8 */
+  @media only screen and (max-width: 375px) {
+  }
+  
+  /* Galaxy S5, Moto G4 */
+  @media only screen and (max-width: 360px) {
+  }
+  
+  /* iPhone 5 or before */
+  @media only screen and (max-width: 320px) {
+  }  
+}