Examples updates (#24898)

* fix cover nav

* Improve signin visuals and alignment with that flexbox love

* rewrite cover example in flexbox

* lighten signin bg

* first pass at pricing example

* redo examples index with data file

* tighten up spacing a bit

* update navbar descriptions

* link pricing

* move that back

* property order

* Fix test errors.

* Compress pricing.png.

* add form validation example

* remove that

* rename that

* restyle and space out

* fix errors

* change order

* cleanup album css and styles

* tweak examples index

* make it a badge

* options

* improve sticky footer alignment

* redesign example index

* brand new blog layout

* start new screenshots

* new product example page a la apple

* add email field

* fix linter, remove unused blog css

* hook up feather icons to start

* redo dashboard

* fix linting

* add floating labels example

* formatting

* formatting

* lint

* fix values on select

* optional input, plus input group

* new dashboard image

* start to reboot the offcanvas example

* updated images

* new offcanvas mostly implemented

* linting

* edit description

* more description changes

* - Add vertical margin to album hero buttons for when they're stacked
- Adjust font-size and padding for pricing header and hero
- Fix checkout's stacked column margins, plus update their check/radio
markup
- Update product's utilities to be responsive
- Made blog cards somewhat responsive (needs a bit more work tbh)

* drop leading zero

* more linting

* swap empty images for holder, fix border

* dist the docs

* navbars have no margin-bottom to begin

* add css var, tweak padding for mobile

* comment headers

* nix commented out code

* nix the navbar structure for a custom one, stack it on mobile

* tweak heading button group for mobile

* Removed narrow jumbotron and justified nav examples as these are easily accomplished with new components in v4

* improve card sizing on pricing

* update and compress

docs/4.0/examples/offcanvas/offcanvas.css

@@ -1,63 +1,80 @@
-/*
- * Style tweaks
- * --------------------------------------------------
- */
 html,
 body {
   overflow-x: hidden; /* Prevent scroll on narrow devices */
 }
+
 body {
-  padding-top: 70px;
-}
-footer {
-  padding: 30px 0;
+  padding-top: 56px;
 }
 
-/*
- * Off Canvas
- * --------------------------------------------------
- */
-@media screen and (max-width: 767.98px) {
-  .row-offcanvas {
-    position: relative;
-    transition: all .25s ease-out;
+@media (max-width: 767.98px) {
+  .offcanvas-collapse {
+    position: fixed;
+    top: 56px; /* Height of navbar */
+    bottom: 0;
+    width: 100%;
+    padding-right: 1rem;
+    padding-left: 1rem;
+    overflow-y: auto;
+    background-color: var(--gray-dark);
+    transition: -webkit-transform .3s ease-in-out;
+    transition: transform .3s ease-in-out;
+    transition: transform .3s ease-in-out, -webkit-transform .3s ease-in-out;
+    -webkit-transform: translateX(100%);
+    transform: translateX(100%);
   }
-
-  .row-offcanvas-right {
-    right: 0;
-  }
-
-  .row-offcanvas-left {
-    left: 0;
-  }
-
-  .row-offcanvas-right .sidebar-offcanvas {
-    right: -100%; /* 12 columns */
-  }
-
-  .row-offcanvas-right.active .sidebar-offcanvas {
-    right: -50%; /* 6 columns */
-  }
-
-  .row-offcanvas-left .sidebar-offcanvas {
-    left: -100%; /* 12 columns */
-  }
-
-  .row-offcanvas-left.active .sidebar-offcanvas {
-    left: -50%; /* 6 columns */
-  }
-
-  .row-offcanvas-right.active {
-    right: 50%; /* 6 columns */
-  }
-
-  .row-offcanvas-left.active {
-    left: 50%; /* 6 columns */
-  }
-
-  .sidebar-offcanvas {
-    position: absolute;
-    top: 0;
-    width: 50%; /* 6 columns */
+  .offcanvas-collapse.open {
+    -webkit-transform: translateX(-1rem);
+    transform: translateX(-1rem); /* Account for horizontal padding on navbar */
   }
 }
+
+.nav-scroller {
+  position: relative;
+  z-index: 2;
+  height: 2.75rem;
+  overflow-y: hidden;
+}
+
+.nav-scroller .nav {
+  display: -webkit-box;
+  display: -ms-flexbox;
+  display: flex;
+  -ms-flex-wrap: nowrap;
+  flex-wrap: nowrap;
+  padding-bottom: 1rem;
+  margin-top: -1px;
+  overflow-x: auto;
+  color: rgba(255, 255, 255, .75);
+  text-align: center;
+  white-space: nowrap;
+  -webkit-overflow-scrolling: touch;
+}
+
+.nav-underline .nav-link {
+  padding-top: .75rem;
+  padding-bottom: .75rem;
+  font-size: .875rem;
+  color: var(--secondary);
+}
+
+.nav-underline .nav-link:hover {
+  color: var(--blue);
+}
+
+.nav-underline .active {
+  font-weight: 500;
+  color: var(--gray-dark);
+}
+
+.text-white-50 { color: rgba(255, 255, 255, .5); }
+
+.bg-purple { background-color: var(--purple); }
+
+.border-bottom { border-bottom: 1px solid #e5e5e5; }
+
+.box-shadow { box-shadow: 0 .25rem .75rem rgba(0, 0, 0, .05); }
+
+.lh-100 { line-height: 1; }
+.lh-125 { line-height: 1.25; }
+.lh-150 { line-height: 1.5; }