Add intro video

docs/_sass/index.sass

@@ -11,6 +11,8 @@
 
 .intro-ghbtns
   height: 30px
+  margin-bottom: 24px
+  // margin-bottom: 46px
 
 .intro-npm
   background: $black-ter
@@ -79,7 +81,7 @@
 
 .intro-spinner,
 .intro-shadow
-  animation-duration: 1000ms
+  animation-duration: 500ms
   animation-easing-function: ease-out
   animation-fill-mode: both
   transform-origin: center
@@ -107,8 +109,7 @@
 
 .intro-shadow
   +overlay
-  background-color: #43647b
-  background-image: url("/images/index/vimeo-placeholder.jpg")
+  background-color: #776e70
   background-position: center center
   background-repeat: no-repeat
   background-size: cover
@@ -118,6 +119,7 @@
 .intro-iframe
   opacity: 0
   padding-top: 52.8125%
+  // padding-top: 56.25%
   position: relative
   transition-duration: 500ms
   transition-property: opacity
@@ -128,6 +130,21 @@
     top: 0
     width: 100%
 
+.intro-author
+  color: $text-light
+  font-size: $size-small
+  margin-top: 1rem
+  text-align: center
+  a
+    color: $text-strong
+    &:hover
+      text-decoration: underline
+  span
+    opacity: 0.5
+    transition: 100ms opacity
+    &:hover
+      opacity: 1
+
 +mobile
   .intro-buttons
     .button