added dependencies

vendor/twbs/bootstrap/site/assets/scss/_masthead.scss

@@ -0,0 +1,74 @@
+// stylelint-disable declaration-no-important
+
+.bd-masthead {
+  position: relative;
+  padding: 3rem ($grid-gutter-width * .5);
+  background: linear-gradient(to right bottom, lighten($bd-purple-light, 16%) 50%, #fff 50%);
+
+  h1 {
+    @include font-size(4rem);
+    line-height: 1;
+  }
+
+  .lead {
+    @include font-size(1.5rem);
+    font-weight: 400;
+    color: $gray-700;
+  }
+
+  .btn {
+    padding: .8rem 2rem;
+    font-weight: 600;
+    @include font-size(1.25rem);
+  }
+
+  .carbonad {
+    margin-top: 0 !important;
+    margin-bottom: -3rem !important;
+  }
+
+  @include media-breakpoint-up(sm) {
+    padding-top: 5rem;
+    padding-bottom: 5rem;
+
+    .carbonad {
+      margin-bottom: 0 !important;
+    }
+  }
+
+  @include media-breakpoint-up(md) {
+    .carbonad {
+      margin-top: 3rem !important;
+    }
+  }
+}
+
+.masthead-followup {
+  h2 {
+    @include font-size(2.5rem);
+  }
+
+  .highlight {
+    @include border-radius(.5rem);
+
+    pre::-webkit-scrollbar {
+      display: none;
+    }
+
+    pre code {
+      display: inline-block;
+      white-space: pre;
+    }
+  }
+}
+
+.masthead-followup-icon {
+  padding: .75rem;
+  background-image: linear-gradient(to bottom right, rgba(255, 255, 255, .2), rgba(255, 255, 255, .01));
+  @include border-radius(.75rem);
+  box-shadow: 0 .125rem .25rem rgba(0, 0, 0, .1);
+}
+
+.masthead-followup-svg {
+  filter: drop-shadow(0 1px 0 rgba(0, 0, 0, .125));
+}