content/static: add icon to jump to button

Adds icon to jump to button in left sidebar.

Change-Id: If0abe4dd94e741f15a17571c4916c7bacbbbeb40
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/259628
Trust: Jamal Carvalho <jamal@golang.org>
Run-TryBot: Jamal Carvalho <jamal@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Julie Qiu <julie@golang.org>
diff --git a/content/static/css/unit_outline.css b/content/static/css/unit_outline.css
index c05adca..6c10f7d 100644
--- a/content/static/css/unit_outline.css
+++ b/content/static/css/unit_outline.css
@@ -57,9 +57,10 @@
 .UnitOutline-jumpTo button {
   background-color: white;
   border: 0.0625rem solid var(--gray-8);
+  color: var(--gray-4);
   cursor: pointer;
   height: 2rem;
-  padding-left: 1rem;
+  padding-left: 1.5rem;
   text-align: left;
   width: 100%;
 }
@@ -76,3 +77,14 @@
   text-align: center;
   width: 1.5rem;
 }
+.UnitOutline-jumpTo::before {
+  align-self: center;
+  border-radius: 0.5rem;
+  color: var(--gray-6);
+  content: url('/static/img/pkg-icon-jumpTo_16x16.svg');
+  font-size: 0.75rem;
+  left: 0.4rem;
+  position: absolute;
+  text-align: center;
+  top: 0.5rem;
+}
diff --git a/content/static/img/pkg-icon-jumpTo_16x16.svg b/content/static/img/pkg-icon-jumpTo_16x16.svg
new file mode 100644
index 0000000..905cd5e
--- /dev/null
+++ b/content/static/img/pkg-icon-jumpTo_16x16.svg
@@ -0,0 +1 @@
+<svg width="16" height="16" xmlns="http://www.w3.org/2000/svg"><defs><filter height="200%" width="200%" y="-50%" x="-50%" id="a"><feGaussianBlur stdDeviation=".2"/></filter><filter id="c"><feGaussianBlur stdDeviation=".2"/></filter><filter id="b"><feGaussianBlur stdDeviation=".2"/></filter></defs><path fill="none" d="M-1-1h802v602H-1z"/><g><path d="M-1-1h18v18H-1V-1z" fill="#fff"/><g fill="#4c4c4c"><path d="M1.992 4h12v1h-12V4z" filter="url(#a)"/><path d="M5.962 10.367h4v1h-4v-1z" filter="url(#b)"/><path d="M4.085 7.13h8v1h-8v-1z" filter="url(#c)"/></g></g></svg>
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