Fix Waitlist button padding issue (internetarchive#11079)

* Join waitlist had a padding error; i've added the join waitlist form as a specification of cta-button-group in book.less; this change should make all paddings uniform.

* fix waitlist btn padding on homepage

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update book.less

* fix specificity and ordering

Author: doct0r-furcation

static/css/components/book.less

@@ -2,7 +2,8 @@
 
 .book {
   & > .cta-button-group,
-  & > .cta-btn {
+  & > .cta-btn,
+  form .cta-button-group {
     margin-top: 10px;
   }