Add spoiler tag shortcode.

hugo.toml

@@ -9,7 +9,7 @@ googleAnalytics = "G-QFK0K7MGCJ"
 
 [params]
   paginate = 10
-  custom_css = ["/css/custom.css"]
+  custom_css = ["/css/custom.css", "/css/spoiler.css"]
   dateFormat = "2006-01-02"
   # Disqus shortname
 #  disqus = ""

layouts/shortcodes/spoiler.html

@@ -0,0 +1 @@
+<span class="inline-spoiler">{{- .Inner | safeHTML -}}</span>

static/css/spoiler.css

@@ -0,0 +1,26 @@
+.inline-spoiler {
+  position: relative;
+  display: inline-block;
+  cursor: help;
+}
+
+.inline-spoiler::before {
+  content: "";
+  position: absolute;
+  top: 0;
+  left: 0;
+  width: 100%;
+  height: 100%;
+  border-radius: 1px;
+  color: white;
+  background: black;
+  opacity: 1;
+  transition: opacity 0.7s ease, transform 0.3s ease;
+}
+
+.inline-spoiler:hover::before {
+  opacity: 0;
+  transform: translateY(-50%) rotateX(80deg);
+  transition: opacity 1s ease, transform 0.5s ease;
+  transition-delay: 0.3s;
+}