feat: contact address with a sheen and a light on its underline

The address is the one thing to act on in the contact section, but it was a
plain underlined line next to a glowing message card. A slow sheen now runs
through the letters and a light travels along the underline; on hover the
whole line lights up.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/app/globals.css

@@ -1224,6 +1224,87 @@ pre:has(code[class*="language-"]) {
   }
 }
 
+/*
+ * The contact address on a dark surface: a slow sheen runs through the letters
+ * and a light travels along the underline. On hover the whole line lights up.
+ */
+.bit-mail {
+  position: relative;
+  display: inline-block;
+  padding-bottom: 0.42em;
+  background: linear-gradient(
+    100deg,
+    #ffffff 0 38%,
+    #a5b4fc 50%,
+    #ffffff 62% 100%
+  );
+  background-size: 260% 100%;
+  -webkit-background-clip: text;
+  background-clip: text;
+  color: transparent;
+  -webkit-text-fill-color: transparent;
+  animation: bit-mail-sheen 7s ease-in-out infinite;
+  transition: filter 300ms ease;
+}
+.bit-mail::before,
+.bit-mail::after {
+  content: "";
+  position: absolute;
+  left: 0;
+  right: 0;
+  border-radius: 4px;
+  pointer-events: none;
+}
+/* The resting underline. */
+.bit-mail::before {
+  bottom: 1px;
+  height: 2px;
+  background: rgba(255, 255, 255, 0.26);
+}
+/* The light travelling along it. */
+.bit-mail::after {
+  bottom: 0;
+  height: 4px;
+  background: linear-gradient(
+      90deg,
+      transparent,
+      #818cf8 30%,
+      #ffffff 50%,
+      #818cf8 70%,
+      transparent
+    )
+    no-repeat;
+  background-size: 42% 100%;
+  filter: drop-shadow(0 0 8px rgba(129, 140, 248, 0.95));
+  animation: bit-mail-run 3.8s ease-in-out infinite alternate;
+  transition: background-size 400ms ease;
+}
+@media (hover: hover) {
+  .bit-mail:hover {
+    filter: drop-shadow(0 0 18px rgba(129, 140, 248, 0.7));
+  }
+  .bit-mail:hover::after {
+    background-size: 100% 100%;
+  }
+}
+@keyframes bit-mail-sheen {
+  0%,
+  100% {
+    background-position: 100% 0;
+  }
+  50% {
+    background-position: 0% 0;
+  }
+}
+@keyframes bit-mail-run {
+  from {
+    background-position: -30% 0;
+  }
+  to {
+    background-position: 130% 0;
+  }
+}
+
 /* Slow light drifting over a dark picture (see PortraitSection). */
 .bit-aurora {
   position: absolute;

apps/web/src/components/home/ClosingCta.tsx

@@ -38,7 +38,7 @@ export const ClosingCta: React.FC<{ contact: Content["contact"] }> = ({
           {contact.lead}
         </p>
         <div className="mt-8">
-          <EmailLink className="inline-block border-b-2 border-white pb-2 font-sans text-2xl font-bold tracking-tight text-white no-underline transition-opacity hover:opacity-70 md:text-4xl" />
+          <EmailLink className="bit-mail font-sans text-3xl font-bold tracking-tight no-underline md:text-5xl" />
         </div>
       </Reveal>
       <Reveal delay={0.15} className="lg:col-span-6">