Add About Modal with developer information

- Create a comprehensive About modal showcasing features and version history
- Add information about PowerData.dk and Michael Bay-Laursen as the developer
- Include version history section for tracking changes
- Style modal for optimal display on all device sizes

🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>

public/css/styles.css

@@ -445,7 +445,7 @@ header {
   transition: opacity 0.3s ease, visibility 0.3s ease;
 }
 
-.modal-backdrop.show {
+.modal-backdrop.show, #about-modal[style*="flex"] {
   opacity: 1;
   visibility: visible;
 }
@@ -463,7 +463,19 @@ header {
   transition: opacity 0.3s ease, transform 0.3s ease;
 }
 
-.modal-backdrop.show .modal {
+#about-modal .modal {
+  max-width: 800px;
+  opacity: 1;
+  transform: none;
+  animation: modalFadeIn 0.3s;
+}
+
+@keyframes modalFadeIn {
+  from { opacity: 0; transform: translateY(-30px); }
+  to { opacity: 1; transform: translateY(0); }
+}
+
+.modal-backdrop.show .modal, #about-modal[style*="flex"] .modal {
   opacity: 1;
   transform: translateY(0);
 }
@@ -493,6 +505,10 @@ header {
   padding: 1rem;
 }
 
+#about-modal .modal-body {
+  padding: 1.5rem;
+}
+
 .modal-footer {
   padding: 1rem;
   border-top: 1px solid var(--border-color);
@@ -500,6 +516,41 @@ header {
   justify-content: flex-end;
 }
 
+/* About modal specific styles */
+#about-modal .version-history {
+  border-left: 3px solid var(--primary-color);
+  padding-left: 20px;
+  margin-bottom: 20px;
+}
+
+#about-modal .version {
+  margin-bottom: 15px;
+}
+
+#about-modal .version h5 {
+  color: var(--primary-color);
+  margin-bottom: 5px;
+}
+
+#about-modal .features-list {
+  list-style-type: none;
+  padding-left: 0;
+}
+
+#about-modal .features-list li {
+  padding: 8px 0;
+  border-bottom: 1px solid var(--border-color);
+}
+
+#about-modal .features-list li:last-child {
+  border-bottom: none;
+}
+
+#about-modal .lead {
+  font-size: 1.1rem;
+  line-height: 1.6;
+}
+
 /* Tabs */
 .tabs {
   display: flex;