fix(content.css): add CRITICAL severity highlight and tooltip badge styles

extension/styles/content.css

@@ -1,4 +1,5 @@
 /* ClauseGuard — Content Script Styles (injected into web pages) */
+/* v4.3: Added CRITICAL severity styles */
 
 /* Highlight severity levels */
 .clauseguard-highlight {
@@ -9,6 +10,16 @@
   position: relative;
 }
 
+/* CRITICAL — purple (most severe) */
+.clauseguard-critical {
+  background: rgba(168, 85, 247, 0.22);
+  border-bottom: 2.5px solid #a855f7;
+}
+.clauseguard-critical:hover {
+  background: rgba(168, 85, 247, 0.38);
+}
+
+/* HIGH — red */
 .clauseguard-high {
   background: rgba(239, 68, 68, 0.22);
   border-bottom: 2.5px solid #ef4444;
@@ -17,6 +28,7 @@
   background: rgba(239, 68, 68, 0.35);
 }
 
+/* MEDIUM — amber */
 .clauseguard-medium {
   background: rgba(245, 158, 11, 0.18);
   border-bottom: 2.5px solid #f59e0b;
@@ -25,6 +37,7 @@
   background: rgba(245, 158, 11, 0.32);
 }
 
+/* LOW — blue */
 .clauseguard-low {
   background: rgba(59, 130, 246, 0.14);
   border-bottom: 2.5px solid #3b82f6;
@@ -74,6 +87,10 @@
   letter-spacing: 0.5px;
 }
 
+.clauseguard-badge-critical {
+  background: #e9d5ff;
+  color: #6b21a8;
+}
 .clauseguard-badge-high {
   background: #fecaca;
   color: #991b1b;