Refactor layout and styling: update HTML structure and apply Bootstrap for improved responsiveness

src/app/issues/issues.css

@@ -2,68 +2,6 @@
   display: block;
 }
 
-.page-header {
-  display: flex;
-  justify-content: space-between;
-  align-items: flex-start;
-  gap: 1rem;
-}
-
-.page-header h1 {
-  margin: 0;
-  font-size: 2rem;
-}
-
-.page-header p {
-  margin: 0.5rem 0 1.5rem;
-  color: #4b5563;
-}
-
-.create-button {
-  border: none;
-  border-radius: 0.5rem;
-  background-color: #2563eb;
-  color: #ffffff;
-  padding: 0.65rem 1rem;
-  font-weight: 600;
-  cursor: pointer;
-}
-
-.create-button:hover {
-  background-color: #1d4ed8;
-}
-
-.table-wrapper {
-  background-color: #ffffff;
-  border: 1px solid #e5e7eb;
-  border-radius: 0.75rem;
-  overflow-x: auto;
-}
-
-table {
-  width: 100%;
-  border-collapse: collapse;
-}
-
-th,
-td {
-  padding: 0.85rem 1rem;
-  text-align: left;
-  border-bottom: 1px solid #e5e7eb;
-}
-
-th {
-  font-size: 0.85rem;
-  text-transform: uppercase;
-  letter-spacing: 0.03em;
-  color: #6b7280;
-  background-color: #f9fafb;
-}
-
-tbody tr:last-child td {
-  border-bottom: none;
-}
-
 .clickable-row {
   cursor: pointer;
 }
@@ -77,9 +15,4 @@ tbody tr:last-child td {
   outline-offset: -2px;
 }
 
-@media (max-width: 768px) {
-  .page-header {
-    flex-direction: column;
-  }
-}