Fix card gap colors: use borders instead of grid gap background

- Remove gap:1px + background:var(--rule) from grid (caused contrasting
  light lines in dark mode and dark lines in light mode)
- Add border-bottom and border-right on cards using var(--rule) instead
- Remove border-right on mobile (single column)
- Add flex:1 to card-content, remove margin-top:auto from card-footer
- This eliminates the visible dark/white space below cards

Author: shehzensidiq

src/app/globals.css

@@ -848,11 +848,10 @@ html, body {
 .projects-grid {
   display: grid;
   grid-template-columns: 1fr;
-  gap: 1px;
-  background: var(--rule);
+  gap: 0;
+  background: transparent;
   width: 100%;
   max-width: 100%;
-  align-items: stretch;
 }
 
 @media (min-width: 769px) {
@@ -888,11 +887,17 @@ html, body {
   position: relative;
   overflow: hidden;
   border: none;
+  border-bottom: 1px solid var(--rule);
+  border-right: 1px solid var(--rule);
   border-radius: 0;
   display: flex;
   flex-direction: column;
-  height: 100%;
-  min-height: 100%;
+}
+
+@media (max-width: 768px) {
+  .project-card {
+    border-right: none;
+  }
 }
 
 .project-card::before {
@@ -917,6 +922,11 @@ html, body {
 }
 
 /* Card internal layout */
+.card-content {
+  flex: 1;
+  min-height: 0;
+}
+
 .card-header {
   display: flex;
   justify-content: space-between;
@@ -1119,7 +1129,6 @@ html, body {
   align-items: center;
   padding-top: 0.75rem;
   border-top: 1px solid var(--rule);
-  margin-top: auto;
 }
 
 .card-links {