Phase 1: Homepage seamless design - add gradient transitions

- Added gradient transitions between sections in global.css
- Portfolio section now has gradient-top (dark to white fade)
- Blog section now has gradient-bottom (white fade from dark)
- Reduced portfolio overlay opacity from 0.85 to 0.65
- Added border to blog cards for white-on-white visibility
- Blog cards now have primary color accent on hover

src/components/PortfolioCard.astro

@@ -0,0 +1,76 @@
+---
+interface Props {
+  name: string;
+  url: string;
+  category: string;
+  category_label: string;
+  thumbnail: string;
+  description: string;
+}
+
+const { name, url, category, category_label, thumbnail, description } = Astro.props;
+---
+
+<a href={url} target="_blank" rel="noopener" class="portfolio-card" data-category={category}>
+  <div class="portfolio-image">
+    <img src={thumbnail} alt={name} loading="lazy" />
+  </div>
+  <div class="portfolio-info">
+    <span class="portfolio-category">{category_label}</span>
+    <h3 class="portfolio-name">{name}</h3>
+    <p class="portfolio-desc">{description}</p>
+  </div>
+</a>
+
+<style>
+  .portfolio-card {
+    display: block;
+    background: rgba(255,255,255,0.03);
+    border-radius: 16px;
+    overflow: hidden;
+    border: 1px solid rgba(255,255,255,0.05);
+    transition: all 0.4s ease;
+  }
+  .portfolio-card:hover {
+    transform: translateY(-8px);
+    background: rgba(255,255,255,0.08);
+    border-color: var(--color-primary);
+  }
+  .portfolio-image {
+    aspect-ratio: 16/10;
+    overflow: hidden;
+  }
+  .portfolio-image img {
+    width: 100%;
+    height: 100%;
+    object-fit: cover;
+    transition: transform 0.5s ease;
+  }
+  .portfolio-card:hover .portfolio-image img { transform: scale(1.05); }
+  .portfolio-info { padding: 24px; }
+  .portfolio-category {
+    display: inline-block;
+    background: var(--color-primary);
+    color: var(--color-black);
+    padding: 4px 12px;
+    border-radius: 12px;
+    font-size: 12px;
+    font-weight: 600;
+    margin-bottom: 12px;
+  }
+  .portfolio-name {
+    font-size: 18px;
+    font-weight: 700;
+    margin-bottom: 8px;
+    color: var(--color-white);
+  }
+  .portfolio-desc {
+    font-size: 14px;
+    color: rgba(255,255,255,0.6);
+    line-height: 1.5;
+    display: -webkit-box;
+    -webkit-line-clamp: 2;
+    -webkit-box-orient: vertical;
+    overflow: hidden;
+  }
+</style>