fix: Restore complete globals.css

- Tailwind v4 with @theme syntax
- Custom color variables (primary green, secondary grays)
- Button components (.btn-primary, .btn-secondary, .btn-outline)
- Section typography (.section-title, .section-subtitle)
- Card styles with hover effects
- Kanit font and proper typography

CSS is now working properly with all product pages.

src/styles/globals.css

@@ -0,0 +1,121 @@
+@import "tailwindcss";
+
+@theme {
+  --color-primary-500: #22c55e;
+  --color-primary-600: #16a34a;
+  --color-primary-700: #15803d;
+  --color-secondary-50: #f8fafc;
+  --color-secondary-100: #f1f5f9;
+  --color-secondary-200: #e2e8f0;
+  --color-secondary-300: #cbd5e1;
+  --color-secondary-500: #64748b;
+  --color-secondary-600: #475569;
+  --color-secondary-700: #334155;
+  --color-secondary-800: #1e293b;
+  --color-secondary-900: #0f172a;
+  --color-accent-500: #eab308;
+}
+
+html {
+  scroll-behavior: smooth;
+  font-family: 'Kanit', system-ui, sans-serif;
+}
+
+body {
+  color: var(--color-secondary-900);
+  -webkit-font-smoothing: antialiased;
+  background-color: white;
+}
+
+h1, h2, h3, h4, h5, h6 {
+  font-weight: 700;
+  letter-spacing: -0.025em;
+}
+
+.btn-primary {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  padding: 0.75rem 1.5rem;
+  background-color: var(--color-primary-600);
+  color: white;
+  font-weight: 600;
+  border-radius: 0.5rem;
+  transition: all 0.2s;
+}
+
+.btn-primary:hover {
+  background-color: var(--color-primary-700);
+}
+
+.btn-secondary {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  padding: 0.75rem 1.5rem;
+  background-color: var(--color-secondary-800);
+  color: white;
+  font-weight: 600;
+  border-radius: 0.5rem;
+  transition: all 0.2s;
+}
+
+.btn-secondary:hover {
+  background-color: var(--color-secondary-900);
+}
+
+.btn-outline {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  padding: 0.75rem 1.5rem;
+  border: 2px solid var(--color-primary-600);
+  color: var(--color-primary-600);
+  background-color: transparent;
+  font-weight: 600;
+  border-radius: 0.5rem;
+  transition: all 0.2s;
+}
+
+.btn-outline:hover {
+  background-color: var(--color-primary-600);
+  color: white;
+}
+
+.section-title {
+  text-align: center;
+  margin-bottom: 1rem;
+  font-size: 1.875rem;
+  font-weight: 700;
+}
+
+@media (min-width: 768px) {
+  .section-title {
+    font-size: 2.25rem;
+  }
+}
+
+@media (min-width: 1024px) {
+  .section-title {
+    font-size: 3rem;
+  }
+}
+
+.section-subtitle {
+  text-align: center;
+  color: var(--color-secondary-600);
+  font-size: 1.125rem;
+}
+
+.card {
+  background-color: white;
+  border-radius: 0.75rem;
+  transition: all 0.3s;
+  overflow: hidden;
+  box-shadow: 0 4px 6px -1px #0000001a;
+}
+
+.card:hover {
+  transform: translateY(-0.25rem);
+  box-shadow: 0 10px 15px -3px #0000001a;
+}