Fix share buttons: Excluir btn-outline de estilos theme.css

PROBLEMA:
- Los botones de compartir se mostraban con fondo azul sólido en lugar de outline
- theme.css aplicaba background-color: var(--primary-color) a TODOS los .btn

SOLUCIÓN:
- Modificar selector en theme.css para excluir botones con "outline" en clase
- Usar :not([class*="outline"]) para preservar estilos Bootstrap outline

Fixes #124

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

wp-content/themes/apus-theme/assets/css/theme.css

@@ -314,11 +314,11 @@ textarea {
 }
 
 /* Buttons */
-button,
-.btn,
-input[type="button"],
-input[type="submit"],
-input[type="reset"] {
+button:not([class*="outline"]),
+.btn:not([class*="outline"]):not(.btn-close),
+input[type="button"]:not([class*="outline"]),
+input[type="submit"]:not([class*="outline"]),
+input[type="reset"]:not([class*="outline"]) {
     display: inline-block;
     padding: 0.5rem 1rem;
     font-family: inherit;
@@ -338,10 +338,10 @@ input[type="reset"] {
     transition: var(--transition-base);
 }
 
-button:hover,
-.btn:hover,
-input[type="button"]:hover,
-input[type="submit"]:hover,
+button:not([class*="outline"]):hover,
+.btn:not([class*="outline"]):not(.btn-close):hover,
+input[type="button"]:not([class*="outline"]):hover,
+input[type="submit"]:not([class*="outline"]):hover,
 input[type="reset"]:hover {
     background-color: #0b5ed7;
     text-decoration: none;