Improve responsive UX/UI consistency across all frontend screens.

This polish pass unifies mobile navigation, spacing, typography hierarchy, and CTA behavior so all core exam workflows remain clear and fully usable on both mobile and desktop.

frontend/src/pages/CreateTemplatePage.jsx

@@ -122,7 +122,7 @@ export default function CreateTemplatePage() {
       <div className="page-header">
         <div>
           <h1>Nuevo examen</h1>
-          <p>Define la estructura. Después podrás subir material y generar preguntas.</p>
+          <p className="page-lead">Define la estructura. Después podrás subir material y generar preguntas.</p>
         </div>
       </div>
 
@@ -192,7 +192,7 @@ export default function CreateTemplatePage() {
                 className="card"
                 style={{ padding: 16, marginBottom: 14, background: "var(--c-surface-2)" }}
               >
-                <div className="flex justify-between items-center mb">
+                <div className="flex justify-between items-center mb wrap gap-sm">
                   <strong>Bloque {idx + 1}</strong>
                   {types.length > 1 && (
                     <Button
@@ -263,7 +263,7 @@ export default function CreateTemplatePage() {
                         }
                       />
                     </Field>
-                    <div style={{ paddingTop: 26 }}>
+                    <div style={{ paddingTop: 8 }}>
                       <Checkbox
                         label="Permitir varias respuestas correctas"
                         checked={t.multiple_correct}
@@ -343,7 +343,7 @@ export default function CreateTemplatePage() {
           </div>
         </div>
 
-        <div className="flex gap justify-between">
+        <div className="flex gap justify-between wrap mobile-stack mt">
           <Button type="button" variant="ghost" onClick={() => navigate("/")}>
             Cancelar
           </Button>