:root {
    --color-principal: #004AAD;
    --color-principal-dark: #003478;
    --color-secundario: #00B0F0;
    --color-acento: #FFCC00;
    --color-fondo: #F2F6FA;
    --color-fondo-alt: #FFFFFF;
    --color-fondo-hero: #E0F0FF;
    --color-fondo-suave: #E8F1FA;
    --color-texto: #1A1A1A;
    --color-texto-inverso: #FFFFFF;
    --color-borde: #D4DEEA;
    --color-sombra: rgba(0,42,110,0.08);
    --color-sombra-hover: rgba(0,42,110,0.16);
  }
  * { box-sizing: border-box; margin:0; padding:0; }
  body { font-family: Arial, sans-serif; color: var(--color-texto); background: var(--color-fondo); line-height:1.6; scroll-behavior:smooth; }
  
  /* Navegación */
  .main-nav { position:sticky; top:0; display:flex; align-items:center; justify-content:space-between; padding:10px 20px; background:var(--color-fondo-alt); border-bottom:1px solid var(--color-borde); z-index:1000; box-shadow:0 2px 4px -2px var(--color-sombra); }
  .main-nav .brand img { height:70px; transition:transform .3s; }
  .main-nav .brand img:hover { transform:scale(1.05); }
  .nav-links { list-style:none; display:flex; gap:30px; }
  .nav-links a { text-decoration:none; font-weight:600; position:relative; color:var(--color-principal-dark); padding:6px 0; transition:color .25s; }
  .nav-links a::after { content:""; position:absolute; left:0; bottom:0; height:3px; width:0; border-radius:2px; background:linear-gradient(90deg,var(--color-principal), var(--color-secundario)); transition:width .3s; }
  .nav-links a:hover, .nav-links a:focus { color:var(--color-principal); }
  .nav-links a:hover::after, .nav-links a:focus::after { width:100%; }
  .nav-toggle { display:none; }
  
  /* Hero */
  .hero { background:var(--color-fondo-hero); color:var(--color-principal-dark); text-align:center; padding:130px 20px 80px; }
  .hero .logo { max-width:260px; margin-bottom:28px; filter:drop-shadow(0 4px 10px rgba(0,0,0,0.1)); }
  .hero h1 { font-size:2.4rem; margin-bottom:12px; letter-spacing:.5px; }
  .hero p { font-size:1.08rem; max-width:760px; margin:0 auto 28px; color:#133a66; }
  .btn-primary { background:var(--color-acento); color:#000; padding:14px 26px; border-radius:12px; font-weight:700; display:inline-flex; align-items:center; gap:10px; text-decoration:none; transition:transform .3s, box-shadow .3s; box-shadow:0 6px 14px -4px var(--color-sombra); }
  .btn-primary:hover { transform:translateY(-4px); box-shadow:0 14px 28px -10px var(--color-sombra-hover); }
  .btn-primary img { width:22px; height:22px; }
  
  /* Secciones */
  section { padding:60px 20px; }
  section h2 { text-align:center; margin-bottom:26px; color:var(--color-principal-dark); font-size:2rem; }
  .servicios { background:var(--color-fondo-alt); }
  .planes { background:var(--color-fondo-suave); }
  .nosotros { background:var(--color-fondo-alt); }
  .regulacion { background:var(--color-principal-dark); color:var(--color-texto-inverso); }
  .regulacion h2 { color:var(--color-texto-inverso); }
  .contacto { background:var(--color-fondo-alt); text-align:center; }
  
  /* Tarjetas */
  .servicios-container, .planes-container { display:flex; flex-wrap:wrap; justify-content:center; gap:24px; margin-top:34px; }
  .servicio-card, .plan-card { background:var(--color-fondo-alt); border:1px solid var(--color-borde); padding:24px 22px 30px; border-radius:16px; width:260px; box-shadow:0 4px 12px -6px var(--color-sombra); transition:transform .25s, box-shadow .25s, border-color .25s; }
  .servicio-card:hover, .plan-card:hover { transform:translateY(-6px); box-shadow:0 16px 32px -12px var(--color-sombra-hover); border-color:var(--color-secundario); }
  .servicio-card img { width:100%; max-width:160px; height:auto; border-radius:12px; margin:0 auto 18px; display:block; object-fit:cover; }
  .servicio-card h3, .plan-card h3 { color:var(--color-principal-dark); font-size:1.05rem; margin-bottom:8px; }
  .servicio-card p { font-size:.92rem; color:#3d4c5c; }
  .plan-card.destacado { border:2px solid var(--color-principal); }
  .plan-card .price { font-size:1.6rem; color:var(--color-principal); font-weight:700; margin:10px 0 6px; }
  .plan-card .speed { font-size:1.02rem; color:#415264; }
  .plan-card button { background:linear-gradient(90deg,var(--color-principal-dark), var(--color-principal)); color:#fff; border:none; padding:10px 18px; border-radius:10px; cursor:pointer; font-size:.95rem; font-weight:600; margin-top:12px; transition:filter .3s, box-shadow .3s; box-shadow:0 6px 14px -6px var(--color-sombra); }
  .plan-card button:hover { filter:brightness(1.12); box-shadow:0 10px 24px -8px var(--color-sombra-hover); }
  
  /* Submenús Regulación (Tabs) */
  .submenu-buttons { display:flex; justify-content:center; flex-wrap:wrap; gap:10px; margin:28px 0 12px; }
  .submenu-buttons button { background:var(--color-fondo-alt); border:1px solid var(--color-borde); padding:10px 22px 14px; cursor:pointer; border-radius:10px; font-weight:600; font-size:.95rem; position:relative; color:var(--color-principal-dark); transition:background .3s,color .3s,box-shadow .3s,border-color .3s; }
  .submenu-buttons button::after { content:""; position:absolute; left:16px; right:16px; bottom:6px; height:3px; border-radius:2px; background:linear-gradient(90deg,var(--color-principal), var(--color-secundario)); transform:scaleX(0); transform-origin:left center; transition:transform .35s ease; }
  .submenu-buttons button:hover { background:#f5faff; border-color:var(--color-secundario); }
  .submenu-buttons button[aria-selected="true"] { background:linear-gradient(90deg,var(--color-principal), var(--color-secundario)); color:#fff; box-shadow:0 4px 14px -6px var(--color-sombra-hover); border-color:var(--color-principal); }
  .submenu-buttons button[aria-selected="true"]::after { transform:scaleX(1); }
  
  .submenu-panel { margin-top:26px; padding:22px 26px 26px; background:var(--color-fondo-alt); border:1px solid var(--color-borde); border-radius:16px; color:var(--color-texto); box-shadow:0 8px 22px -10px var(--color-sombra); animation:fadeIn .35s ease; }
  .submenu-panel[hidden] { display:none; }
  .submenu-panel h3 { margin-top:0; margin-bottom:10px; color:var(--color-principal-dark); }
  
  @keyframes fadeIn { from { opacity:0; transform:translateY(8px);} to { opacity:1; transform:translateY(0);} }
  
  /* Contacto */
  .contacto a { color:var(--color-principal); text-decoration:none; }
  .contacto a:hover { text-decoration:underline; }
  
  /* WhatsApp */
  .whatsapp { position:fixed; bottom:20px; right:20px; width:60px; height:60px; background:#25D366; border-radius:50%; display:flex; align-items:center; justify-content:center; box-shadow:0 10px 24px -10px rgba(0,0,0,0.35); transition:transform .25s, box-shadow .25s; }
  .whatsapp:hover { transform:scale(1.08); box-shadow:0 18px 38px -12px rgba(0,0,0,0.4); }
  .whatsapp img { width:34px; height:34px; }
  
  /* Responsive */
  @media (max-width:820px){
    .nav-toggle { display:block; background:var(--color-principal); color:#fff; border:none; padding:8px 12px; border-radius:8px; cursor:pointer; font-size:1.2rem; }
    .nav-links { flex-direction:column; background:var(--color-fondo-alt); position:absolute; top:100%; right:0; padding:20px 26px; gap:18px; box-shadow:0 14px 28px -14px var(--color-sombra-hover); display:none; }
    .nav-links.open { display:flex; }
    .hero { padding:120px 20px 70px; }
    .hero h1 { font-size:2.05rem; }
    .hero .logo { max-width:220px; }
  }
  
  :focus-visible { outline:3px solid var(--color-secundario); outline-offset:2px; }