.container {
  width: 996px;
  margin: 0 auto;
  font-size: 1em;
}
section, aside {
  padding: 10px;
  background: #ccc;
  border-radius: 5px;
}
section {
  float: left;
  width: 70%;
}
aside {
  float: right;
  width: 25%;
}
nav {
  overflow: hidden;
}
nav ul {
  list-style-type: none;
  float: left;
  padding: 0;
}
nav ul li {
  float: left;
  padding: 3px 10px;
  margin: 2px;
  background: #ccccff;
  border-radius: 5px;
}
footer {
  margin: 10px;
  text-align: center;
  clear: both;
}

/* Responsive para 980px o menos */
@media screen and (max-width:980px) {
  .container {
    width: 98%;
  }
  section {
    width: 68%;
  }
}

/* Responsive para 700px o menos */
@media screen and (max-width:700px) {
  aside, section {
    float: none;
    width: 96%;
  }
  nav, section {
    font-size: 1.2em;
  }
  aside {
    margin-top: 5px;
  }
  nav ul {
    float: none;
    clear: both;
  }
}

/* Responsive para 480px o menos */
@media screen and (max-width:480px) {
  aside {
    display: none;
  }
  nav, section {
    font-size: 1.5em;
  }
  section {
    width: 94%;
  }
  nav ul {
    float: left;
    clear: none;
    width: 50%;
  }
  nav ul li {
    float: none;
  }
}

/* Estilos del formulario */
.contact_form {
  background: #f4f4f4;
  border-radius: 10px;
  padding: 20px;
  margin: 20px auto;
  max-width: 600px;
  font-family: Arial, sans-serif;
}

.contact_form h1, .contact_form h3 {
  text-align: center;
  margin-bottom: 20px;
}

.contact_form input[type="text"],
.contact_form input[type="email"],
.contact_form input[type="whatsapp"],
.contact_form textarea {
  width: 100%;
  padding: 10px;
  margin-top: 6px;
  margin-bottom: 16px;
  border: 1px solid #ccc;
  border-radius: 4px;
  resize: vertical;
}

.contact_form button {
  background-color: #5c9ded;
  color: white;
  padding: 12px 20px;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  width: 100%;
  font-size: 1em;
}

.contact_form button:hover {
  background-color: #4a8cd9;
}

.contact_form .aviso {
  font-size: 0.9em;
  color: #555;
}

.obligatorio {
  color: red;
}