* {
          margin: 0;
          padding: 0;
           box-sizing: border-box;
           font-family: montserrat;
          }

html {height: -webkit-fill-available;}

h1, h2, h3 {color:coral;
            text-align: center;}

body {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    min-height: -webkit-fill-available;
    justify-content: space-between;}

main {flex-grow: 1;
display: flex;}

#contenido {
  display: flex;
  flex-direction: column;
  align-items: center;
  max-width: 20em;
  text-align: center;
  margin-top: 1em;
}

.opciones {
  margin:auto;
  text-align: center;
  max-width: 20em;
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-top: 1em;
}

#presentacion {
  margin:auto;
  text-align: center;
  max-width: 20em;
  display: flex;
  flex-direction: column;
  align-items: center;
}

header {background-color:cadetblue;}

.contenedor {max-width: 50em;
margin: auto;
display: flex;}

header .contenedor {

  display: flex;
  flex-direction: row;
  align-items: center;
  justify-content: space-between;  
}

header ul {list-style: none;
display: flex;}

header ul li {
  width: 2em;
  height: 2em;
  margin-left: .25em;
display: flex;
}

header ul li a {
  width: 100%;
  height: 100%;
  background-color: rgba(0,0,0,0.75);
  color: white;
  text-decoration: none;
  font-weight: bold;
  display: flex;
  justify-content: center;
  align-items: center;
}

.menu {display: flex;
justify-content: space-between;}

button {border-radius: 12px;
padding: 1em;
background-color:chartreuse;
font-size: 1em;
border: none;
color: white;
text-decoration: none;}

#volver {border-radius: 20px;
padding: 0.50em;
background-color: gray;}

img {margin: 1em;}

p, ul {color:#252a34;
margin: 1em;}

main {background-color:#eaeaea;}

footer {background-color:cadetblue;}

@media only screen and (max-width: 600px) {

header .contenedor {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
}

}
main .bloque1{
    padding: 0.80em; 
        margin: auto;
    text-align: center;
    align-items: center;
    
}