indexPlantilla.css

html, body, div, span, applet, object, iframe,
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
a, abbr, acronym, address, big, cite, code,
del, dfn, em, img, ins, kbd, q, s, samp,
small, strike, strong, sub, sup, tt, var,
b, u, i, center,
dl, dt, dd, ol, ul, li,
fieldset, form, label, legend,
table, caption, tbody, tfoot, thead, tr, th, td,
article, aside, canvas, details, embed,
figure, figcaption, footer, header, hgroup,
main, menu, nav, output, ruby, section, summary,
time, mark, audio, video {
  margin: 0;
  padding: 0;
  border: 0;
  font-size: 100%;
  font: inherit;
  vertical-align: baseline;
}

html {
    -webkit-box-sizing: border-box;
            box-sizing: border-box;
  }
  
 *{font-family: Verdana, Arial, Helvetica, sans-serif;}
  
  *, *::after, *::before {
    -webkit-box-sizing: inherit;
            box-sizing: inherit;
  }

html,body {    
    min-height: 100%;    
    height: 100%;
    width: 100%;
}

article, aside, details, figcaption, figure,
footer, header, hgroup, main, menu, nav, section {
  display: block;
}

body {
    min-width: 320px;
    background-color:white;       
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    align-content: stretch;
  }
  section {
    display: flex;
    flex-direction: row;
    align-items: stretch;
    align-content: stretch;
    flex-basis: 100%;
	border: 1px solid red;
  }

article {
    flex-grow: 1;
    border: 1px solid;
}

a {
  text-decoration: none;
  color: black;
  display: block;
  padding: 20px 5px;
  color: white;
}

a:hover {
  background-color: rgb(176,224,230);
  color: black;
}

label {  
  padding: 15px;
  position: absolute;
  z-index: 2;  
  top: -.5em;
}

ul {
  list-style: none;  
  top: 70px;
  position: absolute;
  width: 100%;
}

img {
  width: 40px;
}

input[type="checkbox"] {
  display: none;
  top: -.5em;
}

input[type="checkbox"]:checked ~ nav {
  transform: translateX(350px);
}

nav {
  background-color: rgba(16,16,16,.5);
  width: 350px;
  height: calc(100% + .5em);
  position: absolute;
  left: -350px;
  transition: all .5s;
  top: -.5em;
  z-index: 1;
}

header {
    text-align: center;
    width: 100%;
    line-height: 3.5em;
    background-color: coral;
}

footer {
    text-align: center;
    width: 100%;
    line-height: 1.5em;
    background-color: coral;
    position:fixed;
    left:0px;
    bottom:0px;    
}

.div1 {
    border: 2px solid red;
}

.div2 {
    border: 2px solid red;
}


/* 
  ##Device = Desktops
  ##Screen = 1281px to higher resolution desktops
*/

@media (min-width: 1281px) {
  
    section {
        flex-direction: row;
    }
    
  }
  
  /* 
    ##Device = Laptops, Desktops
    ##Screen = B/w 1025px to 1280px
  */
  
  @media (min-width: 1025px) and (max-width: 1280px) {
    
    section {
        flex-direction: row;
    }
    
  }
  
  /* 
    ##Device = Tablets, Ipads (portrait)
    ##Screen = B/w 768px to 1024px
  */
  
  @media (min-width: 768px) and (max-width: 1024px) {
    
    section {
        flex-direction: row;
    }
    
  }
  
  /* 
    ##Device = Tablets, Ipads (landscape)
    ##Screen = B/w 768px to 1024px
  */
  
  @media (min-width: 768px) and (max-width: 1024px) and (orientation: landscape) {
    
    section {
        flex-direction: row;
    }
    
  }
  
  /* 
    ##Device = Low Resolution Tablets, Mobiles (Landscape)
    ##Screen = B/w 481px to 767px
  */
  
  @media (min-width: 481px) and (max-width: 767px) {
    
    section {
        flex-direction: column;
    }
    
  }
  
  /* 
    ##Device = Most of the Smartphones Mobiles (Portrait)
    ##Screen = B/w 320px to 479px
  */
  
  @media (min-width: 320px) and (max-width: 480px) {
    
    section {
        flex-direction: column;
    }
    
  }