flexbox.css

h {
  color: indigo;
}

.flex-container {
  padding: 0;
  margin: 0;
  list-style: none;
  
  display: -webkit-box;
  display: -moz-box;
  display: -ms-flexbox;
  display: -webkit-flex;
  display: flex;
  
  -webkit-flex-flow: row wrap;
  justify-content: space-around;
}

.flex-item {
  background: tomato;
  padding: 5px;
  width: 125px;
  height: 200px;
  margin-top: 10px;
  
  line-height: 75px;
  color: white;
  font-weight: bold;
  font-size: 3em;
  text-align: left;
}

#weekend {
  background: crimson;
}

#today {
  color: indigo;
  border: 3px solid indigo;
}

#previous {
  background: darkred;
}

.navigation {
  list-style: none;
  margin: 0; 
  
  background: deepskyblue;
  border-bottom: 2px solid gold;
  box-shadow: 0 3px 2px rgba(0,0,0,0.1);
  
  display: -webkit-box;
  display: -moz-box;
  display: -ms-flexbox;
  display: -webkit-flex;
  display: flex;
  
  -webkit-flex-flow: row wrap;
  justify-content: flex-end;
}

.navigation a {
  color: #333;
  text-decoration: none;
  display: block;
  padding: 15px;
  color: white;
  font-weight: bold;
}

.navigation a:hover {
  background: darken(deepskyblue, 2%);
}

@media all and (max-width: 800px) {
  .navigation {
    justify-content: space-around;
  }
}

@media all and (max-width: 600px) {
  .navigation {
    -webkit-flex-flow: column wrap;
    padding: 0;
  }
  
  .navigation a { 
    text-align: center; 
    padding: 10px;
    border-top: 1px solid rgba(255,255,255,0.3); 
    border-bottom: 1px solid rgba(0,0,0,0.1); 
  }

  
  .navigation li:last-of-type a {
    border-bottom: none;
  }
}

html, body { margin: 0; padding: 0 }
     body { background-color:deepskyblue; }
     #container { margin: 3em auto 0 3em; padding-bottom: 3em;
                  background-color: #fff; }
     #month { border-collapse: collapse; margin-left: 2em; }
     #month th, #month td { border: 1px solid #000; }
     #month thead { background-color:#9c9; }
     #month td { width: 7em; height: 7em; padding: .2em; vertical-align: top;
                 overflow: auto; }
     td .day { width: 7em; height: 6em; overflow:auto; margin-top: 0; }
     #month tbody .weekend { background-color:#ded; }
     #month tbody .next, #month tbody .previous { background-color:#ddd; }
     .rtop { display:block; background:#060; }
     .rtop * { display: block; height: 1px; overflow: hidden; background:#fff; }
     .r1{margin: 0 0 0 5px}
     .r2{margin: 0 0 0 3px}
     .r3{margin: 0 0 0 2px}
     .r4{margin: 0 0 0 1px; height: 2px}
     #container h1 { margin: 0 0 .5em .5em;
                     font: 2em Arial, Helvetica, sans-serif;
                     color: #060; }
     #month th { font: 1em bold Arial, Helvetica, sans-serif; }
     p {margin-top: 0; }