:root {
    --bgnav: gray;
    --bgbody: darkgray;
    --fcnav: yellow;
}
* {
    padding:0;
    margin:0;
    box-sizing: border-box;
}
body {
    background:var(--bgbody);
    font-family: Arial, Helvetica, sans-serif;
}
html {
    background:var(--bgbody);
}
nav {
    overflow: hidden;
    background: var(--bgnav);
    color: var(--fcnav);
}
nav > * {
    width:140px;
}
nav > *.fr, nav > *.fr.dropdown {
    float:right;
}

nav a {
    color: var(--fcnav);
    float: left;
    font-size: 16px;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
}

nav .dropdown {
  float: left;
  overflow: hidden;
}

nav .dropdown .dropbtn {
  font-size: 16px;  
  border: none;
  outline: none;
  color:var(--fcnav);
  padding: 14px 16px;
  background-color: inherit;
  font-family: inherit;
  margin: 0;
}
nav a:hover, nav .dropdown:hover .dropbtn {
  background-color: var(--fcnav);
  color:var(--bgnav);
}

nav .dropdown-content a {
    color:var(--bgnav);
    background-color: var(--fcnav);
}
nav .dropdown-content {
  display: none;
  position: absolute;
  background-color: var(--bgnav);
  min-width: 160px;
  z-index: 1;
}

nav .dropdown-content a {
  float: none;
  color: var(--fcnav);
  padding: 12px 16px;
  text-decoration: none;
  display: block;
  text-align: left;
}
nav .dropdown-content a {
  background-color: var(--fcnav);
  color: var(--bgnav);
}
nav .dropdown-content a:hover {
  background-color: var(--bgnav);
  color: var(--fcnav);
}

nav .dropdown:hover .dropdown-content {
  display: block;
}
footer {
    position:fixed;
    bottom:0;
    background: var(--bgnav);
    color: var(--fcnav);
    width:100%;
    text-align:center;
    height:1rem;
}
body > div {
    width:1000px;
    max-width:90%;
    margin: 0 auto;
    background:red;
}
.w50 {
    display: inline-block;
    width:50px;
}
.w150 {
    display: inline-block;
    width: 150px;
}
.w200 {
    display: inline-block;
    width: 200px;
}
.p100 {
    display: inline-block;
    width: 100%;
}
.l {
    text-align: left;
}
.c {
    text-align: center;
}
.r {
    text-align: right;
}
.pl10 {
    padding-left: 10px;
}
.ml10 {
    margin-left: 10px;
}