/*reset browser defaults*/
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
  }
  /*variable for color and font*/
  :root {
    --main-bg-color: white;
    --main-text-color: #353535;
    --container-bg-color: rgb(238, 238, 238);
    --nav-bg-color: black;
    --nav-text-color: lightgray;
    --nav-hover-color: darkgray;
    --nav-active: white;
    --mason-border-color: #999;
    --brand-color: black;
    --font-serif-titles: 'Ubuntu', serif;
    --font-serif-text: 'Montserrat', serif;
    --container-bg-color: #eeeeee;
    --masonry-bg-color: #fff;
    --masonry-link: black;
    --facebook-bg: #3B5998;
    --twitter-bg: #55ACEE;
    --github-bg: #000;
    --icon-hover: goldenrod;
    --icon-color: white;
    --credit-hover-color: white;
    --credit-hover-bg: black;
    --calc-table-border: #ddd;
    --math-color: white;
    --math-bg-color: black;
  }
  /*fonts*/
  h1,
h2,
h3,
h4,
h5,
h6,
footer,
h1 a,
li a {
  font-family: var(--font-serif-titles);
}
figcaption {
  font-family: var(--font-serif-titles);
  font-size: .7rem
}
p {
  font-family: var(--font-serif-text);
}
/*style brand*/
.brand a {
    color: var(--brand-color);
    text-decoration: none;
  }
  /*mobile grid*/
  .container {
    display: grid;
    grid-template-columns: 1fr;
    grid-gap: 5px;
  }
  /*container basic styles*/
  .single-col-container>*,
.container>* {
  color: var(--main-text-color);
  line-height: 1.5;
  background: var(--container-bg-color);
}

.single-col-container nav,
.container nav {
  padding: 10px;
}

.container>aside,
section {
  padding: 20px;
}

footer {
  padding: 0 10px;
}
/*nav style*/
.single-col-container>*,
.container>* {
  color: var(--main-text-color);
  line-height: 1.5;
  background: var(--container-bg-color);
}

.single-col-container nav,
.container nav {
  padding: 10px;
}

.container>aside,
section {
  padding: 20px;
}

footer {
  padding: 0 10px;
}
/*media query large screens*/
@media only screen and (min-width: 600px) {

    /* grid */
    .single-col-container,
    .container {
      grid-template-columns: repeat(4, 1fr);
    }
  
    /* specific item styles */
    .single-col-container,
    .container header,
    .container nav,
    .container footer {
      grid-column: span 4;
    }
  
    .container section {
      grid-column: span 3;
    }
  
    /* nav styles */
    nav ul li {
      display: inline-block;
      width: 100px;
  
    }
  
    /* hide toggle */
    .toggle {
      display: none;
    }
  
    .header {
      width: 100%;
      height: auto;
      background-image: url("../images/fibonacci-numbers.png");
      background-repeat: no-repeat;
      background-size: 100% 100%;
    }
  
  }
  /*media query small screens*/
  @media only screen and (max-width: 599px) {

    #nav {
      transition: transform .3s ease-in-out;
      top: 0;
      bottom: 0;
      position: fixed;
      width: 300px;
      right: -340px;
    }
  
    #nav:target {
      transform: translateX(-340px);
    }
  
    .close {
      text-align: right;
      display: block;
      text-decoration: none;
      font-size: 3em;
      position: relative;
      top: -30px;
    }
  
    .open {
      text-align: left;
      color: var(--main-text-color);
      font-size: 2em;
      padding-left: 5px;
    }
  
  }
  /*layout for masonry*/
  .golden-mason img {
    width: 100%;
  }
  
  .golden-mason article {
    padding: 20px;
    border: 1px solid var(--mason-border-color);
    border-radius: 5px;
    background-color: var(masonry-bg-color);
  }
  
  .golden-mason a:link,
  .golden-mason a:visited {
    color: var(--masonry-link);
  }
  
  .golden-mason h1 {
    margin-top: 0;
    margin-left: 0.75rem;
  }
  
  .golden-mason {
    column-count: 3;
    columns: 250px;
    column-gap: 10px;
  }
  
  .golden-mason article {
    break-inside: avoid-column;
    margin-bottom: 1rem;
  }
  
  .golden-mason p {
    font-size: .9rem;
  }
  /*aside styling*/
  aside p {
    font-size: .9rem;
  }
  /*flexbox for the footer*/
  ul.copyright {
    padding: 0;
    display: flex;
    list-style-type: none;
    justify-content: space-between;
  }
  
  .copyright li {
    font-size: .9rem;
  }
  /*icon bar style*/
  .icon-bar {
    position: fixed;
    top: 1%;
    right: 4%;
  }
  
  icon-bar ul {
    list-style-type: none;
  }
  
  .icon-bar li {
    display: inline-block;
  }
  
  .icon-bar a {
    display: block;
    text-align: center;
    padding: 5px;
    transition: all 0.3s ease;
    font-size: 20px;
  }
  
  .icon-bar a:hover {
    background-color: var(--icon-hover);
  }
  
  .facebook {
    background-color: var(--facebook-bg);
    color: var(--icon-color)
  }
  
  .twitter {
    background-color: var(--twitter-bg);
    color: var(--icon-color);
  }
  
  .github {
    background-color: var(--github-bg);
    color: var(--icon-color);
  }
  /*credits*/
  .credits ul {
    list-style-type: none;
    padding: 0;
  }
  
  .credits a {
    font-size: .7em;
    text-decoration: none;
    color: var(--main-text-color);
  }
  
  .credits a:hover {
    background-color: var(--credit-hover-bg);
    color: var(--credit-hover-color);
    cursor: pointer;
  }
  /*aside styling*/
  .fib-aside {
    display: flex;
    flex-direction: column;
    align-items: center;
  }
  
  .fib-aside img {
    width: 180px;
    height: auto;
  }
  /*Fibs calculations*/
  .calc-table table {
    font-family: arial, sans-serif;
    border-collapse: collapse;
    border-spacing: 0;
    width: 100%;
    border: 1px solid var(--calc-table-border);
  }
  
  .calc-table th,
  .cacl-table td {
    border: 1px solid var(--calc-table-border);
    text-align: left;
    padding: 8px;
  }
  
  .calc-table tr:nth-child(even) {
    background-color: var(--calc-table-border);
  }
  .calc-table caption {
    caption-side:top;
    text-align: left;
    font-style: italic; 
  }
  /*math on fib*/
  .math {
    margin: 20px auto;
    padding: 10px 30px;
    width: 200px;
    background-color: var(--math-bg-color);
    color: var(--math-color);
  }
  /*iframes*/
  .resp-container {
    position: relative;
    overflow: hidden;
    padding-top: 56.25%;
  }
  
  .resp-iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: 0;
  }
  /*iframe containers*/
  .frame-container {
    margin: 0 auto;
    width: 80%;
  }
  
  .frame-container {
    text-align: center;
  }
  
  
  .audio-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); /* see notes below */
  
    background-color: var(--nav-text-color);
    align-items: center;
  }
  @media only screen and (min-width: 600px) {
    .audio-container {
      grid-template-columns: 1fr 1fr;
    }
    .audio-container iframe {
      margin-top: 20px;
    }
  }/*abouts container*/
  .learning-objectives {
    margin: 20px;
  }
  
  .learning-objectives li {
    font-family: var(--font-serif-titles);
  }
  
  .xkcd-container img {
    width: 320px;
    height: auto;
  }