* {
    box-sizing: border-box;
}
body {
    font-family: helvetica, sans-serif;
    background-color: rgb(240, 240, 240);
    padding-left: 2rem;
    padding-right: 2rem;
}
h1, h2, h3, h4, h5, h6 {
    font-family: 'Bungee Inline', 'Times New Roman', Times, serif;
}
header,
main,
footer {
    max-width: 70rem; /* let it expand but keep it reasonable */
    margin-left: auto;
    margin-right: auto;
}

header {
    padding: 1rem 0 2rem 0;
    display: flex; 
    align-items: center;
    /* header as flex parent lets the 
       h1 and nav become flex items and 
       live side by side */
}
/* h1 { padding: 1rem; } */
/* I added the above to show the difference
between rem and em.  I forgot about this when I was doing 
the image replacement.  Ugh.  But, if I had done the
"inspect" and looked at the layout, I would have seen the 
bottom padding.  Which I did do after the Q&A was over! */

header nav {
    margin-top: 0.5rem;
    align-content: flex-end;
    flex-grow: 1;
    /* allow the nav to expand to the 
       width of the header */
}

header h1 {
    margin: 0;
    font-size: 2.5rem;
    background-image: url(../images/our-solar-system.png);
    background-size: contain;
    background-repeat: no-repeat;
    padding-top: 125px;
    padding-bottom: 0; /* this was the thing left of when
    I was struggling in class with this example, which 
    I had mistakenly added to the CSS above.  "Inspect" 
    would have helped me figure this out :(  */ 
    height: 125px;
    overflow: hidden;
    white-space: nowrap; 
}

nav ul {
    display: flex;
    justify-content: flex-end;
    /* ul is now flex parent for the li children */

    list-style: none;
    margin: 0;
    padding: 0;
    /* the above styles essentially remove the 
       default list styles we get from the browser */
}

nav ul li {
    margin-left: 1rem;
}

nav ul li a {
    display: block;
    /* turning the a elements into "block"
       let them take a border and make 
       the content + padding "clickable"
       as links.  This is a common technique for
       hyperlinks in navigation */
}

nav a:link,
nav a:visited,
nav a:hover,
nav a:active {
    color: black;
    text-decoration: none;
    padding: 0.5rem;
    border-bottom: 2px solid transparent;
}

nav a:hover {
    border-bottom: 2px solid black;
    transition: border-color 0.5s;
}

nav li.login a,
nav li.signup a {
    border: 2px solid black;
    border-radius: 10px;
    background-color: white;
    color: black;
}

nav li.login a:hover,
nav li.signup a:hover {
    color: white;
    background-color: black;
    transition: background-color 0.5s, color 0.5s;
}

nav li.login a {
    border-color: rgb(58, 80, 156);
    color: rgb(58, 80, 156);
}
nav li.login a:hover {
    color: white;
    background-color: rgb(58, 80, 156);
}

div.container {
    display: flex;
    gap: 1.5rem;
    flex-wrap: wrap;
    margin: 0 auto;
}

div.container section img {
    max-width: 100%;
}

div.container section {
    flex-basis: calc(33.3333% - 1rem);
    /* two gaps at 1.5rem each is 3rem,
    and 3rem distributed across three items
    is 1rem each, so 33.3333% - 1rem */
    flex-grow: 0;
    flex-shrink: 0;
    border: 2px solid rgb(150,150,150);
    padding: 1rem;
    background-color: white;
}

section h2 {
    text-align: center;
}

section ul {
    padding-left: 1rem;
}

footer {
    margin-top: 3rem;
    padding-top: 1rem;
    margin-bottom: 2rem;
    border-top: 2px solid rgb(150, 150, 150);
}