/* Structure */
body
{
    font-family: Arial, Helvetica, sans-serif;
}

.flex-container
{
    display: flex;
    justify-content: space-evenly;
}

/* Typeography */
#running-man-h1
{
    text-align: center;
}

/* Exercise 1 */
#col1of2
{
    background-color: lightblue;
    padding: 5px;
    margin: 25px;
    width: 50%;
}
.man
{
    /* background-color: blue;
    border: 5px solid blue; */
    width: 75%;
    height: 25%;
}
#walking-man
{
    --x: 0px;
    width: 50px;
    height: 75px;
    background: #fff;
    margin-left: var(--x);
    margin-top: 5px;
}

#running-man
{
    --x: 125px;
    width: 50px;
    height: 75px;
    background: #fff;
    margin-left: var(--x);
    margin-bottom: 75px;
    margin-top: 5px;
}
.hidden
{
    display: none;
}
#button-walk
{
    background: none;
    border: none;
}
#button-run
{
    background: none;
    border: none;
}

/* Exercise 2 */
#rectangle
{
    width: 50px;
    height: 150px;
    background: #fff;
    margin-left: 115px;
    margin-top: 5px;
}

#col2of2
{
    background-color: darkcyan;
    padding: 5px;
    text-align: left;
    width: 50%;
}

#rectangle.red
{
    animation-name: rectangle;
    animation-duration: 4s;
    animation-iteration-count: infinite;
} 

:root
{
    --a: 0%;
    --b: 0%;
}

@keyframes rectangle {
    0% {
        background: linear-gradient(180deg, #fff var(--a), red var(--b));
    }

    50% {
        background: linear-gradient(180deg, #fff var(--a), red var(--b));
    }
   
    100% {
        background: linear-gradient(180deg, #fff var(--a), red var(--b));
    }
}