:root{
    --primary-color:#568CBD;
    --secondary-color:#2a4472;
    --max-width: 1100px;
}
*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body{
    font: normal 1rem/1.5 'Ariel', sans-serif;
    background: var(--primary-color);
    color: #fff;
    overflow-x:hidden;
    padding-bottom: 50px;
}
#main-header{
    background: var(--secondary-color);
    padding: 4rem 0;
}
.container{
    max-width: var(--max-width);
    margin: 0 auto;
    text-align: center;
}
h1{
    font-size: 2.3rem;
}

#timeline ul{
    background: var(--primary-color);
    padding: 50px 0;
}
/* create line */
#timeline ul li{
list-style: none;
position: relative;
width: 6px;
margin: 0 auto;
padding-top: 50px;
background: #fff;
}
/* boxes */
#timeline ul li div{
position: relative;
bottom: 0;
width: 400px;
padding: 1rem;
background: var(--secondary-color);
transition: all 0.5s ease-in-out;
visibility: hidden;
opacity: 0;
}
/* right side */
#timeline ul li:nth-child(odd) div{
    left: 40px;
    transform: translate(200px, 0);
}
/* left side */
#timeline ul li:nth-child(even) div{
    left: -434px;
    transform: translate(-200px, 0);
}
/* dots */
#timeline ul li::after{
    content: '';
    position: absolute;
    left: 50%;
    bottom:0 ;
    width: 25px;
    height: 25px;
    background: inherit;
    transform: translatex(-50%);
    border-radius: 50%;
    transition: background 0.4s ease-in-out;
}

/* Arrows Base */
#timeline div::before{
    content: '';
    position: absolute;
    bottom: 5px;
    width: 0;
    height: 0;
    border-style:solid;
}
/* right side arrows */
#timeline ul li:nth-child(odd) div::before{
    left: -15px;
    border-width: 8px 16px 8px 0;
    border-color: transparent var(--secondary-color) transparent transparent;
}
#timeline ul li:nth-child(even) div::before{
    right: -15px;
    border-width: 8px 0 8px 16px;
    border-color: transparent  transparent transparent var(--secondary-color);
}

/* show boxes */
#timeline ul li.show div{
    transform: none;
    visibility: visible;
    opacity: 1;
}
#timeline ul li.show:after{
    background: var(--secondary-color);

}
@media(max-width: 900px){
    #timeline ul li div{
        width: 250px;
    }
    #timeline ul li:nth-child(even) div{
        left: -284px;
    }
}
@media(max-width:600px) {
    #timeline ul li {
        margin-left: 20px;
    }
    #timeline ul li div{
        width: calc(100vw - 90px);
    }
    #timeline ul li:nth-child(even) div{
        left: 40px;
    }
    #timeline ul li:nth-child(even) div::before{
        left: -15px;
        border-width: 8px 16px 8px 0;
        border-color: transparent var(--secondary-color) transparent transparent;
    }
}