:root {
  --c-tut-table: #419873;
  --c-tut-table-hover: #398564;
}

/* ===================== TUTORIAL PAGE ====================== */


/* ====== recent update ===== */
#recent-update {
list-style-type: none;
margin: 0 auto;
line-height: 100px;
height: 380px;
overflow-y: scroll;
}

#recent-update li {
padding: 0 5px 0 0;
float: left;
}

#recent-update img:hover {
background-color:#000;
opacity:0.8;
}

@media screen and (max-width: 40.5em) {
  #recent-update li {
    display: block;
    padding: 0;
    border: 1px solid black;
    margin: 0 auto;
    text-align:center;
  }
  #recent-update {
    list-style-type: none;
    line-height: 0px;
  }
}



/* ======= tutorial title ====== */
.tut-title {
margin: 0;
padding: 1em 0 0.5em 0;
}

/* ======= ads ========= */
.ads-container {
display: block;
width: 100%;
z-index: 1;
margin: 0;
padding:0;
}

/* ======= tutorial content menu ========= */
.tut-content-menu {
position: fixed;
bottom: 2%;
right: 30%;
z-index: 0;
}

.tut-content-menu img {
max-width: 4em;
border-radius:50%;
box-shadow: 0px 0px 10px #888888;

}

/* ====== switch video button ===== */
div#switch-video-div {
display:block;
margin: 1em auto;
text-align: center;
}
button#switch-video {
display: inline;
background-color: var(--c-n);
border: none;
font-size: 1em;
padding: 0.2em 2em;
color: #DCDCDC;
box-shadow: 0px 0px 20px 2px #888888;
border-radius:5px;
}

button#switch-video:hover {
background-color: var(--c-n-mofan);
}
.collapse{
display:none
}
.collapse.in{
display:block
}

/* ======== table of contents ======== */
.table-of-contents-ul {
background-color: var(--c-tut-table);
padding: 1em;
border-radius: 20px;
color: white;
counter-reset: item;
list-style-type: none;
box-shadow: 0px 0px 20px 2px #888888;
}

.table-of-contents-ul h4 {
color: #DCDCDC;
text-align: left;
}

.chapter-li {
margin: 0 1.5em;
}

.chapter-li ul {
list-style-type: none;
}

.content-li {
padding: 0.3em 0.3em;
display: block;
}

.content-li a {
color: #DCDCDC;
text-decoration: none;
}

.content-li:hover {
background-color: var(--c-tut-table-hover);
}

/* ======== inner page ======== */
.course-summary-image {
padding: 0;
display:block;
margin: 0 auto;
width: 100%;
box-shadow: 0px 0px 20px 2px #888888;
}

.course-image {
padding: 0;
display:block;
margin: 0 auto;
max-width: 85%;
max-height: 450px;
box-shadow: 0px 0px 10px 2px #888888;
}

h4.tut-h4-pad {
padding-top: 5em;
padding-bottom: 1.5em;
}

#tut-content p {
padding: 0;
}

/* ======= tutorial two main parts ====== */
main.tut-post {
margin: 0 auto;
background-color:#FAFAFA;
box-shadow: 0px 0px 30px 5px  #888888;
display: flex;
width: 100%;
}

.tut-main-content {
width: 75%;
}

.tut-main-content-pad {
padding: 0 2em;
}


.side-nav {
position: fixed;
padding: 1em 0.5em;
top: 5em;
background-color:#FAFAFA;
z-index: 1;
width: 19%;
}

.tut-side-menu .ads-container {
position: absolute;
top: 63em;
width: 19%;
height: 800px;
z-index: 0;
}

@media screen and (max-width: 40.5em) {
  .tut-side-menu {
  display: none;
  width: 0;
  }
  .tut-main-content {
  width: 100%;
  padding: 2em 0;
  margin: 0 auto;
  display: block;
  }
  .tut-content-menu {
  right:1em;
  }
}


@media screen and (min-width: 1200px) {
  main.tut-post {
  max-width: 1200px;
  }
  main.tut-post {
  max-width: 1200px;
  max-height: calc(1200/16*9)px;
  margin: 0 auto;
  }
 }

/* ======= video and next previous button ====== */
.link-under-youtube {
text-align: center;
margin: 0;
}

.PageNavigation {
display: block;
width: auto;
overflow: hidden;
}

.PageNavigation a {
display: block;
color: white;
background-color: #14b814;
text-decoration: none;
padding: 0.9em;
margin: 0.5em 0;
border-radius: 10px;
}

.PageNavigation i {
font-size: 1em;
}

.PageNavigation a:hover {
color: #303030;
}

.PageNavigation .prev {
float: left;
}

.PageNavigation .next {
float: right;
text-align: right;
}