style.css

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  width: 100%;
  font-family: 'Roboto', Arial, Helvetica, sans-serif;
}

body {
  font-size: 16px;
  background-color: #fefdfc;
}

button {
  border: none;
  outline: none;
}

p {
  width: 90%;
}

/* Header */

header {
  position: fixed;
  top: 0;
  left: 50%;
  transform: translate(-50%);
  z-index: 1000;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: .8rem 1.5rem;
  height: 3rem;
  max-width: 1930px;
  background-color: #fefdfc;
}

.header-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 3rem;
  background-color: #fefdfc;
  opacity: .6;
  cursor: pointer;
}

.header-btn:hover {
  opacity: 1;
}

.header-btn img {
  width: 24px;
  height: 24px;
}

header a {
  margin: .5rem 1rem;
  width: 12rem;
  min-width: 4rem;
}

header a img {
  height: 30px;
}

.search {
  display: flex;
  margin: 0 2rem 0 6rem;
}

.search-bar {
  padding: .3rem;
  width: 100%;
  height: 1.8rem;
  border: 1px solid #888;
  border-top-right-radius: 0;
  border-bottom-right-radius: 0;
  outline: none;
  font-size: inherit;
}

.search-btn {
  width: 5rem;
  height: 1.8rem;
  border: 1px solid #888;
  border-left: none;
  background-color: #f8f8f8;
  transition: background-color 150ms;
}

.search-btn:hover {
  background-color: #f0f0f0;
}

.sound-input-btn {
  margin-left: .5rem;
  border-radius: 50%;
  background-color: #f8f8f8;
}

.header-btn-group {
  display: flex;
  width: 20rem;
}

.avatar-img {
  height: 36px;
  width: 36px;
  border-radius: 50%;
  background-color: #aaa;
}

/* Main Content Section */

.main-wrapper {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr 1fr;
  padding: .5rem 1.5rem;
  margin: 0 auto;
  margin-top: 3rem;
  max-width: 1930px;
  background-color: #f9f9f9;
}

/* Video Section */

.video {
  grid-column-start: 1;
  grid-column-end: 4;
  grid-row-start: 1;
  grid-row-end: 2;
  border-bottom: 1px solid rgba(0,0,0,.1);
}

/* https://css-tricks.com/fluid-width-video/ */
.video-container {
  position: relative;
  padding-bottom: 56.25%;
}

.video-container iframe {
  position: absolute;
  width: 100%;
  height: 100%;
}

.video h1 {
  padding: 1rem 0;
  font-size: 1.1rem;
  font-weight: normal;
}

.video-info {
  position: relative;
}

.video-info span {
  font-size: .9rem;
  color: #777;
}

.video-icon-grp {
  display: flex;
  flex-direction: row;
  justify-content: flex-end;
  align-items: center;
  text-transform: uppercase;
  font-size: .9rem;
  outline: none;
}

.video-icon-grp a {
  display: flex;
  align-items: center;
  padding-left: .5rem;
  width: auto;
  text-decoration: none;
  letter-spacing: .03rem;
  color: black;
  opacity: .7;
  font-weight: 600;
  border-bottom: 1px solid transparent;
}

.video-icon-grp a:hover {
  border-bottom: 1px solid #777;
  opacity: 1;
}

.video-icon-grp img {
  padding: .3rem;
  width: 2rem;
  height: 2rem;
  opacity: .5;

}

/* Watch More Section */

.watchmore {
  grid-column-start: 4;
  grid-column-end: 5;
  grid-row-start: 1;

  /* Plus one more row than needed for stretching left column down the bottom af a page*/
  grid-row-end: 5;
  padding-left: 1.5rem;
}

.watchmore-video {
  display: flex;
  flex-direction: row;
  padding-bottom: .7rem;
}

.watchmore-video button {
  align-self: flex-start;
  width: 4rem;
  background-color: transparent;
  cursor: pointer;
}

.watchmore-video button img {
  opacity: .5;
}

.watchmore-thumbnail {
  margin-right: .3rem;
  width: 169px;
  height: 94px;
  background-color: #ddd;
}

.watchmore-thumbnail img {
  width: 169px;
  height: 94px;
}

.watchmore-info {
  width: 100%;
  font-size: .7rem;
  color: #777;
}

.watchmore-info a {
  text-decoration: none;
  color: black;
}

.watchmore-info h3 {
  font-size: 1rem;
}

.watchmore-info h4 {
  font-weight: 400;
}

/* Video Description Section */

.dscrp {
  grid-column-start: 1;
  grid-column-end: 4;
  grid-row-start: 2;
  grid-row-end: 3;
  padding: 1rem 0;
  position: relative;
  border-bottom: 1px solid rgba(0,0,0,.1);
}

.dscrp-wrap {
  display: flex;
}

.dscrp-channel_avatar {
  width: 3rem;
  padding-top: 1rem;
}

.dscrp-channel_avatar img {
  border-radius: 50%;
}

.dscrp-text {
  padding: 1rem;
  font-size: 1rem;
}

.dscrp-text a {
  text-decoration: none;
  color: black;
}

.dscrp-text span {
  font-size: .8rem;
  opacity: .5;
}

.dscrp-text p {
  padding-top: 1rem;
}

.dscrp-btn-subscribe {
  margin-top: 1rem;
  position: absolute;
  top: 0;
  right: 0;
  height: 2.5rem;
  width: 7rem;
  font-size: .9rem;
  color: white;
  text-transform: uppercase;
  font-weight: 600;
  background-color: rgb(204,0,0);
  cursor: pointer;
}

/* Comments Section */

.comments {
  grid-column-start: 1;
  grid-column-end: 4;
  grid-row-start: 3;
  grid-row-end: 4;
  padding-top: 1rem;
}

.comments-form h3 {
  display: inline;
  font-size: 1rem;
  font-weight: 400;
  color: #777;
}

.comments-form label {
  padding-left: 2rem;
  margin-right: .5rem;
  text-transform: uppercase;
}

.comments-form label img {
  margin-right: .5rem;
  width: 25px;
  height: 25px;
  vertical-align: middle;
}

.comments-form select {
  margin-right: 1rem;
  width: 15rem;
  cursor: pointer;
}

.comments-form-leave {
  display: flex;
  justify-items: flex-start;
  padding-top: 1rem;
}

.comments-form-leave a {
  width: 3rem;
}

.comments-form-leave input {
  margin: 1rem;
  padding: 0 1rem;
  resize: none;
  border: none;
  outline: none;
  background-color: #f8f8f8;
  font-size: 1rem;
  border-bottom: 1px solid lightgray;
}

.comment-container {
  display: flex;
}

.comment-container a {
  width: 3rem;
  padding-top: 1rem;
}

.comments-text {
  padding: 1rem;
}

.comments-text p {
  margin-top: .5rem;
}

.comments-text-name {
  font-size: .9rem;
  font-weight: 500;
}

.comments-text-date {
  font-size: .8rem;
  color: #777;
}

.comment-feedback {
  display: flex;
  align-items: end;
  justify-items: flex-start;
  margin: 1rem 1rem 1rem 0;
}

.comment-feedback span {
  margin-right: 1rem;
  width: auto;
  font-size: .8rem;
  font-weight: 500;
  color: #777;
}

.comment-feedback button {
  margin-right: 1rem;
  width: 1rem;
  height: 1rem;
  background-color: #f8f8f8;
  text-transform: uppercase;
  font-weight: 600;
  letter-spacing: .03rem;
  white-space: nowrap;
  opacity: .7;
  cursor: pointer;
}

.comment-feedback button:hover {
  opacity: 1;
}

.comments-btn-read-more {
  margin-top: 1rem;
  padding: .5rem 1.5rem;
  width: 90%;
  border: 1px solid #065fd4;
  background-color: #f8f8f8;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .03rem;
  color: #065fd4;
  cursor: pointer;
}

@media (max-width: 740px) {
  .main-wrapper {
    grid-template-columns: 1fr 1fr 1fr;
  }

  .video {
    grid-column-start: 1;
    grid-column-end: 4;
    grid-row-start: 1;
    grid-row-end: 2;
  }

  .watchmore {
    grid-column-start: 1;
    grid-column-end: 4;
    grid-row-start: 4;
    grid-row-end: 5;
    padding-left: 0;
  }

  .dscrp {
    grid-column-start: 1;
    grid-column-end: 4;
    grid-row-start: 2;
    grid-row-end: 3;
    padding: 2rem 0;
    position: relative;
    border-bottom: 1px solid rgba(0,0,0,.1);
  }

  .comments {
    grid-column-start: 1;
    grid-column-end: 4;
    grid-row-start: 3;
    grid-row-end: 4;
    padding: 2rem 0;
  }

  p,
  .comments-btn-read-more {
    width: 100%;
  }

  .search {
    margin-left: 1rem;
  }

}

@media (max-width: 540px) {
  * {
    font-size: 10px;
  }

  header {
    padding: .8rem 1rem;
    height: 4rem;
  }

  .main-wrapper {
    padding: 1rem;
  }

  .search {
    margin-left: 0;
    margin-right: 0;
  }

  .search-bar {
    height: 2.5rem;
  }

  .search-btn {
    height: 2.5rem;
  }

  .dscrp-text {
    margin-left: 1rem;
  }

  .comments-form-leave {
    margin-bottom: 2rem;
  }

  .comments-text {
    margin-left: 1rem;
  }
}

@media (max-width: 340px) {
  * {
    font-size: 8px;
  }

  header {
    padding: .8rem 5px;
  }
  
  .main-wrapper {
    padding: 5px;
  }

  .comments a {
    width: 4.5rem;
  }

  .dscrp-channel_avatar {
    width: 4.5rem;
  }
}