Gradient Timline Progressbar In Pure CSS

Preview:

Description:

A vertical timeline component with an animated gradient progress bar, built with pure CSS/CSS3.

How to use it:

1. Code the HTML for the timeline & progress bar.

<section class="timeline">
  <div class="container">
    <div class="timeline__wrapper">
      <div class="timeline__progressbar"></div>
      <div class="timeline__block">
        <div class="timeline__block__bullet-point">
          <span class="timeline__block__circle"></span>
        </div>
        <div class="timeline__block__head">
          <h1 class="timeline__block__title">January 2020</h1>
        </div>
        <div class="timeline__block__body">
          <p class="timeline__block__text">Lorem ipsum, dolor sit amet consectetur adipisicing elit. Odio nihil id animi et ipsum itaque veniam minima aliquid ad expedita.</p>
          <p class="timeline__block__text">Lorem ipsum, dolor sit amet consectetur adipisicing elit. Odio nihil id animi et ipsum itaque veniam minima aliquid ad expedita.</p>
        </div>
      </div>
      <div class="timeline__block">
        <div class="timeline__block__bullet-point">
          <span class="timeline__block__circle"></span>
        </div>
        <div class="timeline__block__head">
          <h1 class="timeline__block__title">February 2020</h1>
        </div>
        <div class="timeline__block__body">
          <p class="timeline__block__text">Lorem ipsum, dolor sit amet consectetur adipisicing elit. Odio nihil id animi et ipsum itaque veniam minima aliquid ad expedita.</p>
          <p class="timeline__block__text">Lorem ipsum, dolor sit amet consectetur adipisicing elit. Odio nihil id animi et ipsum itaque veniam minima aliquid ad expedita.</p>
        </div>
      </div>
      ...
      <div class="timeline__hider"></div>
    </div>
  </div>
</section>

2. The necessary CSS styles.

.timeline {
  position: relative;
}
.timeline__progressbar {
  --width: 2px;
  --left: -moz-calc(((15vw / 2) + 15px) - (var(--width) / 2));
  --left: calc(((15vw / 2) + 15px) - (var(--width) / 2));
  position: absolute;
  left: var(--left);
  width: var(--width);
  height: 100%;
  background-color: #2c2c2c;
  z-index: -1;
}
.timeline__progressbar::after {
  content: "";
  position: fixed;
  top: 0;
  left: var(--left);
  width: var(--width);
  height: 50vh;
  background: -webkit-gradient(linear, left top, left bottom, from(#b25d46), color-stop(#a74141), color-stop(#743879), to(#4a3ca0));
  background: -webkit-linear-gradient(#b25d46, #a74141, #743879, #4a3ca0);
  background: -moz-linear-gradient(#b25d46, #a74141, #743879, #4a3ca0);
  background: -o-linear-gradient(#b25d46, #a74141, #743879, #4a3ca0);
  background: linear-gradient(#b25d46, #a74141, #743879, #4a3ca0);
}
@media screen and (min-width: 800px) {
  .timeline__progressbar {
    --width: 3px;
    --left: -moz-calc(50% - (var(--width) / 2));
    --left: calc(50% - (var(--width) / 2));
  }
}
.timeline__block {
  display: -ms-grid;
  display: grid;
  -ms-grid-columns: 15vw 1fr;
      grid-template-columns: 15vw 1fr;
  padding-top: 2.5rem;
  padding-bottom: 2.5rem;
  -webkit-box-align: start;
  -webkit-align-items: start;
     -moz-box-align: start;
      -ms-flex-align: start;
          align-items: start;
}
@media screen and (min-width: 800px) {
  .timeline__block {
    -ms-grid-columns: 1fr 15vh 1fr;
        grid-template-columns: 1fr 15vh 1fr;
  }
}
@media screen and (min-width: 800px) {
  .timeline__block__head {
    -ms-grid-column: 1;
    -ms-grid-column-span: 1;
    grid-column: 1 / 2;
    text-align: right;
    position: -webkit-sticky;
    position: sticky;
    top: 50vh;
  }
}
.timeline__block__body {
  grid-column: 2 / -1;
}
@media screen and (min-width: 800px) {
  .timeline__block__body {
    grid-column: 3 / -1;
  }
}
.timeline__block__bullet-point {
  position: -webkit-sticky;
  position: sticky;
  top: 50vh;
  display: -webkit-box;
  display: -webkit-flex;
  display: -moz-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-pack: center;
  -webkit-justify-content: center;
     -moz-box-pack: center;
      -ms-flex-pack: center;
          justify-content: center;
}
@media screen and (min-width: 800px) {
  .timeline__block__bullet-point {
    -ms-grid-column: 2;
    -ms-grid-column-span: 1;
    grid-column: 2 / 3;
  }
}
.timeline__block__circle {
  display: inline-block;
  width: 2rem;
  height: 2rem;
  border: 4px solid #0b0b0b;
  background-color: #ffffff;
  border-radius: 50%;
}
.timeline__block__title {
  font-size: 3rem;
}
@media screen and (max-width: 799px) {
  .timeline__block__title {
    margin-top: -1.5rem;
    margin-bottom: 2rem;
  }
}
@media screen and (min-width: 800px) {
  .timeline__block__title {
    line-height: 0;
  }
}
.timeline__block__text {
  font-size: 1.6rem;
}
@media screen and (min-width: 500px) {
  .timeline__block__text {
    font-size: 1.8rem;
  }
}
.timeline__hider {
  position: -webkit-sticky;
  position: sticky;
  bottom: -2px;
  width: 100%;
  height: 50vh;
  background: -webkit-gradient(linear, left top, left bottom, from(transparent), to(#0b0b0b));
  background: -webkit-linear-gradient(transparent, #0b0b0b);
  background: -moz-linear-gradient(transparent, #0b0b0b);
  background: -o-linear-gradient(transparent, #0b0b0b);
  background: linear-gradient(transparent, #0b0b0b);
  pointer-events: none;
}