*,
*::before,
*::after {
  box-sizing: border-box;
  font-family: Arial, Helvetica, sans-serif;
}

:root {
  --dark-color: hsl(215, 30%, 30%);
  --light-color: hsl(215, 20%, 70%);
  --bg-color: #f9f9fb;
  --card-color: #fff;
  --card-shadow: 0 0 0.5rem 1px var(--light-color);
  --timeline-margin: 2rem;
  --grid-gap: 2rem;
  --avatar-size: 3rem;
}

body {
  margin: 1rem;
  background-color: var(--bg-color);
}

.timeline-section {
  margin-bottom: 3rem;
}

.timeline-section:last-of-type {
  margin-bottom: 0;
}

.timeline-header {
  display: flex;
  justify-content: space-between;
  border-bottom: 1px solid var(--light-color);
  margin-bottom: var(--timeline-margin);
  padding-bottom: 0.5rem;
  font-size: 1.1em;
}

.timeline-title {
  color: var(--dark-color);
  font-weight: bold;
}

.timeline-date {
  color: var(--light-color);
}

.notification-grid {
  display: grid;
  grid-template-columns: 3rem 1fr;
  gap: var(--grid-gap);
  max-width: 50rem;
  margin: 0 auto;
}

.avatar {
  position: relative;
}

.avatar:first-child:before {
  content: "";
  width: 1px;
  position: absolute;
  left: 0;
  right: 0;
  margin: 0 auto;
  top: calc(var(--timeline-margin) * -1);
  bottom: 100%;
  background-color: var(--light-color);
}

.avatar::after {
  content: "";
  width: 1px;
  height: calc(100% + var(--grid-gap));
  position: absolute;
  left: 0;
  right: 0;
  margin: 0 auto;
  top: var(--avatar-size);
  background-color: var(--light-color);
}

.avatar:nth-last-child(2)::after {
  display: none;
}

.avatar > img {
  width: var(--avatar-size);
  height: var(--avatar-size);
  object-fit: cover;
  object-position: top;
  border: 2px solid var(--card-color);
  border-radius: 50%;
  box-shadow: var(--card-shadow);
}

.notification-card {
  background-color: var(--card-color);
  box-shadow: var(--card-shadow);
  border-radius: 4px;
  padding: 1rem;
}

.notification-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.icon {
  height: 1.5em;
}

.notification-title {
  flex: 1;
  color: var(--dark-color);
  font-weight: bold;
}

.notification-time {
  color: var(--light-color);
}

.notification-content {
  margin-top: 1rem;
  padding: 1rem;
  border-radius: 4px;
  background-color: var(--bg-color);
  color: var(--dark-color);
  font-size: 0.9em;
}