:root {
  --white-color: #fafafb;
  --background-color: #17171e;
  --grey-color: #b5b5be;
  --dark-grey-color: #292932;
}

* {
  box-sizing: border-box;
}

html,
body {
  font-family: 'Poppins', sans-serif;
  font-size: 62.5%;
  font-weight: 500;
}

body {
  font-family: 'Poppins', sans-serif;
  font-size: 1.4rem;
  color: var(--white-color);
  height: 100vh;
  background-color: #fafafa;
}

.lead { font-size: 1.5rem; font-weight: 300; }
.container { margin: 150px auto; max-width: 960px; color: #000; }

.side-bar {
  width: 23.2rem;
  height: 100%;
  padding: 2.1rem 1.2rem;
  background-color: #17171e;
  position: fixed;
  transition: all 0.5s ease;
  top: 0;
}

.logo-name-wrapper {
  position: relative;
  margin-bottom: 2.1rem;
  display: flex;
  font-size: 1.2rem;
}

.logo-name {
  display: flex;
  align-items: center;
}

.logo-name__name {
  margin-left: 0.9rem;
  white-space: nowrap;
}
.logo-name__button {
  position: absolute;
  top: 50%;
  right: 0;
  font-size: 1.8rem;
  transform: translateY(-50%);
  background-color: transparent;
  border: none;
  cursor: pointer;
}
.logo-name__icon {
  font-size: 1.8rem;
  color: var(--grey-color);
}

.message {
  background-color: var(--dark-grey-color);
  display: flex;
  align-items: center;
  padding: 1.55rem 0 1.55rem 1.2rem;
  border-radius: 0.4rem;
  margin-bottom: 3.6rem;
  cursor: pointer;
  position: relative;
}

.message-icon {
  font-size: 2rem;
  transform: translateX(3rem);
  transition: all 0.5s ease;
}

.message-text {
  margin-left: 1.1rem;
  font-size: 1.4rem;
  white-space: nowrap;
  transform: translateX(3rem);
  transition: all 0.5s ease;
}

.features-list {
  padding-bottom: 1rem;
  border-bottom: 1px solid #292932;
  list-style: none;
}

.features-item {
  display: flex;
  align-items: center;
  position: relative;
  padding: 0.5rem 0.9rem;
  margin-bottom: 1.1rem;
  color: var(--grey-color);
  cursor: pointer;
  transition: 0.5s ease;
}
.features-item::before {
  transition: 0.5s ease;
  content: '';
  position: absolute;
  left: -1.2rem;
  height: 100%;
  border-left: 3px solid var(--white-color);
  border-radius: 2px;
  opacity: 0;
  visibility: hidden;
}

.features-item:hover {
  color: var(--white-color);
  transition: 0.5s ease;
}

.features-item:hover::before {
  opacity: 1;
  visibility: unset;
}

.features-item-icon {
  font-size: 2rem;
}

.features-item-text {
  margin-left: 1.5rem;
  transition: opacity 0.6s ease;
  opacity: 1;
}

.inbox-number {
  position: absolute;
  top: 50%;
  right: 0;
  transform: translateY(-50%);
  background-color: #1e75ff;
  padding: 0.5rem 0.9rem;
  border-radius: 0.4rem;
  color: var(--white-color);
  opacity: 1;
  transition: 0.6s linear;
}

.inbox-icon {
  position: relative;
}

.inbox-icon .status {
  position: absolute;
  top: 0;
  right: -1px;
  background-color: #1e75ff;
  height: 9px;
  width: 9px;
  border-radius: 50%;
  border: 2px solid var(--white-color);
  opacity: 0;
  transition: 0.6s linear;
}

.category-list {
  padding-top: 2.1rem;
  padding-bottom: 0.9rem;
  color: var(--grey-color);
  list-style: none;
  font-size: 1.2rem;
  font-weight: 500;
  border-bottom: 1px solid #292932;
}

.category-header {
  font-size: 1.2rem;
  text-transform: uppercase;
  line-height: 1.8rem;
  color: var(--white-color);
  margin-bottom: 1.3rem;
  white-space: nowrap;
}

.category-item {
  position: relative;
  padding: 0.9rem 1.1rem;
  line-height: 1.8rem;
  cursor: pointer;
  white-space: nowrap;
}

.category-item-status {
  height: 0.8rem;
  width: 0.8rem;
  border-radius: 50%;
  border: none;
  background-color: white;
  display: inline-block;
}
.category-item-text {
  margin-left: 1rem;
  transition: opacity 0.6s ease;
  opacity: 1;
}

.category-item-number {
  position: absolute;
  top: 50%;
  right: 0;
  transform: translateY(-50%);
}

.chat-list {
  padding: 2.1rem 0;
  font-size: 1.2rem;
}

.chat-header {
  text-transform: uppercase;
  line-height: 1.8rem;
  color: var(--white-color);
  margin-bottom: 1.3rem;
  white-space: nowrap;
}

.chat-new-btn {
  color: #1e75ff;
  background-color: transparent;
  outline: none;
  border: none;
  line-height: 1.8rem;
  display: flex;
  align-items: center;
  padding-bottom: 2.1rem;
  padding-left: 0.1rem;
  cursor: pointer;
  position: relative;
  font-family: 'Poppins', sans-serif;
  font-weight: 500;
}

.chat-new-btn-text {
  white-space: nowrap;
  transition: opacity 0.6s ease;
  opacity: 1;
}

.chat-icon {
  font-size: 2.1rem;
  margin-right: 1.2rem;
}

.chat-item {
  position: relative;
  display: flex;
  align-items: center;
  margin-bottom: 2.1rem;
  color: var(--grey-color);
  cursor: pointer;
}

.chat-item-avatar-wrapper {
  position: relative;
}
.chat-item-avatar-wrapper::before {
  content: '';
  position: absolute;
  top: 0;
  right: -3px;
  border-radius: 50%;
  height: 8px;
  width: 8px;
  background-color: #79d861;
  opacity: 0;
  transition: 0.6s linear;
}

.chat-item-avatar-wrapper.has-message::before {
  background-color: #1e75ff;
  border: 2px solid var(--white-color);
  height: 6px;
  width: 6px;
}

.chat-item-avatar {
  object-fit: cover;
  object-position: top;
  height: 2.1rem;
  width: 2.1rem;
  border-radius: 50%;
  border: 1px solid var(--white-color);
}

/* background color in inline style */
.chat-item-status {
  height: 0.8rem;
  width: 0.8rem;
  border-radius: 50%;
  border: none;
  background-color: white;
  position: absolute;
  top: 50%;
  right: 0;
  transform: translateY(-50%);
  margin-right: 5px;
  opacity: 1;
  transition: 0.6s linear;
}
.chat-item-number {
  position: absolute;
  top: 50%;
  right: 0;
  transform: translateY(-50%);
  background-color: #1e75ff;
  padding: 0.5rem 0.9rem;
  border-radius: 0.4rem;
  color: var(--white-color);
  opacity: 1;
  transition: 0.6s linear;
}

.chat-item-name {
  white-space: nowrap;
  transition: opacity 0.6s ease;
  opacity: 1;
  margin-left: 1.4rem;
}

.tooltip {
  position: absolute;
  top: -2.1rem;
  left: 6.4rem;
  background-color: white;
  color: var(--background-color);
  border-radius: 0.4rem;
  padding: 0.5rem 0.9rem;
  font-size: 1.4rem;
  transition: 0s;
  opacity: 0;
  display: none;
  box-shadow: 0 5px 10px rgba(0, 0, 0, 0.2);
}

.side-bar.collapse .message:hover .tooltip,
.features-item:hover .tooltip,
.category-item:hover .tooltip,
.chat-new-btn:hover .tooltip {
  top: 50%;
  transform: translateY(-50%);
  transition: all 0.5s ease;
  opacity: 1;
}

.side-bar.collapse {
  width: 6.4rem;
}

.side-bar.collapse .tooltip {
  display: block;
}

.side-bar.collapse .logo-name,
.side-bar.collapse .category-header,
.side-bar.collapse .chat-header,
.side-bar.collapse .chat-new-btn-text,
.side-bar.collapse .features-item-text,
.side-bar.collapse .inbox-number,
.side-bar.collapse .category-item-text,
.side-bar.collapse .category-item-number,
.side-bar.collapse .message-text,
.side-bar.collapse .chat-item-name,
.side-bar.collapse .chat-item-number,
.side-bar.collapse .chat-item-status {
  opacity: 0;
  pointer-events: none;
}

.side-bar.collapse .message-text {
  opacity: 0;
  pointer-events: none;
  transform: translateX(0);
}
.side-bar.collapse .message-icon {
  transform: translateX(0);
}
.side-bar.collapse .logo-name__button {
  right: 0.5rem;
}

.side-bar.collapse .inbox-icon .status,
.side-bar.collapse .chat-item-avatar-wrapper::before {
  opacity: 1;
}