/* CSS Reset and Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Plus Jakarta Sans', sans-serif;
  font-size: 16px;
  font-weight: 500;
  line-height: 1.5;
  background-color: hsl(210, 60%, 98%);
  color: hsl(224, 21%, 14%);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}

/* Container */
.container {
  background-color: hsl(0, 0%, 100%);
  border-radius: 15px;
  padding: 2rem;
  max-width: 730px;
  width: 100%;
  box-shadow: 0 20px 60px rgba(73, 97, 168, 0.05);
}

/* Header */
.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.title {
  font-size: 1.5rem;
  font-weight: 800;
  color: hsl(224, 21%, 14%);
}

.notification-count {
  background-color: hsl(219, 85%, 26%);
  color: hsl(0, 0%, 100%);
  font-weight: 800;
  font-size: 1rem;
  padding: 0.25rem 0.75rem;
  border-radius: 6px;
  min-width: 2rem;
  text-align: center;
}

.mark-all-read {
  background: none;
  border: none;
  color: hsl(219, 12%, 42%);
  font-size: 1rem;
  font-weight: 500;
  cursor: pointer;
  transition: color 0.2s ease;
}

.mark-all-read:hover,
.mark-all-read:focus {
  color: hsl(219, 85%, 26%);
  outline: none;
}

/* Notifications List */
.notifications-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

/* Individual Notification */
.notification {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  padding: 1rem;
  border-radius: 8px;
  transition: background-color 0.2s ease;
  position: relative;
}

.notification:hover {
  background-color: hsl(211, 68%, 94%);
}

.notification.unread {
  background-color: hsl(210, 60%, 98%);
}

.notification.unread:hover {
  background-color: hsl(211, 68%, 94%);
}

/* Avatar */
.avatar {
  width: 45px;
  height: 45px;
  border-radius: 50%;
  flex-shrink: 0;
}

/* Notification Content */
.notification-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.notification-text {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  flex-wrap: wrap;
}

.name {
  font-weight: 800;
  color: hsl(224, 21%, 14%);
  cursor: pointer;
  transition: color 0.2s ease;
}

.name:hover {
  color: hsl(219, 85%, 26%);
}

.post-title {
  font-weight: 800;
  color: hsl(219, 12%, 42%);
  cursor: pointer;
  transition: color 0.2s ease;
}

.post-title:hover {
  color: hsl(219, 85%, 26%);
}

.group-name {
  font-weight: 800;
  color: hsl(219, 85%, 26%);
  cursor: pointer;
  transition: color 0.2s ease;
}

.group-name:hover {
  color: hsl(219, 85%, 26%);
}

.unread-dot {
  width: 8px;
  height: 8px;
  background-color: hsl(1, 90%, 64%);
  border-radius: 50%;
  flex-shrink: 0;
  margin-left: 0.25rem;
}

.timestamp {
  color: hsl(219, 12%, 42%);
  font-size: 1rem;
  margin-top: 0.125rem;
}

/* Private Message */
.private-message {
  margin-top: 0.75rem;
  padding: 1rem;
  background-color: hsl(0, 0%, 100%);
  border: 1px solid hsl(205, 33%, 90%);
  border-radius: 5px;
  color: hsl(219, 12%, 42%);
  cursor: pointer;
  transition: background-color 0.2s ease;
}

.private-message:hover {
  background-color: hsl(211, 68%, 94%);
}

/* Picture Thumbnail */
.picture-thumbnail {
  width: 45px;
  height: 45px;
  border-radius: 7px;
  margin-left: auto;
  cursor: pointer;
  transition: transform 0.2s ease;
  flex-shrink: 0;
}

.picture-thumbnail:hover {
  transform: scale(1.05);
}

/* Attribution */
.attribution {
  font-size: 11px;
  text-align: center;
  margin-top: 2rem;
  color: hsl(219, 12%, 42%);
}

.attribution a {
  color: hsl(228, 45%, 44%);
  text-decoration: none;
  transition: color 0.2s ease;
}

.attribution a:hover {
  color: hsl(219, 85%, 26%);
}

/* Responsive Design */
@media (max-width: 768px) {
  body {
    padding: 0;
    justify-content: flex-start;
  }
  
  .container {
    border-radius: 0;
    padding: 1.5rem 1rem;
    min-height: 100vh;
    box-shadow: none;
  }
  
  .header {
    margin-bottom: 1.5rem;
  }
  
  .title {
    font-size: 1.25rem;
  }
  
  .notification {
    padding: 1rem 0.5rem;
  }
  
  .notification-text {
    font-size: 0.95rem;
  }
  
  .timestamp {
    font-size: 0.95rem;
  }
  
  .private-message {
    margin-top: 0.5rem;
    padding: 0.875rem;
    font-size: 0.95rem;
  }
}

@media (max-width: 480px) {
  .header {
    flex-direction: column;
    align-items: flex-start;
    gap: 1rem;
  }
  
  .header-left {
    width: 100%;
  }
  
  .mark-all-read {
    align-self: flex-start;
  }
  
  .notification {
    gap: 0.75rem;
  }
  
  .avatar {
    width: 40px;
    height: 40px;
  }
  
  .picture-thumbnail {
    width: 40px;
    height: 40px;
  }
}

/* Focus states for accessibility */
.notification:focus-within {
  outline: 2px solid hsl(219, 85%, 26%);
  outline-offset: 2px;
}

.name:focus,
.post-title:focus,
.group-name:focus {
  outline: 2px solid hsl(219, 85%, 26%);
  outline-offset: 2px;
  border-radius: 2px;
}

.private-message:focus {
  outline: 2px solid hsl(219, 85%, 26%);
  outline-offset: 2px;
}

.picture-thumbnail:focus {
  outline: 2px solid hsl(219, 85%, 26%);
  outline-offset: 2px;
}

/* Animation for notification count changes */
.notification-count {
  transition: all 0.3s ease;
}

.notification-count.updating {
  transform: scale(1.2);
}

/* Smooth transitions for unread state changes */
.notification {
  transition: background-color 0.3s ease;
}

.unread-dot {
  transition: opacity 0.3s ease;
}