* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background-color: #fff;
  color: #000;
  font-family: "Helvetica Neue", Arial, sans-serif;
  min-height: 100vh;
  display: flex;
  justify-content: center;
}

.app {
  width: min(640px, 100%);
  padding: 32px 16px 96px;
}

.top-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 2px solid #000;
  padding-bottom: 24px;
  margin-bottom: 32px;
}

.brand {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: 0.2em;
  text-transform: uppercase;
}

.controls {
  display: flex;
  gap: 12px;
}

button {
  background-color: #fff;
  color: #000;
  border: 2px solid #000;
  padding: 10px 18px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.1s ease-out, background-color 0.1s ease-out, color 0.1s ease-out;
}

button:hover,
button:focus {
  outline: none;
  background-color: #000;
  color: #fff;
}

button:active {
  transform: translateY(1px);
}

.timeline {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.tweet {
  display: flex;
  gap: 16px;
  border-bottom: 2px solid #000;
  padding-bottom: 24px;
  animation: float-in 0.3s ease-out;
}

.tweet.user {
  border-left: 4px solid #000;
  padding-left: 12px;
}

.tweet.advertisement {
  border: 2px solid #000;
  padding: 24px 16px;
  border-bottom: 2px solid #000;
}

.avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background-color: #fff;
  border: 2px solid #000;
  flex-shrink: 0;
}

.tweet-body {
  display: flex;
  flex-direction: column;
  gap: 12px;
  flex: 1;
}

.tweet.image .tweet-body {
  gap: 16px;
}

.username {
  font-size: 0.95rem;
  font-weight: 600;
}

.tweet-content {
  font-size: clamp(2rem, 6vw, 3.2rem);
  font-weight: 700;
  line-height: 1.1;
}

.tweet-media {
  width: 100%;
  aspect-ratio: 16 / 9;
  border: 2px solid #000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 12px;
  background-color: #fff;
}

.tweet-media .tweet-content {
  margin: 0;
}

.tweet-actions {
  display: flex;
  justify-content: flex-end;
}

.like-button {
  padding: 6px 14px;
  border-radius: 0;
  background-color: #fff;
  color: #000;
  border: 2px solid #000;
  font-size: 1.6rem;
  line-height: 1;
}

.like-button.liked {
  background-color: #000;
  color: #fff;
}

.like-button:disabled {
  cursor: default;
}

.replies {
  display: flex;
  flex-direction: column;
  gap: 12px;
  border-left: 2px solid #000;
  margin-left: 24px;
  padding-left: 16px;
}

.reply {
  font-size: 0.9rem;
  font-weight: 500;
}

.load-hint {
  margin-top: 48px;
  text-align: center;
  font-size: 0.95rem;
}

@keyframes float-in {
  from {
    transform: translateY(16px);
  }
  to {
    transform: translateY(0);
  }
}