.chat-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 24px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
  z-index: 10;
  padding-top: max(12px, env(safe-area-inset-top));
}

.chat-header__left {
  display: flex;
  align-items: center;
  gap: 14px;
}

.chat-header__back-btn {
  padding: 5px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-dim);
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: border-color 0.2s, color 0.2s;
}

.chat-header__back-btn:hover {
  border-color: var(--primary);
  color: var(--primary-light);
}

.chat-header__title {
  font-size: 18px;
  font-weight: 700;
  margin: 0;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--text);
  letter-spacing: -0.3px;
}

.chat-header__logo {
  font-size: 20px;
}

.chat-header__instance {
  font-size: 12px;
  color: var(--text-dim);
  background: var(--surface2);
  padding: 4px 12px;
  border-radius: 20px;
  border: 1px solid var(--border);
  font-weight: 500;
}

.chat-header__actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.chat-header__user {
  font-size: 13px;
  color: var(--text-dim);
  font-weight: 500;
}

.chat-header__btn {
  padding: 6px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text);
  font-size: 14px;
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s;
  font-weight: 500;
}

.chat-header__btn:hover {
  background: var(--surface2);
}

.chat-header__btn--new {
  border-color: var(--primary);
  color: var(--primary-light);
}

.chat-header__btn--new:hover {
  background: rgba(108, 92, 231, 0.1);
}

.chat-header__btn--logout {
  font-size: 13px;
  color: var(--text-dim);
}

.chat-header__btn--logout:hover {
  color: var(--error);
  border-color: var(--error);
  background: rgba(255, 82, 82, 0.06);
}

.chat-app {
  display: flex;
  flex-direction: column;
  height: 100vh;
  height: 100dvh;
  background: var(--bg);
  position: relative;
  z-index: 1;
  overflow: hidden;
}

.chat-app__messages {
  flex: 1;
  overflow-y: auto;
  padding: 24px;
  padding-bottom: 100px;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
}

@media (max-width: 760px) {
  .chat-header {
    padding: max(8px, env(safe-area-inset-top)) 12px 8px;
    align-items: center;
    gap: 8px;
    flex-wrap: nowrap;
  }

  .chat-header__left {
    min-width: 0;
    flex: 1;
    gap: 8px;
  }

  .chat-header__title {
    display: none;
  }

  .chat-header__back-btn,
  .chat-header__btn {
    min-height: 44px;
    padding: 7px 10px;
  }

  .chat-header__instance {
    min-width: 0;
    max-width: 38vw;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
  }

  .chat-header__actions {
    width: auto;
    flex: 0 0 auto;
    gap: 8px;
  }

  .chat-header__user {
    display: none;
  }

  .chat-header__btn--logout {
    display: none;
  }

  .chat-app__messages {
    padding: 16px 14px;
    padding-bottom: 112px;
  }
}

@media (max-width: 420px) {
  .chat-header {
    padding-left: 10px;
    padding-right: 10px;
  }

  .chat-header__instance {
    max-width: 30vw;
    padding-left: 8px;
    padding-right: 8px;
  }

  .chat-header__back-btn {
    font-size: 0;
    width: 44px;
    padding: 0;
  }

  .chat-header__back-btn::before {
    content: "←";
    font-size: 18px;
  }

  .chat-header__btn--new {
    font-size: 0;
    width: 44px;
    padding: 0;
  }

  .chat-header__btn--new::before {
    content: "✨";
    font-size: 16px;
  }
}