.lecture-chat-toggle {
  position: fixed;
  right: 104px;
  bottom: 12px;
  z-index: 180;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border: 1px solid rgba(0, 229, 184, .34);
  background: linear-gradient(135deg, rgba(0, 229, 184, .18), rgba(168, 85, 247, .12)), rgba(7, 11, 20, .9);
  color: #f0f4ff;
  border-radius: 8px;
  padding: 9px 12px;
  font: 700 .82rem/1 Inter, system-ui, sans-serif;
  cursor: pointer;
  box-shadow: 0 12px 36px rgba(0, 0, 0, .38), inset 0 1px 0 rgba(255,255,255,.1);
  backdrop-filter: blur(14px);
  transition: transform .18s ease, border-color .18s ease, color .18s ease;
}

.lecture-chat-toggle-mark {
  display: grid;
  place-items: center;
  width: 20px;
  height: 20px;
  border-radius: 7px;
  background: #00e5b8;
  color: #051016;
  font-weight: 900;
}

.lecture-chat-toggle:hover {
  border-color: rgba(0, 229, 184, .58);
  color: #00e5b8;
  transform: translateY(-1px);
}

.lecture-chat {
  position: fixed;
  right: 24px;
  bottom: 64px;
  width: min(440px, calc(100vw - 32px));
  max-height: min(620px, calc(100vh - 124px));
  z-index: 181;
  display: none;
  grid-template-rows: auto 1fr auto;
  overflow: hidden;
  border: 1px solid rgba(94, 234, 212, .18);
  border-radius: 8px;
  background:
    radial-gradient(circle at 18% 0%, rgba(0, 229, 184, .13), transparent 32%),
    radial-gradient(circle at 100% 12%, rgba(168, 85, 247, .12), transparent 34%),
    rgba(8, 12, 22, .97);
  box-shadow: 0 24px 70px rgba(0, 0, 0, .52), 0 0 0 1px rgba(255, 255, 255, .03) inset;
  backdrop-filter: blur(18px);
}

.lecture-chat.open {
  display: grid;
}

.lecture-chat-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 15px 16px 13px;
  border-bottom: 1px solid rgba(255, 255, 255, .08);
  background: linear-gradient(135deg, rgba(94, 234, 212, .1), rgba(168, 85, 247, .08));
}

.lecture-chat-header::before {
  content: '';
  width: 8px;
  align-self: stretch;
  border-radius: 8px;
  background: linear-gradient(180deg, #00e5b8, #a855f7);
}

.lecture-chat-title {
  color: #f0f4ff;
  font: 800 .92rem/1.2 Inter, system-ui, sans-serif;
}

.lecture-chat-context {
  margin-top: 5px;
  color: #a5afc9;
  font: 500 .72rem/1.35 Inter, system-ui, sans-serif;
  max-width: 320px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.lecture-chat-context::before {
  content: 'Context on · ';
  color: #5eead4;
  font-weight: 800;
}

.lecture-chat-close {
  width: 32px;
  height: 32px;
  border: 1px solid rgba(255, 255, 255, .12);
  border-radius: 8px;
  background: rgba(255, 255, 255, .04);
  color: #8892b0;
  cursor: pointer;
}

.lecture-chat-close:hover {
  color: #f0f4ff;
}

.lecture-chat-messages {
  min-height: 220px;
  overflow-y: auto;
  padding: 16px;
}

.lecture-chat-suggestions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: -2px 0 12px;
}

.lecture-chat-suggestion {
  border: 1px solid rgba(94, 234, 212, .2);
  border-radius: 8px;
  background: rgba(94, 234, 212, .07);
  color: #dbe4ff;
  padding: 8px 10px;
  font: 800 .75rem/1 Inter, system-ui, sans-serif;
  cursor: pointer;
}

.lecture-chat-suggestion:hover {
  border-color: rgba(94, 234, 212, .48);
  color: #5eead4;
  background: rgba(94, 234, 212, .12);
}

.lecture-chat-message {
  margin: 0 0 12px;
  padding: 12px 13px;
  border-radius: 8px;
  color: #dbe4ff;
  font: 500 .88rem/1.48 Inter, system-ui, sans-serif;
  overflow-wrap: anywhere;
  white-space: pre-wrap;
}

.lecture-chat-message::before {
  display: block;
  margin-bottom: 6px;
  color: #5eead4;
  font: 900 .66rem/1 Inter, system-ui, sans-serif;
  letter-spacing: .08em;
  text-transform: uppercase;
}

.lecture-chat-message.assistant::before {
  content: 'Lecture AI';
}

.lecture-chat-message.user::before {
  content: 'You';
  color: #a78bfa;
}

.lecture-chat-message h3 {
  margin: 0 0 7px;
  color: #f0f4ff;
  font: 800 .92rem/1.25 Inter, system-ui, sans-serif;
}

.lecture-chat-message p {
  margin: 0 0 8px;
}

.lecture-chat-message p:last-child {
  margin-bottom: 0;
}

.lecture-chat-message ul {
  margin: 7px 0 0;
  padding-left: 18px;
}

.lecture-chat-message li {
  margin: 5px 0;
}

.lecture-chat-message strong {
  color: #f0f4ff;
  font-weight: 800;
}

.lecture-chat-message code {
  border: 1px solid rgba(255, 255, 255, .1);
  border-radius: 6px;
  padding: 1px 5px;
  background: rgba(255, 255, 255, .07);
  color: #7dd3fc;
  font: 700 .82em/1.4 ui-monospace, SFMono-Regular, Menlo, monospace;
}

.lecture-chat-message a {
  color: #5eead4;
  text-decoration: none;
  border-bottom: 1px solid rgba(94, 234, 212, .35);
}

.lecture-chat-message.intro {
  background: linear-gradient(135deg, rgba(0, 229, 184, .1), rgba(168, 85, 247, .08));
  border-color: rgba(0, 229, 184, .2);
}

.lecture-chat-message.user {
  margin-left: 54px;
  background: linear-gradient(135deg, rgba(0, 229, 184, .16), rgba(0, 229, 184, .07));
  border: 1px solid rgba(0, 229, 184, .28);
}

.lecture-chat-message.assistant {
  margin-right: 36px;
  background: rgba(255, 255, 255, .055);
  border: 1px solid rgba(255, 255, 255, .1);
}

.lecture-chat-message.error {
  background: rgba(239, 68, 68, .1);
  border: 1px solid rgba(239, 68, 68, .24);
  color: #fecaca;
}

.lecture-chat-message.thinking {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-width: 74px;
  padding: 14px 15px;
}

.lecture-chat-message.thinking::before {
  content: 'Thinking';
  margin: 0 4px 0 0;
}

.lecture-chat-thinking-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: #5eead4;
  animation: lecture-chat-thinking 1s infinite ease-in-out;
}

.lecture-chat-thinking-dot:nth-child(2) {
  animation-delay: .14s;
}

.lecture-chat-thinking-dot:nth-child(3) {
  animation-delay: .28s;
}

@keyframes lecture-chat-thinking {
  0%, 80%, 100% { opacity: .35; transform: translateY(0); }
  40% { opacity: 1; transform: translateY(-4px); }
}

.lecture-chat-form {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 10px;
  padding: 12px;
  border-top: 1px solid rgba(255, 255, 255, .08);
  background: linear-gradient(180deg, rgba(255, 255, 255, .015), rgba(94, 234, 212, .035));
}

.lecture-chat-input {
  min-width: 0;
  resize: none;
  height: 44px;
  max-height: 130px;
  border: 1px solid rgba(255, 255, 255, .12);
  border-radius: 8px;
  padding: 12px;
  background: rgba(4, 9, 18, .72);
  color: #f0f4ff;
  font: 500 .88rem/1.35 Inter, system-ui, sans-serif;
}

.lecture-chat-input:focus {
  outline: none;
  border-color: rgba(0, 229, 184, .54);
}

.lecture-chat-send {
  border: 0;
  border-radius: 8px;
  padding: 0 16px;
  background: linear-gradient(135deg, #00e5b8, #7dd3fc);
  color: #061016;
  font: 800 .82rem/1 Inter, system-ui, sans-serif;
  cursor: pointer;
}

.lecture-chat-send:disabled,
.lecture-chat-input:disabled {
  cursor: not-allowed;
  opacity: .58;
}

@media (max-width: 820px) {
  .lecture-chat-toggle {
    right: 84px;
    left: auto;
    bottom: 10px;
    padding: 8px 10px;
    font-size: .78rem;
  }

  .lecture-chat {
    right: 12px;
    left: 12px;
    bottom: 58px;
    width: auto;
    max-height: calc(100vh - 112px);
  }

  .lecture-chat-context {
    max-width: calc(100vw - 112px);
  }

  .lecture-chat-message.user,
  .lecture-chat-message.assistant {
    margin-left: 0;
    margin-right: 0;
  }
}