/* ===== 小乐AI 样式 ===== */
* { margin: 0; padding: 0; box-sizing: border-box; }

html, body { height: 100%; }

body {
  font-family: "Microsoft YaHei", "PingFang SC", sans-serif;
  background: linear-gradient(135deg, #0f172a 0%, #1e1b4b 55%, #4c1d95 100%);
  color: #e2e8f0;
  display: flex;
  flex-direction: column;
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 20px;
  background: rgba(10, 15, 40, 0.9);
  border-bottom: 1px solid rgba(139, 92, 246, 0.4);
  position: sticky;
  top: 0;
  z-index: 20;
}
.nav-brand {
  font-size: 20px;
  font-weight: 800;
  color: #fff;
  text-decoration: none;
  background: linear-gradient(90deg, #fbbf24, #f472b6, #a78bfa);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.mode-switch { display: flex; gap: 6px; }
.mode-btn {
  padding: 7px 14px;
  border-radius: 999px;
  border: 1px solid rgba(167, 139, 250, 0.4);
  background: rgba(30, 27, 75, 0.6);
  color: #c4b5fd;
  cursor: pointer;
  font-size: 13px;
  transition: all .15s;
}
.mode-btn.active {
  background: linear-gradient(135deg, #8b5cf6, #ec4899);
  color: #fff;
  border-color: transparent;
}

.study-panel {
  background: rgba(17, 24, 54, 0.9);
  border-bottom: 1px solid rgba(139, 92, 246, 0.3);
  padding: 10px 20px;
}
.study-row { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.study-row label { font-size: 13px; color: #a5b4fc; }
.study-row select {
  background: rgba(30, 27, 75, 0.8);
  border: 1px solid rgba(167, 139, 250, 0.5);
  color: #e2e8f0;
  border-radius: 8px;
  padding: 6px 10px;
  font-size: 13px;
}
.study-tip { font-size: 12px; color: #94a3b8; margin-top: 6px; }

.chat-main { flex: 1; display: flex; flex-direction: column; min-height: 0; }
.chat-box {
  flex: 1;
  overflow-y: auto;
  padding: 18px 20px;
  width: min(860px, 100%);
  margin: 0 auto;
}
.msg { display: flex; gap: 10px; margin-bottom: 14px; animation: pop .25s ease; }
.msg.me { flex-direction: row-reverse; }
@keyframes pop { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }
.avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
  background: rgba(99, 102, 241, 0.25);
  flex-shrink: 0;
  border: 1px solid rgba(167, 139, 250, 0.5);
}
.msg.me .avatar { background: rgba(245, 158, 11, 0.25); border-color: rgba(251, 191, 36, 0.5); }
.bubble {
  max-width: 78%;
  padding: 11px 16px;
  border-radius: 14px;
  background: rgba(30, 27, 75, 0.85);
  border: 1px solid rgba(139, 92, 246, 0.3);
  line-height: 1.7;
  font-size: 15px;
  white-space: pre-wrap;
  word-break: break-word;
}
.msg.me .bubble {
  background: linear-gradient(135deg, rgba(139, 92, 246, 0.7), rgba(236, 72, 153, 0.6));
  border-color: transparent;
}

/* 打字动画 */
.bubble.typing { display: flex; gap: 4px; padding: 14px 16px; }
.bubble.typing span {
  width: 7px; height: 7px;
  border-radius: 50%;
  background: #a78bfa;
  animation: blink 1.2s infinite;
}
.bubble.typing span:nth-child(2) { animation-delay: .2s; }
.bubble.typing span:nth-child(3) { animation-delay: .4s; }
@keyframes blink { 0%, 80%, 100% { opacity: .25; } 40% { opacity: 1; } }

/* 底部输入 */
.input-bar {
  background: rgba(10, 15, 40, 0.95);
  border-top: 1px solid rgba(139, 92, 246, 0.35);
  padding: 10px 16px;
  padding-bottom: calc(10px + env(safe-area-inset-bottom));
}
.quick {
  display: flex;
  gap: 8px;
  max-width: 860px;
  margin: 0 auto 10px;
  flex-wrap: wrap;
}
.quick button {
  background: rgba(139, 92, 246, 0.15);
  border: 1px solid rgba(167, 139, 250, 0.4);
  color: #c4b5fd;
  border-radius: 999px;
  padding: 5px 13px;
  font-size: 12px;
  cursor: pointer;
}
.quick button:hover { background: rgba(139, 92, 246, 0.35); color: #fff; }
.input-row {
  display: flex;
  gap: 10px;
  max-width: 860px;
  margin: 0 auto;
}
.input-row input {
  flex: 1;
  padding: 12px 16px;
  border-radius: 999px;
  border: 1px solid rgba(167, 139, 250, 0.5);
  background: rgba(30, 27, 75, 0.85);
  color: #e2e8f0;
  font-size: 15px;
  outline: none;
}
.input-row input:focus { border-color: #a78bfa; }
.send {
  padding: 0 24px;
  border: none;
  border-radius: 999px;
  background: linear-gradient(135deg, #8b5cf6, #ec4899);
  color: #fff;
  font-size: 15px;
  font-weight: 700;
  cursor: pointer;
}
.send:hover { filter: brightness(1.15); }

@media (max-width: 640px) {
  .nav { padding: 10px 12px; }
  .nav-brand { font-size: 17px; }
  .mode-btn { padding: 6px 10px; font-size: 12px; }
  .bubble { max-width: 84%; }
}