:root {
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --bg: #ffffff;
  --bg-secondary: #f8fafc;
  --text: #1e293b;
  --text-muted: #94a3b8;
  --border: #e2e8f0;
  --shadow: 0 4px 24px rgba(0,0,0,0.12);
  --radius: 12px;
  --max-width: 380px;
  --max-height: 520px;
  --z-chat: 9999;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: transparent;
}

/* Toggle button */
.chat-toggle {
  position: fixed;
  bottom: 20px;
  right: 20px;
  width: 56px; height: 56px;
  border-radius: 50%;
  border: none;
  background: var(--primary);
  color: #fff;
  font-size: 24px;
  cursor: pointer;
  box-shadow: var(--shadow);
  z-index: var(--z-chat);
  transition: transform 0.2s, opacity 0.2s;
}
.chat-toggle:hover { transform: scale(1.1); }
.chat-toggle.open { opacity: 0; pointer-events: none; }

/* Chat panel */
.chat-panel {
  position: fixed;
  bottom: 20px;
  right: 20px;
  width: var(--max-width);
  height: var(--max-height);
  background: var(--bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  z-index: calc(var(--z-chat) + 1);
  overflow: hidden;
  transition: opacity 0.25s, transform 0.25s;
}
.chat-panel.hidden {
  opacity: 0;
  transform: translateY(20px) scale(0.95);
  pointer-events: none;
}

/* Header */
.chat-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 16px;
  background: var(--primary);
  color: #fff;
  font-weight: 600;
  font-size: 15px;
}
.chat-close {
  background: none; border: none; color: #fff;
  font-size: 18px; cursor: pointer; padding: 4px;
  opacity: 0.8; line-height: 1;
}
.chat-close:hover { opacity: 1; }

/* Messages */
.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.message {
  display: flex;
  max-width: 85%;
}
.message.assistant { align-self: flex-start; }
.message.user { align-self: flex-end; }

.msg-content {
  padding: 10px 14px;
  border-radius: 16px;
  font-size: 14px;
  line-height: 1.5;
  word-break: break-word;
  white-space: pre-wrap;
}
.message.assistant .msg-content {
  background: var(--bg-secondary);
  color: var(--text);
  border-bottom-left-radius: 4px;
}
.message.user .msg-content {
  background: var(--primary);
  color: #fff;
  border-bottom-right-radius: 4px;
}
.msg-content p { margin: 0 0 8px; }
.msg-content p:last-child { margin: 0; }
.msg-content ul, .msg-content ol { padding-left: 20px; }
.msg-content code {
  background: rgba(0,0,0,0.06);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 13px;
}

/* Input area */
.chat-input-area {
  display: flex;
  align-items: flex-end;
  gap: 8px;
  padding: 12px 16px;
  border-top: 1px solid var(--border);
  background: var(--bg);
}
.chat-input-area textarea {
  flex: 1;
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 10px 14px;
  font-size: 14px;
  resize: none;
  outline: none;
  max-height: 80px;
  font-family: inherit;
  line-height: 1.4;
}
.chat-input-area textarea:focus {
  border-color: var(--primary);
}
.chat-send {
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 20px;
  padding: 10px 18px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
}
.chat-send:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

/* Footer */
.chat-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 6px 16px;
  font-size: 11px;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
}
.typing-indicator { color: var(--primary); }
.typing-indicator.hidden { display: none; }

/* Scrollbar */
.chat-messages::-webkit-scrollbar { width: 4px; }
.chat-messages::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 4px;
}

/* Mobile */
@media (max-width: 480px) {
  .chat-panel {
    right: 10px;
    bottom: 10px;
    width: calc(100vw - 20px);
    height: calc(100vh - 80px);
  }
  .chat-toggle {
    bottom: 16px;
    right: 16px;
    width: 52px; height: 52px;
    font-size: 22px;
  }
}