:root { color-scheme: light dark; }
body { margin: 0; font-family: system-ui, sans-serif; background: var(--tg-theme-bg-color, #f6f7f9); color: var(--tg-theme-text-color, #111); }
.center { display: flex; flex-direction: column; align-items: center; justify-content: center; min-height: 70vh; gap: 12px; }
.btn { padding: 12px 20px; border: 0; border-radius: 10px; background: var(--tg-theme-button-color, #0d6efd); color: var(--tg-theme-button-text-color, #fff); cursor: pointer; }
.btn.success { background: #28a745; }
.chat-wrap { display: flex; flex-direction: column; height: 100vh; }
.chat-box { flex: 1; padding: 16px; overflow-y: auto; }
.chat-input { display: flex; gap: 8px; padding: 10px; border-top: 1px solid rgba(0,0,0,.08); }
.chat-input input { flex: 1; padding: 10px 12px; border-radius: 10px; border: 1px solid rgba(0,0,0,.15); background: transparent; color: inherit; }
.message { max-width: 80%; padding: 10px 14px; border-radius: 14px; margin-bottom: 8px; line-height: 1.5; }
.message.bot { background: var(--tg-theme-secondary-bg-color, #e9ecef); align-self: flex-start; }
.message.user { background: var(--tg-theme-button-color, #0d6efd); color: var(--tg-theme-button-text-color, #fff); align-self: flex-end; }