* { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --bg: #0f1117; --panel: #1a1d27; --border: #2a2e3d;
  --text: #e6e8ef; --muted: #8b90a1; --accent: #4f7cff; --accent-h: #6b91ff;
}
body { font-family: -apple-system, "Segoe UI", Roboto, sans-serif; background: var(--bg); color: var(--text); height: 100vh; }
.hidden { display: none !important; }
.muted { color: var(--muted); }
.error { color: #ff6b6b; min-height: 1.2em; margin-top: 8px; }
button { background: var(--accent); color: #fff; border: 0; border-radius: 8px; padding: 10px 16px; cursor: pointer; font-size: 14px; }
button:hover { background: var(--accent-h); }
button.small { padding: 6px 10px; font-size: 12px; background: var(--panel); border: 1px solid var(--border); }
input, textarea { background: var(--panel); border: 1px solid var(--border); border-radius: 8px; color: var(--text); padding: 10px 12px; font-size: 14px; width: 100%; }

/* login */
#login-view { display: flex; align-items: center; justify-content: center; height: 100vh; }
.login-card { background: var(--panel); border: 1px solid var(--border); border-radius: 14px; padding: 36px; width: 340px; text-align: center; }
.login-card h1 { font-size: 22px; margin-bottom: 6px; }
.login-card p { margin-bottom: 20px; font-size: 13px; }
.login-card input { margin-bottom: 12px; }
.login-card button { width: 100%; }

/* chat layout */
#chat-view { display: flex; height: 100vh; }
#sidebar { width: 250px; background: var(--panel); border-right: 1px solid var(--border); display: flex; flex-direction: column; }
.sidebar-top { padding: 12px; }
.sidebar-top button { width: 100%; }
#conversation-list { flex: 1; overflow-y: auto; list-style: none; padding: 0 8px; }
#conversation-list li { padding: 9px 10px; border-radius: 8px; cursor: pointer; font-size: 13px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; display: flex; justify-content: space-between; gap: 6px; }
#conversation-list li:hover, #conversation-list li.active { background: var(--border); }
#conversation-list .del { color: var(--muted); cursor: pointer; }
#conversation-list .del:hover { color: #ff6b6b; }
.sidebar-bottom { padding: 12px; border-top: 1px solid var(--border); display: flex; align-items: center; gap: 8px; font-size: 13px; }
#whoami { flex: 1; overflow: hidden; text-overflow: ellipsis; }

#chat-main { flex: 1; display: flex; flex-direction: column; }
#messages { flex: 1; overflow-y: auto; padding: 24px; display: flex; flex-direction: column; gap: 14px; }
.msg { max-width: 720px; padding: 12px 16px; border-radius: 12px; line-height: 1.5; font-size: 14px; white-space: pre-wrap; word-wrap: break-word; }
.msg.user { align-self: flex-end; background: var(--accent); }
.msg.assistant { align-self: flex-start; background: var(--panel); border: 1px solid var(--border); }
#chat-form { display: flex; gap: 10px; padding: 16px 24px; border-top: 1px solid var(--border); }
#chat-input { resize: none; max-height: 160px; }
#mode-select { background: var(--panel); border: 1px solid var(--border); border-radius: 8px; color: var(--text); padding: 0 10px; font-size: 13px; cursor: pointer; }

/* admin */
#admin-view { display: flex; align-items: flex-start; justify-content: center; padding: 40px; height: 100vh; overflow-y: auto; }
.admin-card { background: var(--panel); border: 1px solid var(--border); border-radius: 14px; padding: 28px; width: 560px; }
.admin-card h2 { margin-bottom: 16px; }
#create-user-form { display: flex; flex-wrap: wrap; gap: 10px; margin-bottom: 20px; align-items: center; }
#create-user-form input[type="text"], #create-user-form input[type="password"] { width: 200px; }
#create-user-form label { font-size: 13px; display: flex; gap: 6px; align-items: center; }
#create-user-form label input { width: auto; }
#admin-msg { width: 100%; font-size: 13px; min-height: 1.2em; }
#user-table { width: 100%; border-collapse: collapse; font-size: 13px; margin-bottom: 16px; }
#user-table th, #user-table td { text-align: left; padding: 8px; border-bottom: 1px solid var(--border); }
#user-table .del-user { color: #ff6b6b; cursor: pointer; }

@media (max-width: 700px) {
  #sidebar { width: 200px; }
  .msg { max-width: 95%; }
}