:root{
  --bg:#14161B; --surface:#1C1F26; --surface-2:#242832; --surface-3:#2C303B;
  --border:#2E323C; --text:#ECEAE3; --text-dim:#9297A3; --text-faint:#5C616D;
  --accent:#6EE7D8; --accent-2:#9C8CFF; --success:#4ADE80; --danger:#FF6B6B;
  --font-display:'Space Grotesk', system-ui, sans-serif;
  --font-body:'Inter', system-ui, sans-serif;
}
*{box-sizing:border-box; margin:0; padding:0;}
body{ font-family:var(--font-body); background:var(--bg); color:var(--text); -webkit-font-smoothing:antialiased; }
::-webkit-scrollbar{width:8px; height:8px;}
::-webkit-scrollbar-thumb{background:var(--surface-3); border-radius:8px;}
::-webkit-scrollbar-track{background:transparent;}

/* ---------- Auth page ---------- */
.auth-body{ height:100vh; display:flex; align-items:center; justify-content:center; }
.auth-card{ width:min(380px, 90vw); background:var(--surface); border:1px solid var(--border); border-radius:20px; padding:36px 30px; text-align:center; }
.onboard-mark{ width:52px; height:52px; border-radius:14px; background:linear-gradient(135deg, var(--accent), var(--accent-2)); margin:0 auto 18px; display:flex; align-items:center; justify-content:center; font-family:var(--font-display); font-weight:700; font-size:22px; color:#101216; }
.auth-card h1{ font-family:var(--font-display); font-size:22px; margin-bottom:6px; }
.auth-card p{ color:var(--text-dim); font-size:14px; margin-bottom:22px; line-height:1.5; }
.auth-card form{ display:flex; flex-direction:column; gap:12px; }
.auth-card input{ width:100%; padding:13px 14px; border-radius:12px; border:1px solid var(--border); background:var(--surface-2); color:var(--text); font-size:15px; font-family:var(--font-body); outline:none; }
.auth-card input:focus{ border-color:var(--accent); }
.btn-primary{ width:100%; padding:13px; border-radius:12px; border:none; cursor:pointer; background:linear-gradient(135deg, var(--accent), var(--accent-2)); color:#0F1013; font-weight:700; font-size:15px; font-family:var(--font-body); transition:transform .15s ease, opacity .15s ease; }
.btn-primary:hover{ transform:translateY(-1px); opacity:.92; }
.btn-primary:disabled{ opacity:.55; cursor:not-allowed; transform:none; }
.switch-line{ margin-top:18px; font-size:13.5px; color:var(--text-dim); }
.switch-line a{ color:var(--accent); text-decoration:none; font-weight:600; margin-left:4px; }
.switch-line a:hover{ text-decoration:underline; }
.error-box{ background:rgba(255,107,107,.12); border:1px solid rgba(255,107,107,.35); color:#FF9B9B; font-size:13.5px; padding:10px 12px; border-radius:10px; margin-bottom:14px; text-align:left; }

/* ---------- App layout ---------- */
html, body.app-body{ height:100%; overflow:hidden; }
#app{ display:flex; height:100vh; }
.sidebar{ width:340px; min-width:340px; background:var(--surface); border-right:1px solid var(--border); display:flex; flex-direction:column; }
.sidebar-header{ padding:20px 18px 14px; display:flex; align-items:center; justify-content:space-between; }
.brand{ display:flex; align-items:center; gap:10px; }
.brand-mark{ width:34px; height:34px; border-radius:10px; background:linear-gradient(135deg, var(--accent), var(--accent-2)); display:flex; align-items:center; justify-content:center; font-family:var(--font-display); font-weight:700; color:#101216; font-size:15px; }
.brand-name{ font-family:var(--font-display); font-weight:700; font-size:17px; }
.header-actions{ display:flex; gap:6px; }
.icon-btn{ width:34px; height:34px; border-radius:10px; border:1px solid var(--border); background:var(--surface-2); color:var(--text-dim); cursor:pointer; display:flex; align-items:center; justify-content:center; font-size:16px; transition:background .15s ease, color .15s ease; }
.icon-btn:hover{ background:var(--surface-3); color:var(--text); }
.me-row{ padding:0 18px 12px; display:flex; align-items:center; gap:10px; }
.me-row .avatar{ width:32px; height:32px; font-size:12px; }
.me-name{ font-size:13.5px; font-weight:600; color:var(--text-dim); }
.search-wrap{ padding:0 18px 14px; }
.search-wrap input{ width:100%; padding:10px 14px; border-radius:10px; border:1px solid var(--border); background:var(--surface-2); color:var(--text); font-size:14px; font-family:var(--font-body); outline:none; }
.search-wrap input:focus{ border-color:var(--accent); }
.conv-list{ flex:1; overflow-y:auto; padding:4px 10px 10px; }
.conv-item{ display:flex; align-items:center; gap:12px; padding:11px 8px; border-radius:12px; cursor:pointer; transition:background .15s ease; position:relative; }
.conv-item:hover{ background:var(--surface-2); }
.conv-item.active{ background:var(--surface-2); }
.conv-item.active::before{ content:''; position:absolute; left:-10px; top:50%; transform:translateY(-50%); width:3px; height:60%; border-radius:4px; background:linear-gradient(var(--accent), var(--accent-2)); }
.avatar{ width:44px; height:44px; border-radius:50%; display:flex; align-items:center; justify-content:center; font-family:var(--font-display); font-weight:600; font-size:15px; color:#101216; flex-shrink:0; position:relative; }
.conv-meta{ flex:1; min-width:0; }
.conv-top{ display:flex; justify-content:space-between; align-items:baseline; gap:6px; }
.conv-name{ font-weight:600; font-size:14.5px; white-space:nowrap; overflow:hidden; text-overflow:ellipsis; }
.conv-time{ font-size:11.5px; color:var(--text-faint); flex-shrink:0; }
.conv-preview{ display:flex; justify-content:space-between; align-items:center; gap:6px; margin-top:2px; }
.conv-last{ font-size:13px; color:var(--text-dim); white-space:nowrap; overflow:hidden; text-overflow:ellipsis; }
.unread-badge{ background:var(--accent); color:#0F1013; font-size:11px; font-weight:700; min-width:19px; height:19px; border-radius:10px; display:flex; align-items:center; justify-content:center; padding:0 5px; flex-shrink:0; }
.empty-list{ text-align:center; color:var(--text-faint); font-size:13px; padding:30px 20px; }

.chat-panel{ flex:1; display:flex; flex-direction:column; min-width:0; }
.chat-empty{ flex:1; display:flex; flex-direction:column; align-items:center; justify-content:center; color:var(--text-faint); gap:10px; }
.chat-empty .glyph{ width:64px; height:64px; border-radius:20px; background:var(--surface); border:1px solid var(--border); display:flex; align-items:center; justify-content:center; font-size:26px; }
.chat-header{ padding:14px 22px; border-bottom:1px solid var(--border); display:flex; align-items:center; justify-content:space-between; gap:10px; background:var(--surface); }
.chat-header-left{ display:flex; align-items:center; gap:12px; min-width:0; }
.back-btn{ display:none; }
.chat-header-name{ font-weight:600; font-size:15px; }
.chat-header-status{ font-size:12.5px; color:var(--text-dim); }
.typing-hint{ color:var(--accent); }
.messages{ flex:1; overflow-y:auto; padding:22px; display:flex; flex-direction:column; gap:4px; background:var(--bg); }
.day-sep{ text-align:center; color:var(--text-faint); font-size:11.5px; margin:16px 0 10px; text-transform:uppercase; letter-spacing:.04em; }
.msg-row{ display:flex; margin-bottom:2px; max-width:100%; }
.msg-row.me{ justify-content:flex-end; }
.bubble{ max-width:min(480px, 72%); padding:10px 14px; border-radius:16px; font-size:14.5px; line-height:1.45; word-wrap:break-word; white-space:pre-wrap; position:relative; }
.msg-row.them .bubble{ background:var(--surface-2); color:var(--text); border-bottom-left-radius:5px; }
.msg-row.me .bubble{ background:linear-gradient(135deg, var(--accent), var(--accent-2)); color:#0F1013; border-bottom-right-radius:5px; font-weight:500; }
.msg-time{ font-size:10.5px; margin-top:4px; opacity:.6; display:block; }
.msg-row.them .msg-time{ color:var(--text-faint); }
.msg-row.me .msg-time{ color:#101216; text-align:right; }
.typing-row{ display:flex; margin-bottom:2px; }
.typing-bubble{ background:var(--surface-2); padding:12px 16px; border-radius:16px; border-bottom-left-radius:5px; display:flex; gap:4px; align-items:center; }
.typing-bubble span{ width:6px; height:6px; border-radius:50%; background:var(--text-faint); animation:bounce 1.2s infinite ease-in-out; }
.typing-bubble span:nth-child(2){ animation-delay:.15s; }
.typing-bubble span:nth-child(3){ animation-delay:.3s; }
@keyframes bounce{ 0%,60%,100%{ transform:translateY(0); opacity:.5;} 30%{ transform:translateY(-4px); opacity:1;} }
.composer{ border-top:1px solid var(--border); padding:14px 18px; background:var(--surface); display:flex; align-items:flex-end; gap:10px; }
.composer textarea{ flex:1; resize:none; border:1px solid var(--border); background:var(--surface-2); color:var(--text); border-radius:14px; padding:11px 14px; font-family:var(--font-body); font-size:14.5px; outline:none; max-height:120px; line-height:1.4; }
.composer textarea:focus{ border-color:var(--accent); }
.send-btn{ width:42px; height:42px; border-radius:12px; border:none; cursor:pointer; flex-shrink:0; background:linear-gradient(135deg, var(--accent), var(--accent-2)); color:#0F1013; display:flex; align-items:center; justify-content:center; font-size:17px; transition:transform .15s ease, opacity .15s ease; }
.send-btn:hover{ transform:scale(1.05); }
.send-btn:disabled{ opacity:.35; cursor:not-allowed; transform:none; }

.modal-overlay{ position:fixed; inset:0; background:rgba(0,0,0,.5); display:none; align-items:center; justify-content:center; z-index:90; }
.modal-overlay.show{ display:flex; }
.modal-card{ width:min(360px, 90vw); max-height:70vh; background:var(--surface); border:1px solid var(--border); border-radius:18px; padding:22px; display:flex; flex-direction:column; }
.modal-card h3{ font-family:var(--font-display); font-size:17px; margin-bottom:14px; }
.modal-card input{ width:100%; padding:11px 13px; border-radius:10px; border:1px solid var(--border); background:var(--surface-2); color:var(--text); font-size:14px; outline:none; margin-bottom:12px; }
.modal-card input:focus{ border-color:var(--accent); }
.user-pick-list{ overflow-y:auto; display:flex; flex-direction:column; gap:4px; margin-bottom:10px; }
.user-pick-item{ display:flex; align-items:center; gap:10px; padding:9px 8px; border-radius:10px; cursor:pointer; }
.user-pick-item:hover{ background:var(--surface-2); }
.btn-secondary{ flex:1; padding:10px; border-radius:10px; border:1px solid var(--border); background:transparent; color:var(--text-dim); cursor:pointer; font-family:var(--font-body); font-size:14px; font-weight:600; }
.btn-secondary:hover{ background:var(--surface-2); }

@media (max-width: 780px){
  .sidebar{ width:100%; min-width:0; }
  .chat-panel{ position:fixed; inset:0; transform:translateX(100%); transition:transform .2s ease; z-index:20; background:var(--bg);}
  #app.chat-open .chat-panel{ transform:translateX(0); }
  #app.chat-open .sidebar{ display:none; }
  .back-btn{ display:flex; }
  .bubble{ max-width:82%; }
}