:root{
  --bg:#0b0f14; --bg2:#0f141b; --panel:#141b24; --panel2:#1b232e; --line:#232c38;
  --fg:#e9eef5; --muted:#8a97a8; --accent:#3d7dff; --accent2:#6a5cff;
  --mine:#2b63d9; --bubble:#1c2531; --ok:#2fbf71; --danger:#e0533d;
  --radius:16px; font-family:system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
}
*{box-sizing:border-box}
html,body{height:100%}
body{margin:0;background:var(--bg);color:var(--fg);overflow:hidden;
  -webkit-tap-highlight-color:transparent}
button{font-family:inherit;cursor:pointer;border:0;background:none;color:inherit}
input,textarea{font-family:inherit}
.hidden{display:none!important}
.spin{width:22px;height:22px;border:2.5px solid var(--line);border-top-color:var(--accent);
  border-radius:50%;animation:sp .7s linear infinite}
@keyframes sp{to{transform:rotate(360deg)}}

/* ---------- Auth ---------- */
#auth{position:fixed;inset:0;display:grid;place-items:center;padding:20px;
  background:radial-gradient(1200px 600px at 50% -10%,#16233b 0%,var(--bg) 60%)}
.auth-card{width:100%;max-width:380px;background:var(--panel);border:1px solid var(--line);
  border-radius:20px;padding:26px 22px}
.brand{display:flex;align-items:center;gap:11px;margin-bottom:6px}
.brand .mark{width:40px;height:40px;border-radius:12px;display:grid;place-items:center;
  background:linear-gradient(135deg,var(--accent),var(--accent2));font-weight:800;color:#fff}
.brand h1{font-size:21px;margin:0;letter-spacing:.3px}
.sub{color:var(--muted);font-size:13px;margin:2px 0 20px}
.field{margin-bottom:12px}
.field label{display:block;font-size:12px;color:var(--muted);margin:0 0 6px 3px}
.field input{width:100%;background:var(--bg2);border:1px solid var(--line);color:var(--fg);
  border-radius:11px;padding:12px 13px;font-size:15px;outline:none}
.field input:focus{border-color:var(--accent)}
.btn{display:block;width:100%;background:var(--accent);color:#fff;font-weight:650;
  border-radius:11px;padding:13px;font-size:15px;margin-top:6px;transition:filter .15s}
.btn:active{filter:brightness(.9)}
.btn.block{opacity:.55;pointer-events:none}
.switch{text-align:center;color:var(--muted);font-size:13.5px;margin-top:16px}
.switch a{color:var(--accent);text-decoration:none;font-weight:600}
.err{color:var(--danger);font-size:13px;margin-top:10px;min-height:16px;text-align:center}

/* ---------- App shell ---------- */
#app{position:fixed;inset:0;display:grid;grid-template-columns:340px 1fr}
@media(max-width:820px){#app{grid-template-columns:1fr}}
.col{min-width:0;display:flex;flex-direction:column;height:100%}
#sidebar{border-right:1px solid var(--line);background:var(--bg2)}
.side-head{display:flex;align-items:center;gap:10px;padding:14px 14px;border-bottom:1px solid var(--line)}
.side-head .mark{width:30px;height:30px;border-radius:9px;display:grid;place-items:center;
  background:linear-gradient(135deg,var(--accent),var(--accent2));font-weight:800;color:#fff;font-size:13px}
.side-head b{font-size:16px;flex:1}
.iconbtn{width:36px;height:36px;border-radius:10px;display:grid;place-items:center;color:var(--muted)}
.iconbtn:hover{background:var(--panel2);color:var(--fg)}
.iconbtn svg{width:19px;height:19px}
.search{padding:10px 12px}
.search input{width:100%;background:var(--panel);border:1px solid var(--line);color:var(--fg);
  border-radius:10px;padding:10px 12px;font-size:14px;outline:none}
.chatlist{flex:1;overflow-y:auto}
.chat-item{display:flex;align-items:center;gap:12px;padding:11px 14px;cursor:pointer;border-bottom:1px solid #0d1219}
.chat-item:hover{background:var(--panel)}
.chat-item.active{background:var(--panel2)}
.avatar{width:46px;height:46px;border-radius:50%;flex-shrink:0;display:grid;place-items:center;
  color:#fff;font-weight:650;font-size:17px;position:relative}
.avatar .pres{position:absolute;right:0;bottom:0;width:12px;height:12px;border-radius:50%;
  border:2.5px solid var(--bg2);background:#55606e}
.avatar .pres.on{background:var(--ok)}
.ci-main{flex:1;min-width:0}
.ci-top{display:flex;justify-content:space-between;align-items:center;gap:8px}
.ci-name{font-weight:600;font-size:15px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.ci-time{font-size:11.5px;color:var(--muted);flex-shrink:0}
.ci-last{color:var(--muted);font-size:13px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;margin-top:2px}
.badge{min-width:20px;height:20px;padding:0 6px;border-radius:999px;background:var(--accent);
  color:#fff;font-size:11.5px;font-weight:700;display:grid;place-items:center}
.me-bar{display:flex;align-items:center;gap:11px;padding:11px 14px;border-top:1px solid var(--line)}
.me-bar .ci-name{font-size:14px}
.me-bar small{color:var(--muted);font-size:12px}

/* ---------- Conversation ---------- */
#convo{background:
  linear-gradient(0deg,rgba(0,0,0,.25),rgba(0,0,0,.25)),
  radial-gradient(900px 500px at 80% -10%,#15213a 0,var(--bg) 55%)}
#convo.empty{display:grid;place-items:center}
.empty-hint{color:var(--muted);text-align:center;font-size:14px;line-height:1.6}
.conv-head{display:flex;align-items:center;gap:12px;padding:11px 14px;border-bottom:1px solid var(--line);
  background:var(--bg2)}
.conv-head .back{display:none}
@media(max-width:820px){.conv-head .back{display:grid}}
.conv-head .avatar{width:40px;height:40px;font-size:15px}
.conv-title{flex:1;min-width:0}
.conv-title b{font-size:15.5px;display:block;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.conv-title small{color:var(--muted);font-size:12.5px}
.messages{flex:1;overflow-y:auto;padding:14px 12px;display:flex;flex-direction:column;gap:3px}
.daysep{align-self:center;background:var(--panel2);color:var(--muted);font-size:11.5px;
  padding:4px 11px;border-radius:999px;margin:10px 0}
.msg{max-width:min(76%,560px);padding:8px 11px 6px;border-radius:14px;background:var(--bubble);
  align-self:flex-start;position:relative;word-wrap:break-word;overflow-wrap:anywhere}
.msg.mine{align-self:flex-end;background:var(--mine)}
.msg.tail{margin-bottom:8px}
.msg .who{font-size:12px;font-weight:700;color:#8fd0ff;margin-bottom:2px}
.msg.mine .who{display:none}
.msg .txt{font-size:14.5px;line-height:1.4;white-space:pre-wrap}
.msg .txt.big{font-size:34px;line-height:1.15}
.msg img{max-width:100%;border-radius:10px;display:block;margin:2px 0}
.msg .time{font-size:10.5px;color:var(--muted);margin-left:8px;float:right;margin-top:4px}
.msg.mine .time{color:#cfe0ff}
.typing{align-self:flex-start;color:var(--muted);font-size:13px;padding:4px 8px}
.composer{display:flex;align-items:flex-end;gap:8px;padding:10px 12px;border-top:1px solid var(--line);
  background:var(--bg2);position:relative}
.composer textarea{flex:1;resize:none;max-height:120px;background:var(--panel);border:1px solid var(--line);
  color:var(--fg);border-radius:14px;padding:11px 13px;font-size:15px;outline:none;line-height:1.35}
.composer textarea:focus{border-color:var(--accent)}
.composer .iconbtn{width:42px;height:42px}
.composer .send{background:var(--accent);color:#fff;border-radius:50%}
.composer .send:disabled{opacity:.45}

/* emoji picker */
.emoji-pop{position:absolute;bottom:64px;left:12px;right:12px;max-width:360px;background:var(--panel);
  border:1px solid var(--line);border-radius:14px;padding:8px;max-height:240px;overflow-y:auto;
  display:grid;grid-template-columns:repeat(8,1fr);gap:2px;box-shadow:0 10px 30px rgba(0,0,0,.4)}
.emoji-pop button{font-size:22px;padding:5px;border-radius:8px}
.emoji-pop button:hover{background:var(--panel2)}

/* modal */
.modal-bg{position:fixed;inset:0;background:rgba(0,0,0,.55);display:grid;place-items:center;z-index:50;padding:18px}
.modal{width:100%;max-width:420px;background:var(--panel);border:1px solid var(--line);border-radius:18px;
  padding:20px;max-height:84vh;overflow-y:auto}
.modal h3{margin:0 0 4px;font-size:18px}
.modal p.sub{margin:0 0 16px}
.pick{display:flex;align-items:center;gap:11px;padding:9px 8px;border-radius:11px;cursor:pointer}
.pick:hover{background:var(--panel2)}
.pick input{width:18px;height:18px;accent-color:var(--accent)}
.codebox{display:flex;gap:8px;align-items:center;background:var(--bg2);border:1px dashed var(--line);
  border-radius:11px;padding:12px;font-size:16px;font-weight:700;letter-spacing:1px;justify-content:space-between}
.modal .row{display:flex;gap:10px;margin-top:16px}
.modal .row .btn{margin-top:0}
.btn.ghost{background:var(--panel2);color:var(--fg)}
.toast{position:fixed;bottom:20px;left:50%;transform:translateX(-50%);background:var(--panel2);
  border:1px solid var(--line);color:var(--fg);padding:11px 16px;border-radius:12px;font-size:14px;z-index:99;
  box-shadow:0 8px 24px rgba(0,0,0,.4)}