.msg-gate{padding:80px 0;text-align:center;max-width:460px}
.msg-gate h1{font-size:32px;margin:0 0 10px}

.chat-app{display:grid;grid-template-columns:320px 1fr;height:calc(100vh - 64px);border-top:1px solid var(--line)}

/* ---------- sidebar ---------- */
.chat-sidebar{border-right:1px solid var(--line);display:flex;flex-direction:column;background:var(--surface)}
.sidebar-top{display:flex;align-items:center;justify-content:space-between;padding:16px 16px 10px}
.sidebar-tabs{display:flex;gap:4px;background:var(--bg);border-radius:8px;padding:3px}
.sidebar-tab{background:none;border:none;padding:7px 14px;font-size:13px;font-family:"Inter",Arial,sans-serif;color:var(--muted);border-radius:6px;cursor:pointer}
.sidebar-tab.active{background:var(--surface);color:var(--ink);box-shadow:0 1px 2px rgba(18,32,58,.08)}
.icon-btn{background:var(--bg);border:1px solid var(--line);width:34px;height:34px;border-radius:50%;font-size:16px;cursor:pointer;color:var(--ink);display:grid;place-items:center;flex:none}
.icon-btn:hover{background:var(--line)}
.sidebar-search{margin:0 16px 12px;padding:9px 12px;border:1px solid var(--line);border-radius:8px;font-family:"Inter",Arial,sans-serif;font-size:14px;background:var(--bg)}
.sidebar-search:focus{outline:none;border-color:var(--accent)}

.sidebar-list{flex:1;overflow-y:auto}
.list-row{display:flex;align-items:center;gap:12px;padding:12px 16px;cursor:pointer;border-bottom:1px solid var(--line)}
.list-row:hover{background:var(--bg)}
.list-row.active{background:var(--bg)}
.list-row .avatar{width:44px;height:44px;font-size:16px}
.list-row-main{flex:1;min-width:0}
.list-row-top{display:flex;justify-content:space-between;gap:8px}
.list-row-name{font-weight:500;font-size:15px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.list-row-time{font-size:11px;color:var(--muted);flex:none}
.list-row-preview{font-size:13px;color:var(--muted);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.list-row-action{font-size:12px;color:var(--accent);flex:none}
.sidebar-empty{padding:30px 20px;color:var(--muted);font-size:14px;text-align:center}

/* ---------- chat panel ---------- */
.chat-panel{display:flex;flex-direction:column;background:var(--bg)}
.chat-empty{flex:1;display:grid;place-items:center;color:var(--muted);font-size:14px;padding:0 20px;text-align:center}

.chat-thread{display:flex;flex-direction:column;height:100%}
.thread-header{display:flex;align-items:center;gap:12px;padding:14px 20px;background:var(--surface);border-bottom:1px solid var(--line)}
.thread-header .avatar{width:40px;height:40px;font-size:15px}
.thread-title{font-weight:500;font-size:15px}
.thread-subtitle{font-size:12px;color:var(--muted)}
.back-btn{display:none}

.thread-messages{flex:1;overflow-y:auto;padding:20px;display:flex;flex-direction:column;gap:10px}
.bubble-row{display:flex}
.bubble-row.mine{justify-content:flex-end}
.bubble{max-width:min(70%,480px);padding:10px 14px;border-radius:14px;font-size:14.5px;line-height:1.45;box-shadow:0 1px 2px rgba(18,32,58,.06)}
.bubble-row:not(.mine) .bubble{background:var(--surface);color:var(--ink);border-bottom-left-radius:4px}
.bubble-row.mine .bubble{background:var(--accent);color:#fff;border-bottom-right-radius:4px}
.bubble-sender{font-size:11px;font-weight:600;margin-bottom:3px;color:var(--accent)}
.bubble-row.mine .bubble-sender{display:none}
.bubble-time{font-size:10px;opacity:.7;margin-top:4px;text-align:right}

.thread-input-row{display:flex;gap:10px;padding:14px 20px;background:var(--surface);border-top:1px solid var(--line)}
.thread-input-row input{flex:1;padding:11px 16px;border:1px solid var(--line);border-radius:22px;font-family:"Inter",Arial,sans-serif;font-size:14.5px;background:var(--bg)}
.thread-input-row input:focus{outline:none;border-color:var(--accent)}
.send-btn{width:42px;height:42px;border-radius:50%;border:none;background:var(--accent);color:#fff;font-size:16px;cursor:pointer;flex:none}
.send-btn:hover{opacity:.9}

/* ---------- modal ---------- */
.modal-overlay{position:fixed;inset:0;background:rgba(18,32,58,.5);display:flex;align-items:center;justify-content:center;z-index:50;padding:20px}
.modal-box{background:var(--surface);border-radius:14px;padding:26px;width:min(420px,100%);max-height:85vh;overflow-y:auto}
.modal-box h2{margin:0 0 16px;font-size:20px}
.modal-people-list{border:1px solid var(--line);border-radius:8px;max-height:220px;overflow-y:auto;margin-bottom:6px}
.modal-person-row{display:flex;align-items:center;gap:10px;padding:10px 12px;border-bottom:1px solid var(--line);font-size:14px}
.modal-person-row:last-child{border-bottom:none}
.modal-person-row .avatar{width:32px;height:32px;font-size:13px}
.modal-actions{display:flex;justify-content:flex-end;gap:10px;margin-top:18px}

/* ---------- mobile: swap list/thread instead of two columns ---------- */
@media (max-width:800px){
  .chat-app{grid-template-columns:1fr}
  .chat-sidebar{display:flex}
  .chat-panel{display:none}
  .chat-app.show-thread .chat-sidebar{display:none}
  .chat-app.show-thread .chat-panel{display:flex}
  .back-btn{display:grid}
}