*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
[data-theme="dark"]{
  --bg:#0f1117;--sidebar:#13161f;--surface:#1a1d27;--surface2:#232734;--border:#2e3345;
  --text:#e4e7ef;--text2:#8b92a8;--text3:#5a6178;--accent:#3b82f6;--accent-hover:#2563eb;
  --accent-subtle:rgba(59,130,246,0.1);--success:#22c55e;--error:#ef4444;--warning:#f59e0b;
  --user-bubble:#1e3a5f;--ai-bubble:#1a1d27;
}
[data-theme="light"]{
  --bg:#f8f9fc;--sidebar:#f0f2f7;--surface:#ffffff;--surface2:#f0f2f5;--border:#e2e5ea;
  --text:#1a1d27;--text2:#6b7280;--text3:#9ca3af;--accent:#3b82f6;--accent-hover:#2563eb;
  --accent-subtle:rgba(59,130,246,0.08);--success:#16a34a;--error:#dc2626;--warning:#d97706;
  --user-bubble:#dbeafe;--ai-bubble:#ffffff;
}
:root{--radius:12px;--radius-sm:8px;--sidebar-w:260px}
html,body{height:100%;overflow:hidden;font-family:'Inter',system-ui,sans-serif;background:var(--bg);color:var(--text);font-size:15px;line-height:1.6}

/* ─── App Shell ─────────────────────────────────────────────── */
.app{display:flex;height:100vh;overflow:hidden}

/* ─── Sidebar ──────────────────────────────────────────────── */
.sidebar{
  width:var(--sidebar-w);flex-shrink:0;background:var(--sidebar);border-right:1px solid var(--border);
  display:flex;flex-direction:column;transition:transform 0.3s ease,width 0.3s ease;overflow:hidden;
}
.sidebar.collapsed{width:0;border-right:none}

.sidebar-header{padding:16px;border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;flex-shrink:0}
.sidebar-header .logo{font-size:0.85rem;font-weight:700;letter-spacing:-0.01em;white-space:nowrap}
.sidebar-header .logo span{color:var(--accent)}

.new-chat-btn{
  margin:12px;padding:10px 14px;background:var(--accent);color:#fff;border:none;border-radius:var(--radius-sm);
  font-size:0.8rem;font-weight:600;font-family:inherit;cursor:pointer;display:flex;align-items:center;gap:6px;
  transition:background 0.2s;white-space:nowrap;
}
.new-chat-btn:hover{background:var(--accent-hover)}

.sidebar-section{padding:8px 12px 4px;font-size:0.65rem;text-transform:uppercase;letter-spacing:0.08em;color:var(--text3);font-weight:600}

.chat-item{
  margin:2px 8px;padding:9px 12px;border-radius:var(--radius-sm);cursor:pointer;
  display:flex;align-items:center;justify-content:space-between;gap:8px;
  transition:background 0.15s;
}
.chat-item:hover{background:var(--surface2)}
.chat-item.active{background:var(--accent-subtle);color:var(--accent)}
.chat-item-title{font-size:0.8rem;font-weight:500;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;flex:1}
.chat-item-meta{font-size:0.65rem;color:var(--text3);white-space:nowrap}
.chat-item-del{opacity:0;background:none;border:none;color:var(--text2);cursor:pointer;font-size:0.75rem;padding:2px 4px;border-radius:4px;transition:opacity 0.15s}
.chat-item:hover .chat-item-del{opacity:1}
.chat-item-del:hover{color:var(--error)}

.sidebar-divider{height:1px;background:var(--border);margin:8px 12px}

/* Sidebar Info Panel */
.info-panel{padding:12px;border-top:1px solid var(--border);margin-top:auto;flex-shrink:0}
.info-row{display:flex;align-items:center;justify-content:space-between;padding:4px 0;font-size:0.72rem}
.info-label{color:var(--text3)}
.info-val{font-weight:500;color:var(--text2);text-align:right;max-width:120px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}

/* ─── Main Area ────────────────────────────────────────────── */
.main{flex:1;display:flex;flex-direction:column;overflow:hidden;min-width:0}

/* Top Bar */
.topbar{
  padding:12px 20px;border-bottom:1px solid var(--border);display:flex;align-items:center;gap:12px;
  flex-shrink:0;background:var(--bg);
}
.topbar-toggle{background:none;border:none;color:var(--text2);cursor:pointer;font-size:1.1rem;padding:4px;border-radius:6px;transition:background 0.15s}
.topbar-toggle:hover{background:var(--surface2)}
.topbar-title{font-size:0.9rem;font-weight:600;flex:1;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.topbar-actions{display:flex;gap:6px;flex-shrink:0}
.topbar-btn{background:none;border:1px solid var(--border);color:var(--text2);cursor:pointer;font-size:0.75rem;padding:5px 10px;border-radius:var(--radius-sm);font-family:inherit;transition:all 0.15s;white-space:nowrap}
.topbar-btn:hover{border-color:var(--text2);color:var(--text)}
.topbar-btn.active{background:var(--accent);color:#fff;border-color:var(--accent)}

/* ─── Pages ────────────────────────────────────────────────── */
.page{flex:1;overflow-y:auto;display:none;flex-direction:column}
.page.visible{display:flex}
.page::-webkit-scrollbar{width:5px}
.page::-webkit-scrollbar-track{background:transparent}
.page::-webkit-scrollbar-thumb{background:var(--border);border-radius:3px}

.page-inner{max-width:720px;margin:0 auto;padding:28px 20px;width:100%}
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:24px;margin-bottom:16px}
.card h2{font-size:1rem;font-weight:600;margin-bottom:4px}
.card p.subtitle{color:var(--text2);font-size:0.78rem;margin-bottom:18px}

/* Forms */
label{display:block;font-size:0.72rem;font-weight:500;color:var(--text2);margin-bottom:6px;text-transform:uppercase;letter-spacing:0.04em}
select,input[type="text"],input[type="password"],textarea{width:100%;padding:10px 13px;background:var(--surface2);border:1px solid var(--border);border-radius:var(--radius-sm);color:var(--text);font-size:0.85rem;font-family:inherit;outline:none;transition:border-color 0.2s;resize:vertical}
select:focus,input:focus,textarea:focus{border-color:var(--accent)}
select{appearance:none;cursor:pointer;background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' fill='%238b92a8' viewBox='0 0 16 16'%3E%3Cpath d='M8 11L3 6h10z'/%3E%3C/svg%3E");background-repeat:no-repeat;background-position:right 12px center;padding-right:32px}
.form-row{margin-bottom:14px}

/* Buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:7px;padding:9px 18px;border:none;border-radius:var(--radius-sm);font-size:0.8rem;font-weight:600;font-family:inherit;cursor:pointer;transition:all 0.2s}
.btn-primary{background:var(--accent);color:#fff}.btn-primary:hover{background:var(--accent-hover)}
.btn-primary:disabled{opacity:0.45;cursor:not-allowed}
.btn-outline{background:transparent;color:var(--text2);border:1px solid var(--border)}.btn-outline:hover{border-color:var(--text2);color:var(--text)}
.btn-danger{background:var(--error);color:#fff}
.btn-group{display:flex;gap:8px;margin-top:16px;flex-wrap:wrap}

/* System Grid */
.sys-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:10px;margin-bottom:16px}
.sys-item{background:var(--surface2);border-radius:var(--radius-sm);padding:14px}
.sys-item .sys-label{font-size:0.65rem;text-transform:uppercase;letter-spacing:0.06em;color:var(--text2);font-weight:600;margin-bottom:4px}
.sys-item .sys-val{font-size:0.88rem;font-weight:600}

/* ─── Chat Page ────────────────────────────────────────────── */
.chat-page{flex:1;overflow:hidden;display:none;flex-direction:column}
.chat-page.visible{display:flex}

/* Welcome Screen */
.welcome{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:40px 20px;text-align:center;gap:12px}
.welcome h2{font-size:1.4rem;font-weight:700;letter-spacing:-0.02em}
.welcome p{color:var(--text2);font-size:0.85rem;max-width:400px}
.welcome-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:10px;width:100%;max-width:520px;margin-top:12px}
.welcome-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-sm);padding:14px;text-align:left;cursor:pointer;transition:all 0.2s;font-size:0.8rem}
.welcome-card:hover{border-color:var(--accent);background:var(--accent-subtle)}
.welcome-card .wc-icon{font-size:1.2rem;margin-bottom:6px}
.welcome-card .wc-title{font-weight:600;margin-bottom:2px}
.welcome-card .wc-desc{color:var(--text2);font-size:0.72rem}

/* Messages */
.messages{flex:1;overflow-y:auto;padding:24px 20px;display:flex;flex-direction:column;gap:20px}
.messages::-webkit-scrollbar{width:5px}
.messages::-webkit-scrollbar-thumb{background:var(--border);border-radius:3px}

.message{display:flex;gap:12px;max-width:780px;width:100%;align-self:flex-start}
.message.user{align-self:flex-end;flex-direction:row-reverse}
.msg-avatar{width:32px;height:32px;border-radius:50%;flex-shrink:0;display:flex;align-items:center;justify-content:center;font-size:0.8rem;font-weight:700}
.msg-avatar.ai{background:var(--accent);color:#fff}
.msg-avatar.user{background:var(--surface2);color:var(--text2)}
.msg-body{flex:1;min-width:0}
.msg-name{font-size:0.72rem;font-weight:600;color:var(--text2);margin-bottom:4px}
.message.user .msg-name{text-align:right}
.msg-bubble{
  background:var(--ai-bubble);border:1px solid var(--border);border-radius:12px;padding:12px 16px;
  font-size:0.88rem;line-height:1.7;word-break:break-word;
}
.message.user .msg-bubble{background:var(--user-bubble);border-color:transparent;color:var(--text)}

/* Markdown in bubbles */
.msg-bubble p{margin-bottom:10px}.msg-bubble p:last-child{margin-bottom:0}
.msg-bubble ul,.msg-bubble ol{padding-left:20px;margin-bottom:10px}
.msg-bubble li{margin-bottom:3px}
.msg-bubble code{background:var(--surface2);padding:2px 6px;border-radius:4px;font-size:0.82em;font-family:'Courier New',monospace}
.msg-bubble pre{background:var(--surface2);border:1px solid var(--border);border-radius:var(--radius-sm);padding:14px;margin:10px 0;overflow-x:auto}
.msg-bubble pre code{background:none;padding:0;font-size:0.82em;line-height:1.5}
.msg-bubble h1,.msg-bubble h2,.msg-bubble h3{font-weight:600;margin:12px 0 6px;line-height:1.3}
.msg-bubble h1{font-size:1.1em}.msg-bubble h2{font-size:1em}.msg-bubble h3{font-size:0.95em}
.msg-bubble blockquote{border-left:3px solid var(--border);padding-left:12px;color:var(--text2);margin:8px 0}
.msg-bubble strong{font-weight:600}.msg-bubble em{font-style:italic}
.msg-bubble a{color:var(--accent);text-decoration:underline}
.msg-bubble hr{border:none;border-top:1px solid var(--border);margin:12px 0}
.msg-bubble table{width:100%;border-collapse:collapse;font-size:0.82em;margin:8px 0}
.msg-bubble th,.msg-bubble td{padding:6px 10px;border:1px solid var(--border);text-align:left}
.msg-bubble th{background:var(--surface2);font-weight:600}

/* Cursor blink */
.cursor{display:inline-block;width:2px;height:1em;background:var(--accent);animation:blink 0.7s step-end infinite;vertical-align:text-bottom;margin-left:2px}
@keyframes blink{0%,100%{opacity:1}50%{opacity:0}}

/* Typing indicator */
.typing-indicator{display:flex;align-items:center;gap:4px;padding:12px 16px}
.typing-dot{width:7px;height:7px;border-radius:50%;background:var(--text3);animation:tdot 1.2s ease-in-out infinite}
.typing-dot:nth-child(2){animation-delay:0.2s}
.typing-dot:nth-child(3){animation-delay:0.4s}
@keyframes tdot{0%,80%,100%{opacity:0.3;transform:scale(0.8)}40%{opacity:1;transform:scale(1)}}

/* Input */
.input-area{padding:16px 20px;border-top:1px solid var(--border);flex-shrink:0;background:var(--bg)}
.input-bar{
  background:var(--surface);border:1px solid var(--border);border-radius:12px;
  display:flex;align-items:flex-end;gap:8px;padding:10px 14px;transition:border-color 0.2s;
}
.input-bar:focus-within{border-color:var(--accent)}
.input-bar textarea{
  flex:1;background:transparent;border:none;outline:none;font-size:0.88rem;font-family:inherit;
  color:var(--text);resize:none;max-height:180px;min-height:24px;line-height:1.5;
}
.input-bar textarea::placeholder{color:var(--text3)}
.send-btn{
  background:var(--accent);border:none;border-radius:8px;color:#fff;width:35px;height:35px;
  cursor:pointer;display:flex;align-items:center;justify-content:center;flex-shrink:0;
  transition:background 0.2s;font-size:0.9rem;
}
.send-btn:hover{background:var(--accent-hover)}
.send-btn:disabled{opacity:0.4;cursor:not-allowed}
.input-hint{font-size:0.68rem;color:var(--text3);margin-top:6px;text-align:center}

/* Toast */
.toast{position:fixed;bottom:20px;right:20px;transform:translateY(80px);background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-sm);padding:12px 20px;font-size:0.8rem;font-weight:500;z-index:200;box-shadow:0 8px 32px rgba(0,0,0,0.3);transition:transform 0.3s;display:flex;align-items:center;gap:8px;max-width:320px}
.toast.show{transform:translateY(0)}
.toast.success{border-color:var(--success)}.toast.error{border-color:var(--error)}

/* Spinner */
.spinner{width:15px;height:15px;border:2px solid var(--border);border-top-color:var(--accent);border-radius:50%;animation:spin 0.6s linear infinite;flex-shrink:0}
@keyframes spin{to{transform:rotate(360deg)}}

/* Responsive */
@media(max-width:700px){
  :root{--sidebar-w:220px}
  .topbar-btn span{display:none}
  .chat-page .messages{padding:16px}
  .input-area{padding:12px}
}
@media(max-width:500px){
  .sidebar{position:fixed;top:0;left:0;height:100%;z-index:100;transform:translateX(-100%)}
  .sidebar.mobile-open{transform:translateX(0)}
  .sidebar.collapsed{transform:translateX(-100%);width:var(--sidebar-w)}
  .page-inner{padding:20px 14px}
  .welcome-grid{grid-template-columns:1fr 1fr}
}