:root {
  --bg: #0d0e11;
  --bg-elev: #16181d;
  --bg-elev-2: #1e2127;
  --sidebar: #0a0b0e;
  --border: #262a31;
  --text: #ececf1;
  --text-dim: #9a9ba6;
  --muted: #6f7079;
  --accent: #7c5cff;
  --accent-2: #9d84ff;
  --user-bubble: #23262e;
  --danger: #ff5c6c;
  --shadow: 0 8px 30px rgba(0,0,0,.35);
  --radius: 14px;
}
[data-theme="light"] {
  --bg: #ffffff;
  --bg-elev: #f7f7f8;
  --bg-elev-2: #eeeef1;
  --sidebar: #f4f4f6;
  --border: #e3e3e8;
  --text: #1a1a1e;
  --text-dim: #55565f;
  --muted: #8a8b93;
  --user-bubble: #ececf1;
  --shadow: 0 8px 30px rgba(0,0,0,.08);
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; }
body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
  overflow: hidden;
}
.hidden { display: none !important; }
.muted { color: var(--muted); }

.brand-mark {
  display: grid; place-items: center;
  width: 56px; height: 56px; border-radius: 16px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #fff; font-weight: 700; font-size: 26px;
  box-shadow: 0 6px 20px rgba(124,92,255,.4);
}
.brand-mark.small { width: 30px; height: 30px; border-radius: 9px; font-size: 16px; box-shadow:none;}
.brand-mark.big { width: 68px; height: 68px; border-radius: 20px; font-size: 32px; margin: 0 auto 4px; }

/* ---------- Login ---------- */
.login-overlay {
  position: fixed; inset: 0; z-index: 100;
  display: grid; place-items: center;
  background: radial-gradient(1200px 600px at 50% -10%, rgba(124,92,255,.15), transparent), var(--bg);
}
.login-card {
  width: 360px; max-width: 90vw; text-align: center;
  background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: 20px; padding: 36px 28px; box-shadow: var(--shadow);
}
.login-card .brand-mark { margin: 0 auto 18px; }
.login-card h1 { font-size: 20px; margin-bottom: 6px; }
.login-card p { font-size: 13px; margin-bottom: 20px; }
#login-form { display: flex; flex-direction: column; gap: 10px; }
#login-password {
  background: var(--bg); border: 1px solid var(--border); color: var(--text);
  padding: 12px 14px; border-radius: 10px; font-size: 14px; outline: none;
}
#login-password:focus { border-color: var(--accent); }
.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #fff; border: none; padding: 12px; border-radius: 10px;
  font-size: 14px; font-weight: 600; cursor: pointer; transition: opacity .15s;
}
.btn-primary:hover { opacity: .92; }
.login-error { color: var(--danger); font-size: 13px; margin-top: 12px; min-height: 16px; }

/* ---------- App layout ---------- */
.app { display: flex; height: 100vh; }

/* Sidebar */
.sidebar {
  width: 268px; flex-shrink: 0; background: var(--sidebar);
  border-right: 1px solid var(--border);
  display: flex; flex-direction: column; padding: 12px;
  transition: width .2s, margin-left .2s;
}
.sidebar.collapsed { margin-left: -268px; }
.sidebar-head { display: flex; align-items: center; justify-content: space-between; padding: 6px 6px 12px; }
.logo { display: flex; align-items: center; gap: 10px; }
.logo-text { font-weight: 700; font-size: 16px; letter-spacing: .5px; }
.new-chat-btn {
  display: flex; align-items: center; gap: 8px; width: 100%;
  background: var(--bg-elev); color: var(--text); border: 1px solid var(--border);
  padding: 11px 12px; border-radius: 10px; font-size: 14px; font-weight: 500;
  cursor: pointer; transition: background .15s;
}
.new-chat-btn:hover { background: var(--bg-elev-2); }
.history { flex: 1; overflow-y: auto; margin-top: 14px; display: flex; flex-direction: column; gap: 2px; }
.history-group-label { font-size: 11px; color: var(--muted); padding: 12px 10px 6px; text-transform: uppercase; letter-spacing: .6px; }
.history-item {
  display: flex; align-items: center; gap: 8px; padding: 9px 10px; border-radius: 9px;
  font-size: 13.5px; color: var(--text-dim); cursor: pointer; position: relative;
  white-space: nowrap; overflow: hidden;
}
.history-item:hover { background: var(--bg-elev); color: var(--text); }
.history-item.active { background: var(--bg-elev-2); color: var(--text); }
.history-item .title { flex: 1; overflow: hidden; text-overflow: ellipsis; }
.history-item .del {
  opacity: 0; border: none; background: transparent; color: var(--muted);
  cursor: pointer; padding: 2px; border-radius: 5px; flex-shrink: 0;
}
.history-item:hover .del { opacity: 1; }
.history-item .del:hover { color: var(--danger); background: var(--bg); }
.sidebar-foot { display: flex; gap: 6px; padding-top: 10px; border-top: 1px solid var(--border); }

.icon-btn {
  display: grid; place-items: center; width: 34px; height: 34px;
  border: none; background: transparent; color: var(--text-dim);
  border-radius: 8px; cursor: pointer; transition: background .15s, color .15s;
}
.icon-btn:hover { background: var(--bg-elev); color: var(--text); }

/* Main */
.main { flex: 1; display: flex; flex-direction: column; min-width: 0; }
.topbar {
  display: flex; align-items: center; gap: 10px; padding: 12px 18px;
  border-bottom: 1px solid var(--border); background: var(--bg);
}
.topbar-spacer { flex: 1; }
.mobile-only { display: none; }

.model-select-wrap { position: relative; }
.model-select {
  display: flex; align-items: center; gap: 8px;
  background: var(--bg-elev); border: 1px solid var(--border); color: var(--text);
  padding: 8px 12px; border-radius: 10px; font-size: 13.5px; font-weight: 600; cursor: pointer;
}
.model-select:hover { background: var(--bg-elev-2); }
.model-menu {
  position: absolute; top: 46px; left: 0; z-index: 40; width: 300px;
  background: var(--bg-elev); border: 1px solid var(--border); border-radius: 12px;
  box-shadow: var(--shadow); padding: 6px; max-height: 60vh; overflow-y: auto;
}
.model-opt { padding: 10px 12px; border-radius: 9px; cursor: pointer; }
.model-opt:hover { background: var(--bg-elev-2); }
.model-opt .row { display: flex; align-items: center; gap: 8px; }
.model-opt .name { font-size: 13.5px; font-weight: 600; }
.model-opt .desc { font-size: 12px; color: var(--muted); margin-top: 2px; }
.badge {
  font-size: 10px; font-weight: 700; padding: 2px 6px; border-radius: 6px; text-transform: uppercase; letter-spacing: .4px;
}
.badge.cheap { background: rgba(46,204,113,.15); color: #43d17a; }
.badge.reasoning { background: rgba(52,152,219,.15); color: #4aa8e0; }
.badge.premium { background: rgba(255,180,0,.15); color: #ffb400; }

/* Chat area */
.chat-scroll { flex: 1; overflow-y: auto; scroll-behavior: smooth; }
.welcome { max-width: 720px; margin: 12vh auto 0; text-align: center; padding: 0 20px; }
.welcome h2 { font-size: 26px; margin: 14px 0 8px; font-weight: 700; }
.welcome p { font-size: 14px; }
.suggestions { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 26px; }
.suggestion {
  text-align: left; background: var(--bg-elev); border: 1px solid var(--border);
  color: var(--text-dim); padding: 14px 16px; border-radius: 12px; font-size: 13.5px;
  cursor: pointer; transition: background .15s, color .15s;
}
.suggestion:hover { background: var(--bg-elev-2); color: var(--text); }

.messages { max-width: 760px; margin: 0 auto; padding: 24px 20px 40px; display: flex; flex-direction: column; gap: 26px; }
.msg { display: flex; gap: 14px; }
.msg .avatar {
  width: 30px; height: 30px; border-radius: 8px; flex-shrink: 0;
  display: grid; place-items: center; font-size: 13px; font-weight: 700; color: #fff;
}
.msg.user .avatar { background: #3a3d46; }
.msg.assistant .avatar { background: linear-gradient(135deg, var(--accent), var(--accent-2)); }
.msg .body { flex: 1; min-width: 0; padding-top: 3px; }
.msg .who { font-size: 12.5px; font-weight: 600; color: var(--text-dim); margin-bottom: 5px; }
.msg .content { font-size: 15px; line-height: 1.7; color: var(--text); word-wrap: break-word; }
.msg .content p { margin: 0 0 12px; }
.msg .content p:last-child { margin-bottom: 0; }
.msg .content pre {
  background: var(--bg-elev-2); border: 1px solid var(--border); border-radius: 10px;
  padding: 14px; overflow-x: auto; margin: 10px 0; font-size: 13px;
}
.msg .content code { font-family: ui-monospace, "SF Mono", Menlo, monospace; font-size: 13px; }
.msg .content :not(pre) > code { background: var(--bg-elev-2); padding: 2px 6px; border-radius: 5px; }
.msg .content ul, .msg .content ol { margin: 0 0 12px; padding-left: 22px; }
.msg .content li { margin-bottom: 5px; }
.msg .content h1,.msg .content h2,.msg .content h3 { margin: 14px 0 8px; }
.msg .content a { color: var(--accent-2); }
.cursor-blink::after { content: "▋"; margin-left: 2px; animation: blink 1s steps(2) infinite; color: var(--accent-2); }
@keyframes blink { 0%,50%{opacity:1} 50.01%,100%{opacity:0} }

/* Composer */
.composer-wrap { padding: 0 20px 22px; background: var(--bg); }
.composer { max-width: 760px; margin: 0 auto; background: var(--bg-elev); border: 1px solid var(--border); border-radius: 18px; padding: 8px; box-shadow: var(--shadow); }
.composer:focus-within { border-color: var(--accent); }
.attachments { display: flex; flex-wrap: wrap; gap: 8px; padding: 6px 6px 0; }
.attachments:empty { display: none; }
.chip {
  display: flex; align-items: center; gap: 6px; background: var(--bg-elev-2);
  border: 1px solid var(--border); border-radius: 8px; padding: 6px 8px; font-size: 12px; color: var(--text-dim);
}
.chip button { border: none; background: transparent; color: var(--muted); cursor: pointer; }
.composer-row { display: flex; align-items: flex-end; gap: 6px; }
.attach-btn { flex-shrink: 0; margin-bottom: 2px; }
#input {
  flex: 1; resize: none; border: none; background: transparent; color: var(--text);
  font-family: inherit; font-size: 15px; line-height: 1.5; padding: 10px 4px; outline: none;
  max-height: 200px;
}
.send-btn {
  flex-shrink: 0; width: 36px; height: 36px; border-radius: 10px; border: none;
  background: linear-gradient(135deg, var(--accent), var(--accent-2)); color: #fff;
  display: grid; place-items: center; cursor: pointer; transition: opacity .15s, transform .1s;
}
.send-btn:hover { opacity: .92; }
.send-btn:active { transform: scale(.94); }
.send-btn:disabled { opacity: .4; cursor: not-allowed; }
.composer-hint { text-align: center; font-size: 11.5px; color: var(--muted); margin-top: 8px; }

/* Scrollbars */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 6px; }
::-webkit-scrollbar-thumb:hover { background: var(--muted); }

/* Mobile */
@media (max-width: 760px) {
  .sidebar { position: fixed; z-index: 50; height: 100%; box-shadow: var(--shadow); }
  .sidebar.collapsed { margin-left: -268px; }
  .mobile-only { display: grid; }
  .suggestions { grid-template-columns: 1fr; }
}