/* TTu — monochrome theme, native system font on every device (PDFs keep their embedded Carlito font). */

:root,[data-theme="dark"]{
  color-scheme:dark;
  --bg:#0a0a0a;--bg-elev:#111;--card:#161616;--ink:#f4f4f4;--muted:#b3b3b3;
  --line:#2a2a2a;--line-strong:#444;--accent:#fff;--accent-ink:#0a0a0a;
  --shadow:0 12px 40px rgba(0,0,0,.5);--header-bg:rgba(10,10,10,.86);
  --bubble:#fff;--bubble-ink:#111;--input:#141414;--focus:#fff;
  --err-bg:#1a1010;--err-line:#6b2a2a;--err-ink:#ffb4ab;
  --notice-bg:#1a1a1a;--notice-line:#3a3a3a;--notice-ink:#e8e8e8;
  --code-bg:#222;--toast-bg:#f4f4f4;--toast-ink:#111;
  --theme-color:#0a0a0a;
}
[data-theme="light"]{
  color-scheme:light;
  --bg:#f5f5f5;--bg-elev:#fff;--card:#fff;--ink:#111;--muted:#5c5c5c;
  --line:#e2e2e2;--line-strong:#c8c8c8;--accent:#111;--accent-ink:#fff;
  --shadow:0 12px 36px rgba(0,0,0,.08);--header-bg:rgba(245,245,245,.9);
  --bubble:#111;--bubble-ink:#fff;--input:#fff;--focus:#111;
  --err-bg:#fff4f2;--err-line:#f0c4c0;--err-ink:#8a1c14;
  --notice-bg:#f3f3f3;--notice-line:#d4d4d4;--notice-ink:#222;
  --code-bg:#efefef;--toast-bg:#111;--toast-ink:#fff;
  --theme-color:#f5f5f5;
}

*,*::before,*::after{box-sizing:border-box}
html,body{margin:0;height:100%}
body:has(main.chat),body:has(main.signin){overflow:hidden}
html{background:var(--bg)}
body{
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,"Noto Sans",sans-serif;
  font-size:16px;line-height:1.6;letter-spacing:-.005em;color:var(--ink);background:var(--bg);
  -webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;
  display:flex;flex-direction:column;min-height:100dvh;
}
a{color:var(--ink);text-underline-offset:3px}
a:hover{text-decoration-thickness:2px}
.hidden{display:none!important}
.muted{color:var(--muted)}
button,input,textarea{font:inherit}

/* ---------- Header ---------- */
.top{
  position:sticky;top:0;z-index:8;display:flex;align-items:center;justify-content:space-between;
  padding:10px 16px;padding-top:max(10px,env(safe-area-inset-top));
  background:var(--header-bg);backdrop-filter:blur(16px) saturate(1.2);
  border-bottom:1px solid var(--line);
}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink);font-weight:700;font-size:22px;letter-spacing:-.4px}
.brand img{border-radius:9px;display:block}
.top-right{display:flex;align-items:center;gap:8px}
.pill{
  font-size:13px;color:var(--ink);background:transparent;border:1px solid var(--line-strong);
  padding:5px 11px;border-radius:999px;white-space:nowrap;
}
.theme-toggle,.avatar{
  width:36px;height:36px;border-radius:50%;border:1px solid var(--line-strong);
  background:transparent;color:var(--ink);cursor:pointer;display:grid;place-items:center;
  transition:background .2s,transform .15s,border-color .2s;
}
.theme-toggle .icon-sun{display:none}
.theme-toggle .icon-moon{display:block}
[data-theme="light"] .theme-toggle .icon-sun{display:block}
[data-theme="light"] .theme-toggle .icon-moon{display:none}
.theme-toggle:hover,.avatar:hover{background:var(--card);border-color:var(--ink)}
.theme-toggle:active,.avatar:active{transform:scale(.94)}
.avatar{font-weight:700;font-size:15px;background:var(--accent);color:var(--accent-ink);border-color:var(--accent)}
.avatar:hover{background:var(--accent);opacity:.9}

.menu{
  position:absolute;right:12px;top:58px;background:var(--card);border:1px solid var(--line);
  border-radius:16px;box-shadow:var(--shadow);min-width:248px;padding:8px;
  display:flex;flex-direction:column;animation:fadeIn .18s ease;
}
.menu button,.menu a{
  all:unset;cursor:pointer;padding:10px 12px;border-radius:10px;font-size:14.5px;color:var(--ink);
}
.menu button:hover,.menu a:hover{background:var(--bg-elev)}
.menu-email{padding:8px 12px 2px;font-weight:700;font-size:14.5px;word-break:break-all}
.menu-usage{padding:0 12px 8px;font-size:12.5px;color:var(--muted);border-bottom:1px solid var(--line);margin-bottom:6px;line-height:1.5}

/* ---------- Sign-in ---------- */
.signin{flex:1;display:grid;place-items:center;padding:24px 16px}
.card{
  background:var(--card);border:1px solid var(--line);border-radius:24px;padding:32px 26px;
  max-width:420px;width:100%;text-align:center;box-shadow:var(--shadow);
  animation:fadeUp .4s ease;
}
.hero-icon{border-radius:22px;box-shadow:0 10px 28px rgba(0,0,0,.35)}
[data-theme="light"] .hero-icon{box-shadow:0 8px 24px rgba(0,0,0,.12)}
.card h1{margin:18px 0 8px;font-size:28px;letter-spacing:-.5px;font-weight:700}
.card p{line-height:1.55}
form label{display:block;text-align:left;font-size:14px;font-weight:700;color:var(--ink);margin:18px 0 8px}
input{
  width:100%;font-size:16px;padding:13px 14px;border-radius:999px;border:1.5px solid var(--line);
  background:var(--input);color:var(--ink);outline:none;transition:border-color .15s,box-shadow .15s;
}
input:focus,textarea:focus{border-color:var(--focus);box-shadow:0 0 0 3px color-mix(in srgb,var(--focus) 22%,transparent)}
#code{letter-spacing:8px;text-align:center;font-size:22px;font-weight:700;border-radius:16px}

.btn{
  font-weight:700;border-radius:999px;padding:13px 18px;border:0;cursor:pointer;width:100%;
  margin-top:12px;font-size:15.5px;transition:transform .12s,opacity .15s,background .15s,box-shadow .15s;
}
.btn:active{transform:scale(.98)}
.btn.primary{background:var(--accent);color:var(--accent-ink);box-shadow:0 6px 18px rgba(0,0,0,.25)}
.btn.primary:hover{box-shadow:0 8px 22px rgba(0,0,0,.32)}
.btn.primary:disabled{opacity:.55;cursor:not-allowed;transform:none}
.btn.outline{background:transparent;color:var(--ink);border:1.5px solid var(--line-strong)}
.btn.outline:hover{border-color:var(--ink)}
.btn.link{background:none;color:var(--muted);font-weight:600;box-shadow:none}
.btn.link:hover{color:var(--ink)}
.btn.small{width:auto;padding:8px 14px;font-size:13px;margin:8px 6px 0 0}

.msg{min-height:20px;margin-top:10px;font-size:14px;color:var(--err-ink)}
.fine{font-size:12.5px;color:var(--muted);margin-top:16px}
.fine a{color:var(--ink)}
.notice{
  text-align:left;font-size:13.5px;padding:12px 14px;border-radius:14px;
  background:var(--notice-bg);border:1px solid var(--notice-line);color:var(--notice-ink);
  margin-top:12px;line-height:1.5;
}
.notice.dev{letter-spacing:0}
.notice.dev .dev-code{display:block;margin-top:6px;font-size:1.25rem;letter-spacing:4px;font-weight:700}

/* ---------- Chat ---------- */
.chat{flex:1;display:flex;flex-direction:column;width:100%;max-width:820px;margin:0 auto;min-height:0}
.thread{flex:1;padding:16px 14px 8px;overflow-y:auto;min-height:0;overscroll-behavior:contain}
.empty{text-align:center;padding:8vh 8px 20px;animation:fadeUp .4s ease}
.empty img{border-radius:18px}
.empty h2{margin:16px 0 6px;font-size:26px;letter-spacing:-.4px;font-weight:700}
.suggest{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;margin-top:20px}
.suggest button{
  font-size:14.5px;background:transparent;border:1px solid var(--line-strong);color:var(--ink);
  border-radius:999px;padding:9px 15px;cursor:pointer;transition:background .15s,border-color .15s,transform .12s;
}
.suggest button:hover{background:var(--card);border-color:var(--ink)}
.suggest button:active{transform:scale(.98)}

.turn{scroll-margin-top:8px;animation:fadeUp .35s ease both}
.q-bubble{
  margin:18px 0 10px auto;max-width:85%;width:fit-content;
  background:var(--bubble);color:var(--bubble-ink);
  padding:11px 16px;border-radius:20px 20px 6px 20px;line-height:1.45;word-wrap:break-word;
  font-weight:500;
}
.a-card{
  background:var(--card);border:1px solid var(--line);border-radius:20px;padding:18px 18px 16px;
  line-height:1.65;box-shadow:var(--shadow);
}
.a-head{display:flex;align-items:center;gap:8px;margin-bottom:8px;font-weight:700;letter-spacing:-.2px}
.a-head img{border-radius:7px}
.badge{
  font-size:11px;font-weight:700;padding:2px 8px;border-radius:999px;
  background:transparent;color:var(--ink);border:1px solid var(--line-strong);letter-spacing:.04em;text-transform:uppercase;
}
.badge.web{background:var(--accent);color:var(--accent-ink);border-color:var(--accent)}
.answer p{margin:.55em 0}
.answer ul{padding-left:1.2em;margin:.4em 0}
.answer li{margin:.25em 0}
.answer h3,.answer h4{margin:.9em 0 .3em;font-size:1.05em;letter-spacing:-.2px}
.answer code{background:var(--code-bg);padding:1px 6px;border-radius:5px;font-size:.92em}
.answer a{color:var(--ink)}
.answer a.cite,.cite{
  display:inline-block;font-size:11px;font-weight:700;min-width:18px;text-align:center;
  padding:0 5px;margin:0 1px;border-radius:6px;background:var(--accent);color:var(--accent-ink);
  text-decoration:none;vertical-align:1px;
}
.cite:hover{opacity:.8}

.imgs{display:flex;gap:8px;overflow-x:auto;margin:12px 0 4px;padding-bottom:4px}
.imgs a{flex:0 0 auto}
.imgs img{height:110px;border-radius:12px;border:1px solid var(--line);object-fit:cover;max-width:200px;background:var(--bg-elev)}

.vids{display:grid;gap:10px;margin:12px 0}
.vid{display:flex;gap:10px;align-items:center;padding:10px 12px;border:1px solid var(--line);border-radius:14px;text-decoration:none;color:var(--ink);font-size:14px;background:var(--bg-elev)}
.vid .play{flex:0 0 32px;height:32px;border-radius:50%;background:var(--accent);color:var(--accent-ink);display:grid;place-items:center}
.vid iframe{width:100%;aspect-ratio:16/9;border:0;border-radius:12px;background:#000;display:block}
.vid[style*="display:block"]{display:block;padding:0;overflow:hidden;background:#000}

.srcs{margin-top:14px;border-top:1px solid var(--line);padding-top:12px}
.srcs h4{margin:0 0 8px;font-size:11px;letter-spacing:.1em;color:var(--muted);font-weight:700}
.srcs ol{margin:0;padding-left:0;list-style:none;display:grid;gap:8px}
.srcs li{font-size:13.5px;line-height:1.45;display:flex;gap:8px}
.srcs li .n{flex:0 0 auto;font-weight:700;color:var(--ink);min-width:1.2em}
.srcs li a{color:var(--ink);text-decoration:none}
.srcs li a:hover{text-decoration:underline}
.srcs .src{font-size:11px;font-weight:700;color:var(--muted);text-transform:uppercase;margin-right:4px;letter-spacing:.04em}
.srcs li .meta{color:var(--muted);font-size:12px}

.a-actions{display:flex;align-items:center;gap:10px;margin-top:16px;flex-wrap:wrap}
.pdf-btn{
  font-weight:700;font-size:14.5px;display:inline-flex;align-items:center;gap:8px;
  padding:10px 18px;border-radius:999px;border:0;background:var(--accent);color:var(--accent-ink);
  cursor:pointer;box-shadow:0 6px 16px rgba(0,0,0,.22);transition:transform .12s,opacity .15s;
}
.pdf-btn:hover{transform:translateY(-1px)}
.pdf-btn:disabled{opacity:.55;cursor:not-allowed;transform:none}
.dl-note{font-size:12.5px;color:var(--muted)}

.typing{display:flex;gap:8px;align-items:center;color:var(--muted);font-size:14.5px}
.dots span{
  display:inline-block;width:7px;height:7px;margin:0 2px;border-radius:50%;
  background:var(--ink);animation:b 1.05s infinite ease-in-out;
}
.dots span:nth-child(2){animation-delay:.15s}
.dots span:nth-child(3){animation-delay:.3s}
@keyframes b{0%,80%,100%{transform:scale(.55);opacity:.4}40%{transform:scale(1);opacity:1}}

.err{background:var(--err-bg);border:1px solid var(--err-line);color:var(--err-ink);border-radius:16px;padding:12px 14px;margin:8px 0;font-size:14.5px}

/* ---------- Composer ---------- */
.composer{
  position:sticky;bottom:0;display:flex;gap:8px;align-items:flex-end;
  margin:0 12px;padding:8px 8px 8px 16px;
  background:var(--card);border:1.5px solid var(--line);border-radius:24px;
  box-shadow:var(--shadow);
}
.composer textarea{flex:1;border:0;outline:0;resize:none;font-size:16.5px;padding:8px 4px;max-height:160px;background:transparent;color:var(--ink)}
.composer textarea::placeholder{color:var(--muted)}
.send{
  flex:0 0 44px;height:44px;border-radius:50%;border:0;background:var(--accent);color:var(--accent-ink);
  cursor:pointer;display:grid;place-items:center;transition:transform .12s,opacity .15s;
}
.send:hover{transform:scale(1.04)}
.send:disabled{opacity:.4;cursor:not-allowed;transform:none}
.composer-note{text-align:center;font-size:12px;color:var(--muted);margin:8px 12px calc(12px + env(safe-area-inset-bottom))}

/* ---------- Paywall / dialogs ---------- */
dialog.sheet{
  border:1px solid var(--line);border-radius:24px;padding:22px 22px 24px;max-width:400px;
  width:calc(100% - 28px);text-align:center;background:var(--card);color:var(--ink);
  box-shadow:var(--shadow);
}
dialog::backdrop{background:rgba(0,0,0,.62)}
.sheet img{border-radius:16px}
.sheet h2{margin:10px 0 2px;font-size:22px;letter-spacing:-.3px}
.price{font-size:16px;margin:6px 0;color:var(--muted)}
.price b{font-size:32px;color:var(--ink);letter-spacing:-.6px}
.perks{text-align:left;padding-left:20px;line-height:1.75;font-size:14.5px}
.close-row{text-align:right;margin:-8px -6px 0}
.close-row button{border:0;background:none;font-size:20px;cursor:pointer;color:var(--muted);line-height:1;padding:4px 8px;border-radius:8px}
.close-row button:hover{color:var(--ink);background:var(--bg-elev)}
.row{display:flex;flex-wrap:wrap}
.pay-btns{margin-top:4px}

.toast{
  position:fixed;left:50%;bottom:96px;transform:translateX(-50%) translateY(8px);
  background:var(--toast-bg);color:var(--toast-ink);padding:11px 18px;border-radius:999px;
  font-size:14.5px;opacity:0;pointer-events:none;transition:opacity .25s,transform .25s;
  max-width:90%;text-align:center;z-index:20;box-shadow:var(--shadow);
}
.toast.show{opacity:1;transform:translateX(-50%) translateY(0)}

/* ---------- Legal / docs ---------- */
.doc{max-width:760px;margin:0 auto;padding:24px 18px 60px;line-height:1.65}
.doc h1{font-size:30px;letter-spacing:-.5px;margin:8px 0 12px}
.doc h2{font-size:19px;margin-top:28px;letter-spacing:-.2px}
.tpl{background:var(--notice-bg);border:1px solid var(--notice-line);color:var(--notice-ink);padding:12px 14px;border-radius:12px;font-size:14.5px}

/* ---------- Motion ---------- */
@keyframes fadeUp{from{opacity:0;transform:translateY(10px)}to{opacity:1;transform:none}}
@keyframes fadeIn{from{opacity:0}to{opacity:1}}
@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{animation:none!important;transition:none!important}
}

/* ---------- Desktop ---------- */
@media (min-width:900px){
  .thread{padding:28px 8px}
  .composer{margin:0}
  .q-bubble{max-width:70%}
  .card{padding:36px 32px}
  .empty{padding-top:11vh}
}
@media (max-width:420px){
  .card{padding:26px 18px}
  .q-bubble{max-width:92%}
}

/* Focus for keyboard users */
:focus-visible{outline:2px solid var(--focus);outline-offset:3px}
button:focus:not(:focus-visible),input:focus:not(:focus-visible),textarea:focus:not(:focus-visible){outline:none}

/* ---------- refined monochrome polish ---------- */
body{background-image:radial-gradient(900px 420px at 50% -180px,color-mix(in srgb,var(--ink) 7%,transparent),transparent 70%);background-repeat:no-repeat}
.card{border-radius:28px;box-shadow:0 1px 0 color-mix(in srgb,var(--ink) 6%,transparent) inset,var(--shadow)}
.card h1,.empty h2{letter-spacing:-.03em}
.brand{letter-spacing:-.03em}
.btn{letter-spacing:-.005em}
.btn.primary:hover{transform:translateY(-1px)}
input{transition:border-color .15s,box-shadow .2s,background .2s}
.top{border-bottom-color:color-mix(in srgb,var(--line) 70%,transparent)}