:root{
  --emerald:#0B5D4B;--emerald-2:#0e7a62;--emerald-d:#073e32;--gold:#D9B26A;--gold-d:#b8904a;
  --bg:#f6f4ee;--card:#ffffff;--ink:#14211d;--muted:#5b6b66;--line:#e3ddd0;
  --ok:#137a4b;--ok-bg:#e5f5ec;--warn:#8a5a00;--warn-bg:#fff3d6;--bad:#a1271b;--bad-bg:#fde8e5;--na:#55605c;--na-bg:#eef0ef;
  --r:16px;--shadow:0 1px 2px rgba(0,0,0,.05),0 6px 24px rgba(11,93,75,.07);
}
@media (prefers-color-scheme:dark){
  :root{--bg:#0d1513;--card:#15201d;--ink:#eef3f1;--muted:#a6b5b0;--line:#26332f;--ok-bg:#12382a;--ok:#7be0ae;--warn-bg:#3a2e12;--warn:#f3c56b;--bad-bg:#3d1a16;--bad:#ff9d90;--na-bg:#1f2a27;--na:#b7c2be;--shadow:none}
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font-family:"IBM Plex Sans Arabic",system-ui,-apple-system,"Segoe UI",Tahoma,sans-serif;font-size:17px;line-height:1.7}
a{color:var(--emerald-2)}
@media (prefers-color-scheme:dark){a{color:var(--gold)}}
.wrap{max-width:860px;margin:0 auto;padding:0 18px}
.top{background:var(--emerald);color:#fff}
.top .wrap{display:flex;align-items:center;gap:12px;min-height:60px}
.top a{color:#fff;text-decoration:none;display:flex;align-items:center;gap:10px;font-weight:700}
.top img{width:34px;height:34px;border-radius:9px}
.top .sp{flex:1}
.top .crumb{font-weight:500;opacity:.9;font-size:15px}
.hero{background:linear-gradient(180deg,var(--emerald) 0,var(--emerald-d) 100%);color:#fff;padding:34px 0 46px}
.hero h1{margin:0 0 8px;font-size:clamp(26px,6vw,40px);line-height:1.3}
.hero p{margin:0;opacity:.92;max-width:640px}
.hero .gold{color:var(--gold)}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--r);box-shadow:var(--shadow);padding:18px}
.lift{margin-top:-28px}
h2{font-size:21px;margin:28px 0 12px}
.grid{display:grid;gap:12px;grid-template-columns:1fr}
@media(min-width:720px){.grid{grid-template-columns:1fr 1fr}}
.tool{display:block;text-decoration:none;color:inherit;position:relative}
.tool h3{margin:6px 0 4px;font-size:19px}
.tool p{margin:0;color:var(--muted);font-size:15px}
.pill{display:inline-block;font-size:13px;font-weight:700;padding:2px 10px;border-radius:99px}
.pill.live{background:var(--ok-bg);color:var(--ok)}
.pill.soon{background:var(--na-bg);color:var(--na)}
.tool.live{border-color:var(--emerald-2);border-width:2px}
.tool.soon{opacity:.82}
.go{display:inline-block;margin-top:10px;font-weight:700;color:var(--emerald-2)}
.steps-how{display:grid;gap:10px;grid-template-columns:1fr}
@media(min-width:720px){.steps-how{grid-template-columns:repeat(3,1fr)}}
.num{display:inline-grid;place-items:center;width:30px;height:30px;border-radius:50%;background:var(--gold);color:#1d1606;font-weight:800;font-size:15px;flex:none}
.stat{font-size:15px;color:var(--muted)}
footer{color:var(--muted);font-size:14px;padding:30px 0 40px}
/* solver */
label.lbl{font-weight:700;display:block;margin-bottom:6px}
textarea{width:100%;min-height:96px;resize:vertical;border:1.5px solid var(--line);border-radius:12px;padding:12px 14px;font:inherit;font-size:18px;background:var(--bg);color:var(--ink);unicode-bidi:plaintext}
textarea:focus{outline:3px solid rgba(217,178,106,.45);border-color:var(--gold)}
.keys{display:flex;flex-wrap:wrap;gap:6px;margin:10px 0 2px;direction:ltr;justify-content:flex-end}
.keys button{min-width:42px;height:40px;border-radius:10px;border:1px solid var(--line);background:var(--card);color:var(--ink);font:inherit;font-size:17px;cursor:pointer}
.actions{display:flex;gap:10px;margin-top:12px;flex-wrap:wrap}
.btn{height:50px;border-radius:12px;border:0;padding:0 20px;font:inherit;font-weight:800;font-size:17px;cursor:pointer;display:inline-flex;align-items:center;gap:8px;justify-content:center}
.btn.primary{background:var(--emerald);color:#fff;flex:1;min-width:150px}
.btn.primary:disabled{opacity:.6;cursor:wait}
.btn.ghost{background:transparent;border:1.5px solid var(--line);color:var(--ink)}
.chips{display:flex;gap:8px;overflow-x:auto;padding:4px 0 2px;scrollbar-width:none}
.chips button{flex:none;border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:99px;padding:6px 12px;font:inherit;font-size:14px;cursor:pointer;white-space:nowrap}
.preview{display:none;align-items:center;gap:10px;margin-top:10px}
.preview img{max-height:90px;max-width:160px;border-radius:10px;border:1px solid var(--line)}
.muted{color:var(--muted);font-size:14px}
.badge{display:flex;gap:10px;align-items:flex-start;border-radius:12px;padding:10px 12px;font-weight:700}
.badge small{display:block;font-weight:500;font-size:14px;opacity:.9}
.badge.verified{background:var(--ok-bg);color:var(--ok)}
.badge.partial{background:var(--warn-bg);color:var(--warn)}
.badge.failed{background:var(--bad-bg);color:var(--bad)}
.badge.unchecked{background:var(--na-bg);color:var(--na)}
.understood{margin:14px 0 4px;padding:10px 12px;border:1px dashed var(--line);border-radius:12px}
.m{direction:ltr;unicode-bidi:isolate;overflow-x:auto;overflow-y:hidden;max-width:100%;padding:2px 0}
.m.disp{display:block;text-align:center;margin:6px 0}
.m:not(.disp){display:inline-block;vertical-align:middle;white-space:nowrap}
ol.steps{list-style:none;padding:0;margin:14px 0 0;counter-reset:s}
ol.steps li{display:flex;gap:12px;padding:12px 0;border-top:1px solid var(--line)}
ol.steps li:first-child{border-top:0}
ol.steps .body{flex:1;min-width:0}
.why{font-size:14px;color:var(--muted);margin-top:2px}
.why b{color:var(--gold-d)}
.answer{margin-top:14px;border-radius:14px;background:var(--emerald);color:#fff;padding:14px 16px}
.answer .lbl2{font-size:14px;opacity:.85}
.answer .m{font-size:1.25em}
.fb{display:flex;gap:8px;align-items:center;margin-top:12px;flex-wrap:wrap}
.fb button{border:1px solid var(--line);background:var(--card);color:var(--ink);border-radius:10px;padding:6px 12px;font:inherit;cursor:pointer}
.err{background:var(--bad-bg);color:var(--bad);border-radius:12px;padding:12px;font-weight:700}
.spinner{width:20px;height:20px;border:3px solid rgba(255,255,255,.35);border-top-color:#fff;border-radius:50%;animation:sp 0.8s linear infinite}
@keyframes sp{to{transform:rotate(360deg)}}
.loading{display:flex;gap:12px;align-items:center;color:var(--muted)}
.loading .spinner{border-color:var(--line);border-top-color:var(--emerald-2)}
.hidden{display:none!important}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0)}
.katex{font-size:1.08em}