/* ============================================================
   AutomataLab · Simulator App Shell
   Light premium theme (Apple/Linear/Stripe-inspired) — matches
   the redesigned landing page. Same class names as before so
   the four module pages didn't need structural changes.
   ============================================================ */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0;}
:root{
  --bg:#FAFBFF; --bg-1:#F2F4FC; --surface:rgba(255,255,255,0.72); --surface-2:#F6F7FD;
  --border:rgba(15,23,42,0.09); --border-soft:rgba(15,23,42,0.06);
  --text:#0F172A; --text-dim:#4B5468; --text-dimmer:#94A0B8;
  --blue:#4F46E5; --blue-soft:rgba(79,70,229,0.12); --purple:#8B5CF6; --purple-soft:rgba(139,92,246,0.12);
  --cyan:#06B6D4; --cyan-soft:rgba(6,182,212,0.12); --green:#0FA968; --green-soft:rgba(15,169,104,0.12);
  --orange:#F59E0B; --orange-soft:rgba(245,158,11,0.12); --red:#E11D48; --red-soft:rgba(225,29,72,0.1);
  --radius-lg:28px; --radius-md:18px; --radius-sm:12px;
  --font-display:'Space Grotesk','Inter',sans-serif;
  --font-body:'Inter',sans-serif;
  --font-mono:'JetBrains Mono',monospace;
  --shadow-soft: 0 20px 60px -24px rgba(15,23,42,0.16);
}
html{scroll-behavior:smooth;}
body{background:var(--bg);color:var(--text);font-family:var(--font-body);line-height:1.55;min-height:100vh;}
a{color:inherit;text-decoration:none;}
h1,h2,h3,h4{font-family:var(--font-display);font-weight:600;letter-spacing:-0.02em;}
button{font-family:inherit;cursor:pointer;}
::selection{background:var(--purple-soft);color:var(--blue);}

.wrap{max-width:1280px;margin:0 auto;padding:0 28px;}
@media (max-width:640px){.wrap{padding:0 18px;}}

/* ---------- Top bar ---------- */
.app-nav{
  position:sticky;top:0;z-index:50;
  background:rgba(255,255,255,0.78);backdrop-filter:blur(14px) saturate(180%);
  border-bottom:1px solid var(--border-soft);
}
.app-nav-inner{display:flex;align-items:center;justify-content:space-between;padding:14px 0;flex-wrap:wrap;gap:12px;}
.app-logo{display:flex;align-items:center;gap:9px;font-family:var(--font-display);font-weight:700;font-size:17px;color:var(--text);}
.app-logo svg{width:26px;height:26px;}
.app-tabs-nav{display:flex;gap:6px;flex-wrap:wrap;background:rgba(15,23,42,0.03);border:1px solid var(--border-soft);padding:4px;border-radius:100px;}
.app-tabs-nav a{
  font-size:13.5px;color:var(--text-dim);padding:8px 14px;border-radius:100px;
  border:1px solid transparent;transition:all .2s;font-weight:500;
}
.app-tabs-nav a:hover{color:var(--text);background:rgba(255,255,255,0.9);}
.app-tabs-nav a.active{color:var(--text);background:#fff;border-color:var(--border);box-shadow:0 1px 2px rgba(15,23,42,0.06);}
.back-home{font-size:13px;color:var(--text-dim);display:flex;align-items:center;gap:6px;}
.back-home:hover{color:var(--blue);}
.back-home svg{width:15px;height:15px;}

/* ---------- Header ---------- */
.module-header{padding:44px 0 8px;}
.module-eyebrow{font-family:var(--font-mono);font-size:12px;letter-spacing:0.07em;text-transform:uppercase;color:var(--blue);font-weight:600;}
.module-header h1{font-size:clamp(26px,3.4vw,36px);margin:10px 0 10px;}
.module-header p{color:var(--text-dim);max-width:640px;font-size:15px;}

/* ---------- Layout ---------- */
.app-grid{display:grid;grid-template-columns:380px 1fr;gap:24px;padding:28px 0 90px;align-items:start;}
@media (max-width:960px){.app-grid{grid-template-columns:1fr;}}

.panel{
  background:var(--surface);backdrop-filter:blur(16px);
  border:1px solid var(--border);border-radius:var(--radius-md);padding:22px;
  box-shadow:var(--shadow-soft);
}
.panel + .panel{margin-top:20px;}
.panel h3{font-size:15px;margin-bottom:16px;display:flex;align-items:center;gap:8px;}
.panel h3 svg{width:17px;height:17px;color:var(--blue);}

/* ---------- Form controls ---------- */
label{display:block;font-size:12.5px;color:var(--text-dimmer);margin-bottom:6px;font-family:var(--font-mono);text-transform:uppercase;letter-spacing:0.04em;}
.field{margin-bottom:16px;}
input[type=text], textarea{
  width:100%;background:#fff;border:1px solid var(--border);
  border-radius:10px;padding:10px 13px;color:var(--text);font-family:var(--font-mono);font-size:13.5px;
  transition:border-color .2s, box-shadow .2s;
}
textarea{resize:vertical;min-height:84px;line-height:1.7;}
input[type=text]:focus, textarea:focus{outline:none;border-color:var(--blue);box-shadow:0 0 0 3px var(--blue-soft);}
.hint{font-size:11.5px;color:var(--text-dimmer);margin-top:5px;font-family:var(--font-body);}
.hint code{background:rgba(15,23,42,0.05);padding:1px 5px;border-radius:4px;}

.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  font-size:14px;font-weight:600;padding:11px 20px;border-radius:100px;border:none;
  transition:transform .2s ease, box-shadow .2s ease;width:100%;
}
.btn-primary{background:linear-gradient(135deg, var(--blue), var(--purple));color:#fff;box-shadow:0 10px 26px -8px rgba(79,70,229,0.45);}
.btn-primary:hover{transform:translateY(-1px);box-shadow:0 14px 32px -8px rgba(139,92,246,0.5);}
.btn-primary:active{transform:scale(0.98);}
.btn-row{display:flex;gap:10px;}
.btn-row .btn{width:auto;flex:1;}
.btn-secondary{background:rgba(255,255,255,0.8);color:var(--text);border:1px solid var(--border);}

.example-chips{display:flex;gap:8px;flex-wrap:wrap;margin-top:8px;}
.chip{
  font-family:var(--font-mono);font-size:11.5px;color:var(--text-dim);
  background:#fff;border:1px solid var(--border);
  padding:5px 11px;border-radius:100px;transition:all .2s;
}
.chip:hover{border-color:var(--blue);color:var(--blue);}

/* ---------- Result / status ---------- */
.result-banner{
  display:flex;align-items:center;gap:10px;padding:14px 18px;border-radius:12px;
  font-family:var(--font-mono);font-weight:600;font-size:14px;margin-bottom:18px;
}
.result-accept{background:var(--green-soft);color:var(--green);border:1px solid rgba(15,169,104,0.3);}
.result-reject{background:var(--red-soft);color:var(--red);border:1px solid rgba(225,29,72,0.3);}
.result-neutral{background:rgba(15,23,42,0.03);color:var(--text-dim);border:1px solid var(--border);}

.error-box{
  background:var(--red-soft);border:1px solid rgba(225,29,72,0.3);color:#B00834;
  padding:12px 16px;border-radius:10px;font-size:13px;margin-bottom:16px;font-family:var(--font-mono);
  white-space:pre-line;
}

/* ---------- Diagram ---------- */
.al-diagram{width:100%;height:auto;display:block;}
.al-node-label{fill:#0F172A;font-size:13px;font-family:'JetBrains Mono',monospace;}
.al-edge-label{fill:#4B5468;font-size:11px;font-family:'JetBrains Mono',monospace;}
.al-node-active{filter:drop-shadow(0 0 8px currentColor);}
.al-empty{color:var(--text-dimmer);font-size:13px;text-align:center;padding:30px 0;}
.diagram-box{background:var(--surface-2);border:1px solid var(--border-soft);border-radius:12px;padding:8px;overflow-x:auto;}

/* ---------- Table ---------- */
table.data-table{width:100%;border-collapse:collapse;font-family:var(--font-mono);font-size:12.5px;}
table.data-table th, table.data-table td{padding:9px 10px;text-align:center;border-bottom:1px solid var(--border-soft);}
table.data-table th{color:var(--text-dimmer);font-weight:500;}
table.data-table td{color:var(--text-dim);}
table.data-table tr.state-start td:first-child::before{content:"→ ";color:var(--text-dimmer);}
table.data-table tr.state-accept td:first-child{color:var(--green);font-weight:600;}
table.data-table td.hl{background:rgba(6,182,212,0.08);color:var(--cyan);border-radius:6px;}

/* ---------- Trace list ---------- */
.trace-list{display:flex;flex-direction:column;gap:0;}
.trace-row{display:grid;grid-template-columns:34px 1fr auto;gap:10px;align-items:center;padding:9px 0;border-bottom:1px solid var(--border-soft);font-family:var(--font-mono);font-size:12.5px;}
.trace-row:last-child{border-bottom:none;}
.trace-idx{color:var(--text-dimmer);}
.trace-states{color:var(--text);display:flex;gap:6px;flex-wrap:wrap;}
.trace-states span{background:rgba(15,23,42,0.04);border:1px solid var(--border);padding:2px 8px;border-radius:100px;}
.trace-sym{color:var(--blue);}

/* ---------- Stack visualization ---------- */
.stack-vis{display:flex;flex-direction:column-reverse;gap:6px;align-items:center;padding:10px 0;min-height:60px;}
.stack-item{font-family:var(--font-mono);font-size:13px;min-width:64px;text-align:center;padding:7px 10px;border:1px solid var(--border);border-radius:6px;background:#fff;}
.stack-item.top{border-color:var(--orange);color:var(--orange);}
.stack-empty{color:var(--text-dimmer);font-size:12.5px;font-family:var(--font-mono);}

/* ---------- Steps / logs ---------- */
.step-list{display:flex;flex-direction:column;}
.step-row{padding:12px 0;border-bottom:1px solid var(--border-soft);}
.step-row:last-child{border-bottom:none;}
.step-row b{font-size:13px;display:block;margin-bottom:6px;color:var(--text);}
.step-row pre{font-family:var(--font-mono);font-size:12px;color:var(--text-dim);white-space:pre-wrap;background:var(--surface-2);padding:10px 12px;border-radius:8px;}

/* ---------- Hierarchy rings ---------- */
.hier-rings{position:relative;width:100%;aspect-ratio:1.3/1;display:flex;align-items:center;justify-content:center;margin:8px 0;}
.ring{position:absolute;border-radius:50%;border:1.5px solid var(--border);display:flex;align-items:flex-start;justify-content:center;padding-top:10px;transition:all .3s;}
.ring span{font-family:var(--font-mono);font-size:10px;color:var(--text-dim);text-align:center;padding:0 8px;}
.ring.detected{border-color:var(--green);background:var(--green-soft);box-shadow:0 0 0 5px var(--green-soft);}
.ring.detected span{color:var(--green);font-weight:700;}

/* ---------- Two column grid ---------- */
.two-col{display:grid;grid-template-columns:1fr 1fr;gap:16px;}
@media (max-width:640px){.two-col{grid-template-columns:1fr;}}

.badge{display:inline-flex;align-items:center;gap:6px;font-family:var(--font-mono);font-size:11.5px;padding:4px 10px;border-radius:100px;background:rgba(15,23,42,0.03);border:1px solid var(--border);color:var(--text-dim);}