:root{
  --bg:#0b0d10;
  --panel:#0f1317;
  --muted:#98a0ab;
  --accent:#2aa86b; /* green accent */
  --accent-strong:#38e78e;
  --white:#ffffff;
  --glass: rgba(255,255,255,0.03);
}
html,body{height:100%;}
body{
  margin:0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
  background: linear-gradient(180deg, #07080a 0%, #0b0d10 100%);
  color:var(--white);
  display:flex;
  align-items:center;
  justify-content:center;
}
.card{
  width:880px;
  max-width:94vw;
  background:linear-gradient(180deg, rgba(255,255,255,0.02), rgba(255,255,255,0.01));
  border-radius:14px;
  padding:28px;
  box-shadow: 0 6px 30px rgba(2,6,12,0.7);
  border:1px solid rgba(255,255,255,0.03);
  text-align:center;
}
.header{
  margin-bottom:18px;
}
h1{margin:0 0 8px 0;font-size:20px;font-weight:600;color:var(--white)}
p.lead{margin:0;color:var(--muted);font-size:13px}

.controls{
  display:flex;
  gap:12px;
  justify-content:center;
  margin-bottom:14px;
}
.toggle{
  appearance:none;
  -webkit-appearance:none;
  padding:8px 12px;
  border-radius:8px;
  border:1px solid rgba(255,255,255,0.04);
  background:var(--glass);
  color:var(--muted);
  cursor:pointer;
  font-size:13px;
  transition:all .12s ease;
  min-width:92px;
}
.toggle.active{
  background: linear-gradient(90deg, rgba(56,231,142,0.10), rgba(42,168,107,0.06));
  color:var(--accent-strong);
  box-shadow: 0 6px 18px rgba(20,60,90,0.12);
  transform:translateY(-2px);
  border-color: rgba(38,166,97,0.15);
}

.start-wrap{display:flex;justify-content:center;margin-bottom:18px}
.start-btn{
  padding:12px 22px;
  border-radius:12px;
  border:1px solid rgba(255,255,255,0.04);
  background:linear-gradient(180deg,#172022,#0f1417);
  color:var(--white);
  font-weight:600;
  cursor:pointer;
  font-size:15px;
  box-shadow: 0 8px 30px rgba(2,6,12,0.6);
  transition:transform .08s ease, box-shadow .08s ease;
}
.start-btn:active{transform:translateY(1px);}

.output{
  margin-top:8px;
  min-height:160px;
  max-height:380px;
  overflow:auto;
  background:rgba(255,255,255,0.02);
  border-radius:10px;
  padding:18px;
  text-align:left;
  font-size:16px;
  line-height:1.5;
  color:var(--white);
  border:1px solid rgba(255,255,255,0.02);
  white-space:pre-wrap;
}

.small-note{margin-top:12px;color:var(--muted);font-size:13px}

/* responsive */
@media (max-width:520px){
  .controls{gap:8px;flex-wrap:wrap}
  .toggle{min-width:78px;padding:8px}
}