:root{
  --bg:#f7f8fb;
  --card:#ffffff;
  --text:#1f2937;
  --muted:#6b7280;
  --primary:#2563eb;       /* น้ำเงินสดใส */
  --primary-600:#1d4ed8;
  --primary-100:#e0e7ff;
  --outline:#e5e7eb;
  --good:#10b981;
  --ok:#f59e0b;
  --bad:#ef4444;
  --shadow:0 6px 24px rgba(17,24,39,0.08);
  --radius:16px;
}

*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family:ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", "Liberation Sans", "Apple Color Emoji", "Segoe UI Emoji";
  background:var(--bg);
  color:var(--text);
}

/* Back Home button */
.back-home-btn{
  position:fixed;
  top:16px;
  right:16px;
  display:inline-block;
  background:var(--primary);
  color:#fff;
  padding:10px 14px;
  border-radius:10px;
  text-decoration:none;
  font-weight:700;
  box-shadow:var(--shadow);
  transition:.2s;
  z-index:10;
}
.back-home-btn:hover{ background:var(--primary-600); transform:translateY(-1px); }

.app{
  max-width:900px;
  margin:84px auto 32px;
  padding:0 16px;
}

.app-header{ text-align:center; margin-bottom:18px; }
.app-header h1{ margin:0 0 6px; font-size:clamp(22px,4vw,32px); }
.subtitle{ color:var(--muted); margin:0; }

.card{
  background:var(--card);
  border:1px solid var(--outline);
  border-radius:var(--radius);
  padding:18px;
  box-shadow:var(--shadow);
}

.output-row{
  display:flex; gap:10px; align-items:center; width:100%;
}
.output{
  flex:1; height:52px; padding:0 14px;
  border:1.5px solid var(--outline); border-radius:12px;
  font-size:18px; outline:none; background:#fff;
}
.output:focus{ border-color:var(--primary); box-shadow:0 0 0 3px var(--primary-100); }

.icon-btn{
  height:52px; width:52px; display:grid; place-items:center;
  background:#fff; border:1.5px solid var(--outline); border-radius:12px; cursor:pointer;
  transition:.2s;
}
.icon-btn:hover{ border-color:var(--primary); }
.icon-btn svg{ fill:var(--muted); }

.primary, .primary.outline, .ghost{
  height:46px; padding:0 16px; border-radius:12px; border:1.5px solid transparent;
  font-weight:700; cursor:pointer; transition:.2s;
}
.primary{ background:var(--primary); color:#fff; }
.primary:hover{ background:var(--primary-600); transform:translateY(-1px); }
.primary.outline{ background:#fff; color:var(--primary); border-color:var(--primary); }
.primary.outline:hover{ background:var(--primary-100); }

.ghost{ background:#fff; border-color:var(--outline); color:var(--text); }
.ghost:hover{ border-color:var(--primary); }

.strength{ margin-top:14px; }
.strength-bar{
  display:grid; grid-template-columns:repeat(4,1fr); gap:8px; margin-bottom:8px;
}
.strength-bar .s{
  height:10px; border-radius:999px; background:#e8ecf3; border:1px solid var(--outline);
  transition:background-color .25s, border-color .25s;
}
.strength-label{ color:var(--muted); font-size:14px; }
.strength-label strong{ color:var(--text); }
.entropy{ margin-left:6px; font-variant-numeric:tabular-nums; }

.controls-grid{
  display:grid; gap:16px; grid-template-columns:1fr;
  margin:18px 0 12px;
}
.control label{ display:block; font-weight:600; margin-bottom:8px; }
#lengthRange{ width:100%; accent-color:var(--primary); }

.toggles{
  display:grid;
  grid-template-columns:repeat(auto-fit,minmax(220px,1fr));
  gap:10px;
}
.toggle{
  display:flex; gap:10px; align-items:center;
  background:#fff; border:1.5px solid var(--outline); border-radius:12px; padding:10px;
}
.toggle input{ width:18px; height:18px; accent-color:var(--primary); }

.actions{ display:flex; gap:10px; flex-wrap:wrap; margin-top:4px; }

.hint{ color:var(--muted); margin-top:12px; }

.toast{
  position:fixed; left:50%; bottom:24px; transform:translateX(-50%) translateY(20px);
  background:#111827; color:#fff; padding:10px 14px; border-radius:10px; opacity:0;
  pointer-events:none; transition:.25s; box-shadow:var(--shadow); font-weight:700;
}
.toast.show{ opacity:1; transform:translateX(-50%) translateY(0); }

.footer{ text-align:center; color:var(--muted); font-size:14px; margin:22px 0 28px; }

/* Strength colors */
.s-on.bad{ background:var(--bad); border-color:var(--bad); }
.s-on.ok{ background:var(--ok); border-color:var(--ok); }
.s-on.good{ background:var(--good); border-color:var(--good); }

/* Responsive tweaks */
@media (min-width: 700px){
  .controls-grid{ grid-template-columns: 1.1fr 1fr; }
}