:root {
  /* Core palette */
  --bg: #0b0d12;
  --bg-2: #0f1320;
  --fg: #e6e9ef;
  --muted: #a7b0be;
  --accent: #3cc47c;
  --accent-2: #2fb56f;
  --danger: #ff4d4f;

  /* Glass surfaces */
  --glass: rgba(255, 255, 255, 0.06);
  --glass-strong: rgba(255, 255, 255, 0.12);
  --glass-border: rgba(255, 255, 255, 0.14);
  --panel: rgba(16, 20, 34, 0.6);
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
  --radius: 14px;

  /* Ads */
  --ad-rail-w: 300px;
  --ad-rail-h: 600px;
  --ad-sticky-h: 64px;
  --ad-sticky-h-lg: 90px;
  --footer-extra: 28px; /* space for version line */
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif;
  color: var(--fg);
  /* Use modern formats when available; fall back to JPEG */
  background:
    radial-gradient(1200px 600px at -10% -10%, rgba(60, 196, 124, 0.12), transparent 60%),
    radial-gradient(800px 500px at 110% 10%, rgba(87, 101, 242, 0.12), transparent 60%),
    linear-gradient(180deg, rgba(11, 13, 18, 0.85), rgba(15, 19, 32, 0.85)),
    image-set(
      url('/public/bg.avif') type('image/avif'),
      url('/public/bg.webp') type('image/webp'),
      url('/public/bg.jpg') type('image/jpeg')
    ) center / cover no-repeat fixed;
}
a { color: var(--fg); text-decoration: none; }
/* Show focus only for keyboard users to avoid click highlight */
a:focus-visible, button:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
/* Avoid default focus ring on programmatic focus to main container */
main#app:focus { outline: none; }
.btn {
  background: var(--glass);
  color: var(--fg);
  border: 1px solid var(--glass-border);
  padding: .65rem .95rem;
  border-radius: var(--radius);
  cursor: pointer;
  backdrop-filter: saturate(125%) blur(10px);
  box-shadow: var(--shadow);
  transition: transform .12s ease, background .2s ease, border-color .2s ease;
}
.btn:hover { background: var(--glass-strong); transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn[disabled], .btn[aria-disabled="true"] { opacity: .6; cursor: not-allowed; }

/* Icon button */
.btn.btn-icon { width: 40px; height: 40px; padding: 0; display: inline-flex; align-items: center; justify-content: center; }
.btn.btn-icon svg, .btn.btn-icon i { width: 20px; height: 20px; color: var(--fg); display: block; font-size: 20px; line-height: 1; }
/* Visually hidden text helper */
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }

h1, h2, h3 { margin: .5rem 0 1rem; letter-spacing: 0.2px; }
p { color: var(--muted); }
.panel {
  background: var(--panel);
  padding: 1rem;
  border-radius: var(--radius);
  margin-block: 1rem;
  border: 1px solid var(--glass-border);
  backdrop-filter: blur(10px) saturate(120%);
  box-shadow: var(--shadow);
}

.ad { background: rgba(15,18,32,0.6); border: 1px dashed rgba(102,119,153,0.35); min-height: 60px; border-radius: var(--radius); }

/* KBD style for shortcuts */
.kbd { font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace; background: rgba(255,255,255,0.08); border: 1px solid var(--glass-border); padding: 0 .35rem; border-radius: 6px; }

/* Skip link */
.skip-link { position: absolute; left: -9999px; top: auto; width: 1px; height: 1px; overflow: hidden; }
.skip-link:focus { position: fixed; left: 1rem; top: 1rem; width: auto; height: auto; padding: .5rem .75rem; background: #111827; color: #fff; z-index: 1000; border-radius: 8px; border: 1px solid var(--glass-border); }