* { margin: 0; padding: 0; box-sizing: border-box; }
html, body { height: 100%; }
body {
  font-family: "Avenir Next", "Segoe UI", system-ui, -apple-system, sans-serif;
  background: #0b1118; color: #d9e6f2;
  overflow: hidden;
}
.btn-big {
  display: inline-block; border: 0; cursor: pointer;
  font: inherit; font-weight: 700; font-size: 1.05rem;
  letter-spacing: 0.06em; color: #06231a;
  background: linear-gradient(135deg, #77ffc4, #6ff2cf 55%, #56d9ff);
  padding: 0.85em 2.2em; border-radius: 99px;
  box-shadow: 0 0 24px rgba(119, 255, 196, 0.45), 0 6px 18px rgba(0,0,0,0.5);
  text-decoration: none;
  transition: transform 0.15s, box-shadow 0.15s;
}
.btn-big:hover { transform: translateY(-2px) scale(1.03); box-shadow: 0 0 34px rgba(119,255,196,0.65); }