* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Segoe UI', sans-serif;
}

body {
  height: 100vh;
  background: #050a14;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  overflow: hidden;
}

/* Fundo animado */
.bg {
  position: absolute;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, #00ffff11 1px, transparent 1px);
  background-size: 50px 50px;
  animation: move 25s linear infinite;
}

@keyframes move {
  from { transform: translate(0,0); }
  to { transform: translate(-300px,-300px); }
}

.calc {
  position: relative;
  width: 320px;
  backdrop-filter: blur(25px);
  background: rgba(255,255,255,0.05);
  border-radius: 20px;
  padding: 20px;
  box-shadow: 0 0 50px #00ffff33;
}

.display {
  margin-bottom: 15px;
}

#history {
  font-size: 12px;
  color: #00ffffaa;
  min-height: 20px;
}

#result {
  width: 100%;
  font-size: 28px;
  background: transparent;
  border: none;
  color: white;
  text-align: right;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

button {
  padding: 15px;
  border: none;
  border-radius: 12px;
  background: rgba(255,255,255,0.08);
  color: white;
  font-size: 16px;
  cursor: pointer;
  transition: 0.2s;
}

button:hover {
  transform: scale(1.1);
  box-shadow: 0 0 10px #00ffff;
}

.equal {
  background: #00ffff;
  color: black;
}

.zero {
  grid-column: span 2;
}