* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html, body {
  height: 100%;
  font-family: 'Segoe UI', sans-serif;
  background: #000;
}

/* FUNDO */
.fundo {
  background: linear-gradient(45deg, #000, #960019);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: white;
  text-align: center;
  padding: 20px;
}

/* CALCULADORA */
.calculadora {
  background: rgba(0, 0, 0, 0.88);
  padding: 25px;
  border-radius: 20px;
  width: 320px;
  box-shadow: 0 0 20px rgba(220, 20, 60, 0.8);
  backdrop-filter: blur(4px);
  border: 1px solid rgba(255, 255, 255, 0.15);
}

/* TÍTULO */
.titulo {
  font-size: 2rem;
  margin-bottom: 20px;
  color: crimson;
  text-shadow: 0 0 8px crimson;
}

/* DISPLAY */
#resultado {
  width: 100%;
  font-size: 2rem;
  padding: 12px;
  margin-bottom: 20px;
  text-align: right;
  border-radius: 10px;
  border: none;
  background-color: #f6f6f6;
  color: #111;
  box-shadow: inset 0 0 10px #000;
}

/* TABELA */
table {
  width: 100%;
  border-spacing: 12px;
}

/* BOTÕES */
button {
  width: 100%;
  padding: 15px;
  font-size: 1.3rem;
  font-weight: bold;
  border: none;
  border-radius: 10px;
  background-color: #1c1c1c;
  color: #fff;
  cursor: pointer;
  transition: 0.2s ease;
  box-shadow: 0 0 10px rgba(255, 0, 30, 0.2);
}

button:hover {
  background-color: crimson;
  transform: scale(1.08);
  box-shadow: 0 0 12px crimson;
}

/* BOTÃO IGUAL */
.igual {
  height: 100%;
  background-color: darkred;
  box-shadow: 0 0 12px rgba(255, 0, 30, 0.4);
}

.igual:hover {
  background-color: crimson;
  box-shadow: 0 0 15px crimson;
}

/* RODAPÉ */
.rodape {
  margin-top: 25px;
  font-size: 1rem;
  opacity: 0.9;
  text-shadow: 0 0 6px crimson;
}

/* RESPONSIVO */
@media (max-width: 400px) {
  .calculadora {
    width: 90%;
  }

  #resultado {
    font-size: 1.7rem;
  }

  button {
    font-size: 1.1rem;
  }
}