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

body {
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background: linear-gradient(135deg, #0f172a, #1e3a8a, #0f172a);
  background-size: 400% 400%;
  animation: gradientMove 12s ease infinite;
  padding: 20px;
}

@keyframes gradientMove {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

.container {
  width: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
}

.calculator {
  width: 360px;
  max-width: 95%;
  padding: 25px;
  border-radius: 28px;
  background: rgba(255, 255, 255, 0.08);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  border: 1px solid rgba(255, 255, 255, 0.15);
  box-shadow: 
    0 20px 50px rgba(0, 0, 0, 0.45),
    inset 0 1px 0 rgba(255, 255, 255, 0.08);
}

.title {
  text-align: center;
  color: #ffffff;
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 20px;
  letter-spacing: 1px;
  text-shadow: 0 0 12px rgba(255, 255, 255, 0.15);
}

.input-section {
  margin-bottom: 20px;
}

.input-section input {
  width: 100%;
  height: 85px;
  border: none;
  outline: none;
  border-radius: 18px;
  padding: 0 20px;
  text-align: right;
  font-size: 2.4rem;
  color: #ffffff;
  background: rgba(255, 255, 255, 0.08);
  box-shadow: 
    inset 0 4px 12px rgba(0, 0, 0, 0.35),
    0 8px 20px rgba(0, 0, 0, 0.18);
}

.row {
  display: flex;
  justify-content: space-between;
  margin: 12px 0;
  gap: 12px;
}

.row input {
  flex: 1;
  height: 62px;
  border: none;
  outline: none;
  border-radius: 18px;
  font-size: 1.25rem;
  font-weight: 600;
  color: #ffffff;
  cursor: pointer;
  background: rgba(255, 255, 255, 0.08);
  box-shadow: 
    0 8px 18px rgba(0, 0, 0, 0.25),
    inset 0 1px 0 rgba(255, 255, 255, 0.08);
  transition: all 0.2s ease;
}

.row input:hover {
  transform: translateY(-2px);
  background: rgba(255, 255, 255, 0.14);
  box-shadow: 
    0 12px 22px rgba(0, 0, 0, 0.35),
    0 0 10px rgba(59, 130, 246, 0.2);
}

.row input:active {
  transform: scale(0.96);
}

.row .operator {
  color: #38bdf8;
  font-weight: 700;
  background: rgba(56, 189, 248, 0.12);
}

.row .operator:hover {
  background: rgba(56, 189, 248, 0.22);
  box-shadow: 
    0 12px 22px rgba(0, 0, 0, 0.35),
    0 0 12px rgba(56, 189, 248, 0.35);
}

.row .top-btn {
  color: #f8fafc;
  background: rgba(148, 163, 184, 0.12);
}

.row .top-btn:hover {
  background: rgba(148, 163, 184, 0.22);
}

.row .equal {
  flex: 2.15;
  background: linear-gradient(135deg, #2563eb, #06b6d4);
  color: #ffffff;
  font-size: 1.35rem;
  font-weight: 800;
}

.row .equal:hover {
  background: linear-gradient(135deg, #1d4ed8, #0891b2);
  box-shadow: 
    0 14px 28px rgba(0, 0, 0, 0.35),
    0 0 18px rgba(37, 99, 235, 0.45);
}

@media (max-width: 480px) {
  .calculator {
    width: 100%;
    padding: 18px;
    border-radius: 22px;
  }

  .input-section input {
    height: 75px;
    font-size: 2rem;
  }

  .row input {
    height: 56px;
    font-size: 1.1rem;
    border-radius: 14px;
  }

  .title {
    font-size: 1.2rem;
  }
}