body {
  margin: 0;
  font-family: 'Pretendard', 'Noto Sans KR', Arial, sans-serif;
  background: #f4f6fb;
  min-height: 100vh;
}

.top-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  position: sticky;
  top: 0;
  background: #2563eb;
  color: #fff;
  height: 56px;
  box-shadow: 0 2px 8px rgba(37,99,235,0.08);
  z-index: 10;
}

.home-btn {
  position: absolute;
  left: 16px;
  background: none;
  border: none;
  color: #fff;
  font-size: 1.5rem;
  cursor: pointer;
  padding: 0 8px;
  height: 100%;
  display: flex;
  align-items: center;
  transition: background 0.2s;
}
.home-btn:active {
  background: rgba(255,255,255,0.1);
}

.title {
  margin: 0;
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: 0.05em;
}

.calculator-container {
  display: flex;
  justify-content: center;
  align-items: flex-start;
  min-height: calc(100vh - 56px);
  padding: 32px 0 0 0;
}

.calculator {
  background: #fff;
  border-radius: 18px;
  box-shadow: 0 4px 24px rgba(37,99,235,0.10);
  padding: 24px 20px 20px 20px;
  width: 100%;
  max-width: 340px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.calculator-display {
  width: 100%;
  height: 48px;
  font-size: 2rem;
  border: none;
  border-radius: 8px;
  background: #f0f4ff;
  color: #2563eb;
  text-align: right;
  padding: 0 12px;
  margin-bottom: 8px;
  box-sizing: border-box;
}

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

.btn {
  font-size: 1.2rem;
  padding: 16px 0;
  border: none;
  border-radius: 8px;
  background: #e7edfb;
  color: #2563eb;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}
.btn:active {
  background: #d1e0fa;
}

.btn.operator {
  background: #2563eb;
  color: #fff;
}
.btn.operator:active {
  background: #1741a6;
}

.btn.equal {
  grid-column: span 4;
  background: #2563eb;
  color: #fff;
  font-size: 1.3rem;
  font-weight: 700;
  margin-top: 6px;
}
.btn.equal:active {
  background: #1741a6;
}

@media (max-width: 480px) {
  .calculator {
    max-width: 100vw;
    padding: 16px 4vw 16px 4vw;
  }
  .calculator-display {
    font-size: 1.4rem;
    height: 38px;
  }
  .btn {
    font-size: 1rem;
    padding: 12px 0;
  }
  .top-bar {
    height: 48px;
  }
}