html, body, main, header, footer {
  padding: 0px;
  margin: 0px;
}

#app {
  max-width: 720px;
  margin: 0 auto;
  padding: 20px 16px;
}

#app h1 {
  text-align: center;
  font-size: 1.6rem;
  color: #1a73e8;
  margin-bottom: 24px;
}

#calculator {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

#input-area {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.time-group {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}

.time-group label {
  font-size: 0.95rem;
  font-weight: 600;
  color: #333;
}

.time-inputs {
  display: flex;
  align-items: center;
  gap: 4px;
}

.time-input {
  width: 64px;
  height: 48px;
  text-align: center;
  font-size: 1.3rem;
  font-weight: 600;
  border: 2px solid #d0d0d0;
  border-radius: 8px;
  outline: none;
  background: #fff;
  color: #333;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
  -moz-appearance: textfield;
}

.time-input::-webkit-outer-spin-button,
.time-input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

.time-input:focus {
  border-color: #1a73e8;
  box-shadow: 0 0 0 3px rgba(26, 115, 232, 0.15);
}

.time-separator {
  font-size: 1.3rem;
  font-weight: 700;
  color: #666;
}

.icon-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border: 2px solid #d0d0d0;
  border-radius: 50%;
  background: #fff;
  color: #1a73e8;
  cursor: pointer;
  transition: background 0.2s ease, transform 0.3s ease, border-color 0.2s ease;
}

.icon-btn:hover {
  background: #e8f0fe;
  border-color: #1a73e8;
  transform: scale(1.05);
}

.icon-btn:active {
  transform: scale(0.95);
}

#swap-btn svg {
  transition: transform 0.3s ease;
}

#swap-btn:hover svg {
  transform: rotate(180deg);
}

#action-area {
  display: flex;
  gap: 12px;
  margin-top: 4px;
}

.action-btn {
  padding: 10px 28px;
  font-size: 1rem;
  font-weight: 600;
  color: #fff;
  background: #1a73e8;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.2s ease, transform 0.15s ease;
}

.action-btn:hover {
  background: #1557b0;
  transform: scale(1.03);
}

.action-btn:active {
  transform: scale(0.97);
}

#result-area {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.result-card {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 20px;
  background: #f8f9fa;
  border-radius: 10px;
  border: 1px solid #e8e8e8;
  animation: fadeInUp 0.4s ease both;
}

.result-card:nth-child(2) {
  animation-delay: 0.05s;
}

.result-card:nth-child(3) {
  animation-delay: 0.1s;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.result-label {
  font-size: 0.95rem;
  color: #666;
}

.result-value {
  font-size: 1.2rem;
  font-weight: 700;
  color: #1a73e8;
  font-variant-numeric: tabular-nums;
}

#features,
#scenarios,
#FAQ {
  max-width: 720px;
  margin: 24px auto 0;
}

#features h2,
#scenarios h2,
#FAQ h2 {
  font-size: 1.2rem;
  color: #333;
  margin-bottom: 8px;
}

#features p {
  font-size: 0.95rem;
  color: #555;
  line-height: 1.7;
}

#scenarios ul {
  padding-left: 20px;
}

#scenarios li {
  font-size: 0.95rem;
  color: #555;
  line-height: 1.8;
}

#FAQ dl {
  padding: 0;
}

#FAQ dt {
  font-size: 0.95rem;
  font-weight: 600;
  color: #333;
  margin-top: 12px;
}

#FAQ dd {
  font-size: 0.9rem;
  color: #666;
  margin-left: 0;
  margin-top: 4px;
  line-height: 1.6;
}

@media (min-width: 768px) {
  #calculator {
    flex-direction: row;
    gap: 32px;
  }

  #input-area {
    flex: 1;
  }

  #result-area {
    flex: 1;
    justify-content: center;
  }
}