*, *::before, *::after {
  box-sizing: border-box;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Microsoft YaHei", "Segoe UI", sans-serif;
  background: #f0f4f8;
  color: #1e293b;
  line-height: 1.6;
  min-height: 100vh;
}

header {
  width: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 16px 0;
  background: #ffffff;
  border-bottom: 1px solid #e2e8f0;
}

main {
  width: 100%;
}

#app {
  max-width: 680px;
  margin: 0 auto;
  padding: 32px 24px 48px;
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.card {
  background: #ffffff;
  border-radius: 16px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08), 0 4px 16px rgba(0, 0, 0, 0.04);
  padding: 32px;
  transition: box-shadow 0.3s ease;
}

.card:hover {
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.12), 0 8px 24px rgba(0, 0, 0, 0.06);
}

.card-title {
  margin: 0 0 8px;
  font-size: 1.5rem;
  font-weight: 700;
  color: #1e293b;
}

.card-desc {
  margin: 0 0 24px;
  font-size: 0.9rem;
  color: #64748b;
}

.input-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 16px;
}

.input-group label {
  font-size: 0.85rem;
  font-weight: 600;
  color: #475569;
}

.input-group input,
.input-group select {
  height: 44px;
  padding: 0 14px;
  font-size: 1rem;
  font-family: inherit;
  border: 1.5px solid #cbd5e1;
  border-radius: 10px;
  background: #f8fafc;
  color: #1e293b;
  transition: border-color 0.2s, box-shadow 0.2s;
  outline: none;
  width: 100%;
}

.input-group input:focus,
.input-group select:focus {
  border-color: #2563eb;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.12);
  background: #ffffff;
}

.input-group select {
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 36px;
}

.input-row {
  display: flex;
  gap: 16px;
}

.input-row .input-group {
  flex: 1;
}

.btn-primary {
  width: 100%;
  height: 48px;
  font-size: 1rem;
  font-weight: 600;
  font-family: inherit;
  color: #ffffff;
  background: #2563eb;
  border: none;
  border-radius: 12px;
  cursor: pointer;
  transition: background 0.2s, transform 0.1s, box-shadow 0.2s;
  letter-spacing: 0.02em;
}

.btn-primary:hover {
  background: #1d4ed8;
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.3);
}

.btn-primary:active {
  transform: scale(0.98);
}

.result-area {
  margin-top: 24px;
  padding: 24px;
  background: #f0f7ff;
  border-radius: 12px;
  border: 1px solid #dbeafe;
}

.result-area.hidden {
  display: none;
}

.result-main {
  text-align: center;
  font-size: 1.8rem;
  font-weight: 700;
  color: #1e40af;
  margin-bottom: 20px;
}

.result-sub {
  text-align: center;
  font-size: 1.1rem;
  color: #475569;
  margin-top: 8px;
}

.result-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 12px;
}

.result-item {
  background: #ffffff;
  border-radius: 10px;
  padding: 14px 10px;
  text-align: center;
  border: 1px solid #e2e8f0;
}

.result-item .label {
  display: block;
  font-size: 0.78rem;
  color: #64748b;
  margin-bottom: 4px;
}

.result-item .value {
  display: block;
  font-size: 1.1rem;
  font-weight: 700;
  color: #1e293b;
}

.result-dual {
  display: flex;
  gap: 16px;
}

.result-panel {
  flex: 1;
  background: #ffffff;
  border-radius: 12px;
  padding: 20px 16px;
  text-align: center;
  border: 1px solid #e2e8f0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
}

.panel-icon {
  font-size: 2.5rem;
}

.panel-title {
  font-size: 0.8rem;
  font-weight: 600;
  color: #64748b;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.panel-value {
  font-size: 1.3rem;
  font-weight: 700;
  color: #1e293b;
}

.panel-range {
  font-size: 0.8rem;
  color: #94a3b8;
}

.error-msg {
  margin-top: 16px;
  padding: 12px 16px;
  background: #fef2f2;
  border: 1px solid #fecaca;
  border-radius: 10px;
  color: #dc2626;
  font-size: 0.9rem;
  text-align: center;
}

.error-msg.hidden {
  display: none;
}

.count-up {
  animation: countFadeIn 0.5s ease-out;
}

@keyframes countFadeIn {
  0% {
    opacity: 0;
    transform: translateY(8px);
  }
  100% {
    opacity: 1;
    transform: translateY(0);
  }
}

#section-intro .intro-text {
  margin: 0 0 20px;
  font-size: 0.95rem;
  color: #475569;
  line-height: 1.8;
}

#section-intro .intro-text strong {
  color: #1e40af;
}

.intro-features {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
}

.feature-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 16px;
  background: #f8fafc;
  border-radius: 10px;
  border: 1px solid #e2e8f0;
}

.feature-icon {
  font-size: 1.4rem;
  flex-shrink: 0;
}

.feature-text {
  font-size: 0.85rem;
  color: #334155;
  font-weight: 500;
}

.scenario-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.scenario-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 16px;
  background: #f8fafc;
  border-radius: 12px;
  border: 1px solid #e2e8f0;
  transition: background 0.2s, border-color 0.2s;
}

.scenario-item:hover {
  background: #f0f7ff;
  border-color: #dbeafe;
}

.scenario-icon {
  font-size: 2rem;
  flex-shrink: 0;
  line-height: 1;
}

.scenario-content h4 {
  margin: 0 0 4px;
  font-size: 1rem;
  font-weight: 700;
  color: #1e293b;
}

.scenario-content p {
  margin: 0;
  font-size: 0.85rem;
  color: #64748b;
  line-height: 1.6;
}

footer {
  width: 100%;
  text-align: center;
  padding: 24px 16px;
  background: #ffffff;
  border-top: 1px solid #e2e8f0;
}

.page-info {
  font-size: 0.82rem;
  color: #94a3b8;
}

.page-info a {
  color: #64748b;
  text-decoration: none;
}

.page-info a:hover {
  color: #2563eb;
  text-decoration: underline;
}

@media (max-width: 767px) {
  #app {
    padding: 24px 24px 40px;
    gap: 24px;
  }
  .card {
    padding: 24px 20px;
    border-radius: 14px;
  }
  .card-title {
    font-size: 1.3rem;
  }
  .result-main {
    font-size: 1.5rem;
  }
  .result-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .result-dual {
    flex-direction: column;
  }
  .input-row {
    flex-direction: column;
    gap: 0;
  }
  .intro-features {
    grid-template-columns: 1fr 1fr;
  }
  .scenario-icon {
    font-size: 1.6rem;
  }
}

@media (max-width: 599px) {
  #app {
    padding: 20px 16px 36px;
    gap: 20px;
  }
  .card {
    padding: 20px 16px;
    border-radius: 12px;
  }
  .card-title {
    font-size: 1.2rem;
  }
  .card-desc {
    font-size: 0.82rem;
  }
  .result-main {
    font-size: 1.3rem;
  }
  .result-grid {
    grid-template-columns: 1fr 1fr;
    gap: 8px;
  }
  .result-item {
    padding: 10px 8px;
  }
  .result-item .value {
    font-size: 1rem;
  }
  .btn-primary {
    height: 44px;
    font-size: 0.95rem;
  }
  .intro-features {
    grid-template-columns: 1fr;
  }
  .scenario-item {
    gap: 12px;
    padding: 12px;
  }
  .scenario-icon {
    font-size: 1.4rem;
  }
  .scenario-content h4 {
    font-size: 0.9rem;
  }
  .scenario-content p {
    font-size: 0.8rem;
  }
}