:root {
  color-scheme: light dark;
  
  /* 色彩系统 */
  --bg: #f4f6fb;
  --card-bg: rgba(255, 255, 255, 0.95);
  --text: #1b2430;
  --accent: #2b8cff;
  --accent-dark: #1b6fd6;
  --accent-light: #60a5ff;
  --muted: #586174;
  --border: #dde3ef;
  --highlight: #fef3c7;
  --success: #10b981;
  
  /* 间距系统 */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  
  /* 圆角 */
  --radius-sm: 0.5rem;
  --radius-md: 0.75rem;
  --radius-lg: 1rem;
  --radius-xl: 1.25rem;
  
  /* 阴影 */
  --shadow-sm: 0 2px 8px rgba(27, 36, 48, 0.08);
  --shadow-md: 0 8px 24px rgba(27, 36, 48, 0.12);
  --shadow-lg: 0 20px 45px rgba(27, 36, 48, 0.15);
  --shadow-focus: 0 0 0 4px rgba(43, 140, 255, 0.15);
  
  font-family: "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: linear-gradient(145deg, #d7e3fc, #eef2ff);
  color: var(--text);
  display: flex;
  flex-direction: column;
  animation: fadeIn 0.5s ease-out;
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

.app-header,
.app-footer {
  text-align: center;
  padding: 1.5rem 1rem;
}

.app-header {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-sm);
}

.app-header h1 {
  margin-bottom: 0.5rem;
  font-size: clamp(1.5rem, 4vw, 2.5rem);
  font-weight: 700;
  letter-spacing: 0.05em;
  background: linear-gradient(135deg, var(--accent), var(--accent-dark));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.app-header p {
  margin: 0 auto;
  max-width: 38rem;
  color: var(--muted);
  font-size: 1.05rem;
  line-height: 1.6;
}

.efficiency-banner {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  margin-top: var(--spacing-sm);
  padding: 0.65rem 1rem;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, rgba(43, 140, 255, 0.16), rgba(43, 140, 255, 0.08));
  color: var(--accent-dark);
  font-weight: 600;
  box-shadow: var(--shadow-sm);
}

.efficiency-banner strong {
  color: var(--accent);
}

.app-main {
  flex: 1;
  display: grid;
  gap: 1.5rem;
  padding: 1.5rem;
}

.card {
  background: var(--card-bg);
  border: 1px solid rgba(255, 255, 255, 0.8);
  border-radius: var(--radius-xl);
  padding: var(--spacing-lg);
  box-shadow: var(--shadow-lg);
  backdrop-filter: blur(16px);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  animation: slideUp 0.5s ease-out;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 24px 56px rgba(27, 36, 48, 0.18);
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.card h2 {
  margin-top: 0;
  margin-bottom: var(--spacing-lg);
  color: var(--text);
  font-size: 1.5rem;
  font-weight: 600;
}

.inputs-card form {
  display: grid;
  gap: var(--spacing-lg);
}

label {
  font-weight: 600;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  color: var(--text);
  font-size: 0.95rem;
}

.efficiency-control {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.efficiency-control select,
.efficiency-control input {
  flex: 1 1 0;
}

.efficiency-control input[hidden] {
  display: none;
}

input,
select {
  padding: 0.85rem 1rem;
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-family: inherit;
  background: rgba(255, 255, 255, 0.6);
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

input:hover,
select:hover {
  border-color: var(--accent-light);
  background: rgba(255, 255, 255, 0.8);
}

input:focus,
select:focus {
  outline: none;
  border-color: var(--accent);
  background: #fff;
  box-shadow: var(--shadow-focus);
  transform: translateY(-1px);
}

.btn-primary,
.btn-secondary {
  padding: 0.9rem 1.5rem;
  border: none;
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-dark));
  color: #fff;
  box-shadow: 0 8px 20px rgba(43, 140, 255, 0.35);
}

.btn-primary:hover {
  box-shadow: 0 12px 28px rgba(43, 140, 255, 0.45);
  transform: translateY(-2px);
}

.btn-primary:active {
  transform: translateY(0);
  box-shadow: 0 4px 12px rgba(43, 140, 255, 0.3);
}

.btn-secondary {
  background: rgba(27, 36, 48, 0.06);
  color: var(--text);
  border: 2px solid var(--border);
}

.btn-secondary:hover {
  background: rgba(27, 36, 48, 0.1);
  border-color: var(--accent-light);
  transform: translateY(-1px);
}

.btn-secondary:active {
  transform: translateY(0);
}

.results-card {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  animation-delay: 0.1s;
}

.result-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 1.05rem;
  padding: 1rem 1.25rem;
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, rgba(255, 255, 255, 0.8), rgba(255, 255, 255, 0.6));
  transition: all 0.3s ease;
  animation: resultFadeIn 0.5s ease-out;
}

.result-item:hover {
  border-color: var(--accent-light);
  transform: translateX(4px);
  box-shadow: var(--shadow-sm);
}

@keyframes resultFadeIn {
  from {
    opacity: 0;
    transform: translateX(-10px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.result-label {
  color: var(--muted);
  font-weight: 500;
}

.result-value {
  font-weight: 700;
  color: var(--accent-dark);
  font-size: 1.15rem;
}

.result-note {
  margin-top: var(--spacing-sm);
  padding: var(--spacing-md);
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.5;
  background: rgba(43, 140, 255, 0.05);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-sm);
}

.app-footer small {
  color: var(--muted);
}

/* 平板及以上 */
@media (min-width: 768px) {
  .app-main {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    padding: 2rem 5vw;
    gap: 2rem;
    max-width: 1400px;
    margin: 0 auto;
  }

  .card {
    padding: var(--spacing-xl);
  }

  .card h2 {
    font-size: 1.65rem;
  }

  .result-item {
    font-size: 1.1rem;
    padding: 1.25rem 1.5rem;
  }

  .result-value {
    font-size: 1.25rem;
  }
}

/* 移动端优化 */
@media (max-width: 767px) {
  .app-header {
    padding: 1.25rem 1rem;
  }

  .app-header h1 {
    font-size: clamp(1.35rem, 6vw, 2rem);
  }

  .app-header p {
    font-size: 0.95rem;
  }

  .efficiency-banner {
    width: 100%;
    justify-content: center;
    text-align: center;
    flex-wrap: wrap;
  }

  .efficiency-control {
    flex-direction: column;
    align-items: stretch;
  }

  input,
  select {
    font-size: 16px; /* 防止iOS缩放 */
    padding: 0.9rem 1rem;
  }

  .btn-primary,
  .btn-secondary {
    padding: 1rem 1.25rem;
    font-size: 1.05rem;
    min-height: 48px; /* 触摸友好 */
  }

  .result-item {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--spacing-sm);
  }

  .result-value {
    font-size: 1.3rem;
  }
}

/* 深色模式优化 */
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f172a;
    --card-bg: rgba(30, 41, 59, 0.9);
    --text: #f1f5f9;
    --accent: #60a5fa;
    --accent-dark: #3b82f6;
    --accent-light: #93c5fd;
    --muted: #94a3b8;
    --border: rgba(148, 163, 184, 0.2);
    --highlight: #422006;
    --success: #34d399;
    
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 20px 45px rgba(0, 0, 0, 0.5);
    --shadow-focus: 0 0 0 4px rgba(96, 165, 250, 0.2);
  }

  body {
    background: linear-gradient(145deg, #1e293b, #0f172a);
  }

  .card {
    border-color: rgba(148, 163, 184, 0.15);
    box-shadow: var(--shadow-lg), 0 0 0 1px rgba(148, 163, 184, 0.1);
  }

  .card:hover {
    box-shadow: 0 24px 56px rgba(0, 0, 0, 0.6), 0 0 0 1px rgba(148, 163, 184, 0.15);
  }

  input,
  select {
    background: rgba(30, 41, 59, 0.6);
    border-color: rgba(148, 163, 184, 0.2);
    color: var(--text);
  }

  input:hover,
  select:hover {
    background: rgba(30, 41, 59, 0.8);
  }

  input:focus,
  select:focus {
    background: rgba(30, 41, 59, 0.95);
  }

  .btn-primary {
    box-shadow: 0 8px 20px rgba(96, 165, 250, 0.25);
  }

  .btn-primary:hover {
    box-shadow: 0 12px 28px rgba(96, 165, 250, 0.35);
  }

  .btn-secondary {
    background: rgba(148, 163, 184, 0.1);
    border-color: rgba(148, 163, 184, 0.2);
  }

  .btn-secondary:hover {
    background: rgba(148, 163, 184, 0.15);
    border-color: var(--accent-light);
  }

  .result-item {
    background: linear-gradient(135deg, rgba(30, 41, 59, 0.8), rgba(30, 41, 59, 0.6));
    border-color: rgba(148, 163, 184, 0.2);
  }

  .result-item:hover {
    border-color: var(--accent);
    background: linear-gradient(135deg, rgba(30, 41, 59, 0.9), rgba(30, 41, 59, 0.7));
  }

  .result-value {
    color: var(--accent-light);
  }

  .result-note {
    background: rgba(96, 165, 250, 0.08);
    border-left-color: var(--accent);
  }
}