:root {
  --accent: #007bff;
  --accent-bg: #eaf2ff;
  --fg: #1a1a1a;
  --fg-muted: #5a5a5a;
  --bg: #f7f7f5;
  --card-bg: #ffffff;
  --border: #e4e4e2;
  --font-sans: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic UI", "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--fg);
  line-height: 1.7;
  min-height: 100vh;
}

.app-header {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 12px 16px;
  background: var(--card-bg);
  border-bottom: 1px solid var(--border);
}
.app-header h1 { font-size: 1rem; margin: 0; font-weight: 500; color: var(--fg-muted); }
.app-header .back { color: var(--fg); text-decoration: none; font-size: .9rem; }
.app-header .back:hover { color: var(--accent); }

.app-wrapper {
  max-width: 680px;
  margin: 0 auto;
  padding: 28px 20px 60px;
}
.lede { margin: 0 0 24px; color: var(--fg-muted); font-size: .95rem; }

.form-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 24px;
  margin-bottom: 24px;
  box-shadow: 0 1px 3px rgba(0,0,0,.04);
}
.form-card h2 {
  font-size: 1.1rem;
  margin: 0 0 16px;
  color: var(--fg);
}

.field { display: block; margin-bottom: 14px; }
.field span {
  display: block;
  font-size: .85rem;
  color: var(--fg-muted);
  margin-bottom: 4px;
}
.field input[type="number"] {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 1rem;
  font-family: inherit;
  font-variant-numeric: tabular-nums;
  background: #fff;
  color: var(--fg);
}
.field input[type="number"]:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(0,123,255,.18);
}
.field input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
}

.result {
  margin-top: 18px;
  font-size: 1.4rem;
  font-weight: 700;
  background: var(--accent);
  color: #fff;
  padding: 14px;
  border-radius: 10px;
  text-align: center;
  font-variant-numeric: tabular-nums;
  box-shadow: 0 4px 12px rgba(0,123,255,.15);
}

.wp-content {
  margin: 40px 0 0;
  color: var(--fg-muted);
  line-height: 1.9;
}
.wp-content h2 {
  font-size: 1.1rem;
  color: var(--fg);
  margin: 24px 0 10px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}
.wp-content h2:first-child { border-top: none; padding-top: 0; margin-top: 0; }
.wp-content h3 { font-size: 1rem; margin: 16px 0 8px; color: var(--fg); }
.wp-content p { margin: 0 0 12px; }
.wp-content ul { padding-left: 1.4em; }
.wp-content .note { font-size: .85rem; opacity: .8; }

@media (max-width: 520px) {
  .app-wrapper { padding: 20px 14px 40px; }
  .form-card { padding: 18px; }
  .result { font-size: 1.2rem; }
}