:root {
  color-scheme: light;
  --accent: #2a5bff;
  --accent-hover: #1e4acc;
  --fg: #1a1a1a;
  --fg-muted: #5a5a5a;
  --bg: #f7f7f5;
  --card-bg: #ffffff;
  --input-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 12px; color: var(--fg); font-size: .95rem; }
.lede.muted { color: var(--fg-muted); margin-bottom: 24px; font-size: .88rem; }

.form-card {
  background: var(--card-bg); border: 1px solid var(--border); border-radius: 14px;
  padding: 24px; box-shadow: 0 1px 3px rgba(0,0,0,.04);
}

.field { display: block; margin-bottom: 14px; }
.field span { display: block; font-size: .85rem; color: var(--fg-muted); margin-bottom: 4px; }
.field input, .field select {
  width: 100%; max-width: 100%; min-width: 0; padding: 10px 12px; border: 1px solid var(--border);
  border-radius: 8px; font-size: 1rem; font-family: inherit; background: var(--input-bg); color: var(--fg);
}
.field input:focus, .field select:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px rgba(42,91,255,.15); }

#calcBtn {
  display: block; width: 100%; padding: 12px; background: var(--accent); color: #fff;
  border: none; border-radius: 10px; font-size: 1rem; font-weight: 600; font-family: inherit;
  cursor: pointer; margin-top: 10px; transition: background-color .2s;
}
#calcBtn:hover { background: var(--accent-hover); }

.section-heading { margin: 24px 0 10px; font-size: 1.05rem; color: var(--fg); }

.result {
  background: #eef3ff; color: var(--accent); padding: 16px; border-radius: 10px;
  text-align: center; font-variant-numeric: tabular-nums;
}
.result .amount { font-weight: 700; font-size: 1.4rem; }
.result .error { color: #cb2431; }

.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 h3 { font-size: 1rem; margin: 18px 0 8px; color: var(--fg); }
.wp-content p { margin: 0 0 12px; }
.wp-content ul { padding-left: 1.4em; }
.wp-content strong { color: var(--fg); }

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

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #121212;
  --card-bg: #1d1d1d;
  --input-bg: #2a2a2a;
  --fg: #f0f0f0;
  --fg-muted: #a0a0a0;
  --border: #2a2a2a;
  --accent: #5a82ff;
  --accent-hover: #2a5bff;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --bg: #121212;
    --card-bg: #1d1d1d;
    --input-bg: #2a2a2a;
    --fg: #f0f0f0;
    --fg-muted: #a0a0a0;
    --border: #2a2a2a;
    --accent: #5a82ff;
    --accent-hover: #2a5bff;
  }
}

.owt-theme-toggle {
  position: fixed;
  top: 10px;
  right: 12px;
  z-index: 9999;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  padding: 0;
  border: 1px solid rgba(127, 127, 127, 0.4);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.85);
  color: #333;
  cursor: pointer;
  font-size: 1.05rem;
  line-height: 1;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.06), 0 4px 12px rgba(0, 0, 0, 0.08);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: background .15s ease, border-color .15s ease, transform .15s ease;
}
.owt-theme-toggle:hover { transform: translateY(-1px); border-color: rgba(127, 127, 127, 0.7); }
.owt-theme-toggle:focus-visible { outline: 2px solid currentColor; outline-offset: 2px; }
:root[data-theme="dark"] .owt-theme-toggle {
  background: rgba(40, 40, 40, 0.85);
  color: #eee;
  border-color: rgba(200, 200, 200, 0.25);
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .owt-theme-toggle {
    background: rgba(40, 40, 40, 0.85);
    color: #eee;
    border-color: rgba(200, 200, 200, 0.25);
  }
}
@media print { .owt-theme-toggle { display: none; } }