:root {
  --fg: #1a1a1a;
  --bg: #fffaeb;
  --primary: #06c755;
  --primary-dark: #05b34c;
  --error: #c62828;
  --border: #d4c89a;
}
html, body {
  margin: 0;
  font-family: 'Hiragino Sans', 'Noto Sans JP', sans-serif;
  background: var(--bg);
  color: var(--fg);
  font-size: 16px;
  line-height: 1.6;
}
.centered {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 16px;
}
.card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  max-width: 480px;
  width: 100%;
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}
h1 { font-size: 22px; font-weight: 700; margin: 0 0 16px; line-height: 1.4; }
h2 { font-size: 18px; font-weight: 700; margin: 24px 0 8px; line-height: 1.4; }
.balance-big {
  font-size: 48px;
  font-weight: 700;
  color: var(--primary-dark);
  text-align: center;
  margin: 16px 0;
}
.units-big {
  font-size: 32px;
  font-weight: 700;
  text-align: center;
  color: var(--primary);
  margin-bottom: 24px;
}
.primary {
  display: block;
  width: 100%;
  min-height: 56px;
  font-size: 18px;
  font-weight: 700;
  color: #fff;
  background: var(--primary);
  border: none;
  border-radius: 8px;
  cursor: pointer;
  text-decoration: none;
  box-sizing: border-box;
  text-align: center;
  line-height: 56px;
  padding: 0;
}
button.primary:disabled { background: #999; cursor: not-allowed; }
.error { color: var(--error); font-weight: 700; }
.history { list-style: none; padding: 0; margin: 0; }
.history li { padding: 12px 0; border-bottom: 1px solid var(--border); font-size: 15px; }
input[type=text] {
  width: 100%;
  font-size: 20px;
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 6px;
  box-sizing: border-box;
}