:root {
  --color-bg: #05070f;
  --color-panel: #0c1124;
  --color-panel-raised: #121a33;
  --color-panel-border: #1f2a4a;
  --color-text: #eef1fb;
  --color-text-muted: #9aa6c8;
  --color-accent: #f2cf7e;
  --color-accent-soft: rgba(242, 207, 126, 0.14);
  --color-accent-text: #1a1406;
  --color-input-bg: #070b18;
  --color-error: #ff9d8f;
  --font-sans: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  --font-serif: "Hiragino Mincho ProN", "Yu Mincho", "Noto Serif JP", serif;
  --radius-card: 20px;
  --radius-control: 12px;
  color-scheme: dark;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  /* 上から夜空が深くなっていくような背景にして、星図と地続きに見せる */
  background:
    radial-gradient(ellipse 80% 50% at 50% -10%, rgba(60, 90, 180, 0.28), transparent 70%),
    var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-sans);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

/* ---- ヘッダー ---- */
.site-header {
  padding: 56px 16px 40px;
  text-align: center;
}

.site-header h1 {
  margin: 0;
  font-family: var(--font-serif);
  font-size: clamp(2.2rem, 6vw, 3.4rem);
  font-weight: 500;
  letter-spacing: 0.16em;
}

.site-tagline {
  margin: 4px 0 16px;
  font-family: var(--font-serif);
  font-size: clamp(1rem, 2.4vw, 1.25rem);
  letter-spacing: 0.1em;
}

.site-lead {
  margin: 0;
  color: var(--color-text-muted);
  font-size: 0.95rem;
}

/* ---- 全体の配置 ----
   PC: 左に入力と設定、右に星空（スクロールしても星空が見え続ける）
   スマホ: 入力 → 星空 → 設定 → 空の要約 の順に縦へ並べる */
.layout {
  display: grid;
  grid-template-columns: minmax(340px, 440px) minmax(0, 1fr);
  grid-template-areas:
    "input chart"
    "custom chart"
    "info chart";
  gap: 24px 40px;
  align-items: start;
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 16px 64px;
}

.step-card { grid-area: input; }
.chart { grid-area: chart; }
.customize { grid-area: custom; }
.summary { grid-area: info; }

.card {
  padding: 28px;
  background: var(--color-panel);
  border: 1px solid var(--color-panel-border);
  border-radius: var(--radius-card);
}

/* ---- 手順の見出し ---- */
.step + .step {
  margin-top: 28px;
  padding-top: 24px;
  border-top: 1px solid var(--color-panel-border);
}

.step-title {
  display: flex;
  gap: 12px;
  align-items: center;
  margin: 0 0 16px;
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.step-number {
  display: inline-grid;
  flex: none;
  place-items: center;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--color-accent);
  color: var(--color-accent-text);
  font-size: 0.95rem;
  font-weight: 700;
}

.step-lead {
  margin: -8px 0 20px 42px;
  color: var(--color-text-muted);
  font-size: 0.88rem;
}

/* ---- ボタン ---- */
.button-primary,
.button-secondary {
  min-height: 48px;
  padding: 12px 22px;
  border-radius: 999px;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.12s, filter 0.15s, border-color 0.15s;
}

.button-primary {
  width: 100%;
  margin-top: 8px;
  background: var(--color-accent);
  border: none;
  color: var(--color-accent-text);
  font-size: 1.05rem;
  letter-spacing: 0.06em;
}

.button-primary:hover {
  filter: brightness(1.06);
}

.button-primary:active,
.button-secondary:active {
  transform: scale(0.98);
}

.button-secondary {
  background: transparent;
  border: 1px solid #3a4a78;
  color: var(--color-text);
  white-space: nowrap;
}

.button-secondary:hover {
  border-color: var(--color-accent);
}

button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

/* ---- 星空と書き出し ---- */
.chart {
  position: sticky;
  top: 24px;
  text-align: center;
}

.chart-status {
  margin: 12px 0 0;
  color: var(--color-text-muted);
  font-size: 0.85rem;
}

.chart-status:empty {
  display: none;
}

/* ---- フッター ---- */
.site-footer {
  padding: 32px 16px 48px;
  border-top: 1px solid var(--color-panel-border);
  color: var(--color-text-muted);
  font-size: 0.78rem;
  text-align: center;
}

.site-footer p {
  max-width: 880px;
  margin: 0 auto 6px;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

@media (max-width: 900px) {
  .layout {
    grid-template-columns: minmax(0, 1fr);
    grid-template-areas: "input" "chart" "custom" "info";
  }

  .chart {
    position: static;
  }

  .card {
    padding: 22px 18px;
  }
}