:root {
  --text: #1a1a1a;
  --muted: #666;
  --line: #e5e5e5;
  --accent: #2f5bd3;
  --bg: #fff;
}

@media (prefers-color-scheme: dark) {
  :root {
    --text: #eaeaea;
    --muted: #9a9a9a;
    --line: #333;
    --accent: #8aa8ff;
    --bg: #141414;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue", "Hiragino Sans", "Noto Sans JP", sans-serif;
  font-size: 17px;
  line-height: 1.7;
}

.wrap {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 24px;
}

.site-header {
  border-bottom: 1px solid var(--line);
  padding: 56px 0 24px;
  margin-bottom: 16px;
}

.eyebrow,
.num {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

h1 {
  margin: 4px 0 20px;
  font-size: 40px;
  line-height: 1.2;
}

nav a {
  margin-right: 20px;
  color: var(--accent);
  text-decoration: none;
}

nav a:hover { text-decoration: underline; }

section {
  padding: 32px 0;
  border-bottom: 1px solid var(--line);
}

h2 {
  margin: 0 0 12px;
  font-size: 26px;
}

h3 {
  margin: 4px 0 8px;
  font-size: 21px;
}

h4 {
  margin: 20px 0 4px;
  font-size: 15px;
}

.lead { color: var(--muted); }

.challenge {
  margin-top: 32px;
  padding-top: 24px;
  border-top: 1px dashed var(--line);
}

.placeholder {
  color: var(--muted);
  font-style: italic;
}

footer {
  padding: 32px 24px 56px;
  color: var(--muted);
  font-size: 14px;
}

.work {
  display: block;
  margin-top: 12px;
  padding: 16px 20px;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: inherit;
  text-decoration: none;
}

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

.work-title {
  display: block;
  margin-bottom: 4px;
  color: var(--accent);
  font-weight: 600;
}

.work-desc {
  display: block;
  color: var(--muted);
  font-size: 15px;
}

/* Language switching: html[lang] decides which version shows. */
html[lang="ja"] .en,
html[lang="en"] .ja { display: none; }

.lang-bar {
  border-bottom: 1px solid var(--line);
  padding: 10px 0;
}

.lang-bar .wrap {
  display: flex;
  justify-content: flex-end;
}

.lang-switch {
  display: inline-flex;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 2px;
}

.lang-switch button {
  border: 0;
  border-radius: 999px;
  padding: 4px 14px;
  background: transparent;
  color: var(--muted);
  font: inherit;
  font-size: 14px;
  cursor: pointer;
}

.lang-switch button[aria-pressed="true"] {
  background: var(--text);
  color: var(--bg);
}

.site-header { padding-top: 32px; }