*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* ─────────────────────────────────────────────────────────────────
   Design System: Japanese Minimalism
   Ma (間) — Negative space, breathing room
   Kanso (簡素) — Simplicity, elimination of clutter
   Shibui (渋い) — Subtle, understated elegance
   ───────────────────────────────────────────────────────────────── */

:root {
  /* Neutral palette — clean white */
  --bg: #ffffff;
  --surface: #f8f8f8;
  --surface-hover: #f0f0f0;
  --border: #e5e2dc;
  --border-subtle: #f0ede8;
  
  /* Text — ink-like depth */
  --text: #1a1a1a;
  --text-2: #5a5855;
  --text-3: #9a9895;
  
  /* Accent — deeper, less saturated */
  --accent: #2c5aa0;
  --accent-hover: #1a3d6e;
  --accent-subtle: #e8eef5;
  
  /* Spacing — generous ma (間) */
  --space-xs: 0.25rem;   /* 4px */
  --space-sm: 0.5rem;    /* 8px */
  --space-md: 1rem;      /* 16px */
  --space-lg: 1.5rem;    /* 24px */
  --space-xl: 2.5rem;    /* 40px */
  --space-2xl: 4rem;     /* 64px */
  --space-3xl: 6rem;     /* 96px */
  
  --max-w: 680px;
  --radius: 6px;
  
  /* Typography — vertical rhythm + character spacing */
  --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --leading-tight: 1.4;
  --leading-normal: 1.7;
  --leading-relaxed: 1.9;
  
  /* Tracking (letter-spacing) for readability */
  --tracking-tight: -0.02em;     /* Large display text only */
  --tracking-normal: 0.01em;     /* Body text — slightly wider for readability */
  --tracking-wide: 0.02em;        /* Small text, captions */
  --tracking-wider: 0.04em;      /* Labels, uppercase (optical compensation) */
}

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: var(--leading-normal);
  letter-spacing: var(--tracking-normal);  /* Slightly wider character spacing */
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: inherit;
  text-decoration: none;
}

/* ── Nav — floating, breathing ── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.nav {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 0.9375rem;
  font-weight: 500;
  letter-spacing: -0.01em;
  color: var(--text);
}

.nav-links {
  display: flex;
  gap: var(--space-xl);
}

.nav-links a {
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: var(--tracking-wide);
  color: var(--text-2);
  position: relative;
  transition: color 0.2s ease;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 100%;
  height: 1px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform 0.25s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text);
}

.nav-links a:hover::after,
.nav-links a.active::after {
  transform: scaleX(1);
}

/* ── Main layout — generous ma ── */
main {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  flex: 1;
}

/* ── Hero — deliberate asymmetry ── */
.hero {
  padding: var(--space-3xl) 0 var(--space-2xl);
}

.hero-label {
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-3);
  margin-bottom: var(--space-md);
}

.hero-name {
  font-size: clamp(2.25rem, 6vw, 3.5rem);
  font-weight: 500;
  letter-spacing: -0.03em;
  line-height: var(--leading-tight);
  color: var(--text);
  margin-bottom: var(--space-lg);
}

.hero-bio {
  font-size: 1.0625rem;
  color: var(--text-2);
  max-width: 480px;
  line-height: var(--leading-relaxed);
  letter-spacing: var(--tracking-normal);
  margin-bottom: var(--space-xl);
}

.hero-links {
  display: flex;
  gap: var(--space-lg);
  flex-wrap: wrap;
}

.hero-links a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--accent);
  padding: var(--space-sm) 0;
  position: relative;
  transition: color 0.2s ease;
}

.hero-links a::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 0;
  width: 100%;
  height: 1px;
  background: currentColor;
  transform: scaleX(0);
  transform-origin: right;
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.hero-links a:hover {
  color: var(--accent-hover);
}

.hero-links a:hover::after {
  transform: scaleX(1);
  transform-origin: left;
}

/* ── Section — clear separation with ma ── */
.section {
  padding: var(--space-2xl) 0;
  border-top: 1px solid var(--border);
}

.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: var(--space-xl);
}

.section-label {
  font-size: 0.6875rem;
  font-weight: 500;
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-3);
}

.section-more {
  font-size: 0.8125rem;
  color: var(--text-2);
  transition: color 0.2s ease;
}

.section-more:hover {
  color: var(--accent);
}

/* ── Project cards — subtle elevation on interaction ── */
.project-list {
  display: flex;
  flex-direction: column;
}

.project-card {
  display: block;
  padding: var(--space-lg) var(--space-md);
  margin: 0 calc(-1 * var(--space-md));
  border-radius: var(--radius);
  transition: background-color 0.2s ease, transform 0.2s ease;
}

.project-card:hover {
  background: var(--surface);
  transform: translateX(4px);
}

.project-card-top {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-xs);
}

.project-title {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text);
}

.project-desc {
  font-size: 0.875rem;
  color: var(--text-2);
  line-height: var(--leading-normal);
  letter-spacing: var(--tracking-normal);
  margin-bottom: var(--space-sm);
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

.project-tags span {
  font-size: 0.6875rem;
  font-weight: 500;
  color: var(--text-3);
  background: var(--border-subtle);
  padding: 2px 8px;
  border-radius: 100px;
  letter-spacing: var(--tracking-wide);
}

/* ── Badges — reduced visual weight ── */
.badge {
  font-size: 0.625rem;
  font-weight: 600;
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  padding: 2px 6px;
  border-radius: 4px;
}

.badge-progress {
  background: transparent;
  color: #b8860b;
  border: 1px solid #d4b668;
}

.badge-beta {
  background: transparent;
  color: var(--accent);
  border: 1px solid #a8c4e8;
}

.badge-done {
  background: transparent;
  color: #4a7c59;
  border: 1px solid #8fbc8f;
}

.badge-live {
  background: transparent;
  color: #6b5b95;
  border: 1px solid #b8a9c9;
}

/* ── Article list — horizontal breathing room ── */
.article-list {
  display: flex;
  flex-direction: column;
}

.article-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-lg);
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--border);
  transition: all 0.2s ease;
}

.article-row:first-child {
  border-top: 1px solid var(--border);
}

.article-row:hover {
  padding-left: var(--space-sm);
  color: var(--accent);
}

.article-row:hover .article-title {
  color: var(--accent);
}

.article-title {
  font-size: 0.9375rem;
  color: var(--text);
  flex: 1;
  min-width: 0;
  transition: color 0.2s ease;
}

.article-meta {
  font-size: 0.75rem;
  color: var(--text-3);
  white-space: nowrap;
  flex-shrink: 0;
  font-variant-numeric: tabular-nums;
}

/* ── Projects page — spacious grid ── */
.page-header {
  padding: var(--space-2xl) 0 var(--space-xl);
}

.page-header h1 {
  font-size: clamp(1.5rem, 4vw, 2rem);
  font-weight: 500;
  letter-spacing: -0.02em;
  line-height: var(--leading-tight);
  margin-bottom: var(--space-sm);
}

.page-header p {
  font-size: 0.9375rem;
  color: var(--text-2);
  letter-spacing: var(--tracking-normal);
}

.projects-grid {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
  margin-bottom: var(--space-3xl);
}

.project-item {
  padding: var(--space-xl) var(--space-lg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

.project-item:hover {
  border-color: var(--text-3);
  background: var(--surface);
}

.project-item-head {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-sm);
}

.project-item-title {
  font-size: 1rem;
  font-weight: 500;
  letter-spacing: -0.01em;
}

.project-item-year {
  font-size: 0.75rem;
  color: var(--text-3);
  margin-left: auto;
  font-variant-numeric: tabular-nums;
}

.project-item-desc {
  font-size: 0.875rem;
  color: var(--text-2);
  line-height: var(--leading-normal);
  letter-spacing: var(--tracking-normal);
  margin-bottom: var(--space-md);
}

.project-item-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
  margin-bottom: var(--space-md);
}

.project-item-tags span {
  font-size: 0.6875rem;
  font-weight: 500;
  color: var(--text-3);
  background: var(--border-subtle);
  padding: 2px 8px;
  border-radius: 100px;
  letter-spacing: var(--tracking-wide);
}

.project-item-links {
  display: flex;
  gap: var(--space-md);
}

.project-item-links a {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--accent);
  position: relative;
  transition: color 0.2s ease;
}

.project-item-links a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 100%;
  height: 1px;
  background: currentColor;
  transform: scaleX(0);
  transform-origin: right;
  transition: transform 0.25s ease;
}

.project-item-links a:hover {
  color: var(--accent-hover);
}

.project-item-links a:hover::after {
  transform: scaleX(1);
  transform-origin: left;
}

/* ── Articles page ── */
.articles-list {
  padding-bottom: var(--space-3xl);
}

.articles-group {
  margin-bottom: var(--space-2xl);
}

.articles-year {
  font-size: 0.6875rem;
  font-weight: 500;
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-3);
  margin-bottom: var(--space-xs);
  padding-bottom: var(--space-md);
  border-bottom: 1px solid var(--border);
}

.article-item {
  display: block;
  padding: var(--space-lg) 0;
  border-bottom: 1px solid var(--border);
  transition: padding-left 0.2s ease;
}

.article-item:hover {
  padding-left: var(--space-sm);
}

.article-item:hover .article-item-title {
  color: var(--accent);
}

.article-item-tag {
  font-size: 0.6875rem;
  color: var(--text-3);
  margin-bottom: var(--space-xs);
  text-transform: uppercase;
  letter-spacing: var(--tracking-wide);
}

.article-item-title {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text);
  margin-bottom: var(--space-xs);
  transition: color 0.2s ease;
}

.article-item-excerpt {
  font-size: 0.8125rem;
  color: var(--text-2);
  line-height: var(--leading-normal);
  letter-spacing: var(--tracking-normal);
}

/* ── Article detail ── */
.article-detail {
  padding: var(--space-2xl) 0 var(--space-3xl);
}

.article-detail-back {
  font-size: 0.8125rem;
  color: var(--text-3);
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-bottom: var(--space-2xl);
  transition: color 0.2s ease;
}

.article-detail-back:hover {
  color: var(--accent);
}

.article-detail-meta {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  margin-bottom: var(--space-md);
  flex-wrap: wrap;
}

.article-detail-series {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--accent);
}

.article-detail-date {
  font-size: 0.75rem;
  color: var(--text-3);
  font-variant-numeric: tabular-nums;
}

.article-detail h1 {
  font-size: clamp(1.5rem, 4vw, 2.25rem);
  font-weight: 500;
  letter-spacing: -0.02em;
  line-height: var(--leading-tight);
  margin-bottom: var(--space-sm);
}

.article-detail-tags {
  display: flex;
  gap: var(--space-xs);
  flex-wrap: wrap;
  margin-bottom: var(--space-2xl);
}

.article-detail-tags span {
  font-size: 0.6875rem;
  font-weight: 500;
  letter-spacing: var(--tracking-wide);
  color: var(--text-3);
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 2px 10px;
  border-radius: 100px;
}

.article-cover {
  width: 100%;
  aspect-ratio: 2 / 1;
  object-fit: cover;
  border-radius: var(--radius);
  margin-bottom: var(--space-2xl);
  background: var(--surface);
}

.article-body h2 {
  font-size: 1.125rem;
  font-weight: 500;
  letter-spacing: -0.01em;
  margin: var(--space-2xl) 0 var(--space-md);
  color: var(--text);
}

.article-body p {
  font-size: 0.9375rem;
  color: var(--text-2);
  line-height: var(--leading-relaxed);
  letter-spacing: var(--tracking-normal);
  margin-bottom: var(--space-lg);
}

.article-body figure {
  margin: var(--space-xl) 0;
}

.article-body figure img {
  width: 100%;
  border-radius: var(--radius);
  display: block;
}

.article-body figcaption {
  font-size: 0.75rem;
  color: var(--text-3);
  text-align: center;
  letter-spacing: var(--tracking-wide);
  margin-top: var(--space-sm);
}

.series-nav {
  margin-top: var(--space-2xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--border);
}

.series-nav-label {
  font-size: 0.6875rem;
  font-weight: 500;
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-3);
  margin-bottom: var(--space-md);
}

.series-nav-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.series-nav-item {
  display: block;
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius);
  font-size: 0.875rem;
  color: var(--text-2);
  transition: background-color 0.2s ease, color 0.2s ease;
}

.series-nav-item:hover {
  background: var(--surface);
  color: var(--text);
}

.series-nav-item.current {
  background: var(--surface);
  color: var(--text);
  font-weight: 500;
}

/* ── Skills section ── */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: var(--space-xl);
  margin-bottom: var(--space-2xl);
}

.skill-category {
  padding: var(--space-lg) var(--space-md);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: transparent;
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

.skill-category:hover {
  border-color: var(--text-3);
  background: var(--surface);
}

.skill-title {
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-3);
  margin-bottom: var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--border-subtle);
}

.skill-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.skill-list li {
  font-size: 0.875rem;
  color: var(--text-2);
  line-height: var(--leading-normal);
  letter-spacing: var(--tracking-normal);
  position: relative;
  padding-left: var(--space-sm);
}

.skill-list li::before {
  content: "·";
  position: absolute;
  left: 0;
  color: var(--accent);
}

@media (max-width: 640px) {
  .skills-grid {
    grid-template-columns: 1fr;
    gap: var(--space-lg);
  }
}

/* ── Footer — quieter, grounded ── */
.site-footer {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: var(--space-xl) var(--space-lg);
  border-top: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  flex-wrap: wrap;
  font-size: 0.75rem;
  letter-spacing: var(--tracking-wide);
  color: var(--text-3);
}

.site-footer a {
  color: var(--text-2);
  transition: color 0.2s ease;
}

.site-footer a:hover {
  color: var(--accent);
}

/* ── Responsive — maintain breathing room ── */
@media (max-width: 640px) {
  :root {
    --space-lg: 1.25rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
  }

  .nav {
    height: 56px;
    padding: 0 var(--space-md);
  }

  .nav-links {
    gap: var(--space-lg);
  }

  .hero {
    padding: var(--space-2xl) 0 var(--space-xl);
  }

  .hero-bio {
    font-size: 1rem;
  }

  main {
    padding: 0 var(--space-md);
  }

  .article-row {
    flex-direction: column;
    gap: var(--space-xs);
    padding: var(--space-sm) 0;
  }

  .article-row:hover {
    padding-left: 0;
  }

  .project-item {
    padding: var(--space-lg) var(--space-md);
  }

  .site-footer {
    flex-direction: column;
    gap: var(--space-xs);
    text-align: center;
    padding: var(--space-lg) var(--space-md);
  }
}

/* ── Selection — subtle, intentional ── */
::selection {
  background: var(--accent-subtle);
  color: var(--accent);
}