/* ============================================================
   Academic Minimalist — Main Stylesheet
   Design system: DESIGN.md
   ============================================================ */

/* --- Tokens ------------------------------------------------- */
:root {
  /* Colors */
  --color-bg:          #F8FAFC;
  --color-surface:     #FFFFFF;
  --color-primary:     #0F172A;   /* Deep Navy */
  --color-secondary:   #475569;   /* Slate Gray */
  --color-accent:      #C2A269;   /* Academic Gold */
  --color-accent-bg:   #FDF6E9;   /* Gold tint for chips */
  --color-border:      #E2E8F0;
  --color-muted:       #94A3B8;

  /* Typography */
  --font-serif:  'Newsreader', Georgia, 'Times New Roman', serif;
  --font-sans:   'Inter', system-ui, -apple-system, sans-serif;

  /* Scale */
  --text-display:  clamp(36px, 5vw, 48px);
  --text-h1:       clamp(28px, 4vw, 32px);
  --text-h2:       24px;
  --text-body-lg:  18px;
  --text-body-md:  16px;
  --text-label:    14px;
  --text-caption:  12px;

  /* Spacing (8px baseline) */
  --space-1:  8px;
  --space-2:  16px;
  --space-3:  24px;
  --space-4:  32px;
  --space-5:  40px;
  --space-6:  48px;
  --space-8:  64px;
  --space-10: 80px;
  --space-12: 96px;
  --space-15: 120px;

  /* Layout */
  --container-max:  1120px;
  --gutter:         24px;
  --margin-mobile:  20px;

  /* Radius */
  --radius-sm:  2px;
  --radius-md:  4px;
  --radius-lg:  8px;

  /* Shadow (floating only) */
  --shadow-float: 0 10px 25px -5px rgba(15, 23, 42, 0.05);
}

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

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  font-size: var(--text-body-md);
  line-height: 1.6;
  color: var(--color-primary);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

img { display: block; max-width: 100%; }
a  { color: inherit; text-decoration: none; }

/* --- Layout ------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

/* --- Navigation -------------------------------------------- */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(248, 250, 252, 0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
}

.site-nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.site-nav__brand {
  font-family: var(--font-serif);
  font-size: 18px;
  font-weight: 600;
  color: var(--color-primary);
  letter-spacing: -0.01em;
}

.site-nav__links {
  display: flex;
  gap: var(--space-5);
  list-style: none;
}

.site-nav__links a {
  font-size: var(--text-label);
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-secondary);
  transition: color 0.15s;
}

.site-nav__links a:hover,
.site-nav__links a[aria-current="page"] {
  color: var(--color-primary);
}

.site-nav__links a[aria-current="page"] {
  position: relative;
}

.site-nav__links a[aria-current="page"]::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  background-color: var(--color-accent);
  border-radius: 1px;
}

/* --- Hero --------------------------------------------------- */
.hero {
  padding-top: var(--space-15);
  padding-bottom: var(--space-12);
  border-bottom: 1px solid var(--color-border);
}

.hero__eyebrow {
  font-family: var(--font-sans);
  font-size: var(--text-label);
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-2);
}

.hero__name {
  font-family: var(--font-serif);
  font-size: var(--text-display);
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--color-primary);
  margin-bottom: var(--space-3);
}

.hero__title {
  font-family: var(--font-sans);
  font-size: var(--text-body-lg);
  color: var(--color-secondary);
  margin-bottom: var(--space-6);
}

.hero__rule {
  width: 48px;
  height: 2px;
  background-color: var(--color-accent);
  border: none;
  margin-bottom: var(--space-5);
}

.hero__bio {
  max-width: 680px;
  font-size: var(--text-body-lg);
  line-height: 1.7;
  color: var(--color-secondary);
  margin-bottom: var(--space-6);
}

.hero__bio strong {
  color: var(--color-primary);
  font-weight: 500;
}

.hero__ctas {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
}

/* --- Buttons ----------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-sans);
  font-size: var(--text-label);
  font-weight: 600;
  letter-spacing: 0.02em;
  padding: 12px 24px;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: background-color 0.15s, color 0.15s, border-color 0.15s;
  text-decoration: none;
}

.btn--primary {
  background-color: var(--color-primary);
  color: #FFFFFF;
  border-color: var(--color-primary);
}

.btn--primary:hover {
  background-color: #1E293B;
  border-color: #1E293B;
}

.btn--secondary {
  background-color: transparent;
  color: var(--color-secondary);
  border-color: var(--color-border);
}

.btn--secondary:hover {
  color: var(--color-primary);
  border-color: var(--color-secondary);
}

/* --- Section ----------------------------------------------- */
.section {
  padding-top: var(--space-10);
  padding-bottom: var(--space-10);
  border-bottom: 1px solid var(--color-border);
}

.section:last-of-type {
  border-bottom: none;
}

.section__header {
  margin-bottom: var(--space-6);
}

.section__label {
  font-size: var(--text-label);
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-muted);
  margin-bottom: var(--space-1);
}

.section__title {
  font-family: var(--font-serif);
  font-size: var(--text-h1);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.01em;
}

/* --- Research Area Chips ----------------------------------- */
.chips {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}

.chip {
  display: inline-block;
  font-size: var(--text-caption);
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 6px 14px;
  border-radius: var(--radius-md);
  background-color: var(--color-accent-bg);
  color: #8A6A2E;
  border: 1px solid rgba(194, 162, 105, 0.3);
}

/* --- Writing Cards ----------------------------------------- */
.writing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--space-3);
}

.post-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
  transition: background-color 0.15s;
  text-decoration: none;
  display: block;
}

.post-card:hover {
  background-color: #F1F5F9;
}

.post-card__meta {
  font-size: var(--text-caption);
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-muted);
  margin-bottom: var(--space-2);
}

.post-card__title {
  font-family: var(--font-serif);
  font-size: var(--text-h2);
  font-weight: 500;
  line-height: 1.3;
  color: var(--color-primary);
  margin-bottom: var(--space-2);
}

.post-card__excerpt {
  font-size: var(--text-body-md);
  line-height: 1.6;
  color: var(--color-secondary);
}

/* --- About Page -------------------------------------------- */
.about-hero {
  padding-top: var(--space-15);
  padding-bottom: var(--space-10);
  border-bottom: 1px solid var(--color-border);
}

.about-hero__label {
  font-size: var(--text-label);
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-2);
}

.about-hero__title {
  font-family: var(--font-serif);
  font-size: var(--text-h1);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.01em;
  margin-bottom: var(--space-6);
}

.about-hero__bio {
  max-width: 680px;
  font-size: var(--text-body-lg);
  line-height: 1.7;
  color: var(--color-secondary);
}

.about-hero__bio strong {
  color: var(--color-primary);
  font-weight: 500;
}

/* --- Education --------------------------------------------- */
.edu-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
}

.edu-item {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: var(--space-3);
  padding-bottom: var(--space-5);
  border-bottom: 1px solid var(--color-border);
}

.edu-item:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.edu-item__degree {
  font-family: var(--font-serif);
  font-size: var(--text-h2);
  font-weight: 500;
  margin-bottom: 4px;
}

.edu-item__school {
  font-size: var(--text-body-md);
  color: var(--color-secondary);
  margin-bottom: 4px;
}

.edu-item__note {
  font-size: var(--text-label);
  color: var(--color-accent);
  font-weight: 600;
}

.edu-item__year {
  font-size: var(--text-label);
  font-weight: 600;
  color: var(--color-muted);
  letter-spacing: 0.03em;
  white-space: nowrap;
  padding-top: 4px;
}

/* --- Writing Page ------------------------------------------ */
.writing-hero {
  padding-top: var(--space-15);
  padding-bottom: var(--space-10);
  border-bottom: 1px solid var(--color-border);
}

.writing-hero__label {
  font-size: var(--text-label);
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-2);
}

.writing-hero__title {
  font-family: var(--font-serif);
  font-size: var(--text-h1);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.01em;
  margin-bottom: var(--space-3);
}

.writing-hero__desc {
  max-width: 560px;
  font-size: var(--text-body-lg);
  line-height: 1.7;
  color: var(--color-secondary);
}

.writing-list {
  list-style: none;
  display: flex;
  flex-direction: column;
}

.writing-list__item {
  display: grid;
  grid-template-columns: 80px 1fr;
  gap: var(--space-4);
  padding: var(--space-5) 0;
  border-bottom: 1px solid var(--color-border);
  text-decoration: none;
  transition: background-color 0.12s;
}

.writing-list__item:hover .writing-list__title {
  color: var(--color-accent);
}

.writing-list__date {
  font-size: var(--text-label);
  font-weight: 600;
  color: var(--color-muted);
  letter-spacing: 0.02em;
  padding-top: 4px;
}

.writing-list__title {
  font-family: var(--font-serif);
  font-size: var(--text-h2);
  font-weight: 500;
  line-height: 1.3;
  color: var(--color-primary);
  margin-bottom: 8px;
  transition: color 0.12s;
}

.writing-list__excerpt {
  font-size: var(--text-body-md);
  color: var(--color-secondary);
  line-height: 1.6;
}

/* --- Post Detail Page -------------------------------------- */
.post-loading {
  padding-top: var(--space-15);
  padding-bottom: var(--space-10);
}

.post-header {
  padding-top: var(--space-15);
  padding-bottom: var(--space-10);
  border-bottom: 1px solid var(--color-border);
}

.post-back {
  display: inline-block;
  font-size: var(--text-label);
  font-weight: 600;
  letter-spacing: 0.03em;
  color: var(--color-muted);
  margin-bottom: var(--space-4);
  transition: color 0.15s;
}

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

.post-category {
  font-size: var(--text-label);
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--space-2);
}

.post-title {
  font-family: var(--font-serif);
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 600;
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--color-primary);
  max-width: 760px;
  margin-bottom: var(--space-3);
}

.post-excerpt {
  max-width: 680px;
  font-size: var(--text-body-lg);
  line-height: 1.7;
  color: var(--color-secondary);
  margin-bottom: var(--space-3);
}

.post-date {
  display: block;
  font-size: var(--text-label);
  font-weight: 600;
  color: var(--color-muted);
  letter-spacing: 0.03em;
}

.post-body {
  padding-top: var(--space-10);
  padding-bottom: var(--space-12);
}

.post-content {
  max-width: 680px;
  font-family: var(--font-serif);
  font-size: 19px;
  line-height: 1.75;
  color: var(--color-primary);
}

.post-content p {
  margin-bottom: var(--space-4);
}

.post-content h2 {
  font-family: var(--font-serif);
  font-size: var(--text-h2);
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -0.01em;
  margin-top: var(--space-8);
  margin-bottom: var(--space-3);
  color: var(--color-primary);
}

.post-content h3 {
  font-family: var(--font-serif);
  font-size: 20px;
  font-weight: 600;
  line-height: 1.3;
  margin-top: var(--space-6);
  margin-bottom: var(--space-2);
  color: var(--color-primary);
}

.post-content ul,
.post-content ol {
  padding-left: var(--space-4);
  margin-bottom: var(--space-4);
}

.post-content li {
  margin-bottom: var(--space-1);
  line-height: 1.7;
}

.post-content strong {
  font-weight: 600;
  color: var(--color-primary);
}

.post-content em {
  font-style: italic;
}

.post-content a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.post-content a:hover {
  color: var(--color-primary);
}

.post-content hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: var(--space-8) 0;
}

.post-content blockquote {
  border-left: 3px solid var(--color-accent);
  padding-left: var(--space-4);
  margin: var(--space-6) 0;
  color: var(--color-secondary);
  font-style: italic;
}

@media (max-width: 768px) {
  .post-header { padding-top: var(--space-10); padding-bottom: var(--space-8); }
  .post-body   { padding-top: var(--space-8);  padding-bottom: var(--space-10); }
  .post-content { font-size: 17px; }
}

/* --- Footer ------------------------------------------------ */
.site-footer {
  padding-top: var(--space-10);
  padding-bottom: var(--space-8);
  border-top: 1px solid var(--color-border);
  background-color: var(--color-bg);
}

.site-footer__inner {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: var(--space-6);
  align-items: start;
}

.site-footer__name {
  font-family: var(--font-serif);
  font-size: 20px;
  font-weight: 600;
  margin-bottom: var(--space-1);
}

.site-footer__bio {
  font-size: var(--text-body-md);
  color: var(--color-secondary);
  max-width: 500px;
  line-height: 1.6;
}

.site-footer__links {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  align-items: flex-end;
}

.site-footer__links a {
  font-size: var(--text-label);
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-secondary);
  transition: color 0.15s;
}

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

.site-footer__copy {
  margin-top: var(--space-6);
  padding-top: var(--space-4);
  border-top: 1px solid var(--color-border);
  font-size: var(--text-caption);
  color: var(--color-muted);
}

/* --- Responsive -------------------------------------------- */
@media (max-width: 768px) {
  .container { padding-inline: var(--margin-mobile); }

  .hero { padding-top: var(--space-10); padding-bottom: var(--space-8); }
  .about-hero, .writing-hero { padding-top: var(--space-10); padding-bottom: var(--space-8); }
  .section { padding-top: var(--space-8); padding-bottom: var(--space-8); }

  .hero__name { font-size: 32px; }

  .site-nav__links { gap: var(--space-3); }
  .site-nav__links a { font-size: 12px; }

  .edu-item {
    grid-template-columns: 1fr;
  }

  .site-footer__inner {
    grid-template-columns: 1fr;
  }

  .site-footer__links {
    align-items: flex-start;
    flex-direction: row;
    flex-wrap: wrap;
    gap: var(--space-2);
  }

  .writing-list__item {
    grid-template-columns: 1fr;
    gap: var(--space-1);
  }

  .writing-list__date {
    font-size: var(--text-caption);
  }
}