/* ============================================
   SEISAMUSE — Academic Personal Website
   Minimalist stylesheet for Jun Xie
   ============================================ */

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

:root {
  --text:    #1a1a2e;
  --bg:      #f5f5f0;
  --accent:  #b85c38;
  --muted:   #6b7280;
  --border:  #d1d5db;
  --card-bg: #ffffff;
  --nav-bg:  #ffffffcc;
  --code-bg: #f0ede6;
  --max-w:   720px;
}

html {
  font-size: 17px;
  scroll-behavior: smooth;
}

body {
  font-family: 'Palatino Linotype', Palatino, Georgia, 'Times New Roman', serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.75;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* --- Typography --- */
h1, h2, h3, h4 {
  font-family: Georgia, 'Times New Roman', serif;
  font-weight: 700;
  line-height: 1.3;
  margin-top: 1.6em;
  margin-bottom: 0.6em;
}

h1 { font-size: 1.8rem; }
h2 { font-size: 1.4rem; }
h3 { font-size: 1.15rem; }
h4 { font-size: 1rem; }

p { margin-bottom: 1em; }

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s;
}
a:hover {
  border-bottom-color: var(--accent);
}

blockquote {
  border-left: 3px solid var(--accent);
  padding: 0.5em 1em;
  margin: 1.2em 0;
  color: var(--muted);
  font-style: italic;
  background: var(--card-bg);
}

code {
  font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
  font-size: 0.88em;
  background: var(--code-bg);
  padding: 0.15em 0.4em;
  border-radius: 3px;
}

pre {
  background: var(--code-bg);
  padding: 1em;
  border-radius: 4px;
  overflow-x: auto;
  margin: 1.2em 0;
  line-height: 1.5;
}
pre code {
  background: none;
  padding: 0;
}

hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 2em 0;
}

img {
  max-width: 100%;
  height: auto;
  border-radius: 4px;
}

ul, ol {
  padding-left: 1.5em;
  margin-bottom: 1em;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.2em 0;
}
th, td {
  padding: 0.5em 0.75em;
  border-bottom: 1px solid var(--border);
  text-align: left;
}
th {
  font-weight: 700;
  border-bottom-width: 2px;
}

/* --- Layout --- */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 1.5rem;
  width: 100%;
}

main {
  flex: 1;
  padding: 2rem 0;
}

/* --- Transition Banner --- */
.transition-banner {
  background: var(--accent);
  color: #fff;
  padding: 0.5em 0;
  text-align: center;
  font-size: 0.9rem;
}

.transition-banner a {
  color: #fff;
  text-decoration: underline;
  border-bottom: none;
}

.transition-banner a:hover {
  opacity: 0.9;
}

/* --- Navigation --- */
nav {
  background: var(--nav-bg);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
  padding: 0.8rem 0;
}

nav .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.site-title {
  font-family: Georgia, serif;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: 0.04em;
}
.site-title:hover {
  border-bottom-color: transparent;
  color: var(--accent);
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 1.5rem;
  padding: 0;
  margin: 0;
}

.nav-links a {
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
.nav-links a:hover,
.nav-links a.active {
  color: var(--accent);
}

/* Mobile nav toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text);
}

/* --- Hero / Homepage Header --- */
.hero {
  text-align: center;
  padding: 2.5rem 0 1.5rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 2rem;
}

.hero .avatar {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  object-fit: cover;
  margin-bottom: 1rem;
  border: 3px solid var(--border);
}

.hero h1 {
  margin-top: 0.3em;
  margin-bottom: 0.2em;
  font-size: 2rem;
}

.hero .subtitle {
  color: var(--muted);
  font-size: 1rem;
  margin-bottom: 0.3em;
}

.hero .affiliation {
  color: var(--muted);
  font-size: 0.9rem;
  margin-bottom: 0.8em;
}

.hero .bio {
  font-size: 1rem;
  max-width: 540px;
  margin: 0 auto 1em;
  font-style: italic;
  color: var(--muted);
}

.hero .social-links {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.hero .social-links a {
  font-size: 0.88rem;
  padding: 0.35em 0.8em;
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--muted);
}
.hero .social-links a:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* --- Section Headers --- */
.section-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 1rem;
  border-bottom: 2px solid var(--text);
  padding-bottom: 0.3em;
}

.section-header h2 {
  margin: 0;
}

.section-header a {
  font-size: 0.85rem;
  color: var(--muted);
}

/* --- Blog Post Cards --- */
.post-list {
  list-style: none;
  padding: 0;
}

.post-item {
  padding: 1rem 0;
  border-bottom: 1px solid var(--border);
}
.post-item:last-child {
  border-bottom: none;
}

.post-item .post-date {
  font-size: 0.82rem;
  color: var(--muted);
  font-family: system-ui, -apple-system, sans-serif;
}

.post-item h3 {
  margin: 0.2em 0 0.3em;
  font-size: 1.1rem;
}

.post-item h3 a {
  color: var(--text);
}
.post-item h3 a:hover {
  color: var(--accent);
}

.post-item .excerpt {
  font-size: 0.92rem;
  color: var(--muted);
  margin: 0;
}

.post-tags {
  margin-top: 0.4em;
}
.post-tags a {
  font-size: 0.78rem;
  background: var(--code-bg);
  padding: 0.15em 0.5em;
  border-radius: 3px;
  color: var(--muted);
  margin-right: 0.4em;
  display: inline-block;
  border-bottom: none;
}
.post-tags a:hover {
  background: var(--accent);
  color: #fff;
}

/* --- Single Post --- */
.post-header {
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}

.post-header h1 {
  margin-top: 0;
  margin-bottom: 0.3em;
}

.post-meta {
  font-size: 0.85rem;
  color: var(--muted);
  font-family: system-ui, -apple-system, sans-serif;
}

.post-content {
  margin-bottom: 2rem;
}

.post-nav {
  display: flex;
  justify-content: space-between;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  font-size: 0.9rem;
}

/* --- Link List --- */
.link-list {
  list-style: none;
  padding: 0;
  margin: 1.2rem 0;
}
.link-list li {
  padding: 0.4rem 0;
  border-bottom: 1px solid var(--border);
}
.link-list li:last-child {
  border-bottom: none;
}
.link-list a {
  color: var(--accent);
  font-weight: 600;
}
.link-list .muted {
  color: var(--muted);
  font-size: 0.9rem;
}

/* Breadcrumb navigation */
.breadcrumb {
  font-size: 0.85rem;
  color: var(--muted);
  margin-bottom: 0.5rem;
}
.breadcrumb a {
  color: var(--accent);
}
.breadcrumb span {
  margin: 0 0.3em;
}

/* Back link */
.back-link {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}
.back-link a {
  color: var(--accent);
  font-size: 0.9rem;
}

/* Link sub-page content */
.link-subpage {
  min-height: 30vh;
}

/* --- About Page --- */
.about-content h2 {
  margin-top: 2em;
}
.about-content h2:first-child {
  margin-top: 0;
}

/* --- Donation / Support --- */
.support-section {
  text-align: center;
  padding: 2rem 0;
  margin-top: 2rem;
  border-top: 1px solid var(--border);
}

.support-section p {
  color: var(--muted);
  font-size: 0.92rem;
  margin-bottom: 0.8em;
}

.btn {
  display: inline-block;
  padding: 0.5em 1.5em;
  background: var(--accent);
  color: #fff;
  border-radius: 4px;
  font-size: 0.9rem;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: opacity 0.2s;
}
.btn:hover {
  opacity: 0.85;
  border-bottom: none;
  color: #fff;
}

/* --- Donate Modal --- */
.modal-overlay {
  display: none;
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background: rgba(0,0,0,0.5);
  z-index: 1000;
  justify-content: center;
  align-items: center;
}

.modal-content {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 2rem;
  max-width: 420px;
  width: 90%;
  text-align: center;
  position: relative;
}

.modal-content h3 {
  margin-top: 0;
  margin-bottom: 0.5em;
}

.modal-close {
  position: absolute;
  top: 0.5rem; right: 0.8rem;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--muted);
  line-height: 1;
}
.modal-close:hover {
  color: var(--accent);
}

.qr-codes {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  margin-top: 1rem;
}

.qr-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
}

.qr-item img {
  width: 160px;
  height: 160px;
  object-fit: contain;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 4px;
  background: #fff;
}

.qr-item span {
  font-size: 0.85rem;
  color: var(--muted);
}

/* --- Footer --- */
footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 0;
  text-align: center;
  font-size: 0.82rem;
  color: var(--muted);
}

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

/* --- Page Title (for Blog, About, Links) --- */
.page-title {
  margin-top: 0;
  margin-bottom: 1.5rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--text);
}

/* --- Pagination --- */
.pagination {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 2rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}

.pagination a {
  padding: 0.4em 0.8em;
  border: 1px solid var(--border);
  border-radius: 4px;
  font-size: 0.88rem;
}
.pagination a:hover {
  border-color: var(--accent);
  border-bottom-color: var(--accent);
}

.pagination .disabled {
  color: var(--border);
  font-size: 0.88rem;
}

.pagination .page-info {
  font-size: 0.85rem;
  color: var(--muted);
}

/* --- Dark Mode --- */
@media (prefers-color-scheme: dark) {
  :root {
    --text:    #e0e0e0;
    --bg:      #1a1a2e;
    --accent:  #e8a87c;
    --muted:   #9ca3af;
    --border:  #374151;
    --card-bg: #22223b;
    --nav-bg:  #1a1a2ecc;
    --code-bg: #2a2a3e;
  }
}

/* --- Responsive --- */
@media (max-width: 640px) {
  html { font-size: 15.5px; }

  .hero h1 { font-size: 1.6rem; }
  .hero .avatar { width: 90px; height: 90px; }

  nav .container {
    flex-wrap: wrap;
  }

  .nav-toggle {
    display: block;
  }

  .nav-links {
    display: none;
    width: 100%;
    flex-direction: column;
    gap: 0.5rem;
    padding-top: 0.8rem;
  }
  .nav-links.open {
    display: flex;
  }

  .section-header {
    flex-direction: column;
    gap: 0.3em;
  }
}