/* ==== Minimal, elegant, single-accent design ==== */
:root {
  --bg: #fafaf8;
  --surface: #ffffff;
  --text: #1a1d23;
  --text-dim: #666b76;
  --text-faint: #9198a3;
  --accent: #0f5b78;
  --accent-soft: #e8f1f4;
  --border: #e4e2dc;
  --radius-sm: 6px;
  --radius: 10px;
  --maxw: 1100px;
  --maxw-narrow: 860px;
  --shadow: 0 10px 26px -12px rgba(15,25,35,0.16);
  --transition: 0.18s ease;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

.container { max-width: var(--maxw); margin: 0 auto; padding: 0 28px; }
.container-narrow { max-width: var(--maxw-narrow); margin: 0 auto; padding: 0 28px; }
a { color: var(--accent); text-decoration: none; transition: color var(--transition); }
a:hover { color: #0a3f52; }
h1, h2, h3 { line-height: 1.25; letter-spacing: -0.015em; font-weight: 700; color: var(--text); }

.site-header { border-bottom: 1px solid var(--border); position: sticky; top: 0; background: rgba(250,250,248,0.92); backdrop-filter: blur(10px); z-index: 30; }
.header-inner { display: flex; justify-content: space-between; align-items: center; padding: 20px 28px; gap: 16px; flex-wrap: wrap; max-width: var(--maxw); margin: 0 auto; }
.logo { font-weight: 700; font-size: 1.02rem; color: var(--text); letter-spacing: -0.01em; display: flex; align-items: center; gap: 8px; }
.logo img,
.logo-icon {
  width: 22px !important;
  height: 22px !important;
  max-width: 22px !important;
  max-height: 22px !important;
  min-width: 22px !important;
  min-height: 22px !important;
  border-radius: 4px;
  object-fit: cover;
  flex-shrink: 0;
  display: block;
}
.logo:hover { color: var(--accent); }
.header-right { display: flex; align-items: center; gap: 22px; }
.main-nav { display: flex; align-items: center; }
.main-nav a { margin-left: 26px; color: var(--text-dim); font-size: 0.88rem; font-weight: 500; position: relative; padding-bottom: 3px; cursor: pointer; }
.main-nav a:first-child { margin-left: 0; }
.main-nav a.active, .main-nav a:hover { color: var(--text); }
.main-nav a.active::after { content: ""; position: absolute; left: 0; right: 0; bottom: -3px; height: 2px; background: var(--accent); }

.lang-switch { display: flex; gap: 2px; }
.lang-switch button { border: 1px solid transparent; background: transparent; color: var(--text-faint); font-size: 0.72rem; font-weight: 600; padding: 4px 8px; cursor: pointer; transition: all var(--transition); border-radius: var(--radius-sm); letter-spacing: 0.03em; }
.lang-switch button.active { color: var(--accent); background: var(--accent-soft); }
.lang-switch button:hover { color: var(--accent); }

.hero { padding: 88px 0 72px; position: relative; background-image: linear-gradient(180deg, rgba(250,250,248,0.35) 0%, rgba(250,250,248,0.65) 60%, rgba(250,250,248,0.96) 100%), url('../img/hero-bg.jpg'); background-size: cover; background-position: center 42%; background-repeat: no-repeat; border-bottom: 1px solid var(--border); }
.hero .container-narrow h1 { font-size: clamp(2.2rem, 4.8vw, 3.2rem); margin: 0 0 10px; color: var(--text); }
.subtitle { color: var(--accent); font-size: 1.08rem; font-weight: 600; margin: 0 0 22px; }
.hero-text { max-width: 560px; color: var(--text); font-size: 1.02rem; }
.hero-links { margin-top: 30px; display: flex; gap: 12px; flex-wrap: wrap; }

.btn { display: inline-flex; align-items: center; padding: 11px 22px; border-radius: var(--radius-sm); font-weight: 600; font-size: 0.9rem; transition: all var(--transition); border: 1px solid transparent; cursor: pointer; }
.btn-primary { background: var(--accent); color: #ffffff; }
.btn-primary:hover { background: #0a3f52; color: #ffffff; }
.btn-secondary { border-color: var(--border); color: var(--text); background: var(--surface); }
.btn-secondary:hover { border-color: var(--accent); color: var(--accent); }

.section { padding: 56px 0; }
.section-narrow { padding: 56px 0; }
.section h2 { font-size: 1.4rem; margin-bottom: 6px; }
.section-intro-text { color: var(--text-dim); max-width: 620px; margin-bottom: 8px; }
.page-header { padding: 60px 0 30px; border-bottom: 1px solid var(--border); }
.page-header h1 { font-size: clamp(1.8rem, 3.6vw, 2.3rem); margin-bottom: 10px; }
.page-header p { color: var(--text-dim); font-size: 0.98rem; max-width: 600px; }
.see-all { margin-top: 20px; font-weight: 600; font-size: 0.88rem; }

.card-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; margin-top: 22px; }
.article-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; cursor: pointer; transition: transform var(--transition), box-shadow var(--transition); display: flex; flex-direction: column; }
.article-card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.article-card-image { width: 100%; aspect-ratio: 1 / 1; background-size: cover; background-position: center; background-color: var(--accent-soft); }
.article-card-placeholder { display: flex; align-items: center; justify-content: center; }
.placeholder-initial { color: rgba(255,255,255,0.85); font-size: 2.4rem; font-weight: 800; font-family: "Inter", sans-serif; }
.article-card-body { padding: 14px 16px 16px; flex-grow: 1; display: flex; flex-direction: column; }
.article-card h3 { font-size: 0.92rem; margin: 0 0 6px; line-height: 1.3; }
.article-card .meta { color: var(--text-faint); font-size: 0.7rem; margin-bottom: 6px; font-weight: 500; text-transform: uppercase; letter-spacing: 0.02em; }
.article-card p { color: var(--text-dim); font-size: 0.8rem; margin: 0 0 8px; flex-grow: 1; }
.article-card .tag-row { margin-top: auto; }
.article-card .tag { font-size: 0.65rem; padding: 2px 8px; }

.grid-sentinel { height: 1px; }
.grid-status { text-align: center; padding: 20px 0; color: var(--text-faint); font-size: 0.85rem; grid-column: 1 / -1; }

.filters { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 4px; }
.filter-btn { background: var(--surface); border: 1px solid var(--border); color: var(--text-dim); border-radius: var(--radius-sm); padding: 5px 14px; font-size: 0.8rem; font-weight: 600; cursor: pointer; transition: all var(--transition); }
.filter-btn.active, .filter-btn:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }

.detail-view { display: none; }
.detail-view.visible { display: block; }
.list-view.hidden { display: none; }

.sticky-bar { position: sticky; top: 73px; background: rgba(250,250,248,0.95); backdrop-filter: blur(10px); border-bottom: 1px solid var(--border); padding: 14px 0; z-index: 15; margin-bottom: 30px; }
.sticky-bar .container-narrow { display: flex; align-items: center; justify-content: space-between; gap: 16px; flex-wrap: wrap; }
.back-link { font-weight: 600; font-size: 0.85rem; color: var(--accent); cursor: pointer; display: inline-flex; align-items: center; gap: 6px; }
.reading-indicator { font-size: 0.76rem; color: var(--text-faint); font-weight: 500; }
.reading-indicator strong { color: var(--text); font-weight: 600; }

.detail-body { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 36px; margin-bottom: 40px; }
.detail-hero-image { width: 100%; border-radius: var(--radius-sm); margin-bottom: 24px; aspect-ratio: 16 / 9; object-fit: cover; display: block; }
.detail-hero-placeholder { background-size: cover; }
.detail-body h1 { font-size: clamp(1.5rem, 3.4vw, 2rem); margin: 0 0 10px; }
.detail-body .meta { color: var(--text-faint); font-size: 0.8rem; margin-bottom: 20px; font-weight: 500; text-transform: uppercase; letter-spacing: 0.03em; }
.detail-body .tag-row { margin-bottom: 24px; }
.detail-body p { color: var(--text); font-size: 1rem; margin-bottom: 18px; white-space: pre-line; }

.tag { background: var(--accent-soft); color: var(--accent); border-radius: var(--radius-sm); padding: 3px 10px; font-size: 0.72rem; font-weight: 600; display: inline-block; }
.tag-row { display: flex; flex-wrap: wrap; gap: 6px; }

.draft-badge { display: inline-block; background: #fdf3e3; color: #9a6a12; font-size: 0.72rem; font-weight: 700; padding: 3px 10px; border-radius: var(--radius-sm); text-transform: uppercase; letter-spacing: 0.04em; margin-bottom: 14px; }

.tree { margin-top: 24px; }
.tree-category { border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 12px; overflow: hidden; background: var(--surface); }
.tree-category-header { padding: 18px 22px; display: flex; justify-content: space-between; align-items: center; cursor: pointer; transition: background var(--transition); }
.tree-category-header:hover { background: var(--accent-soft); }
.tree-category-header h3 { margin: 0; font-size: 1.05rem; }
.tree-category-count { color: var(--text-faint); font-size: 0.8rem; font-weight: 500; }
.tree-chevron { transition: transform var(--transition); color: var(--text-faint); font-size: 0.85rem; display: inline-block; }
.tree-category.expanded .tree-chevron { transform: rotate(90deg); }
.tree-entries { display: none; border-top: 1px solid var(--border); }
.tree-category.expanded .tree-entries { display: block; }
.tree-entry { padding: 14px 22px 14px 40px; cursor: pointer; border-bottom: 1px solid var(--border); transition: background var(--transition); font-size: 0.93rem; color: var(--text-dim); font-weight: 500; }
.tree-entry:last-child { border-bottom: none; }
.tree-entry:hover { background: var(--accent-soft); color: var(--accent); }

.breadcrumb { font-size: 0.8rem; color: var(--text-faint); font-weight: 500; }
.breadcrumb strong { color: var(--text); }

.about-content p { color: var(--text-dim); font-size: 0.98rem; }
.about-content h2 { margin-top: 36px; font-size: 1.2rem; }
.skills-list { color: var(--text-dim); padding-left: 20px; }
.skills-list li { margin-bottom: 8px; font-size: 0.95rem; }
.skills-list li::marker { color: var(--accent); }

.site-footer { border-top: 1px solid var(--border); padding: 26px 0; color: var(--text-faint); font-size: 0.82rem; }

@media (max-width: 980px) { .card-grid { grid-template-columns: repeat(3, 1fr); } }
@media (max-width: 700px) { .card-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 480px) { .card-grid { grid-template-columns: 1fr; } }

@media (max-width: 640px) {
  .header-inner { flex-wrap: wrap; }
  .main-nav a { margin-left: 0; margin-right: 18px; }
  .header-right { width: 100%; justify-content: space-between; order: 3; margin-top: 10px; }
  .hero { padding: 56px 0; }
  .detail-body { padding: 22px; }
  .sticky-bar { top: 0; }
  .tree-entry { padding-left: 28px; }
}