/* Shared site-wide styles for jingnanliu.com (hand-written, no framework). */

:root {
  --bg: #ffffff;
  --surface: #ffffff;
  --surface-strong: #f8f8f8;
  --text: #2d2d2d;
  --muted: #666666;
  --line: #e5e5e5;
  --accent: #2271b2;
  --accent-soft: #4a6c8c;
  --shadow: 0 6px 18px rgba(0, 0, 0, 0.05);
  --radius: 10px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; font-size: 18px; }

body {
  margin: 0;
  font-family: "Source Serif Pro", Georgia, serif;
  font-size: 18px;
  line-height: 1.6;
  background: var(--bg);
  color: var(--text);
}

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

img { max-width: 100%; height: auto; }

h1, h2, h3, h4 {
  font-family: "Lora", Georgia, serif;
  font-weight: 700;
  line-height: 1.2;
}

.page-shell {
  width: 100%;
  margin: 0;
  padding: 0 0 72px;
}

/* --- Layout primitives (replace Bootstrap equivalents) --- */

.container-xl {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding-left: 20px;
  padding-right: 20px;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
}

.d-none { display: none !important; }
.d-inline-flex { display: inline-flex !important; }

@media (min-width: 768px) {
  .d-md-inline-flex { display: inline-flex !important; }
  .d-md-none       { display: none !important; }
}

@media (min-width: 992px) {
  .d-lg-inline-flex { display: inline-flex !important; }
  .d-lg-none       { display: none !important; }
}

/* --- Navbar --- */

#navbar-main {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(0, 0, 0, 0.82);
  backdrop-filter: saturate(140%) blur(6px);
  -webkit-backdrop-filter: saturate(140%) blur(6px);
}

#navbar-main .container-xl {
  min-height: 64px;
  padding-top: 8px;
  padding-bottom: 8px;
}

.navbar-brand {
  font-family: "Lora", serif;
  color: #fff;
  text-decoration: none;
  font-size: 1.15rem;
  font-weight: 700;
  margin-right: 20px;
}
.navbar-brand:hover { color: #fff; opacity: 0.85; }

.navbar-brand-mobile-wrapper {
  flex: 1;
}

.navbar-toggler {
  background: transparent;
  color: #fff;
  border: 1px solid rgba(255, 255, 255, 0.35);
  border-radius: 4px;
  padding: 6px 10px;
  font-size: 1.05rem;
  cursor: pointer;
  margin-left: auto;
}
.navbar-toggler:focus { outline: 2px solid rgba(255, 255, 255, 0.4); }

@media (min-width: 768px) {
  .navbar-toggler { display: none; }
}

.navbar-collapse {
  flex-basis: 100%;
  display: flex;
}

.navbar-collapse.collapse:not(.show) {
  display: none;
}

@media (min-width: 768px) {
  .navbar-collapse,
  .navbar-collapse.collapse:not(.show) {
    display: flex !important;
    flex-basis: auto;
  }
}

.justify-content-end { justify-content: flex-end; }

.navbar-nav {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
}
@media (min-width: 768px) {
  .navbar-nav { flex-direction: row; }
}

.nav-item { position: relative; }

.nav-link {
  display: block;
  padding: 12px 16px;
  color: #ffffff;
  font-family: "Lora", serif;
  text-decoration: none;
  transition: color 0.15s ease;
}
.nav-link:hover,
.nav-link.active { color: #87cefa; }

/* --- Dropdown --- */

.dropdown-toggle::after {
  content: "";
  display: inline-block;
  margin-left: 6px;
  vertical-align: middle;
  border-top: 4px solid currentColor;
  border-right: 4px solid transparent;
  border-left: 4px solid transparent;
}

.dropdown-menu {
  display: none;
  position: static;
  background: #ffffff;
  color: #212529;
  border: 1px solid var(--line);
  border-radius: 6px;
  box-shadow: var(--shadow);
  min-width: 220px;
  padding: 6px 0;
  margin: 0 12px 4px;
}
@media (min-width: 768px) {
  .dropdown-menu {
    position: absolute;
    top: 100%;
    right: 0;
    margin: 0;
  }
}

.dropdown.show > .dropdown-menu { display: block; }

.dropdown-item {
  display: block;
  padding: 8px 16px;
  color: #212529 !important;
  text-decoration: none;
  font-family: "Lora", serif;
}
.dropdown-item:hover,
.dropdown-item:focus {
  background: #f7f7f7;
  color: #212529 !important;
}

/* --- Page sections --- */

main { padding-top: 64px; }

.page-section { width: 100%; }
.page-section-white { background: #ffffff; }
.page-section-gray  { background: #f7f7f7; }

.section-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 60px 20px;
}

.section-heading {
  margin-bottom: 28px;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--accent-soft);
  font-family: "Montserrat", sans-serif;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* --- Footer --- */

footer {
  padding: 28px 20px;
  color: var(--muted);
  font-size: 0.9rem;
  text-align: center;
  border-top: 1px solid var(--line);
}

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