/* ── variables (overridden by theme-vars.css) ──────────────── */
:root {
  --bg:          #faf9f5;
  --text:        #0f2840;
  --text-muted:  #3a5570;
  --accent:      #780000;
  --accent-h:    #ba0000;
  --nav-bg:      #3d0000;
  --nav-text:    #f0d0d0;
  --nav-active:  #fff;
  --footer-bg:   #f0eeea;
  --border:      #d8d4c8;
  --max:         1020px;
  --gap:         24px;
  --sidebar-w:   190px;
  --widget-w:    220px;
  --font-body:   Georgia, 'Times New Roman', serif;
  --font-head:   Georgia, 'Times New Roman', serif;
  --line-gap:    1.8rem;
  --line-color:  #d4e8a0;
}

/* ── reset ─────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; scroll-behavior: smooth; }
body {
  font-family: var(--font-body);
  color: var(--text);
  background-color: var(--bg);
  line-height: var(--line-gap);
  border-left: 3px dashed #ba0000;
  background-image:
    repeating-linear-gradient(
      to bottom,
      transparent,
      transparent calc(var(--line-gap) - 1px),
      var(--line-color) calc(var(--line-gap) - 1px),
      var(--line-color) var(--line-gap)
    ),
    url("../theme/equations.svg");
  background-attachment: local;
  background-repeat: repeat, repeat;
  background-position: top left, top left;
  background-size: auto, 1200px 900px;
}
img { max-width: 100%; height: auto; display: block; }
a   { color: var(--accent); }
a:hover { color: var(--accent-h); }

/* ── layout helpers ────────────────────────────────────────── */
.container { max-width: var(--max); margin: 0 auto; padding: 0 var(--gap); }

/* ── header / nav ──────────────────────────────────────────── */
.site-header {
  background: var(--nav-bg);
  position: sticky; top: 0; z-index: 100;
  box-shadow: 0 2px 8px rgba(0,0,0,.35);
  border-left: 3px dashed #ba0000;
}
.header-inner {
  display: flex; align-items: center;
  justify-content: space-between;
  padding: 0 var(--gap); height: 60px;
}
.site-title { font-family: var(--font-head); font-size: 1.5rem; font-weight: normal; letter-spacing: .01em; }
.site-title a { color: var(--nav-active); text-decoration: none; }
.site-title a:hover { color: #f0c0c0; }

.nav-menu { display: flex; list-style: none; gap: 4px; }
.nav-menu > li > a {
  display: block; padding: 5px 11px;
  border: 1px solid rgba(186,0,0,.5);
  border-radius: 2px;
  color: var(--nav-text); text-decoration: none; font-size: 0.88rem; white-space: nowrap;
}
.nav-menu > li > a:hover { color: #ff7519; border-color: #ff7519; }
.nav-menu li.active > a { color: #fff; border-color: #fff; font-weight: bold; }

.nav-menu li { position: relative; }
.nav-menu li > ul {
  display: none; position: absolute; top: 100%; left: 0;
  background: var(--nav-bg); min-width: 200px; padding: 6px 0;
  border-top: 2px solid #ba0000;
  box-shadow: 0 6px 16px rgba(0,0,0,.4); z-index: 200; list-style: none;
}
.nav-menu li > ul a {
  display: block; padding: 8px 16px; font-size: 0.85rem;
  color: var(--nav-text); text-decoration: none;
}
.nav-menu li > ul a:hover { color: #ff7519; }
.nav-menu li:hover > ul { display: block; }

.nav-toggle {
  display: none; background: none; border: none; cursor: pointer;
  color: var(--nav-text); font-size: 1.5rem; line-height: 1; padding: 4px 8px;
}
@media (max-width: 700px) {
  .nav-toggle { display: block; }
  .nav-menu {
    display: none; flex-direction: column; gap: 0;
    position: absolute; top: 60px; left: 0; right: 0;
    background: var(--nav-bg); padding: 8px 0; border-top: 1px solid rgba(186,0,0,.4);
  }
  .nav-menu.open { display: flex; }
  .nav-menu > li > a { margin: 2px var(--gap); }
  .nav-menu li > ul {
    display: block; position: static; box-shadow: none; border-top: none;
    border-left: 2px solid #ba0000;
    margin-left: var(--gap); padding: 0; min-width: 0; background: transparent;
  }
  .nav-menu li > ul a { padding: 7px var(--gap); font-size: 0.95rem; }
}

/* ── page layout ───────────────────────────────────────────── */
.page-wrap { padding: 32px 0 64px; min-height: calc(100vh - 60px - 120px); }

.page-with-sidebar {
  display: grid; grid-template-columns: var(--sidebar-w) 1fr;
  gap: 36px; align-items: start;
}
@media (max-width: 700px) { .page-with-sidebar { grid-template-columns: 1fr; } }

/* ── sidebar menu ──────────────────────────────────────────── */
.child-menu { list-style: none; }
.child-menu a {
  display: block; padding: 5px 10px; font-size: 0.88rem;
  color: var(--text-muted); text-decoration: none;
  border-left: 3px solid transparent; line-height: var(--line-gap);
}
.child-menu a:hover  { color: var(--accent); border-color: var(--accent); }
.child-menu li.active a { color: var(--accent); font-weight: bold; border-color: var(--accent); }

/* ── page title ────────────────────────────────────────────── */
.page-title {
  font-family: var(--font-head); font-size: 1.8rem; font-weight: normal;
  color: #cc0000;
  margin-bottom: 24px; padding-bottom: 10px;
  border-bottom: 2px solid var(--accent);
  line-height: calc(var(--line-gap) * 2);
}
.page-title:empty { display: none; }

/* ── content typography ────────────────────────────────────── */
.content h1,.content h2,.content h3 { font-family: var(--font-head); font-weight: normal; margin: 1.4em 0 .5em; }
.content h1 { font-size: 1.5rem; color: #cc0000; }
.content h2 { font-size: 1.25rem; color: #4a0093; border-bottom: 1px solid var(--border); padding-bottom: 4px; }
.content h3 { font-size: 1.05rem; color: #005500; }
.content p  { margin-bottom: var(--line-gap); }
.content ul,.content ol { margin: 0 0 var(--line-gap) 1.5em; }
.content li { margin-bottom: .25em; }
.content img { border-radius: 2px; margin: .5em 0; }
.content img[style*="float: left"],.content img[style*="float:left"]   { margin-right: 14px; margin-bottom: 8px; }
.content img[style*="float: right"],.content img[style*="float:right"] { margin-left:  14px; margin-bottom: 8px; }
.content iframe { max-width: 100%; }
.content a { color: var(--accent); }
.content a:hover { color: var(--accent-h); }
.content hr { border: none; border-top: 1px solid var(--border); margin: 1.5em 0; }
.content table { border-collapse: collapse; width: 100%; margin-bottom: 1em; }
.content th,.content td { padding: 7px 10px; border: 1px solid var(--border); text-align: left; }
.content th { background: var(--footer-bg); }
.content pre,.content code { font-family: 'Courier New', monospace; font-size: 0.88em; background: #eeeae4; padding: 2px 5px; border-radius: 2px; }
.content pre { padding: 12px; overflow-x: auto; line-height: 1.5; }

/* ── wide / centered template ──────────────────────────────── */
.centered-content { max-width: 700px; margin: 0 auto; }

/* ── footer ────────────────────────────────────────────────── */
.site-footer {
  background: var(--footer-bg); border-top: 2px solid var(--accent);
  padding: 24px 0 16px; font-size: 0.85rem; color: var(--text-muted);
}
.footer-inner {
  display: grid; grid-template-columns: 1fr 1fr; gap: 32px; margin-bottom: 16px;
}
@media (max-width: 600px) { .footer-inner { grid-template-columns: 1fr; } }
.footer-copy { text-align: center; color: #999; font-size: 0.8rem; padding-top: 12px; border-top: 1px solid var(--border); margin-top: 12px; }