/* ============================================================
   FLAVOR THEME v2 — layout.css
   "Vivid" — Header (glassmorphism), footer (mesh), grids, nav
   ============================================================ */

/* ----- Skip link ----- */
.skip-link {
  position: absolute;
  top: -100%;
  left: 1rem;
  z-index: 9999;
  padding: 0.75rem 1.5rem;
  background: var(--t-primary);
  color: #fff;
  border-radius: var(--t-radius-sm);
  font-weight: 600;
  transition: top 200ms;
}
.skip-link:focus {
  top: 1rem;
}

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

.content-narrow {
  max-width: var(--t-content-width);
  margin: 0 auto;
}

.content-wide {
  max-width: var(--t-wide-width);
  margin: 0 auto;
}

.full-bleed {
  width: 100vw;
  margin-left: calc(-50vw + 50%);
}

/* ----- Header ----- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--t-header-height);
  display: flex;
  align-items: center;
  transition: background-color var(--t-duration) var(--t-easing),
              box-shadow var(--t-duration) var(--t-easing),
              backdrop-filter var(--t-duration) var(--t-easing),
              transform var(--t-duration) var(--t-easing);
}

/* Sticky-blur variant — Vivid glassmorphism */
.site-header--sticky-blur {
  background: transparent;
}
.site-header--sticky-blur.is-scrolled {
  background: rgba(254,253,251,0.78);
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
  box-shadow: 0 1px 3px var(--t-shadow), 0 0 0 1px var(--t-border);
}
[data-theme="dark"] .site-header--sticky-blur.is-scrolled,
.dark .site-header--sticky-blur.is-scrolled {
  background: rgba(10,10,15,0.80);
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .site-header--sticky-blur.is-scrolled {
    background: rgba(10,10,15,0.80);
  }
}

/* Transparent variant */
.site-header--transparent {
  background: transparent;
  transform: translateY(0);
}
.site-header--transparent.is-hidden {
  transform: translateY(-100%);
}
.site-header--transparent.is-scrolled {
  background: rgba(254,253,251,0.92);
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
  box-shadow: 0 1px 3px var(--t-shadow);
}
[data-theme="dark"] .site-header--transparent.is-scrolled {
  background: rgba(10,10,15,0.92);
}

/* Solid variant */
.site-header--solid {
  background: var(--t-surface);
  border-bottom: 1px solid var(--t-border);
  box-shadow: 0 1px 3px var(--t-shadow);
}

/* Header inner */
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  max-width: var(--t-max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 100%;
}

/* Logo */
.site-logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--t-font-heading);
  font-size: 1.5rem;
  font-weight: 400;
  color: var(--t-text);
  text-decoration: none;
  flex-shrink: 0;
}
.site-logo img {
  height: 36px;
  width: auto;
}

/* Desktop navigation */
.nav-desktop {
  display: flex;
  align-items: center;
  gap: 2rem;
}
.nav-desktop a {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--t-text-secondary);
  transition: color var(--t-duration) var(--t-easing);
  padding: 0.5rem 0;
  position: relative;
}
.nav-desktop a:hover,
.nav-desktop a.active {
  color: var(--t-text);
}
.nav-desktop a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--t-primary), var(--t-accent));
  border-radius: 1px;
  transition: width var(--t-duration) var(--t-easing);
}
.nav-desktop a:hover::after,
.nav-desktop a.active::after {
  width: 100%;
}

/* Header right */
.header-right {
  display: flex;
  align-items: center;
  gap: 1rem;
}

/* Mobile hamburger */
.hamburger {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  color: var(--t-text);
  min-width: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
}
.hamburger svg {
  width: 24px;
  height: 24px;
}

/* ----- Mobile drawer ----- */
.mobile-overlay {
  position: fixed;
  inset: 0;
  z-index: 200;
  background: var(--t-overlay);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--t-duration) var(--t-easing), visibility var(--t-duration);
}
.mobile-overlay.is-open {
  opacity: 1;
  visibility: visible;
}

.mobile-drawer {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  z-index: 201;
  width: min(320px, 85vw);
  background: var(--t-surface);
  border-left: 1px solid var(--t-border);
  box-shadow: -8px 0 30px var(--t-shadow-hover);
  transform: translateX(100%);
  transition: transform var(--t-duration) var(--t-easing);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}
.mobile-drawer.is-open {
  transform: translateX(0);
}

.drawer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--t-border);
}

.drawer-close {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--t-text);
  padding: 0.5rem;
  min-width: 44px;
  min-height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--t-radius-sm);
  transition: background var(--t-duration);
}
.drawer-close:hover {
  background: var(--t-primary-light);
}

.drawer-nav {
  display: flex;
  flex-direction: column;
  padding: 1rem 0;
  flex: 1;
}
.drawer-nav a {
  display: block;
  padding: 0.875rem 1.5rem;
  font-size: 1.0625rem;
  font-weight: 500;
  color: var(--t-text);
  transition: background var(--t-duration), color var(--t-duration);
}
.drawer-nav a:hover,
.drawer-nav a.active {
  background: var(--t-primary-light);
  color: var(--t-primary);
}

.drawer-footer {
  padding: 1.5rem;
  border-top: 1px solid var(--t-border);
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

/* ----- Main content spacer ----- */
.main-content {
  padding-top: var(--t-header-height);
  min-height: calc(100vh - var(--t-header-height));
}

/* ----- Footer ----- */
.site-footer {
  position: relative;
  background: var(--t-surface-alt);
  border-top: 1px solid var(--t-border);
  padding: 4rem 0 0;
  margin-top: 4rem;
  overflow: hidden;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr repeat(3, 1fr);
  gap: 3rem;
  margin-bottom: 3rem;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.footer-brand .site-logo {
  font-size: 1.25rem;
}
.footer-brand p {
  font-size: 0.9375rem;
  color: var(--t-text-secondary);
  line-height: 1.6;
}

.footer-col h4 {
  font-family: var(--t-font-body);
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--t-text-muted);
  margin-bottom: 1.25rem;
}

.footer-col ul {
  display: flex;
  flex-direction: column;
  gap: 0.625rem;
}
.footer-col a {
  font-size: 0.9375rem;
  color: var(--t-text-secondary);
  transition: color var(--t-duration) var(--t-easing);
}
.footer-col a:hover {
  color: var(--t-primary);
}

.footer-bottom {
  border-top: 1px solid var(--t-border);
  padding: 1.5rem 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}

.footer-copyright {
  font-size: 0.875rem;
  color: var(--t-text-muted);
}

.footer-social {
  display: flex;
  gap: 0.75rem;
}
.footer-social a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  border: 1px solid var(--t-border);
  color: var(--t-text-muted);
  transition: color var(--t-duration), background var(--t-duration), border-color var(--t-duration), box-shadow var(--t-duration);
}
.footer-social a:hover {
  color: var(--t-primary);
  background: var(--t-primary-light);
  border-color: var(--t-border-hover);
  box-shadow: 0 2px 8px var(--t-shadow);
}

/* ----- Grid system ----- */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}
.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}
.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
}

/* Article layout with TOC sidebar */
.article-layout {
  display: grid;
  grid-template-columns: 1fr 250px;
  gap: 3rem;
  align-items: start;
}
.article-main {
  min-width: 0;
}

/* ----- Responsive ----- */
@media (max-width: 1024px) {
  .nav-desktop { display: none; }
  .hamburger { display: flex; }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .article-layout {
    grid-template-columns: 1fr;
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  .container { padding: 0 1rem; }
  .footer-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 640px) {
  .grid-2 { grid-template-columns: 1fr; }
  .grid-3 { grid-template-columns: 1fr; }
  .grid-4 { grid-template-columns: 1fr; }
}