*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  margin: 0;
  padding: 0;
}

body {
  margin: 0;
  padding: 0;
  min-height: 100vh;
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--page-gradient);
}

a {
  color: var(--color-primary);
}

a[target="_blank"]::after {
  content: " ↗";
}

img {
  display: block;
  max-width: 100%;
}

button {
  font: inherit;
}

[hidden] {
  display: none !important;
}

pre {
  margin: 0;
  display: block;
  unicode-bidi: isolate;
  white-space: pre;
  margin-block: 0em 0em;
  margin-inline: 0px;
  background-color: var(--highlighter);
  width: fit-content;
}

code {
  line-height: 1;
  margin: 0;
  font-size: 2rem;
  font-family: var(--font-handwriting);
}


:root {
  --rail-width: 72px;
  --sidebar-panel-width: 320px;
  --sidebar-open-width: calc(var(--rail-width) + var(--sidebar-panel-width));
}

/* visibility helpers */
.mobile-only {
  display: inline-flex !important;
}

.desktop-only {
  display: none !important;
}

/* top bar */
.topbar {
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--header-height);
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 0.75rem;
  padding: 0 1rem;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  backdrop-filter: blur(16px);
}

.topbar__left,
.topbar__center,
.topbar__right {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.topbar__center {
  min-width: 0;
}

.topbar__right {
  justify-content: flex-end;
  margin-left: auto;
}

.brand {
  color: var(--color-text);
  text-decoration: none;
  font-family: var(--font-display);
  font-weight: 700;
  white-space: nowrap;
}

.topbar__nav {
  display: flex;
  align-items: center;
  gap: var(--space-5);
  justify-self: center;
}

.topbar__nav a,
.topbar-menu a {
  color: var(--color-text);
  text-decoration: none;
}

.icon-button,
.theme-toggle,
.sidebar__rail-toggle,
.sidebar__close {
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text);
  cursor: pointer;
}

.icon-button {
  width: 2.5rem;
  height: 2.5rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  border-radius: 999px;
}

.theme-toggle {
  padding: 0.65rem 1rem;
  border-radius: 999px;
}

.topbar-menu {
  position: fixed;
  top: calc(var(--header-height) + var(--space-2));
  right: var(--space-4);
  z-index: var(--z-menu);
}

.topbar-menu__panel {
  min-width: 12rem;
  display: grid;
  gap: var(--space-2);
  padding: var(--space-3);
  border-radius: var(--radius-md);
  background: var(--color-paper);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-2);
}

.theme-toggle--menu {
  width: 100%;
}

/* overlay */
.sidebar-overlay {
  position: fixed;
  inset: 0;
  z-index: var(--z-scrim);
  background: rgba(15, 23, 42, 0.35);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.24s ease;
}

.sidebar-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

/* shell */
.shell {
  min-height: calc(100vh - var(--header-height));
}

.page-main {
  width: min(100%, var(--browse-max));
  margin: 0 auto;
  padding: var(--space-6) var(--space-4) var(--space-7);
  min-width: 0;
  transition: padding-left 0.24s ease;
}

.browse-layout {
  display: grid;
  gap: var(--space-6);
}

.article-layout {
  display: grid;
  gap: var(--space-6);
  justify-items: center;
}

/* sidebar base */
.sidebar {
  z-index: var(--z-sidebar);
}

.sidebar__inner {
  height: 100%;
  overflow-y: auto;
  overflow-x: hidden;
  padding: var(--space-4);
  position: relative;
  z-index: 2;
  background: var(--color-paper);
}

.sidebar__head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-4);
  margin-bottom: var(--space-5);
}

.sidebar__title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.1rem;
}

.sidebar__intro {
  margin: var(--space-2) 0 0;
  color: var(--color-muted);
  line-height: 1.5;
}

.sidebar__close {
  width: 2.25rem;
  height: 2.25rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 999px;
  flex: 0 0 auto;
}

.sidebar-nav {
  display: grid;
  gap: 0.75rem;
}

.sidebar-section {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  overflow: hidden;
  box-shadow: var(--shadow-1);
}

.sidebar-section-toggle {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.75rem;
  padding: 0.95rem 1rem;
  border: 0;
  background: transparent;
  color: var(--color-text);
  cursor: pointer;
}

.section-title {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  font-weight: 600;
  text-align: left;
}

.section-icon {
  display: inline-grid;
  place-items: center;
  width: 1.35rem;
  height: 1.35rem;
  border-radius: 999px;
  background: var(--color-primary-soft);
  color: var(--color-primary);
  font-size: 0.8rem;
}

.arrow {
  transition: transform 0.2s ease;
  flex: 0 0 auto;
}

.sidebar-list-wrap {
  display: none;
  padding: 0 1rem 1rem;
}

.sidebar-section.open .sidebar-list-wrap {
  display: block;
}

.sidebar-section.open .arrow {
  transform: rotate(90deg);
}

.sidebar-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.35rem;
}

.sidebar-list a {
  display: block;
  padding: 0.45rem 0.6rem;
  border-radius: 10px;
  color: var(--color-text);
  text-decoration: none;
}

.sidebar-list a[aria-current="page"],
.sidebar-list a:hover {
  background: var(--color-primary-soft);
  text-decoration: none;
}

/* mobile */
@media (max-width: 1023px) {
  .sidebar {
    position: fixed;
    top: var(--header-height);
    left: 0;
    bottom: 0;
    width: min(var(--sidebar-panel-width), calc(100vw - 1rem));
    transform: translateX(calc(-100% - 1rem));
    transition: transform 0.24s ease;
  }

  .sidebar.active {
    transform: translateX(0);
  }

  .sidebar__rail {
    display: none;
  }

  .sidebar__panel {
    height: 100%;
    background: var(--color-paper);
    border-right: 1px solid var(--color-border);
    box-shadow: var(--shadow-2);
  }

  .page-main {
    padding: var(--space-6) var(--space-4) var(--space-7);
  }
}

/* desktop */
@media (min-width: 1024px) {
  .desktop-only {
    display: inline-flex !important;
  }

  .mobile-only {
    display: none !important;
  }

  .sidebar-overlay {
    display: none !important;
  }

  .topbar {
    padding-left: calc(var(--rail-width) + 1rem);
    padding-right: 1rem;
    transition: padding-left 0.24s ease;
  }

  .sidebar {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: var(--sidebar-open-width);
    pointer-events: none;
  }

  .sidebar__rail {
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    width: var(--rail-width);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    padding: 1rem 0.75rem;
    background: var(--color-surface);
    border-right: 1px solid var(--color-border);
    pointer-events: auto;
    z-index: 2;
  }

  .sidebar__rail-toggle {
    width: 2.75rem;
    height: 2.75rem;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 14px;
    padding: 0;
    box-shadow: var(--shadow-1);
  }

  .sidebar__rail-label {
    margin-top: 0.35rem;
    writing-mode: vertical-rl;
    transform: rotate(180deg);
    text-transform: uppercase;
    letter-spacing: 0.12em;
    font-size: 0.78rem;
    font-weight: 700;
    color: var(--color-muted);
  }

  .sidebar__panel {
    position: absolute;
    top: 0;
    left: var(--rail-width);
    bottom: 0;
    width: var(--sidebar-panel-width);
    transform: translateX(-100%);
    transition: transform 0.24s ease;
    background: var(--color-paper);
    border-right: 1px solid var(--color-border);
    box-shadow: var(--shadow-2);
    pointer-events: auto;
    z-index: 1;
  }

  .sidebar.active .sidebar__panel {
    transform: translateX(0);
  }

  .page-main {
    padding:
      var(--space-6) max(var(--space-6), 5vw) var(--space-7) max(calc(var(--space-6) + var(--rail-width)), 6vw);
  }

  body.sidebar-open .page-main {
    padding-left: max(calc(var(--sidebar-open-width) + var(--space-6)), 28rem);
  }

  body.sidebar-open .topbar {
    padding-left: calc(var(--sidebar-open-width) + 1rem);
  }
}