:root {
  color-scheme: light dark;
  --background: #f5f5f5;
  --sidebar-bg: #ffffff;
  --sidebar-border: #d9d9d9;
  --text: #222222;
  --muted: #666666;
  --accent: #3056d3;
  --header-height: 64px;
  font-family: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: #111418;
    --sidebar-bg: #161a20;
    --sidebar-border: #2a303a;
    --text: #f1f5f9;
    --muted: #94a3b8;
    --accent: #93c5fd;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--background);
  color: var(--text);
  min-height: 100vh;
  max-width: 100vw;
  display: grid;
  grid-template-columns: 320px 1fr;
  grid-template-rows: auto 1fr;
  overflow: hidden;
}

header {
  grid-column: 1 / -1;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--sidebar-border);
  background: var(--sidebar-bg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: relative;
  z-index: 100;
  min-width: 0;
  max-width: 100%;
  overflow: hidden;
  width: 100%;
  box-sizing: border-box;
}

header h1 {
  margin: 0;
  font-size: 1.4rem;
  font-weight: 600;
  flex: 1 1 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  min-width: 0;
  max-width: 100%;
}

.header-controls {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-left: 1rem;
  flex-shrink: 0;
}

.header-controls .control-button:not(.menu-toggle) {
  display: flex;
}

.sidebar-controls {
  display: none;
  padding: 1rem;
  border-bottom: 1px solid var(--sidebar-border);
  gap: 0.5rem;
  flex-direction: column;
}

.sidebar-controls .control-button {
  width: 100%;
  justify-content: center;
}

.control-button {
  background: none;
  border: 1px solid var(--sidebar-border);
  color: inherit;
  padding: 0.5rem 0.75rem;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.9rem;
  transition: background-color 0.15s ease, border-color 0.15s ease;
}

.control-button:hover {
  background: rgba(48, 86, 211, 0.12);
  border-color: var(--accent);
}

.control-button.active {
  background: rgba(48, 86, 211, 0.2);
  border-color: var(--accent);
}

.paren-help {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  background: var(--sidebar-bg);
  border: 1px solid var(--sidebar-border);
  border-radius: 8px;
  padding: 1rem 1.25rem;
  max-width: 320px;
  font-size: 0.85rem;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  z-index: 200;
  display: none;
}

.paren-help.visible {
  display: block;
}

.paren-help h3 {
  margin: 0 0 0.75rem 0;
  font-size: 1rem;
  font-weight: 600;
}

.paren-help ul {
  margin: 0;
  padding-left: 1.25rem;
  list-style: disc;
}

.paren-help li {
  margin-bottom: 0.5rem;
  line-height: 1.5;
}

.paren-help-close {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  background: none;
  border: none;
  color: var(--muted);
  cursor: pointer;
  font-size: 1.2rem;
  padding: 0.25rem 0.5rem;
  line-height: 1;
}

.paren-help-close:hover {
  color: var(--text);
}

.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  color: inherit;
  flex-shrink: 0;
  margin-left: 1rem;
  position: relative;
  width: 40px;
  height: 40px;
  justify-content: center;
  align-items: center;
}

.menu-toggle:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}

.hamburger {
  width: 24px;
  height: 20px;
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.hamburger span {
  display: block;
  height: 2px;
  width: 100%;
  background: currentColor;
  border-radius: 2px;
  transition: all 0.3s ease;
  transform-origin: center;
}

.menu-toggle[aria-expanded="true"] .hamburger span:nth-child(1) {
  transform: translateY(9px) rotate(45deg);
}

.menu-toggle[aria-expanded="true"] .hamburger span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}

.menu-toggle[aria-expanded="true"] .hamburger span:nth-child(3) {
  transform: translateY(-9px) rotate(-45deg);
}

#sidebar {
  border-right: 1px solid var(--sidebar-border);
  background: var(--sidebar-bg);
  display: flex;
  flex-direction: column;
  min-height: 0;
  max-height: calc(100vh - var(--header-height));
  overflow: hidden;
  transition: transform 0.3s ease;
  position: relative;
  z-index: 50;
}

.sidebar-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 40;
  opacity: 0;
  transition: opacity 0.3s ease;
  pointer-events: none;
}

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

#search {
  margin: 1rem;
  padding: 0.55rem 0.75rem;
  border-radius: 8px;
  border: 1px solid var(--sidebar-border);
  background: transparent;
  color: inherit;
  font-size: 0.95rem;
}

#file-list {
  list-style: none;
  margin: 0;
  padding: 0.5rem 0.5rem 1.5rem;
  overflow-y: auto;
  flex: 1;
}

#file-list li {
  border-bottom: none;
}

#file-list button {
  width: 100%;
  padding: 0.75rem 1rem;
  text-align: left;
  background: none;
  border: none;
  color: inherit;
  font-size: 0.95rem;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  cursor: pointer;
}

#file-list button:hover,
#file-list button:focus-visible,
#file-list button.active {
  background: rgba(48, 86, 211, 0.12);
  outline: none;
}

.file-category {
  font-size: 0.75rem;
  text-transform: uppercase;
  color: var(--muted);
  letter-spacing: 0.06em;
}

.tree-group {
  margin-left: 0.25rem;
  border-left: 1px solid rgba(96, 125, 255, 0.12);
  padding-left: 0.75rem;
}

details > summary {
  cursor: pointer;
  padding: 0.6rem 0.75rem;
  border-radius: 6px;
  margin-bottom: 0.25rem;
  font-weight: 600;
}

details > summary:hover,
details[open] > summary {
  background: rgba(48, 86, 211, 0.12);
}

.file-list-group {
  margin: 0.25rem 0 0.75rem;
  padding-left: 0;
}

.file-list-group li {
  border-bottom: 1px solid var(--sidebar-border);
}

.series-group {
  margin: 0.35rem 0;
  border-left: 1px solid rgba(48, 86, 211, 0.16);
  padding-left: 0.6rem;
}

.series-group > summary {
  cursor: pointer;
  padding: 0.55rem 0.6rem;
  border-radius: 6px;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  font-size: 0.78rem;
}

.series-group > summary:hover,
.series-group[open] > summary {
  background: rgba(48, 86, 211, 0.12);
}

.file-section-title {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  margin: 1rem 0 0.35rem 0.75rem;
}

main {
  padding: clamp(1.25rem, 3vw, 3.25rem) clamp(1.25rem, 5vw, 3.5rem);
  overflow-y: auto;
  max-height: calc(100vh - var(--header-height));
}

#content {
  max-width: min(1120px, 100%);
  margin: 0 auto 3rem;
}

.editor-demo {
  max-width: min(1120px, 100%);
  margin: 0 auto 3rem;
}

.editor-demo h2 {
  font-size: 1.4rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
}

.editor-surface {
  font-family: "Fira Code", monospace;
  font-size: 0.95rem;
  line-height: 1.65;
  min-height: 220px;
  padding: 18px;
  border-radius: 12px;
  border: 1px solid rgba(96, 165, 250, 0.25);
  background: rgba(15, 23, 42, 0.9);
  color: #cbd5f5;
  white-space: pre-wrap;
  outline: none;
}

.editor-surface:focus-visible {
  border-color: rgba(96, 165, 250, 0.55);
  box-shadow: 0 0 0 2px rgba(96, 165, 250, 0.25);
}

.demo-hint {
  margin-top: 0.75rem;
  font-size: 0.9rem;
  color: var(--muted);
}

#content h1,
#content h2,
#content h3,
#content h4,
#content h5 {
  margin-top: 2em;
  margin-bottom: 0.6em;
  line-height: 1.2;
}

#content p,
#content ul,
#content ol,
#content blockquote,
#content pre {
  line-height: 1.65;
  margin-bottom: 1.25em;
}

#content pre {
  background: rgba(12, 18, 28, 0.85);
  color: #e2e8f0;
  padding: 1rem;
  border-radius: 6px;
  overflow-x: auto;
  font-size: 0.9rem;
  text-wrap: auto;
}

#content code {
  font-family: "SFMono-Regular", ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  background: rgba(48, 86, 211, 0.12);
  padding: 0.15rem 0.35rem;
  border-radius: 4px;
  font-size: 0.9em;
}

#status {
  font-size: 0.9rem;
  color: var(--muted);
  margin-bottom: 1rem;
}

.demo-content {
  display: block;
}

.demo-content.hidden {
  display: none;
}

@media (max-width: 960px) {
  body {
    grid-template-columns: 1fr;
    grid-template-rows: auto 1fr;
    overflow: hidden;
  }

  .menu-toggle {
    display: flex;
  }

  .sidebar-overlay {
    display: block;
  }

  #sidebar {
    position: fixed;
    top: var(--header-height);
    left: 0;
    bottom: 0;
    width: 320px;
    max-width: 85vw;
    max-height: calc(100vh - var(--header-height));
    transform: translateX(-100%);
    z-index: 50;
    box-shadow: 2px 0 8px rgba(0, 0, 0, 0.15);
  }

  #sidebar.open {
    transform: translateX(0);
  }

  main {
    grid-row: 2;
    max-height: calc(100vh - var(--header-height));
    overflow-y: auto;
  }

  body.sidebar-open {
    overflow: hidden;
  }

  .paren-help {
    bottom: 1rem;
    right: 1rem;
    left: 1rem;
    max-width: none;
  }

  .header-controls {
    gap: 0.5rem;
    margin-left: 0.5rem;
  }

  .header-controls .control-button:not(.menu-toggle) {
    display: none;
  }

  .sidebar-controls {
    display: flex;
  }

  .control-button {
    padding: 0.4rem 0.6rem;
    font-size: 0.85rem;
  }
}