*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg: #1a1b26;
  --bg-light: #24283b;
  --bg-lighter: #292e42;
  --border: #3b4261;
  --text: #c0caf5;
  --text-dim: #737aa2;
  --accent-ruby: #f7768e;
  --accent-crystal: #bb9af7;
  --accent-python: #7aa2f7;
  --accent-typescript: #e0af68;
  --accent-elixir: #a855f7;
  --accent: var(--accent-ruby);
  --tree-hover: #292e42;
  --tree-active: #3b4261;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header {
  padding: 1.25rem 1.5rem 0.75rem;
  border-bottom: 1px solid var(--border);
}

header h1 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--accent);
}

.tagline {
  font-size: 0.8rem;
  color: var(--text-dim);
  margin-top: 0.15rem;
}

/* Language tabs */
.tabs {
  display: flex;
  gap: 0;
  border-bottom: 1px solid var(--border);
  padding: 0 1.5rem;
}

.tab {
  background: none;
  border: none;
  color: var(--text-dim);
  padding: 0.6rem 1.25rem;
  font-size: 0.85rem;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}

.tab:hover {
  color: var(--text);
}

.tab.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

.tab[data-lang="ruby"].active { color: var(--accent-ruby); border-bottom-color: var(--accent-ruby); }
.tab[data-lang="crystal"].active { color: var(--accent-crystal); border-bottom-color: var(--accent-crystal); }
.tab[data-lang="python"].active { color: var(--accent-python); border-bottom-color: var(--accent-python); }
.tab[data-lang="typescript"].active { color: var(--accent-typescript); border-bottom-color: var(--accent-typescript); }
.tab[data-lang="elixir"].active { color: var(--accent-elixir); border-bottom-color: var(--accent-elixir); }

/* Main layout */
main {
  flex: 1;
  overflow: hidden;
}

.panels {
  display: flex;
  height: calc(100vh - 8rem);
}

/* File tree */
.file-tree {
  width: 260px;
  min-width: 200px;
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 0.5rem 0;
}

.tree-item {
  display: flex;
  align-items: center;
  padding: 0.2rem 0.75rem;
  cursor: pointer;
  font-size: 0.8rem;
  color: var(--text-dim);
  white-space: nowrap;
  user-select: none;
}

.tree-item:hover {
  background: var(--tree-hover);
  color: var(--text);
}

.tree-item.active {
  background: var(--tree-active);
  color: var(--text);
}

.tree-item.dir {
  color: var(--text);
  font-weight: 500;
}

.tree-icon {
  width: 1rem;
  margin-right: 0.35rem;
  text-align: center;
  font-size: 0.7rem;
  flex-shrink: 0;
}

.tree-item.dir .tree-icon::before { content: "\25B6"; }
.tree-item.dir.open .tree-icon::before { content: "\25BC"; }
.tree-item.file .tree-icon::before { content: ""; }

.tree-children {
  display: none;
}

.tree-children.open {
  display: block;
}

/* Code panel */
.code-panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.code-header {
  padding: 0.5rem 1rem;
  font-size: 0.8rem;
  color: var(--text-dim);
  background: var(--bg-light);
  border-bottom: 1px solid var(--border);
  font-family: "SF Mono", "Fira Code", "Cascadia Code", monospace;
}

.code-content {
  flex: 1;
  overflow: auto;
  padding: 1rem;
  background: var(--bg);
  font-family: "SF Mono", "Fira Code", "Cascadia Code", monospace;
  font-size: 0.8rem;
  line-height: 1.5;
  tab-size: 2;
  white-space: pre;
  color: var(--text);
}

/* Override highlight.js theme background to match our palette */
.code-content.hljs {
  background: var(--bg);
}

/* Footer */
footer {
  padding: 0.5rem 1.5rem;
  border-top: 1px solid var(--border);
  font-size: 0.75rem;
}

footer a {
  color: var(--text-dim);
  text-decoration: none;
}

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

/* Loading state */
.loading {
  padding: 2rem;
  text-align: center;
  color: var(--text-dim);
}