/* ── Notebook toolbar (in nav) ───────────────────────────────────────────── */
.nb-toolbar {
  display: flex;
  align-items: center;
  gap: .5rem;
}
.toolbar-sep {
  width: 1px;
  height: 20px;
  background: rgba(255,255,255,.25);
  flex-shrink: 0;
}

/* Kernel status indicator */
.kernel-status-wrap {
  display: flex;
  align-items: center;
  gap: .4rem;
  font-size: .8125rem;
  color: rgba(255,255,255,.85);
  white-space: nowrap;
}
.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: #94a3b8;
  transition: background 200ms ease;
  flex-shrink: 0;
}
.status-dot[data-state="idle"]    { background: #4ade80; }
.status-dot[data-state="busy"]    { background: #facc15; animation: pulse 1s ease-in-out infinite; }
.status-dot[data-state="starting"]{ background: #60a5fa; animation: pulse 1.5s ease-in-out infinite; }
.status-dot[data-state="error"]   { background: #f87171; }

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50%       { opacity: .4; }
}

.nb-back { margin-left: .25rem; }

/* ── Loading overlay ─────────────────────────────────────────────────────── */
.loading-overlay {
  position: fixed;
  inset: 0;
  z-index: 200;
  background: rgba(15, 23, 42, .65);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}
.loading-overlay.hidden { display: none; }

.loading-card {
  background: #fff;
  border-radius: 16px;
  padding: 2.5rem 2rem;
  max-width: 380px;
  width: 100%;
  text-align: center;
  box-shadow: 0 20px 60px rgba(0,0,0,.25);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}

.spinner {
  width: 44px;
  height: 44px;
  border: 3px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin .8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

.loading-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text);
}
.loading-sub {
  font-size: .875rem;
  color: var(--text-muted);
}

.steps-list {
  list-style: none;
  width: 100%;
  text-align: left;
  display: flex;
  flex-direction: column;
  gap: .4rem;
}
.step {
  font-size: .8125rem;
  color: var(--text-muted);
  padding: .3rem .5rem;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  gap: .5rem;
}
.step::before {
  content: '○';
  font-size: .9em;
  flex-shrink: 0;
}
.step.done  { color: #16a34a; }
.step.done::before  { content: '✓'; }
.step.active { color: var(--primary); font-weight: 500; }
.step.active::before { content: '◉'; }
.step.error { color: #dc2626; }
.step.error::before { content: '✕'; }

/* ── Notebook page layout ────────────────────────────────────────────────── */
.nb-page {
  max-width: 900px;
  margin: 0 auto;
  padding: 1.5rem 1.5rem 5rem;
}

.nb-header {
  margin-bottom: 1.5rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}
.nb-title {
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: -.03em;
  color: var(--text);
  margin-bottom: .4rem;
}
.nb-meta {
  display: flex;
  flex-wrap: wrap;
  gap: .35rem;
}

/* ── Cell container ──────────────────────────────────────────────────────── */
.cells-container {
  display: flex;
  flex-direction: column;
  gap: 0;
}

/* ── Individual cells ────────────────────────────────────────────────────── */
.cell {
  position: relative;
  border-left: 3px solid transparent;
  transition: border-color 150ms ease;
}
.cell:hover { border-left-color: var(--border); }
.cell.cell-active { border-left-color: var(--primary); }
.cell.cell-running { border-left-color: #f59e0b; }
.cell.cell-error   { border-left-color: #ef4444; }

/* ── Markdown cells ──────────────────────────────────────────────────────── */
.markdown-cell {
  padding: .5rem 1rem .5rem 1.25rem;
  color: var(--text);
  line-height: 1.7;
}
.markdown-cell h1,
.markdown-cell h2,
.markdown-cell h3,
.markdown-cell h4 {
  margin-top: 1.4em;
  margin-bottom: .5em;
  font-weight: 600;
  letter-spacing: -.02em;
  color: var(--text);
}
.markdown-cell h1:first-child,
.markdown-cell h2:first-child { margin-top: .25em; }
.markdown-cell p { margin-bottom: .75em; }
.markdown-cell ul,
.markdown-cell ol { margin: .5em 0 .75em 1.5em; }
.markdown-cell li { margin-bottom: .25em; }
.markdown-cell code {
  font-family: var(--mono);
  font-size: .85em;
  background: var(--border-subtle);
  padding: .1em .35em;
  border-radius: 3px;
  color: #c7254e;
}
.markdown-cell pre {
  background: #1e2433;
  color: #abb2bf;
  padding: .85rem 1rem;
  border-radius: var(--radius-sm);
  overflow-x: auto;
  margin: .75rem 0;
}
.markdown-cell pre code {
  background: none;
  color: inherit;
  padding: 0;
}
.markdown-cell blockquote {
  border-left: 3px solid var(--border);
  margin: .75rem 0;
  padding: .25rem 1rem;
  color: var(--text-muted);
}
.markdown-cell table {
  width: 100%;
  border-collapse: collapse;
  margin: .75rem 0;
  font-size: .875rem;
}
.markdown-cell th,
.markdown-cell td {
  border: 1px solid var(--border);
  padding: .4rem .75rem;
  text-align: left;
}
.markdown-cell th { background: var(--border-subtle); font-weight: 600; }
.markdown-cell img { max-width: 100%; border-radius: var(--radius-sm); }
.markdown-cell a { color: var(--primary); }

/* ── Code cells ──────────────────────────────────────────────────────────── */
.code-cell {
  display: flex;
  flex-direction: column;
}
.cell-input-row {
  display: flex;
  align-items: flex-start;
  gap: 0;
  position: relative;
}

.cell-prompt {
  width: 52px;
  flex-shrink: 0;
  padding: .55rem .25rem .55rem 0;
  text-align: right;
  font-family: var(--mono);
  font-size: .75rem;
  color: var(--text-light);
  user-select: none;
  line-height: 1.5;
}
.cell-prompt::before { content: '['; }
.cell-prompt::after  { content: ']'; }
/* When running, JS sets textContent='*' and adds class .running */
.cell-prompt.running { color: #f59e0b; }

.cell-editor-wrap {
  flex: 1;
  min-width: 0;
  position: relative;
}

/* ── CodeMirror customisation ────────────────────────────────────────────── */
.CodeMirror {
  font-family: var(--mono) !important;
  font-size: .875rem !important;
  line-height: 1.6 !important;
  height: auto !important;
  border-radius: var(--radius-sm);
  padding: .25rem 0;
  /* Fallback keeps code visible even if the chosen theme CSS fails to load */
  background: #282a36;
  color: #f8f8f2;
}
.CodeMirror-scroll { min-height: 2.5rem; }
.CodeMirror-focused { outline: none; }

/* Run button overlay (top-right of editor) */
.cell-run-btn {
  position: absolute;
  top: 4px;
  right: 4px;
  z-index: 5;
  opacity: 0;
  transition: opacity 150ms ease;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 4px;
  width: 26px;
  height: 26px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
}
.cell-run-btn:hover { background: var(--primary-dark); }
.cell-editor-wrap:hover .cell-run-btn,
.cell-active .cell-run-btn { opacity: 1; }
.cell-run-btn svg { pointer-events: none; }

/* ── Cell outputs ────────────────────────────────────────────────────────── */
.cell-output {
  margin-left: 52px;
  border-left: 2px solid var(--border-subtle);
  padding: .5rem .75rem .5rem .75rem;
  display: flex;
  flex-direction: column;
  gap: .35rem;
}
.cell-output:empty { display: none; }

.output-item { max-width: 100%; overflow-x: auto; }

.output-stdout,
.output-stderr,
.output-text {
  font-family: var(--mono);
  font-size: .8125rem;
  line-height: 1.5;
  white-space: pre-wrap;
  word-break: break-word;
  margin: 0;
  padding: .35rem 0;
}
.output-stderr { color: #dc2626; }

.output-html { font-size: .875rem; }
.output-html table { border-collapse: collapse; width: 100%; font-size: .875rem; }
.output-html th, .output-html td {
  border: 1px solid var(--border);
  padding: .3rem .6rem;
  text-align: left;
}
.output-html th { background: var(--border-subtle); font-weight: 600; }

.output-image img {
  max-width: 100%;
  height: auto;
  display: block;
  border-radius: var(--radius-sm);
}

.output-error {
  border: 1px solid #fecaca;
  background: #fff5f5;
  border-radius: var(--radius-sm);
  overflow: hidden;
}
.error-name {
  font-family: var(--mono);
  font-size: .8125rem;
  font-weight: 600;
  color: #b91c1c;
  padding: .4rem .75rem;
  background: #fee2e2;
  border-bottom: 1px solid #fecaca;
}
.error-traceback {
  font-family: var(--mono);
  font-size: .78rem;
  line-height: 1.5;
  white-space: pre-wrap;
  word-break: break-word;
  padding: .5rem .75rem;
  margin: 0;
  color: var(--text);
  overflow-x: auto;
}

/* ── ANSI colours (used in tracebacks and stdout) ────────────────────────── */
.ansi-bold          { font-weight: 700; }
.ansi-italic        { font-style: italic; }
.ansi-underline     { text-decoration: underline; }
.ansi-fg-black      { color: #1e2433; }
.ansi-fg-red        { color: #e06c75; }
.ansi-fg-green      { color: #98c379; }
.ansi-fg-yellow     { color: #e5c07b; }
.ansi-fg-blue       { color: #61afef; }
.ansi-fg-magenta    { color: #c678dd; }
.ansi-fg-cyan       { color: #56b6c2; }
.ansi-fg-white      { color: #abb2bf; }
.ansi-fg-bright-red     { color: #f44747; }
.ansi-fg-bright-green   { color: #89d185; }
.ansi-fg-bright-yellow  { color: #f5d67b; }
.ansi-fg-bright-blue    { color: #75beff; }
.ansi-fg-bright-magenta { color: #d77ee0; }
.ansi-fg-bright-cyan    { color: #73c4cc; }
.ansi-fg-bright-white   { color: #d7dae0; }
.ansi-bg-red        { background: #5c1a1a; }
.ansi-bg-green      { background: #1a3a1a; }
.ansi-bg-yellow     { background: #3a2a00; }
.ansi-bg-blue       { background: #1a2a5c; }

/* ── Raw cells ───────────────────────────────────────────────────────────── */
.raw-cell {
  margin-left: 52px;
  padding: .5rem .75rem;
  font-family: var(--mono);
  font-size: .8125rem;
  color: var(--text-muted);
  white-space: pre-wrap;
  word-break: break-word;
  border-left: 2px solid var(--border-subtle);
}

/* ── Divider between cells ───────────────────────────────────────────────── */
.cell + .cell { margin-top: .25rem; }

/* ── Responsive ──────────────────────────────────────────────────────────── */
@media (max-width: 640px) {
  .nb-page { padding: 1rem .75rem 4rem; }
  .nb-toolbar { gap: .25rem; }
  .kernel-status-wrap { display: none; }
}