:root {
  --bg:        #0e1116;
  --bg-elev:   #161b22;
  --bg-input:  #0b0f14;
  --border:    #262c36;
  --text:      #e6edf3;
  --text-dim:  #8b949e;
  --accent:    #2f81f7;
  --accent-2:  #3fb950;
  --danger:    #f85149;
  --warn:      #d29922;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 16px;
  overscroll-behavior-y: none;
}

body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  min-height: 100dvh;
}

/* ---------- Top bar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: max(env(safe-area-inset-top), 10px) 14px 10px;
  background: var(--bg-elev);
  border-bottom: 1px solid var(--border);
}
.brand { display: flex; align-items: center; gap: 8px; }
.logo { color: var(--accent-2); font-size: 15px; }
.title { font-weight: 700; letter-spacing: .3px; }

.topbar-right { display: flex; align-items: center; gap: 12px; }
.kernel-status {
  display: flex;
  align-items: center;
  gap: 7px;
  font-size: 13px;
  color: var(--text-dim);
  font-family: var(--mono);
}
.icon-btn {
  background: var(--bg-input);
  border: 1px solid var(--border);
  color: var(--text-dim);
  font-family: var(--mono);
  font-size: 16px;
  font-weight: 700;
  line-height: 1;
  padding: 8px 10px;
  cursor: pointer;
  border-radius: 8px;
  transition: color .12s, border-color .12s, transform .04s;
}
.icon-btn:active { transform: scale(.92); }
.icon-btn.open { color: var(--accent); border-color: var(--accent); }
.dot {
  width: 9px; height: 9px; border-radius: 50%;
  background: var(--warn);
  box-shadow: 0 0 0 0 rgba(210,153,34,.6);
  animation: pulse 1.4s infinite;
}
.dot.ready { background: var(--accent-2); animation: none; }
.dot.busy  { background: var(--accent); animation: pulse 1s infinite; }
.dot.error { background: var(--danger); animation: none; }
@keyframes pulse {
  0%   { box-shadow: 0 0 0 0 rgba(47,129,247,.5); }
  70%  { box-shadow: 0 0 0 7px rgba(47,129,247,0); }
  100% { box-shadow: 0 0 0 0 rgba(47,129,247,0); }
}

/* ---------- Toolbar ---------- */
.toolbar {
  position: sticky;
  top: 0;
  display: flex;
  gap: 8px;
  padding: 8px 12px;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
}
.nb-select {
  flex: 1;
  min-width: 0;
  background: var(--bg-elev);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 12px;
  font-size: 16px;
  font-family: var(--sans);
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%238b949e' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 34px;
}
.toolbar-btns { display: flex; gap: 6px; }

/* ---------- Buttons ---------- */
.btn {
  background: var(--bg-elev);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 12px;
  font-size: 15px;
  font-family: var(--sans);
  cursor: pointer;
  transition: background .12s, border-color .12s, transform .04s;
  min-height: 42px;
  min-width: 42px;
}
.btn:active { transform: scale(.96); }
.btn.accent  { border-color: var(--accent);   color: #cfe4ff; }
.btn.danger  { border-color: transparent; color: var(--danger); }
.btn.wide    { flex: 1; }
.btn:disabled { opacity: .45; cursor: not-allowed; }

/* ---------- Cells ---------- */
.cells {
  flex: 1;
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.cell {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}
.cell-head {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px 8px 6px 12px;
  border-bottom: 1px solid var(--border);
}
.cell-label {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-dim);
}
.cell-time {
  flex: 1;
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-dim);
  margin-left: 10px;
}
.cell-time.running { color: var(--accent); }
.cell-head .btn { padding: 6px 10px; min-height: 34px; min-width: 34px; font-size: 14px; }

/* Editor: highlighted <pre> under a transparent <textarea> */
.editor { position: relative; }
.editor-hl,
.cell-input {
  margin: 0;
  padding: 12px;
  border: 0;
  font-family: var(--mono);
  font-size: 15px;
  line-height: 1.5;
  tab-size: 4;
  -moz-tab-size: 4;
  white-space: pre-wrap;
  word-break: break-word;
  overflow-wrap: break-word;
  letter-spacing: 0;
}
.editor-hl {
  min-height: 44px;
  color: var(--text);
  pointer-events: none;
  background: transparent;
}
.editor-hl code { font: inherit; }
.cell-input {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  resize: none;
  outline: none;
  overflow: hidden;
  background: transparent;
  color: transparent;
  -webkit-text-fill-color: transparent;
  caret-color: var(--accent-2);
}
.cell-input::placeholder { color: #4b5563; -webkit-text-fill-color: #4b5563; }
.cell-input::selection { background: rgba(47, 129, 247, .35); }

/* Python token colors */
.tok-keyword   { color: #ff7b72; }
.tok-string    { color: #a5d6ff; }
.tok-number    { color: #79c0ff; }
.tok-comment   { color: #8b949e; font-style: italic; }
.tok-builtin   { color: #ffa657; }
.tok-decorator { color: #d2a8ff; }

.cell-output {
  border-top: 1px solid var(--border);
  padding: 10px 12px;
  font-family: var(--mono);
  font-size: 14px;
  line-height: 1.5;
  white-space: pre-wrap;
  word-break: break-word;
  overflow-x: auto;
}
.cell-output.empty { display: none; }
.cell-output .result-img {
  display: block;
  max-width: 100%;
  height: auto;
  border-radius: 8px;
  margin: 6px 0;
  background: #fff;
}
.cell-output .stdout { color: var(--text); }
.cell-output .result { color: var(--accent-2); }
.cell-output .result:not(.result--math)::before { content: "» "; color: var(--text-dim); }
.cell-output .err    { color: var(--danger); }

/* Rendered LaTeX (KaTeX) results */
.cell-output .result--math {
  color: var(--text);
  overflow-x: auto;
  overflow-y: hidden;
  padding: 4px 2px 2px;
}
.cell-output .result--math .katex { font-size: 1.25em; }
.cell-output .result--math .katex-display { margin: 0; text-align: left; }

/* ---------- Run-all / footer ---------- */
.run-all-row {
  display: flex;
  gap: 8px;
  padding: 4px 12px 12px;
}
/* ---------- Options bottom sheet ---------- */
.backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, .5);
  opacity: 0;
  pointer-events: none;
  transition: opacity .22s ease;
  z-index: 40;
}
.backdrop.open { opacity: 1; pointer-events: auto; }

.sheet {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 45;
  background: var(--bg-elev);
  border-top: 1px solid var(--border);
  border-radius: 16px 16px 0 0;
  padding: 8px 16px calc(env(safe-area-inset-bottom) + 18px);
  transform: translateY(105%);
  transition: transform .26s cubic-bezier(.22, 1, .36, 1);
  box-shadow: 0 -12px 40px rgba(0, 0, 0, .45);
}
.sheet.open { transform: translateY(0); }
.sheet-handle {
  width: 40px;
  height: 4px;
  border-radius: 2px;
  background: var(--border);
  margin: 6px auto 12px;
}
.sheet-title { margin: 0 0 14px; font-size: 16px; font-weight: 700; }
/* ---- Console ---- */
.console-log {
  max-height: 42vh;
  overflow-y: auto;
  overflow-x: auto;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 12px;
  font-family: var(--mono);
  font-size: 14px;
  line-height: 1.5;
  -webkit-overflow-scrolling: touch;
}
.console-hint { color: var(--text-dim); white-space: pre-wrap; }
.console-in { display: flex; gap: 8px; margin-top: 8px; }
.console-ps { color: var(--accent-2); user-select: none; flex-shrink: 0; }
.console-code { white-space: pre-wrap; word-break: break-word; color: var(--text); }
.console-out {
  white-space: pre-wrap;
  word-break: break-word;
  color: var(--text);
  margin: 2px 0 2px 26px;
}
.console-out.ok  { color: var(--accent-2); }
.console-out.bad { color: var(--danger); }
.console-out .err { color: var(--danger); }
.console-out .result { color: var(--accent-2); }
.console-out .dim { color: var(--text-dim); }
.console-out .result-img { margin: 4px 0; }

.console-input-row {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  margin-top: 10px;
}
.console-input-row .console-ps { padding-top: 11px; }
.console-input {
  flex: 1;
  min-width: 0;
  background: var(--bg-input);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 12px;
  font-size: 16px;
  font-family: var(--mono);
  line-height: 1.5;
  outline: none;
  resize: none;
  overflow: hidden;
}
.console-input:focus { border-color: var(--accent); }

.console-foot {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px solid var(--border);
}

.sheet-hint {
  margin: 10px 2px 0;
  font-size: 12px;
  line-height: 1.5;
  color: var(--text-dim);
}
.sheet-hint code {
  font-family: var(--mono);
  color: var(--text);
  background: var(--bg-input);
  padding: 1px 5px;
  border-radius: 5px;
}
.pip-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.pip-empty { font-size: 12px; color: var(--text-dim); }
.pip-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 5px 6px 5px 12px;
  font-family: var(--mono);
  font-size: 13px;
  color: var(--text);
}
.pip-chip-x {
  border: none;
  background: transparent;
  color: var(--text-dim);
  font-size: 12px;
  cursor: pointer;
  padding: 2px 4px;
  border-radius: 50%;
  line-height: 1;
}
.pip-chip-x:active { color: var(--danger); }

/* ---------- Toast ---------- */
.toast {
  position: fixed;
  left: 50%;
  bottom: 84px;
  transform: translateX(-50%) translateY(20px);
  background: #1c2430;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 16px;
  font-size: 14px;
  max-width: 88vw;
  text-align: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity .2s, transform .2s;
  z-index: 50;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }
.toast.err  { border-color: var(--danger); color: #ffd7d5; }