:root {
  --bg: #f6f6f3;
  --panel: #ffffff;
  --ink: #1c1d21;
  --muted: #6b6e76;
  --line: #e2e2dc;
  --accent: #2f6fde;
  --err: #c2372d;
  --hover: #eef3fd;
  --result: #0f5b3a;
  --input: #3a3d45;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #15161a; --panel: #1d1f24; --ink: #e8e8ea; --muted: #9a9ca4; --line: #30333a;
    --accent: #7aa7ff; --err: #ff7b6e; --hover: #232837; --result: #7fdcaa; --input: #c9cbd2;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #15161a; --panel: #1d1f24; --ink: #e8e8ea; --muted: #9a9ca4; --line: #30333a;
  --accent: #7aa7ff; --err: #ff7b6e; --hover: #232837; --result: #7fdcaa; --input: #c9cbd2;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 15px/1.45 system-ui, -apple-system, "Segoe UI", sans-serif;
  display: flex;
  flex-direction: column;
}
button, select {
  font: inherit;
  color: inherit;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 4px 10px;
  cursor: pointer;
}
button:hover { border-color: var(--accent); }
button.primary { background: var(--accent); border-color: var(--accent); color: var(--panel); }

header {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 8px 16px;
  border-bottom: 1px solid var(--line);
  background: var(--panel);
  flex-wrap: wrap;
}
h1 { font-size: 18px; margin: 0; letter-spacing: .02em; }
nav { display: flex; gap: 8px; margin-left: auto; align-items: center; flex-wrap: wrap; }
.credit { color: var(--muted); font-size: 13px; text-decoration: none; }
.credit:hover { color: inherit; text-decoration: underline; }
.opt { color: var(--muted); font-size: 13px; display: flex; gap: 6px; align-items: center; }
.status { font-size: 12px; padding: 2px 8px; border-radius: 10px; border: 1px solid var(--line); color: var(--muted); }
.status.loading, .status.busy { color: var(--accent); border-color: var(--accent); }
.status.bad { color: var(--err); border-color: var(--err); }

.menu { position: relative; }
.dropdown {
  display: none;
  position: absolute;
  top: calc(100% + 4px);
  right: 0;
  z-index: 20;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 6px;
  min-width: 220px;
  box-shadow: 0 6px 24px rgba(0, 0, 0, .18);
}
.menu.open .dropdown { display: flex; flex-direction: column; gap: 2px; }
.dropdown button { border: none; text-align: left; padding: 5px 10px; }
.dropdown button:hover { background: var(--hover); }
.dropdown .sep { border-top: 1px solid var(--line); margin: 4px 0; }
.dropdown { max-height: calc(100vh - 70px); overflow-y: auto; }
.dropdown .mhead { font-size: 11px; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); padding: 4px 10px 2px; }
.dropdown button small { float: right; margin-left: 16px; color: var(--muted); font-size: 12px; }
#matrix-menu { min-width: 300px; }

main {
  flex: 1;
  display: grid;
  grid-template-columns: minmax(360px, 48%) 1fr;
  min-height: 0;
}

/* ---- console (TI-89 home screen) */
#console {
  display: flex;
  flex-direction: column;
  min-height: 0;
  border-right: 1px solid var(--line);
}
#history {
  flex: 1;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  padding: 8px 0;
}
#history > :first-child { margin-top: auto; }   /* fill from the bottom, like a calculator */
.history-empty { color: var(--muted); text-align: center; font-size: 14px; padding: 24px 16px; margin: auto 0 0; }
.h {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 2px 16px;
  padding: 6px 16px;
  border-bottom: 1px solid var(--line);
}
.h:hover { background: var(--hover); }
.h-in { color: var(--input); font-size: 17px; cursor: pointer; max-width: 100%; overflow-x: auto; }
.h-out {
  margin-left: auto;
  text-align: right;
  color: var(--result);
  font-size: 19px;
  max-width: 100%;
  overflow-x: auto;
}
.h-out .res { cursor: pointer; }
.h-out .approx { color: var(--muted); font-size: 15px; cursor: pointer; }
.h-out .note { color: var(--muted); font-size: 12px; font-style: italic; }
.h-out .err { color: var(--err); font-size: 14px; }
.h-out .pending { color: var(--muted); font-size: 13px; }
.h-tools {
  position: absolute; top: 4px; right: 8px;
  display: none; gap: 4px;
}
.h:hover .h-tools { display: flex; }
.h-tools button { padding: 0 7px; font-size: 12px; background: var(--panel); }
.entry-bar {
  display: flex;
  gap: 8px;
  align-items: center;
  padding: 8px 12px;
  border-top: 2px solid var(--accent);
  background: var(--panel);
}
.entry-bar math-field { flex: 1; min-width: 0; }
.console-bar {
  display: flex; align-items: center; gap: 8px;
  padding: 4px 12px 8px; background: var(--panel); font-size: 12px; color: var(--muted);
}
.console-bar button { margin-left: auto; font-size: 12px; padding: 2px 8px; }

math-field {
  font-size: 21px;
  background: transparent;
  border: none;
  outline: none;
  color: var(--ink);
  padding: 4px 2px;
  --caret-color: var(--accent);
  --selection-background-color: color-mix(in srgb, var(--accent) 25%, transparent);
  --contains-highlight-background-color: color-mix(in srgb, var(--accent) 10%, transparent);
}
math-field::part(virtual-keyboard-toggle), math-field::part(menu-toggle) { color: var(--muted); }

/* ---- graph */
#graph-panel { display: flex; flex-direction: column; min-width: 0; min-height: 0; }
.graph-bar { display: flex; gap: 12px; align-items: center; padding: 6px 12px; border-bottom: 1px solid var(--line); font-size: 13px; }
.tabs { display: flex; }
.tabs button { border-radius: 0; }
.tabs button:first-child { border-radius: 6px 0 0 6px; }
.tabs button:last-child { border-radius: 0 6px 6px 0; margin-left: -1px; }
.tabs button.on { background: var(--accent); color: var(--panel); border-color: var(--accent); }
.tabs .count { font-size: 11px; opacity: .8; }
#btn-home { margin-left: auto; }
.plots { flex: 1; min-height: 220px; position: relative; overflow: hidden; }
.plot { position: absolute; inset: 0; }
.plot[hidden] { display: none; }
/* Anaglyph: each eye renders in grey, a multiply tint keeps one channel (red | green+blue),
   and the right eye is screen-blended over the left, which adds the channels back together. */
#stage3d { isolation: isolate; }
.eye { position: absolute; inset: 0; isolation: isolate; }
.eye[hidden] { display: none; }
.eye .tint { position: absolute; inset: 0; pointer-events: none; mix-blend-mode: multiply; display: none; }
.eye-l, .eye-l * { pointer-events: none !important; }
#stage3d.ana .plot { filter: grayscale(1); }
#stage3d.ana .tint { display: block; }
#stage3d.ana .eye-l .tint { background: #ff0000; }
#stage3d.ana .eye-r .tint { background: #00ffff; }
#stage3d.ana .eye-r { mix-blend-mode: screen; }

#glist {
  max-height: 42%;
  overflow-y: auto;
  border-top: 1px solid var(--line);
  background: var(--panel);
}
#graphs { list-style: none; margin: 0; padding: 0; }
.g {
  display: grid;
  grid-template-columns: 30px 1fr auto;
  gap: 2px 8px;
  align-items: center;
  padding: 2px 10px 2px 8px;
  border-bottom: 1px solid var(--line);
}
.g:focus-within { background: var(--hover); }
.g math-field { font-size: 18px; width: 100%; }
.dot {
  width: 20px; height: 20px; margin: 0 auto;
  border-radius: 50%;
  border: 2px solid var(--c);
  padding: 0;
  background: transparent;
}
.dot.on { background: var(--c); }
.g .del { padding: 0 7px; font-size: 12px; opacity: .5; }
.g:hover .del, .g:focus-within .del { opacity: 1; }
.g .gerr { grid-column: 2 / 4; color: var(--err); font-size: 12px; padding-bottom: 4px; }
.g .gerr:empty, .g .sliders:empty { display: none; }
.sliders { grid-column: 2 / 4; display: flex; flex-direction: column; gap: 2px; padding-bottom: 4px; }
.slider { display: flex; gap: 8px; align-items: center; font-size: 12px; color: var(--muted); }
.slider .name { min-width: 64px; color: var(--ink); font-size: 15px; }
.slider input[type=range] { flex: 1; accent-color: var(--accent); }
.slider input[type=number] {
  width: 56px; font: inherit; color: var(--ink); background: var(--bg);
  border: 1px solid var(--line); border-radius: 4px; padding: 1px 4px;
}
.gadd { display: grid; grid-template-columns: 30px 1fr; gap: 8px; align-items: center; padding: 2px 10px 2px 8px; }
.gplus { text-align: center; color: var(--muted); font-size: 18px; }
.gadd math-field { font-size: 18px; width: 100%; }

dialog {
  max-width: 740px; width: calc(100% - 32px);
  background: var(--panel); color: var(--ink);
  border: 1px solid var(--line); border-radius: 10px; padding: 8px 24px 20px;
}
dialog::backdrop { background: rgba(0, 0, 0, .45); }
dialog h2 { font-size: 16px; margin: 16px 0 6px; }
dialog .close { float: right; border: none; font-size: 22px; line-height: 1; }
dialog table { border-collapse: collapse; font-size: 14px; }
dialog td { padding: 3px 12px 3px 0; }
dialog ul { padding-left: 18px; }
dialog li { margin: 4px 0; }
.cmds { font-family: ui-monospace, Menlo, monospace; font-size: 13px; line-height: 1.8; }
kbd, code {
  font: 12.5px ui-monospace, Menlo, monospace;
  background: var(--bg); border: 1px solid var(--line); border-radius: 4px; padding: 0 4px;
}

.toast {
  position: fixed; bottom: 20px; left: 50%; transform: translateX(-50%);
  background: var(--ink); color: var(--bg); padding: 6px 14px; border-radius: 6px; font-size: 13px;
  z-index: 50;
}

@media (max-width: 820px) {
  body { display: block; }
  main { display: flex; flex-direction: column; }
  #console { height: 70vh; border-right: none; border-bottom: 1px solid var(--line); }
  #graph-panel { height: 90vh; }
  .entry-bar { padding: 8px 16px; }
}