:root {
  --bg: #16181d;
  --panel: #1c1f26;
  --panel-2: #21252e;
  --line: #2c313c;
  --text: #d6dae1;
  --dim: #838c9c;
  --dimmer: #5d6675;
  --green: #6cc07a;
  --red: #e2686d;
  --yellow: #d8ab5c;
  --blue: #6fa8dc;
  --accent: #7aa2f7;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 13px/1.5 var(--mono);
  overflow: hidden;
}

button {
  font: inherit;
  border-radius: 4px;
  padding: 4px 10px;
  cursor: pointer;
  border: 1px solid var(--line);
  background: var(--panel-2);
  color: var(--text);
}
button:hover:not(:disabled) { border-color: var(--dimmer); background: #262b35; }
button:disabled { opacity: .4; cursor: default; }
button.primary { background: #2b3c5e; border-color: #3c5488; color: #e7edf7; }
button.primary:hover:not(:disabled) { background: #334870; }
kbd {
  font: 11px var(--mono);
  color: var(--dim);
  border: 1px solid var(--line);
  border-radius: 3px;
  padding: 0 3px;
  margin-left: 4px;
}
.spacer { flex: 1; }

/* ---------------------------------------------------------------- header */

header {
  display: flex;
  align-items: center;
  gap: 14px;
  height: 38px;
  padding: 0 12px;
  background: var(--panel);
  border-bottom: 1px solid var(--line);
}
.brand { color: var(--dim); white-space: nowrap; }
.progress { display: flex; align-items: center; gap: 8px; }
.bar {
  width: 150px;
  height: 6px;
  background: var(--panel-2);
  border: 1px solid var(--line);
  border-radius: 3px;
  overflow: hidden;
}
.bar span {
  display: block;
  height: 100%;
  width: 0;
  background: var(--green);
  transition: width .2s;
}
#bar-text { color: var(--dim); font-size: 12px; }
.boot { color: var(--yellow); font-size: 12px; }
.boot.ready { color: var(--green); }
.boot.failed { color: var(--red); }

/* --------------------------------------------------------------- layout */

main { display: flex; height: calc(100% - 38px); }

#sidebar {
  width: 250px;
  flex: none;
  overflow-y: auto;
  background: var(--panel);
  border-right: 1px solid var(--line);
  padding: 6px 0 40px;
}
#work { flex: 1; display: flex; flex-direction: column; min-width: 0; }

#crumbs {
  display: flex;
  align-items: center;
  gap: 10px;
  height: 32px;
  padding: 0 12px;
  border-bottom: 1px solid var(--line);
  background: var(--panel);
  font-size: 12px;
}
#crumb-module { color: var(--dim); }
#crumb-problem { color: var(--text); font-weight: 600; }
#crumb-aside { color: var(--yellow); font-size: 11px; }

#panes { flex: 1; display: flex; min-height: 0; }
#reading {
  width: 46%;
  overflow-y: auto;
  padding: 12px 16px 60px;
  border-right: 1px solid var(--line);
}
#grip { width: 5px; cursor: col-resize; background: transparent; margin-left: -3px; flex: none; }
#grip:hover { background: var(--line); }
#doing { flex: 1; display: flex; flex-direction: column; min-width: 0; }

/* -------------------------------------------------------------- sidebar */

.mod {
  padding: 5px 10px 5px 12px;
  cursor: pointer;
  display: flex;
  gap: 8px;
  align-items: baseline;
  color: var(--dim);
  border-left: 2px solid transparent;
}
.mod:hover { background: var(--panel-2); }
.mod.open { color: var(--text); }
.mod .num { color: var(--dimmer); font-size: 11px; }
.mod .count { margin-left: auto; font-size: 11px; color: var(--dimmer); }
.mod.done .count { color: var(--green); }
.mod .locked { color: var(--yellow); font-size: 11px; }

.prob {
  padding: 3px 10px 3px 32px;
  cursor: pointer;
  display: flex;
  gap: 8px;
  align-items: center;
  color: var(--dim);
  font-size: 12px;
  border-left: 2px solid transparent;
}
.prob:hover { background: var(--panel-2); }
.prob.current { background: #232a38; border-left-color: var(--accent); color: var(--text); }
.dot { width: 7px; height: 7px; border-radius: 50%; background: var(--line); flex: none; }
.dot.pass { background: var(--green); }
.dot.failed { background: var(--red); }
.dot.crashed { background: var(--yellow); }
.dot.started { background: var(--blue); }
.prob .name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

/* -------------------------------------------------------------- reading */

#reading pre {
  margin: 0;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  font: 12.5px/1.65 var(--mono);
}
#problem-theory { color: var(--dim); }
#problem-task { color: var(--text); }
#topic-label {
  color: var(--accent);
  font-size: 11px;
  letter-spacing: .06em;
  text-transform: uppercase;
  margin: 4px 0 8px;
}
.hr { height: 1px; background: var(--line); margin: 14px 0; }

details { margin: 0 0 10px; }
details summary {
  cursor: pointer;
  color: var(--dimmer);
  font-size: 11.5px;
  padding: 3px 0;
  list-style: none;
}
details summary::-webkit-details-marker { display: none; }
details summary::before { content: "> "; }
details[open] summary::before { content: "v "; }
details summary:hover { color: var(--dim); }
#module-theory-body { color: var(--dim); padding: 8px 0 4px; }
#solution-wrap { margin-top: 22px; border-top: 1px solid var(--line); padding-top: 8px; }
#solution-body { color: var(--green); padding-top: 8px; }

/* --------------------------------------------------------------- doing */

#editor-wrap { flex: 1; min-height: 120px; overflow: hidden; }
.CodeMirror {
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font: 13px/1.55 var(--mono);
}
.CodeMirror-gutters { background: var(--bg); border-right: 1px solid var(--line); }
.CodeMirror-linenumber { color: #3d4553; }
.CodeMirror-cursor { border-left: 1px solid var(--text); }
.CodeMirror-selected { background: #2d3444 !important; }
.CodeMirror-line::selection, .CodeMirror-line > span::selection { background: #2d3444; }
.cm-s-default .cm-keyword { color: #c39bd8; }
.cm-s-default .cm-string { color: #a3cc8a; }
.cm-s-default .cm-number { color: #d8ab5c; }
.cm-s-default .cm-def { color: #7aa2f7; }
.cm-s-default .cm-builtin { color: #6fa8dc; }
.cm-s-default .cm-comment { color: #5d6675; }
.cm-s-default .cm-operator { color: #b8c0cc; }
.CodeMirror-matchingbracket { color: var(--yellow) !important; text-decoration: none; }
.line-error { background: rgba(226, 104, 109, .16); }

#actions {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 10px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: var(--panel);
}
.chk { color: var(--dim); font-size: 12px; cursor: pointer; user-select: none; }
.chk input { vertical-align: -1px; }

#scratch-wrap[hidden] { display: none; }
#scratch-wrap {
  border-bottom: 1px solid var(--line);
  background: var(--panel-2);
  padding: 8px 10px;
  display: flex;
  gap: 8px;
  align-items: flex-start;
}
#scratch {
  flex: 1;
  height: 62px;
  resize: vertical;
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 6px 8px;
  font: 12.5px/1.5 var(--mono);
}
#scratch:focus, #data-box:focus { outline: 1px solid var(--accent); }

#output {
  height: 34%;
  min-height: 90px;
  overflow-y: auto;
  padding: 8px 12px 20px;
  background: var(--panel);
}
#output .idle { color: var(--dimmer); }
#output pre {
  margin: 0;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  font: 12.5px/1.6 var(--mono);
}
.res { display: flex; gap: 8px; align-items: baseline; margin-bottom: 2px; }
.tag { flex: none; width: 52px; font-size: 11px; letter-spacing: .04em; }
.tag.pass { color: var(--green); }
.tag.failed { color: var(--red); }
.tag.crashed { color: var(--yellow); }
.tag.todo { color: var(--dimmer); }
.msg { color: var(--dim); padding: 2px 0 8px 60px; }
.msg .em { color: var(--text); }
.banner { margin-bottom: 8px; }
.banner.good { color: var(--green); }
.banner.bad { color: var(--red); }
.banner.warn { color: var(--yellow); }
.stdout-label { color: var(--dimmer); font-size: 11px; margin: 10px 0 2px; }
.stdout { color: var(--blue); }

/* -------------------------------------------------------------- dialog */

dialog {
  background: var(--panel);
  color: var(--text);
  border: 1px solid var(--line);
  border-radius: 6px;
  width: min(620px, 90vw);
  font: 13px/1.5 var(--mono);
}
dialog::backdrop { background: rgba(0, 0, 0, .55); }
dialog h3 { margin: 0 0 6px; font-size: 14px; }
dialog p { color: var(--dim); margin: 0 0 10px; font-size: 12px; }
#data-box {
  width: 100%;
  height: 200px;
  background: var(--bg);
  color: var(--dim);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 8px;
  font: 11.5px/1.4 var(--mono);
  resize: vertical;
}
dialog .row { display: flex; gap: 8px; margin-top: 10px; align-items: center; }