/* SiliconDV Practice Lab styles.
   Paper background, ink text, one accent color. Borders are 1px,
   corners stay small. Nothing glows, nothing gradients. */

:root {
  --paper: #FAF9F6;
  --card: #FFFFFF;
  --ink: #23272E;
  --muted: #6B7280;
  --line: #E5E1D8;
  --accent: #B3401F;
  --accent-dark: #93331a;
  --code-bg: #F1EFE9;
  --radius: 6px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
}

.mono, code, pre {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas,
    "Liberation Mono", monospace;
}

.wrap {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Demo mode strip. Honest and hard to miss. */
.demo-strip {
  background: #F6EFDD;
  border-bottom: 1px solid var(--line);
  color: var(--ink);
  font-size: 13px;
  padding: 8px 0;
  text-align: center;
}
.demo-strip strong { font-weight: 700; }

/* Header */
header.site {
  border-bottom: 1px solid var(--line);
  background: var(--paper);
}
header.site .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 14px;
  padding-bottom: 14px;
}
.brand {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-weight: 700;
  font-size: 17px;
  color: var(--ink);
  text-decoration: none;
}
.brand .dot { color: var(--accent); }
nav.main a {
  color: var(--muted);
  text-decoration: none;
  margin-left: 18px;
  font-size: 14px;
}
nav.main a:hover, nav.main a.active { color: var(--ink); }
nav.main .who {
  color: var(--ink);
  font-size: 14px;
  margin-left: 18px;
}
nav.main button.linklike {
  background: none;
  border: none;
  color: var(--muted);
  cursor: pointer;
  font-size: 14px;
  margin-left: 18px;
  padding: 0;
  font-family: inherit;
}
nav.main button.linklike:hover { color: var(--ink); text-decoration: underline; }

/* Main */
main .wrap { padding-top: 32px; padding-bottom: 64px; }

h1 { font-size: 32px; line-height: 1.25; margin: 0 0 12px; letter-spacing: -0.01em; }
h2 { font-size: 22px; margin: 32px 0 12px; }
h3 { font-size: 17px; margin: 24px 0 8px; }
p { margin: 0 0 14px; }
.lede { font-size: 18px; color: #3a3f47; max-width: 640px; }

a { color: var(--accent); }
a:hover { color: var(--accent-dark); }

/* Hero */
.hero { padding: 28px 0 8px; }
.hero .kicker {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 13px;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 10px;
}

/* Why I built this */
.why {
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent);
  background: var(--card);
  border-radius: var(--radius);
  padding: 20px 22px;
  margin: 32px 0;
  max-width: 700px;
}
.why p:last-child { margin-bottom: 0; }
.why .sig { color: var(--muted); font-size: 14px; margin-top: 10px; }

/* Track cards */
.cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin: 20px 0 8px;
}
.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
  display: flex;
  flex-direction: column;
}
.card h3 { margin: 0 0 8px; font-size: 18px; }
.card h3 a { color: var(--ink); text-decoration: none; }
.card h3 a:hover { color: var(--accent); }
.card p { color: var(--muted); font-size: 14px; flex: 1; }
.card .meta {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 12px;
  color: var(--muted);
  margin-top: 12px;
}
.card .go { margin-top: 12px; font-size: 14px; font-weight: 600; }

/* Steps */
.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin: 16px 0;
  counter-reset: step;
}
.step {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
  padding: 18px;
}
.step .n {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 13px;
  color: var(--accent);
  font-weight: 700;
}
.step h3 { margin: 6px 0 6px; }
.step p { font-size: 14px; color: var(--muted); margin: 0; }

/* Buttons */
.btn {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  border: 1px solid var(--accent);
  border-radius: var(--radius);
  padding: 10px 20px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  font-family: inherit;
}
.btn:hover { background: var(--accent-dark); border-color: var(--accent-dark); color: #fff; }
.btn-ghost {
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--line);
}
.btn-ghost:hover { border-color: var(--ink); background: transparent; color: var(--ink); }
.btn-row { display: flex; gap: 12px; margin: 20px 0; flex-wrap: wrap; }

/* Forms */
.form-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px;
  max-width: 480px;
}
.field { margin-bottom: 16px; }
.field label {
  display: block;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 6px;
}
.field input {
  width: 100%;
  padding: 10px 12px;
  font-size: 15px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--paper);
  color: var(--ink);
  font-family: inherit;
}
.field input:focus { outline: 2px solid var(--accent); outline-offset: 0; border-color: var(--accent); }
.form-note { font-size: 13px; color: var(--muted); margin-top: 14px; }
.form-error {
  display: none;
  background: #F9E9E2;
  border: 1px solid #E3B79F;
  color: #7A2E14;
  border-radius: var(--radius);
  padding: 10px 14px;
  font-size: 14px;
  margin-bottom: 16px;
}
.form-error.show { display: block; }

/* Progress */
.track-progress {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px 22px;
  margin-bottom: 14px;
}
.track-progress .top {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
}
.track-progress h3 { margin: 0; }
.track-progress h3 a { color: var(--ink); text-decoration: none; }
.track-progress h3 a:hover { color: var(--accent); }
.count { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 13px; color: var(--muted); }
.bar {
  height: 8px;
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: 4px;
  margin: 12px 0 10px;
  overflow: hidden;
}
.bar > span { display: block; height: 100%; background: var(--accent); }
.levels { font-size: 13px; color: var(--muted); }
.empty {
  border: 1px dashed var(--line);
  border-radius: var(--radius);
  padding: 24px;
  color: var(--muted);
  margin: 8px 0 24px;
  background: var(--card);
}

/* Problem list */
.level-group { margin-bottom: 28px; }
.level-group > h3 {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  margin-bottom: 10px;
}
.prow {
  display: flex;
  align-items: center;
  gap: 14px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 12px 16px;
  margin-bottom: 8px;
  text-decoration: none;
  color: var(--ink);
}
.prow:hover { border-color: var(--accent); }
.prow .num {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 13px;
  color: var(--muted);
  min-width: 36px;
}
.prow .t { flex: 1; font-weight: 600; font-size: 15px; }
.prow .t small { display: block; font-weight: 400; color: var(--muted); font-size: 13px; }

/* Badges */
.badge {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 3px 8px;
  white-space: nowrap;
  color: var(--muted);
  background: var(--paper);
}
.badge.beginner { color: #2F7D4F; border-color: #BFD9C8; background: #EFF6F1; }
.badge.intermediate { color: #8A5E0E; border-color: #E3CF9E; background: #FAF3E2; }
.badge.advanced { color: var(--accent); border-color: #E3B79F; background: #F9ECE4; }
.badge.done { color: #2F7D4F; border-color: #BFD9C8; background: #EFF6F1; }
.badge.tried { color: #8A5E0E; border-color: #E3CF9E; background: #FAF3E2; }

/* Code blocks */
pre.code {
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px 18px;
  font-size: 13.5px;
  line-height: 1.55;
  overflow-x: auto;
  margin: 12px 0 20px;
}
.code-label {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  margin: 20px 0 0;
}
.solution-label {
  display: inline-block;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent);
  border: 1px solid #E3B79F;
  background: #F9ECE4;
  border-radius: 4px;
  padding: 3px 8px;
  margin: 20px 0 0;
}
.done-note {
  border: 1px solid #BFD9C8;
  background: #EFF6F1;
  color: #2F7D4F;
  border-radius: var(--radius);
  padding: 12px 16px;
  font-size: 14px;
  margin: 20px 0;
}

/* Materials */
.mat-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin-top: 16px;
}
.mat-note { font-size: 13px; color: var(--muted); margin-top: 20px; }

/* Not found */
.notfound {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
  padding: 40px;
  text-align: center;
  max-width: 560px;
  margin: 40px auto;
}
.notfound h1 { font-size: 24px; }

/* Tables (admin) */
table.data {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
  margin: 12px 0 28px;
  background: var(--card);
}
table.data th, table.data td {
  border: 1px solid var(--line);
  padding: 8px 12px;
  text-align: left;
}
table.data th {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  background: var(--code-bg);
}
.admin-key { display: flex; gap: 10px; margin: 16px 0; max-width: 520px; }
.admin-key input {
  flex: 1;
  padding: 10px 12px;
  font-size: 15px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
  color: var(--ink);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

/* Footer */
footer.site {
  border-top: 1px solid var(--line);
  padding: 24px 0 40px;
  color: var(--muted);
  font-size: 13px;
}
footer.site .wrap { display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; }

@media (max-width: 720px) {
  .cards, .steps, .mat-grid { grid-template-columns: 1fr; }
  h1 { font-size: 26px; }
  nav.main a { margin-left: 12px; }
  .prow { flex-wrap: wrap; }
}

/* Problem list: filters and table */

.filters {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
  padding: 14px 16px;
  margin: 16px 0 8px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.chip-row { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.chip-label {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  margin-right: 4px;
}
.chip {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 20px;
  padding: 4px 12px;
  font-size: 13px;
  font-family: inherit;
  color: var(--muted);
  cursor: pointer;
}
.chip:hover { border-color: var(--ink); color: var(--ink); }
.chip.on { background: var(--ink); border-color: var(--ink); color: #fff; }
.search-row input {
  width: 100%;
  max-width: 360px;
  padding: 8px 12px;
  font-size: 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--paper);
  color: var(--ink);
  font-family: inherit;
}
.search-row input:focus { outline: 2px solid var(--accent); border-color: var(--accent); }

table.plist {
  width: 100%;
  border-collapse: collapse;
  font-size: 15px;
  margin: 8px 0 12px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}
table.plist th, table.plist td {
  padding: 10px 14px;
  text-align: left;
  border-bottom: 1px solid var(--line);
}
table.plist thead th {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  background: var(--code-bg);
}
table.plist tbody tr:last-child td { border-bottom: none; }
table.plist tbody tr:hover td { background: #FBFAF7; }
.c-num { width: 56px; color: var(--muted); font-size: 13px; }
.c-diff { width: 110px; }
.c-status { width: 70px; text-align: center; }
.c-title a { color: var(--ink); text-decoration: none; font-weight: 600; }
.c-title a:hover { color: var(--accent); }
.c-track {
  display: block;
  font-size: 12px;
  color: var(--muted);
  font-weight: 400;
}

.diff { font-weight: 600; font-size: 14px; }
.diff-beginner { color: #2F7D4F; }
.diff-intermediate { color: #8A5E0E; }
.diff-advanced { color: var(--accent); }

.st { font-size: 16px; line-height: 1; }
.st-done { color: #2F7D4F; font-weight: 700; }
.st-tried { color: #8A5E0E; }
.st-none { color: #C9C4B8; }

.muted-line { font-size: 13px; color: var(--muted); }
.tiny { font-size: 12px; margin-top: 6px; }
.legend { margin-top: 4px; }

/* Problem page: two pane layout */

.prob-head .pnum { color: var(--muted); font-size: 0.6em; }
.pstatus { font-size: 14px; margin-left: 10px; }
.ps-done { color: #2F7D4F; font-weight: 600; }
.ps-tried { color: #8A5E0E; font-weight: 600; }
.ps-none { color: var(--muted); }

.prob-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-top: 20px;
  align-items: start;
}
.pane {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px 22px;
  min-width: 0;
}

.tabs {
  display: flex;
  gap: 4px;
  border-bottom: 1px solid var(--line);
  margin: -4px -6px 16px;
  padding: 0 6px;
}
.tab {
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  padding: 10px 12px;
  font-size: 14px;
  font-weight: 600;
  color: var(--muted);
  cursor: pointer;
  font-family: inherit;
  margin-bottom: -1px;
}
.tab:hover { color: var(--ink); }
.tab.on { color: var(--ink); border-bottom-color: var(--accent); }

.constraints { margin: 8px 0 16px; padding-left: 20px; }
.constraints li { margin-bottom: 6px; font-size: 15px; }

.locked {
  border: 1px dashed var(--line);
  border-radius: var(--radius);
  padding: 24px;
  text-align: center;
  color: var(--muted);
  margin-top: 12px;
}

#notes {
  width: 100%;
  padding: 12px 14px;
  font-size: 14px;
  line-height: 1.6;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--paper);
  color: var(--ink);
  font-family: inherit;
  resize: vertical;
}
#notes:focus { outline: 2px solid var(--accent); border-color: var(--accent); }

/* Hand rolled code editor: textarea plus a synced line number gutter */

.editor {
  display: flex;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--code-bg);
  overflow: hidden;
  margin-top: 8px;
}
.gutter {
  padding: 14px 10px 14px 14px;
  text-align: right;
  color: #A8A294;
  background: var(--code-bg);
  border-right: 1px solid var(--line);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 13.5px;
  line-height: 1.55;
  user-select: none;
  overflow: hidden;
  white-space: pre;
  min-width: 44px;
}
#ed {
  flex: 1;
  min-height: 340px;
  padding: 14px 16px;
  border: none;
  background: transparent;
  color: var(--ink);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 13.5px;
  line-height: 1.55;
  resize: vertical;
  white-space: pre;
  overflow: auto;
}
#ed:focus { outline: 2px solid var(--accent); outline-offset: -2px; }

.self-note {
  font-size: 13px;
  color: var(--muted);
  align-self: center;
}

/* Concept check quiz */

.quiz-head { margin-top: 28px; }
.quiz-q {
  border-top: 1px solid var(--line);
  padding: 14px 0;
}
.quiz-q .qq { font-size: 15px; margin-bottom: 10px; }
.quiz-q .qnum {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 12px;
  color: var(--muted);
}
.choices { display: flex; flex-direction: column; gap: 8px; }
.choice {
  text-align: left;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 8px 12px;
  font-size: 14px;
  font-family: inherit;
  color: var(--ink);
  cursor: pointer;
}
.choice:hover:not(:disabled) { border-color: var(--ink); }
.choice:disabled { cursor: default; opacity: 0.9; }
.choice .clett {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 12px;
  color: var(--muted);
  margin-right: 8px;
}
.choice.right { border-color: #2F7D4F; background: #EFF6F1; }
.choice.wrong { border-color: var(--accent); background: #F9ECE4; }
.quiz-q .why {
  font-size: 14px;
  color: #3a3f47;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 10px 14px;
  margin-top: 10px;
}

/* Track card extras on the landing page */
.card .covers { font-size: 14px; color: #3a3f47; margin: 8px 0; }
.card .whofor { font-size: 14px; color: var(--muted); font-style: italic; margin: 8px 0 0; }

/* Hints: progressive reveal on the problem page */
#hints { margin: 8px 0 18px; }
#hints .tiny { margin-bottom: 10px; }
.hint-list { margin: 12px 0 0; padding-left: 0; list-style: none; counter-reset: hint; }
.hint-list .hint {
  counter-increment: hint;
  font-size: 15px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 10px 14px 10px 44px;
  margin-bottom: 8px;
  position: relative;
}
.hint-list .hint::before {
  content: counter(hint);
  position: absolute;
  left: 14px;
  top: 10px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 13px;
  color: var(--accent);
  font-weight: 700;
}

/* Takeaway shown at the end of a revealed solution */
.takeaway {
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent);
  background: var(--card);
  border-radius: var(--radius);
  padding: 12px 16px;
  margin-top: 16px;
  font-size: 15px;
}

/* Dashboard: difficulty breakdown and activity */

.diff-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin: 8px 0 8px;
}
.diff-cell {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px 18px;
}
.diff-cell .diff-top {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 10px;
}
ul.activity { list-style: none; margin: 0; padding: 0; }
ul.activity li {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 10px 14px;
  margin-bottom: 8px;
  font-size: 14px;
}
ul.activity a { color: var(--ink); text-decoration: none; font-weight: 600; }
ul.activity a:hover { color: var(--accent); }

@media (max-width: 860px) {
  .prob-grid { grid-template-columns: 1fr; }
  .diff-grid { grid-template-columns: 1fr; }
  table.plist { font-size: 14px; }
  .c-diff { width: 80px; }
}