/* SQL Simulator — design tokens & layout */

:root {
  --paper:      oklch(0.985 0.004 80);
  --paper-2:    oklch(0.965 0.006 80);
  --paper-3:    oklch(0.945 0.008 80);
  --line:       oklch(0.88 0.008 80);
  --line-soft:  oklch(0.92 0.006 80);
  --ink:        oklch(0.22 0.012 80);
  --ink-2:      oklch(0.38 0.010 80);
  --ink-3:      oklch(0.58 0.008 80);
  --ink-mute:   oklch(0.72 0.006 80);

  --accent:     oklch(0.62 0.14 50);   /* warm amber */
  --accent-2:   oklch(0.72 0.13 55);
  --accent-soft: oklch(0.94 0.04 65);
  --accent-ink: oklch(0.32 0.10 45);

  --ok:         oklch(0.58 0.10 155);
  --ok-soft:    oklch(0.94 0.04 155);
  --err:        oklch(0.55 0.16 30);
  --err-soft:   oklch(0.95 0.04 30);

  --kw:         oklch(0.42 0.12 280);  /* keywords - deep indigo */
  --string:     oklch(0.50 0.10 145);  /* strings - olive green */
  --num:        oklch(0.55 0.13 40);   /* numbers - amber */
  --comment:    oklch(0.65 0.012 80);  /* comments - muted */
  --punct:      oklch(0.45 0.012 80);

  --r-sm: 4px;
  --r-md: 6px;
  --r-lg: 10px;

  --font-sans: "Inter", "Helvetica Neue", system-ui, sans-serif;
  --font-mono: "Geist Mono", "JetBrains Mono", ui-monospace, "SF Mono", Menlo, monospace;
  --font-serif: "Instrument Serif", "Georgia", serif;
}

* { box-sizing: border-box; }

html, body, #root {
  height: 100%;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-sans);
  background: var(--paper);
  color: var(--ink);
  font-size: 13px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  font-feature-settings: "ss01", "cv11";
}

button {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
  border: none;
  background: none;
  cursor: pointer;
  padding: 0;
}

textarea, input { font-family: inherit; }

/* ---------- App shell ---------- */

.app {
  display: grid;
  grid-template-rows: 48px 1fr;
  height: 100vh;
  background:
    linear-gradient(var(--paper), var(--paper));
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 18px;
  border-bottom: 1px solid var(--line);
  background: var(--paper);
  position: relative;
}
.topbar::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, var(--line-soft) 1px, transparent 1px);
  background-size: 8px 100%;
  opacity: 0.35;
  pointer-events: none;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.02em;
  position: relative;
  z-index: 1;
}
.brand-mark {
  width: 22px; height: 22px;
  background: var(--ink);
  color: var(--paper);
  display: grid;
  place-items: center;
  font-weight: 600;
  font-size: 11px;
  border-radius: 3px;
  font-family: var(--font-mono);
}
.brand-name { font-weight: 600; color: var(--ink); }
.brand-sep { color: var(--ink-mute); }
.brand-tag {
  color: var(--ink-3);
  font-size: 11px;
}

.topbar-meta {
  display: flex;
  align-items: center;
  gap: 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--ink-3);
  position: relative; z-index: 1;
}
.status-dot {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.status-dot i {
  width: 7px; height: 7px;
  border-radius: 50%;
  background: var(--ok);
  box-shadow: 0 0 0 3px oklch(0.94 0.04 155 / 0.6);
}
.status-dot.loading i { background: var(--ink-mute); box-shadow: none; }

/* ---------- Workspace grid ---------- */

.workspace {
  display: grid;
  grid-template-columns:
    var(--col-schema-w, 260px)
    6px
    minmax(0, 1fr)
    6px
    var(--col-results-w, 360px);
  height: 100%;
  min-height: 0;
}

.col-resizer {
  position: relative;
  cursor: col-resize;
  background: var(--line);
  opacity: 0.4;
  transition: opacity 120ms ease, background 120ms ease;
  user-select: none;
  touch-action: none;
}
.col-resizer::after {
  content: "";
  position: absolute;
  inset: 0 -3px;
}
.col-resizer:hover,
.col-resizer.is-dragging {
  opacity: 1;
  background: var(--accent, var(--ink-3));
}
body.is-resizing,
body.is-resizing * {
  cursor: col-resize !important;
  user-select: none !important;
}

.col {
  border-right: 1px solid var(--line);
  display: flex;
  flex-direction: column;
  min-width: 0;
  min-height: 0;
  background: var(--paper);
}
.col:last-child { border-right: none; }

.col-schema { background: var(--paper-2); }
.col-results { background: var(--paper-2); border-left: 1px solid var(--line); border-right: none; }

/* ---------- Pane headers ---------- */

.pane-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 14px;
  border-bottom: 1px solid var(--line);
  background: var(--paper);
  min-height: 38px;
}
.col-schema .pane-header,
.col-results .pane-header { background: var(--paper-2); }

.pane-eyebrow {
  font-family: var(--font-mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--ink-3);
}
.pane-meta {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--ink-mute);
}

/* ---------- Schema viewer ---------- */

.schema-viewer {
  display: flex;
  flex-direction: column;
  height: 100%;
  min-height: 0;
}
.schema-list {
  flex: 1;
  overflow-y: auto;
  padding: 4px 0 16px;
}
.schema-table {
  border-bottom: 1px solid var(--line-soft);
}
.schema-table.is-active {
  background: var(--accent-soft);
}
.schema-table-head {
  display: grid;
  grid-template-columns: 14px 1fr auto;
  align-items: center;
  gap: 8px;
  width: 100%;
  padding: 8px 14px;
  text-align: left;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink);
}
.schema-table-head:hover { background: var(--paper-3); }
.chev {
  font-size: 10px;
  color: var(--ink-3);
  display: inline-block;
  transform: rotate(0deg);
  transition: transform 0.12s;
}
.chev.open { transform: rotate(90deg); }
.schema-table-name { font-weight: 600; }
.schema-rowcount {
  font-size: 10px;
  color: var(--ink-mute);
  background: var(--paper-3);
  padding: 1px 6px;
  border-radius: 8px;
}
.schema-table.is-active .schema-rowcount { background: var(--paper); }

.schema-cols {
  padding: 2px 0 6px;
  border-top: 1px dashed var(--line-soft);
}
.schema-col {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 4px 14px 4px 36px;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--ink-2);
  text-align: left;
  position: relative;
}
.schema-col:hover { background: var(--paper-3); color: var(--ink); }
.schema-col::before {
  content: "·";
  position: absolute;
  left: 22px;
  color: var(--ink-mute);
}
.col-name { display: inline-flex; align-items: center; gap: 6px; }
.col-type { color: var(--ink-mute); font-size: 10px; }
.col-tag {
  font-size: 8.5px;
  font-weight: 600;
  padding: 1px 4px;
  border-radius: 2px;
  letter-spacing: 0.06em;
}
.col-tag.pk { background: oklch(0.92 0.06 280); color: oklch(0.36 0.13 280); }
.col-tag.fk { background: var(--accent-soft); color: var(--accent-ink); }

.schema-foot {
  border-top: 1px solid var(--line);
  padding: 10px 14px;
  background: var(--paper);
}
.legend {
  display: flex;
  flex-direction: column;
  gap: 4px;
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--ink-3);
}
.legend-item { display: flex; align-items: center; gap: 6px; }
.dot { width: 8px; height: 8px; border-radius: 2px; display: inline-block; }
.pk-dot { background: oklch(0.36 0.13 280); }
.fk-dot { background: var(--accent); }

/* ---------- Lesson rail (top of center column) ---------- */

.lesson-rail {
  border-bottom: 1px solid var(--line);
  background: var(--paper);
  padding: 0 0 0 0;
  flex: 0 0 auto;
}
.rail-label {
  font-family: var(--font-mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--ink-3);
  padding: 10px 14px 6px;
}
.rail-list {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 0;
  border-top: 1px solid var(--line-soft);
}
.rail-item {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  padding: 10px 12px 12px;
  text-align: left;
  border-right: 1px solid var(--line-soft);
  border-bottom: 2px solid transparent;
  transition: border-color 0.15s, background 0.15s;
  min-height: 64px;
}
.rail-item:last-child { border-right: none; }
.rail-item:hover { background: var(--paper-2); }
.rail-item.is-active {
  background: var(--paper);
  border-bottom-color: var(--accent);
}
.rail-num {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--ink-mute);
  margin-top: 2px;
}
.rail-item.is-active .rail-num { color: var(--accent-ink); }
.rail-text { display: flex; flex-direction: column; gap: 2px; min-width: 0; }
.rail-level {
  font-family: var(--font-mono);
  font-size: 9.5px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-3);
}
.rail-title {
  font-size: 12.5px;
  font-weight: 500;
  color: var(--ink);
  line-height: 1.3;
  text-wrap: pretty;
}

/* ---------- Editor pane ---------- */

.editor-pane {
  flex: 1 1 0;
  display: flex;
  flex-direction: column;
  min-height: 220px;
}
.col-editor {
  display: flex;
  flex-direction: column;
  min-height: 0;
  overflow: hidden;
}

.editor-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 14px;
  border-bottom: 1px solid var(--line);
  background: var(--paper);
  gap: 10px;
}
.editor-toolbar-left {
  display: flex;
  align-items: center;
  gap: 12px;
}
.tool-tabs {
  display: flex;
  align-items: center;
  background: var(--paper-2);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  padding: 2px;
  gap: 0;
}
.tool-tab {
  padding: 4px 10px;
  font-size: 11px;
  font-family: var(--font-mono);
  color: var(--ink-3);
  border-radius: 4px;
}
.tool-tab.is-active {
  background: var(--paper);
  color: var(--ink);
  box-shadow: 0 1px 2px oklch(0.2 0 0 / 0.06);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  font-size: 12px;
  font-weight: 500;
  border-radius: var(--r-md);
  border: 1px solid var(--line);
  background: var(--paper);
  color: var(--ink);
  transition: background 0.12s, border-color 0.12s, transform 0.05s;
}
.btn:hover { background: var(--paper-2); }
.btn:active { transform: translateY(1px); }
.btn-primary {
  background: var(--ink);
  color: var(--paper);
  border-color: var(--ink);
}
.btn-primary:hover { background: oklch(0.28 0.012 80); }
.btn-primary .kbd { color: oklch(0.78 0.01 80); }
.btn-ghost {
  background: transparent;
  border-color: transparent;
  color: var(--ink-2);
}
.btn-ghost:hover { background: var(--paper-2); }
.btn-secondary {
  background: var(--paper);
  border-color: var(--line);
  color: var(--ink-2);
}
.btn-icon {
  width: 26px; height: 26px;
  display: grid; place-items: center;
  border-radius: var(--r-md);
  border: 1px solid var(--line);
  background: var(--paper);
  font-size: 13px;
  color: var(--ink-2);
}
.btn-icon:disabled { opacity: 0.35; cursor: not-allowed; }
.btn-icon:not(:disabled):hover { background: var(--paper-2); }

.kbd {
  font-family: var(--font-mono);
  font-size: 10px;
  padding: 1px 4px;
  background: oklch(0.95 0 0 / 0.15);
  border-radius: 3px;
  margin-left: 2px;
}

/* ---------- SQL Editor ---------- */

.sql-editor {
  display: grid;
  grid-template-columns: 44px 1fr;
  flex: 1;
  min-height: 0;
  background:
    repeating-linear-gradient(
      to bottom,
      var(--paper) 0,
      var(--paper) 21px,
      var(--paper) 21px,
      var(--paper) 22px
    );
  position: relative;
}
.gutter {
  background: var(--paper-2);
  border-right: 1px solid var(--line-soft);
  padding: 12px 0;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--ink-mute);
  text-align: right;
  user-select: none;
  overflow: hidden;
}
.gutter-line {
  padding: 0 8px;
  line-height: 21px;
}
.editor-area {
  position: relative;
  min-height: 0;
  overflow: hidden;
}
.editor-highlight,
.editor-textarea {
  position: absolute;
  inset: 0;
  margin: 0;
  padding: 12px 14px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  line-height: 21px;
  white-space: pre;
  overflow: auto;
  tab-size: 2;
}
.editor-highlight {
  pointer-events: none;
  color: var(--ink);
}
.editor-textarea {
  background: transparent;
  color: transparent;
  caret-color: var(--ink);
  border: none;
  outline: none;
  resize: none;
}
.editor-textarea::selection { background: oklch(0.85 0.10 65 / 0.45); color: transparent; }

.tok-k { color: var(--kw); font-weight: 600; }
.tok-s { color: var(--string); }
.tok-n { color: var(--num); }
.tok-c { color: var(--comment); font-style: italic; }
.tok-p { color: var(--punct); }
.tok-i { color: var(--ink); }

/* ---------- Lesson stepper ---------- */

.lesson-stepper {
  border-top: 1px solid var(--line);
  background: var(--paper-2);
  padding: 14px 18px 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  flex: 0 0 auto;
  max-height: 38vh;
  overflow-y: auto;
}
.stepper-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
}
.stepper-eyebrow {
  font-family: var(--font-mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--ink-3);
  margin-bottom: 4px;
}
.stepper-title {
  font-family: var(--font-serif);
  font-size: 22px;
  font-weight: 400;
  margin: 0;
  letter-spacing: -0.01em;
  line-height: 1.15;
}
.stepper-blurb {
  margin: 4px 0 0;
  font-size: 12.5px;
  color: var(--ink-2);
  max-width: 56ch;
}

.step-track {
  display: flex;
  align-items: center;
  gap: 0;
  padding: 4px 0;
}
.step-node {
  display: flex;
  align-items: center;
  flex: 0 0 auto;
}
.step-line {
  display: inline-block;
  width: 36px;
  height: 1px;
  background: var(--line);
  margin: 0 6px;
}
.step-dot-btn { padding: 2px; }
.step-dot {
  width: 22px; height: 22px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 600;
  background: var(--paper);
  border: 1px solid var(--line);
  color: var(--ink-3);
}
.step-done .step-dot { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.step-current .step-dot { background: var(--accent); color: var(--paper); border-color: var(--accent); box-shadow: 0 0 0 4px var(--accent-soft); }
.step-done + .step-line, .step-current + .step-line { background: var(--ink-3); }

.step-card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  padding: 14px 16px;
}
.step-card-head {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 6px;
}
.step-pill {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.04em;
  background: var(--ink);
  color: var(--paper);
  padding: 2px 7px;
  border-radius: 3px;
}
.step-label {
  font-weight: 500;
  font-size: 13px;
  color: var(--ink);
}
.step-note {
  margin: 0 0 12px;
  font-size: 12.5px;
  color: var(--ink-2);
  line-height: 1.55;
  max-width: 64ch;
}
.step-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}
.step-nav { display: flex; gap: 6px; }

/* ---------- Result table ---------- */

.col-results { width: 100%; }

.result-tabs {
  display: flex;
  gap: 0;
  padding: 0 6px;
  border-bottom: 1px solid var(--line);
  background: var(--paper-2);
}
.result-tab {
  padding: 9px 12px;
  font-size: 11.5px;
  font-family: var(--font-mono);
  color: var(--ink-3);
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
}
.result-tab.is-active {
  color: var(--ink);
  border-bottom-color: var(--accent);
}
.result-tab .count {
  margin-left: 6px;
  font-size: 10px;
  background: var(--paper-3);
  padding: 1px 5px;
  border-radius: 8px;
  color: var(--ink-3);
}

.result-body {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
}

.result-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 14px;
  border-bottom: 1px solid var(--line-soft);
  background: var(--paper-2);
}
.result-meta {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--ink-3);
}

.result-table-wrap {
  flex: 1;
  overflow: auto;
  background: var(--paper);
}
.result-table {
  border-collapse: collapse;
  width: 100%;
  font-family: var(--font-mono);
  font-size: 11.5px;
}
.result-table thead {
  position: sticky;
  top: 0;
  background: var(--paper-2);
  z-index: 1;
}
.result-table th, .result-table td {
  padding: 6px 12px;
  text-align: left;
  border-bottom: 1px solid var(--line-soft);
  border-right: 1px solid var(--line-soft);
  white-space: nowrap;
}
.result-table th {
  font-weight: 600;
  font-size: 10.5px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-2);
  border-bottom: 1px solid var(--line);
}
.result-table tr:hover td { background: var(--paper-2); }
.result-table .rownum {
  width: 36px;
  color: var(--ink-mute);
  background: var(--paper-2);
  text-align: right;
  font-size: 10px;
}
.result-table td.is-null { color: var(--ink-mute); font-style: italic; }
.result-table td.is-num { text-align: right; }

.result-empty,
.result-error {
  flex: 1;
  display: grid;
  place-items: center;
  padding: 36px;
}
.result-empty {
  color: var(--ink-3);
  text-align: center;
}
.result-empty-glyph {
  font-size: 36px;
  color: var(--ink-mute);
  margin-bottom: 12px;
}
.result-empty-title {
  font-size: 14px;
  color: var(--ink-2);
  margin-bottom: 4px;
}
.result-empty-sub {
  font-size: 12px;
  color: var(--ink-3);
  max-width: 36ch;
  margin: 0 auto;
}
.result-error {
  align-items: stretch;
  justify-items: stretch;
}
.error-tag {
  font-family: var(--font-mono);
  font-size: 10px;
  background: var(--err);
  color: var(--paper);
  padding: 3px 8px;
  border-radius: 3px;
  align-self: flex-start;
  margin-bottom: 8px;
}
.error-msg {
  background: var(--err-soft);
  border: 1px solid oklch(0.85 0.08 30);
  padding: 12px 14px;
  border-radius: var(--r-md);
  color: oklch(0.40 0.14 30);
  font-family: var(--font-mono);
  font-size: 11.5px;
  white-space: pre-wrap;
  margin: 0;
}

/* ---------- Examples panel ---------- */

.examples-panel {
  border-top: 1px solid var(--line);
  background: var(--paper-2);
  padding: 12px 14px;
  max-height: 38%;
  overflow-y: auto;
}
.examples-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 8px;
}
.examples-title {
  font-family: var(--font-mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--ink-3);
}
.examples-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.example-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 8px 10px;
  border: 1px solid var(--line-soft);
  border-radius: var(--r-md);
  background: var(--paper);
  text-align: left;
}
.example-item:hover {
  border-color: var(--ink-mute);
  background: var(--paper);
}
.example-text {
  display: flex;
  flex-direction: column;
  gap: 2px;
  min-width: 0;
}
.example-name { font-size: 12px; color: var(--ink); }
.example-snippet {
  font-family: var(--font-mono);
  font-size: 10.5px;
  color: var(--ink-3);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.example-arrow { color: var(--ink-mute); font-size: 14px; }

/* ---------- Loading ---------- */
.boot {
  position: fixed;
  inset: 0;
  display: grid;
  place-items: center;
  background: var(--paper);
  z-index: 50;
}
.boot-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  font-family: var(--font-mono);
  color: var(--ink-3);
}
.boot-mark {
  width: 36px; height: 36px;
  background: var(--ink);
  color: var(--paper);
  border-radius: 4px;
  display: grid; place-items: center;
  font-weight: 600;
  animation: pulse 1.4s ease-in-out infinite;
}
@keyframes pulse {
  0%, 100% { transform: scale(1); opacity: 1; }
  50% { transform: scale(0.92); opacity: 0.7; }
}

/* small screens */
@media (max-width: 1100px) {
  .workspace {
    grid-template-columns:
      var(--col-schema-w, 220px)
      6px
      minmax(0, 1fr)
      6px
      var(--col-results-w, 320px);
  }
  .rail-list { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

@media (max-width: 760px) {
  .workspace {
    grid-template-columns: 1fr;
  }
  .col-resizer { display: none; }
}