/*
 * Chapter 03 local styles
 * Only polynomial structure diagrams and local explanatory layouts live here.
 * Public layout and visual tokens come from learning-page-system.css?v=20260805-2.
 */

.title-continuation {
  display: inline-block;
}

.method-note {
  display: grid;
  grid-template-columns: 1.65rem minmax(0, 1fr);
  gap: .75rem;
  align-items: start;
  margin: 1rem 0 1.35rem;
  padding: .85rem 1rem .9rem .85rem;
  border: 1px solid var(--amber-line);
  border-left: 4px solid var(--amber);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: rgba(255, 242, 220, .72);
}

.method-note-icon {
  display: grid;
  width: 1.65rem;
  height: 1.65rem;
  place-items: center;
  border-radius: 50%;
  background: var(--amber);
  color: #fff;
  font-size: .92rem;
  font-weight: 900;
  line-height: 1;
}

.method-note strong {
  display: block;
  margin: 0 0 .18rem;
  color: var(--amber-deep);
  font-size: .82rem;
  font-weight: 900;
  letter-spacing: .04em;
}

.method-note p {
  margin: 0;
  color: #67461f;
  line-height: 1.72;
}

.formula-focus {
  min-width: 0;
  overflow-x: auto;
  text-align: center;
}

.formula-focus[data-tone="blue"] {
  border-color: var(--blue-line);
  background: var(--blue-soft);
}

.formula-focus[data-tone="purple"] {
  border-color: var(--purple-line);
  background: var(--purple-soft);
}

.formula-focus[data-tone="green"] {
  border-color: var(--cyan-line);
  background: var(--cyan-soft);
}

.formula-focus mjx-container[display="true"] {
  margin: .35em 0 !important;
}

.formula-bridge {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(120px, .42fr) minmax(0, 1fr);
  gap: 1rem;
  align-items: center;
  margin: 1.5rem 0;
  padding: 1.15rem 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.formula-bridge > div:not(.bridge-arrows) {
  min-width: 0;
  text-align: center;
}

.formula-bridge small,
.root-pair small {
  display: block;
  color: var(--muted);
  font-size: .8rem;
  font-weight: 850;
}

.bridge-arrows {
  display: grid;
  gap: .15rem;
  color: var(--blue-deep);
  font-size: .8rem;
  font-weight: 900;
  text-align: center;
}

.bridge-direction-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: .3rem;
  white-space: nowrap;
}

.bridge-arrow {
  display: inline-block;
  font: inherit;
}

.lesson-list {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: .8rem;
  margin: 1.3rem 0;
}

.chapter03-lesson-card {
  display: grid;
  gap: .65rem;
  align-content: start;
  min-width: 0;
  padding: 1rem;
  border: 1px solid var(--line);
  border-top: 3px solid var(--blue);
  border-radius: var(--radius-md);
  background: var(--paper);
  box-shadow: var(--soft-shadow);
  text-decoration: none;
  transition: border-color .18s ease, transform .18s ease;
}

.chapter03-lesson-card:hover,
.chapter03-lesson-card:focus-visible {
  border-color: var(--blue-line);
  transform: translateY(-2px);
}

.lesson-tag {
  display: inline-flex;
  width: max-content;
  padding: .2rem .55rem;
  border-radius: var(--radius-pill);
  background: var(--blue-soft);
  color: var(--blue-deep);
  font-size: .72rem;
  font-weight: 900;
}

.lesson-tag[data-tone="amber"] {
  background: var(--amber-soft);
  color: var(--amber-deep);
}

.lesson-tag[data-tone="purple"] {
  background: var(--purple-soft);
  color: var(--purple-deep);
}

.chapter03-lesson-card strong {
  display: block;
  font-size: 1.07rem;
}

.chapter03-lesson-card p {
  margin: 0;
  font-size: .92rem;
}

.lesson-formula {
  display: grid;
  min-height: 58px;
  margin-top: auto;
  padding: .55rem;
  place-items: center;
  border-top: 1px solid var(--line);
  color: var(--ink);
  font-size: .82rem;
  font-weight: 850;
  text-align: center;
}

.decision-list {
  display: grid;
  margin: 1.35rem 0;
  padding: 0;
  border-top: 1px solid var(--line);
  counter-reset: decision;
  list-style: none;
}

.decision-list li {
  display: grid;
  grid-template-columns: 38px minmax(160px, .5fr) minmax(0, 1fr);
  gap: .8rem;
  align-items: baseline;
  padding: .9rem 0;
  border-bottom: 1px solid var(--line);
  counter-increment: decision;
}

.decision-list li::before {
  color: var(--blue);
  font-family: var(--font-serif);
  font-weight: 850;
  content: "0" counter(decision);
}

.decision-list span {
  color: var(--body);
}

.method-branches {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: .65rem;
  min-width: 0;
}

.method-branches > span {
  display: grid;
  gap: .3rem;
  align-content: start;
  min-width: 0;
  padding: .7rem .8rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, .58);
}

.method-branches > [data-boundary] {
  grid-column: 1 / -1;
  border-color: var(--amber-line);
  background: var(--amber-soft);
}

.method-branches b {
  color: var(--body);
  font-size: .88rem;
  line-height: 1.55;
}

.method-branches em {
  color: var(--blue-deep);
  font-size: .82rem;
  font-style: normal;
  font-weight: 900;
}

.formula-condition-list li {
  grid-template-columns: 38px minmax(380px, .8fr) minmax(0, 1fr);
  align-items: center;
}

.formula-condition-list strong {
  display: block;
  min-width: 0;
  max-width: 100%;
  overflow-x: auto;
  overflow-y: hidden;
  font-size: 1rem;
  white-space: nowrap;
}

.formula-condition-list li > span {
  padding-left: 1rem;
  border-left: 2px solid var(--blue-line);
}

.summary-panel {
  position: relative;
  margin: 1.4rem 0;
  padding: clamp(1.35rem, 3vw, 2rem);
}

.summary-panel::after {
  position: absolute;
  top: -92px;
  right: -72px;
  width: 220px;
  height: 220px;
  border: 38px solid rgba(47, 118, 93, .06);
  border-radius: 50%;
  content: "";
  pointer-events: none;
}

.summary-formula {
  position: relative;
  z-index: 1;
  min-width: 0;
  max-width: 100%;
  padding: 0 0 1rem;
  overflow-x: auto;
  overflow-y: hidden;
  border-bottom: 1px solid var(--cyan-line);
  color: var(--ink);
}

.summary-formula mjx-container[display="true"] {
  margin: .2em 0 !important;
}

.summary-paths {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.4rem;
  padding-top: 1rem;
}

.summary-path {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: .7rem;
  align-items: start;
}

.summary-path-index {
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  border: 1px solid var(--cyan-line);
  border-radius: 50%;
  background: var(--paper);
  color: var(--cyan-deep);
  font-family: var(--font-serif);
  font-weight: 900;
}

.summary-path h3 {
  margin: .05rem 0 .25rem;
  color: var(--cyan-deep);
  font-size: 1rem;
}

.summary-path p {
  margin: 0;
  color: var(--body);
  font-size: .94rem;
  line-height: 1.75;
}

.calc-steps {
  display: grid;
}

.calc-step {
  display: grid;
  grid-template-columns: minmax(255px, .78fr) minmax(0, 1fr);
  gap: 1.2rem;
  align-items: center;
  min-width: 0;
  padding: 1rem 0;
  border-bottom: 1px solid var(--line);
}

.calc-step:first-child {
  padding-top: 0;
}

.calc-step:last-child {
  padding-bottom: 0;
  border-bottom: 0;
}

.calc-step > .formula-line {
  min-width: 0;
  max-width: 100%;
  overflow-x: auto;
  overflow-y: hidden;
  color: var(--ink);
  text-align: center;
}

.calc-step > .formula-line mjx-container[display="true"] {
  margin: .3em 0 !important;
}

.calc-step > .step-note {
  margin: 0;
  padding-left: 1rem;
  border-left: 3px solid var(--blue-line);
  font-size: .94rem;
}

.compact-flow .calc-step {
  padding: .75rem 0;
}

.route-formula {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem .7rem;
  align-items: center;
  margin-bottom: .9rem;
}

.route-formula span {
  color: var(--ink);
  font-weight: 850;
}

.route-formula b {
  color: var(--blue);
}

.coefficient-map {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin: 1.2rem 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.coefficient-map div {
  min-width: 0;
  padding: .85rem;
  text-align: center;
}

.coefficient-map div + div {
  border-left: 1px solid var(--line);
}

.coefficient-map small {
  display: block;
  color: var(--muted);
  font-weight: 800;
}

.coefficient-map strong {
  color: var(--purple-deep);
}

.comparison-lines {
  display: grid;
  margin: 1.15rem 0;
  border-top: 1px solid var(--line);
}

.comparison-lines > div {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr) auto;
  gap: .8rem;
  align-items: center;
  padding: .8rem 0;
  border-bottom: 1px solid var(--line);
}

.comparison-lines em {
  color: var(--red-deep);
  font-size: .82rem;
  font-style: normal;
  font-weight: 850;
}

.comparison-lines .is-match em {
  color: var(--cyan-deep);
}

.cross-diagram {
  margin: 1.45rem 0;
}

.cross-grid {
  position: relative;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 2.5rem 5rem;
  max-width: 560px;
  margin: auto;
  padding: 1.1rem;
}

.cross-grid::before,
.cross-grid::after {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 48%;
  height: 2px;
  background: var(--amber-line);
  content: "";
  transform-origin: center;
}

.cross-grid::before {
  transform: translate(-50%, -50%) rotate(24deg);
}

.cross-grid::after {
  transform: translate(-50%, -50%) rotate(-24deg);
}

.cross-grid span {
  position: relative;
  z-index: 1;
  padding: .55rem;
  border: 1px solid var(--amber-line);
  border-radius: var(--radius-sm);
  background: var(--paper);
  font-weight: 850;
  text-align: center;
}

.cross-diagram figcaption {
  display: flex;
  flex-wrap: wrap;
  gap: .55rem 1rem;
  justify-content: center;
  padding-top: .6rem;
  color: var(--body);
  font-size: .88rem;
}

.cross-diagram figcaption strong {
  color: var(--cyan-deep);
}

.delta-comparison {
  display: grid;
  margin: 1.25rem 0;
  border-top: 1px solid var(--line);
}

.delta-comparison > div {
  display: grid;
  grid-template-columns: 110px minmax(0, .75fr) minmax(0, 1fr);
  gap: 1rem;
  padding: .9rem 0;
  border-bottom: 1px solid var(--line);
}

.delta-comparison strong {
  color: var(--blue-deep);
}

.delta-comparison [data-state="no-real-roots"] strong {
  color: var(--red-deep);
}

.root-pair {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  margin: 1.2rem 0;
}

.root-pair > div {
  min-width: 0;
  padding: .9rem;
  overflow-x: auto;
  overflow-y: hidden;
  border-top: 3px solid var(--blue);
  background: rgba(255, 255, 255, .45);
  text-align: center;
}

@media (max-width: 1023px) {
  .calc-step {
    grid-template-columns: minmax(0, 1fr);
  }

  .calc-step > .formula-line {
    max-width: 100%;
    overflow-x: auto;
    overflow-y: hidden;
  }

  .calc-step > .step-note {
    padding-top: .7rem;
    padding-left: 0;
    border-top: 1px dashed var(--blue-line);
    border-left: 0;
  }
}

@media (max-width: 820px) {
  .lesson-list,
  .formula-bridge {
    grid-template-columns: minmax(0, 1fr);
  }

  .bridge-arrows {
    gap: .4rem;
  }

  .bridge-arrows > span:not(.bridge-direction-row) {
    transform: rotate(90deg);
  }

  .bidirectional-bridge .bridge-arrows {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: .75rem;
  }

  .bidirectional-bridge .bridge-arrow {
    transform: rotate(90deg);
  }

  .formula-condition-list li {
    grid-template-columns: 38px minmax(0, 1fr);
  }

  .formula-condition-list strong,
  .formula-condition-list li > span {
    grid-column: 2;
  }

  .formula-condition-list li > span {
    padding-top: .55rem;
    padding-left: 0;
    border-top: 2px solid var(--blue-line);
    border-left: 0;
  }

  .decision-branch-step {
    grid-template-columns: 38px minmax(0, 1fr);
  }

  .decision-branch-step strong,
  .decision-branch-step .method-branches {
    grid-column: 2;
  }

  .root-pair {
    grid-template-columns: minmax(0, 1fr);
  }
}

@media (max-width: 640px) {
  .calc-step {
    padding: .85rem;
  }

  .compact-flow .calc-step {
    padding: .75rem;
  }

  .calc-step:first-child {
    padding-top: .85rem;
  }

  .calc-step:last-child {
    padding-bottom: .85rem;
    border-bottom: 1px solid var(--line);
  }

  .method-note {
    gap: .6rem;
    padding: .8rem .8rem .85rem .7rem;
  }

  .formula-focus {
    margin: 1rem 0;
    padding: .85rem .75rem;
    border: 1px solid var(--line);
    border-radius: var(--radius-md);
  }

  .decision-list li {
    grid-template-columns: 34px minmax(0, 1fr);
  }

  .decision-list li span {
    grid-column: 2;
  }

  .formula-condition-list li > span {
    padding-top: .55rem;
    padding-left: 0;
    border-top: 2px solid var(--blue-line);
    border-left: 0;
  }

  .summary-panel {
    padding: 1rem;
  }

  .summary-panel::after {
    display: none;
  }

  .summary-paths {
    grid-template-columns: minmax(0, 1fr);
    gap: .9rem;
  }

  .comparison-lines > div {
    grid-template-columns: minmax(0, 1fr);
    gap: .25rem;
  }

  .comparison-lines em {
    grid-column: auto;
  }

  .method-branches {
    grid-template-columns: minmax(0, 1fr);
  }

  .decision-branch-step .method-branches > span {
    grid-column: auto;
  }

  .delta-comparison > div {
    grid-template-columns: minmax(0, 1fr);
  }

  .delta-comparison span:last-child {
    grid-column: 1;
  }

  .coefficient-map,
  .root-pair {
    grid-template-columns: minmax(0, 1fr);
  }

  .coefficient-map div + div {
    border-top: 1px solid var(--line);
    border-left: 0;
  }

  .cross-grid {
    gap: 2.2rem 2.2rem;
    padding: .8rem;
  }

  .cross-grid::before,
  .cross-grid::after {
    width: 58%;
  }

  .route-formula {
    align-items: flex-start;
  }
}

@media (max-width: 360px) {
  .cross-grid {
    gap: 1.8rem 1.4rem;
  }
}

@media print {
  .formula-focus,
  .method-note,
  .root-pair > div {
    background: transparent;
  }
}