:root {
  --slide-width: 1920;
  --slide-height: 1080;
  --bg: #f7fafc;
  --paper: #ffffff;
  --ink: #172033;
  --muted: #5c6b7d;
  --line: #d7e0ea;
  --blue: #2563eb;
  --green: #159957;
  --orange: #f28c28;
  --red: #e84a5f;
  --violet: #7c3aed;
  --yellow: #eab308;
  --shadow: 0 24px 70px rgba(26, 41, 61, 0.14);
}

* { box-sizing: border-box; }

html,
body {
  width: 100%;
  height: 100%;
  margin: 0;
}

body {
  position: relative;
  overflow: hidden;
  background: var(--bg);
  color: var(--ink);
  font-family: "Apple SD Gothic Neo", "Noto Sans KR", system-ui, sans-serif;
}

button,
input { font: inherit; }

.deck {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 1920px;
  height: 1080px;
  container-type: size;
  transform: translate(-50%, -50%) scale(var(--deck-scale, 1));
  transform-origin: center;
  overflow: hidden;
  background: var(--paper);
  box-shadow: var(--shadow);
}

.slide {
  position: absolute;
  inset: 0;
  display: none;
  padding: clamp(30px, 3.4cqw, 52px);
}

.slide.active {
  display: flex;
  flex-direction: column;
  gap: clamp(14px, 1.5cqw, 22px);
}

.slide::before {
  position: absolute;
  inset: 0 0 auto;
  height: 12px;
  background: linear-gradient(90deg, var(--blue), var(--green), var(--orange));
  content: "";
}

.slide-header { position: relative; z-index: 1; }

.unit {
  margin: 0 0 8px;
  color: var(--blue);
  font-size: clamp(24px, 2.2cqw, 36px);
  font-weight: 900;
}

.page-ref {
  position: absolute;
  top: 4px;
  right: 0;
  border: 2px solid var(--line);
  border-radius: 999px;
  padding: 8px 16px;
  background: #f6f8fb;
  color: var(--muted);
  font-size: clamp(18px, 1.45cqw, 24px);
  font-weight: 900;
}

h1,
h2,
p { margin: 0; }

h1 {
  font-size: clamp(50px, 5.2cqw, 76px);
  line-height: 1;
  letter-spacing: 0;
}

.subtitle {
  margin-top: 10px;
  color: var(--muted);
  font-size: clamp(23px, 2.15cqw, 32px);
  font-weight: 800;
}

.sort-intro {
  display: grid;
  grid-template-columns: 1.2fr 0.9fr 0.9fr;
  gap: 18px;
  flex: 1;
  min-height: 0;
}

.definition,
.order-card,
.sim-panel,
.steps-panel,
.practice-card,
.search-definition,
.binary-card {
  border: 2px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.definition {
  display: grid;
  align-content: center;
  gap: 24px;
  padding: 32px;
}

.definition h2,
.order-card h2,
.search-definition h2,
.binary-card h2,
.practice-card h2 {
  color: var(--green);
  font-size: clamp(32px, 2.8cqw, 44px);
}

.definition p {
  font-size: clamp(24px, 2.05cqw, 32px);
  font-weight: 800;
  line-height: 1.35;
}

.example-row,
.search-examples {
  display: grid;
  gap: 12px;
}

.example-row span,
.search-examples span {
  border-left: 10px solid var(--blue);
  border-radius: 8px;
  padding: 16px 20px;
  background: #f6f8fb;
  font-size: clamp(22px, 2cqw, 32px);
  font-weight: 900;
}

.example-row span:nth-child(2),
.search-examples span:nth-child(2) { border-left-color: var(--green); }

.example-row span:nth-child(3),
.search-examples span:nth-child(3) { border-left-color: var(--orange); }

.order-card {
  display: grid;
  align-content: center;
  gap: 22px;
  padding: 30px;
}

.order-card p,
.search-definition p,
.data-line {
  color: var(--muted);
  font-size: clamp(24px, 2.2cqw, 34px);
  font-weight: 900;
  line-height: 1.25;
}

.order-items {
  display: flex;
  gap: 12px;
}

.order-items span,
.array-cell {
  display: grid;
  place-items: center;
  width: clamp(70px, 5.8cqw, 96px);
  height: clamp(70px, 5.8cqw, 96px);
  border: 4px solid #d7e0ea;
  border-radius: 8px;
  background: #eef5ff;
  color: var(--blue);
  font-size: clamp(32px, 3.2cqw, 50px);
  font-weight: 900;
}

.desc .order-items span { background: #fff8ef; color: var(--orange); }
.order-card b { font-size: clamp(22px, 1.9cqw, 30px); }

.sim-layout {
  display: grid;
  grid-template-columns: minmax(0, 0.95fr) minmax(0, 1fr) minmax(0, 1fr);
  gap: 18px;
  flex: 1;
  min-height: 0;
}

.problem-layout {
  display: grid;
  grid-template-columns: minmax(0, 0.95fr) minmax(0, 1fr) minmax(0, 1fr);
  gap: 18px;
  flex: 1;
  min-height: 0;
}

.sim-panel,
.problem-card,
.history-panel,
.explain-panel {
  display: grid;
  align-content: start;
  gap: 18px;
  padding: 22px;
  min-height: 0;
  min-width: 0;
}

.history-panel,
.explain-panel,
.problem-card {
  grid-template-rows: auto 1fr;
  border: 2px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.history-panel h2,
.explain-panel h2,
.problem-card h2 {
  color: var(--green);
  font-size: clamp(28px, 2.2cqw, 38px);
}

.problem-card {
  grid-template-rows: auto auto 1fr auto auto;
}

.control-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 10px;
}

.target-input {
  grid-column: 1 / -1;
}

.control-row input {
  min-width: 0;
  border: 2px solid var(--line);
  border-radius: 8px;
  padding: 12px 14px;
  font-size: clamp(20px, 1.8cqw, 28px);
  font-weight: 800;
}

.primary-btn,
.ghost-btn,
.check-btn {
  border: 0;
  border-radius: 8px;
  padding: 12px 18px;
  color: #fff;
  background: var(--blue);
  font-size: clamp(19px, 1.55cqw, 25px);
  font-weight: 900;
  cursor: pointer;
}

.ghost-btn { background: #64748b; }
.check-btn { background: var(--green); }

.array-view {
  display: flex;
  align-items: end;
  justify-content: center;
  gap: clamp(2px, 0.35cqw, 6px);
  min-height: 230px;
  width: 100%;
  min-width: 0;
  border-bottom: 5px solid #334155;
}

.array-item {
  display: grid;
  align-content: end;
  justify-items: center;
  gap: 8px;
}

.bar {
  display: grid;
  place-items: end center;
  width: clamp(28px, 2.3cqw, 44px);
  min-height: 46px;
  border-radius: 8px 8px 0 0;
  padding-bottom: 8px;
  background: var(--blue);
  color: #fff;
  font-size: clamp(18px, 1.35cqw, 24px);
  font-weight: 900;
  transition: height 0.25s ease, background 0.25s ease;
}

.compare .bar { background: var(--yellow); color: #172033; }
.swap .bar { background: var(--red); }
.fixed .bar,
.found .bar { background: var(--green); }
.range .bar { background: #93c5fd; }
.out .bar { opacity: 0.32; }

.history-list,
.explain-list {
  display: grid;
  align-content: start;
  gap: 9px;
  min-height: 0;
  overflow: auto;
}

.history-group,
.explain-group,
.history-line,
.explain-row {
  border: 2px solid #e2e8f0;
  border-left: 8px solid transparent;
  border-radius: 8px;
  padding: 10px 12px;
  background: #f6f8fb;
}

.history-group.active,
.explain-group.active,
.history-line.active,
.explain-row.active {
  border-left-color: var(--orange);
  background: #fff8ef;
}

.history-group {
  display: grid;
  grid-template-columns: 70px max-content;
  align-items: start;
  gap: 10px;
}

.explain-group {
  display: grid;
  grid-template-columns: 82px 1fr;
  align-items: start;
  gap: 10px;
}

.history-line {
  width: max-content;
  max-width: 100%;
  padding: 8px 10px;
}

.group-lines {
  display: grid;
  gap: 8px;
}

.round-label {
  color: var(--muted);
  font-size: clamp(15px, 1.05cqw, 19px);
  font-weight: 900;
  line-height: 1.2;
}

.step-boxes {
  display: flex;
  gap: 7px;
  flex-wrap: nowrap;
}

.step-cell {
  display: grid;
  min-width: 40px;
  height: 40px;
  place-items: center;
  border: 3px solid #d7e0ea;
  border-radius: 8px;
  background: #fff;
  color: var(--blue);
  font-size: clamp(17px, 1.25cqw, 23px);
  font-weight: 900;
}

.problem-cell {
  width: 40px;
  height: 40px;
  min-width: 40px;
  border: 3px solid #d7e0ea;
  border-radius: 8px;
  background: #fff;
  color: var(--blue);
  text-align: center;
  font-size: clamp(17px, 1.25cqw, 23px);
  font-weight: 900;
}

.bubble-choice,
.binary-choice,
.selection-choice {
  display: grid;
  width: 40px;
  height: 40px;
  min-width: 40px;
  place-items: center;
  border: 3px solid #d7e0ea;
  border-radius: 8px;
  background: #fff;
  color: var(--blue);
  font-size: clamp(17px, 1.25cqw, 23px);
  font-weight: 900;
  cursor: pointer;
}

.binary-choice-row:not(.active) .binary-choice,
.bubble-task-row.locked .bubble-choice,
.selection-task-row.locked .selection-choice {
  cursor: default;
}

.history-group.locked,
.sort-answer-row.locked,
.bubble-task-row.locked,
.selection-task-row.locked {
  opacity: 0.42;
}

.hidden-explain {
  display: none;
}

.hidden-step {
  display: none !important;
}

.correct-choice {
  border-color: var(--green);
  background: #eaf8f0;
  color: var(--green);
}

.wrong-choice {
  border-color: var(--red);
  background: #fff1f2;
  color: var(--red);
}

.sort-answer-row.active,
.bubble-task-row.active,
.selection-task-row.active {
  border-left-color: var(--orange);
  background: #fff8ef;
}

.correct-row {
  border-left-color: var(--green);
  background: #eaf8f0;
}

.wrong-row {
  border-left-color: var(--red);
  background: #fff1f2;
}

.correct-row .problem-cell {
  border-color: var(--green);
  background: #eaf8f0;
  color: var(--green);
}

.wrong-row .problem-cell {
  border-color: var(--red);
  background: #fff1f2;
  color: var(--red);
}

.task-prompt {
  margin-bottom: 8px;
  color: var(--muted);
  font-size: clamp(15px, 1.05cqw, 19px);
  font-weight: 900;
  line-height: 1.2;
}

.bubble-task-row,
.binary-choice-row,
.selection-task-row {
  display: grid;
  gap: 8px;
}

.bubble-choice.pair-preview {
  background: #fff7d6;
  border-color: var(--orange);
  color: #7a4b00;
}

.binary-choice-row.preview-left .binary-choice[data-side="left"]:not(.out-cell),
.binary-choice-row.preview-right .binary-choice[data-side="right"]:not(.out-cell) {
  background: #dbeafe;
  box-shadow: inset 0 0 0 999px rgba(37, 99, 235, 0.1);
}

.binary-choice-row.chosen-left .binary-choice[data-side="left"]:not(.out-cell),
.binary-choice-row.chosen-right .binary-choice[data-side="right"]:not(.out-cell) {
  border-color: var(--green);
  background: #eaf8f0;
  color: var(--green);
}

.binary-choice-row.wrong-side-left .binary-choice[data-side="left"]:not(.out-cell),
.binary-choice-row.wrong-side-right .binary-choice[data-side="right"]:not(.out-cell) {
  border-color: var(--red);
  background: #fff1f2;
  color: var(--red);
}

.selection-task-row.locked input,
.bubble-task-row.locked input,
.bubble-task-row.locked button,
.selection-task-row.locked button,
.binary-choice-row.solved button {
  pointer-events: none;
}

.compare-cell {
  border-color: var(--yellow);
  background: #fef3c7;
  color: #7a4b00;
}

.swap-cell {
  border-color: var(--red);
  background: #fff1f2;
  color: var(--red);
}

.fixed-cell,
.found-cell {
  border-color: var(--green);
  background: #eaf8f0;
  color: var(--green);
}

.range-cell {
  background: #eef5ff;
}

.out-cell {
  opacity: 0.35;
}

.explain-row {
  color: var(--ink);
  font-size: clamp(18px, 1.35cqw, 24px);
  font-weight: 900;
  line-height: 1.28;
}

.practice-grid,
.binary-practice {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
  flex: 1;
  min-height: 0;
}

.practice-card,
.binary-card {
  display: grid;
  align-content: start;
  gap: 14px;
  padding: 22px;
  min-height: 0;
}

.practice-card.compact {
  padding: 16px;
  gap: 10px;
}

.practice-start {
  display: flex;
  gap: 8px;
}

.practice-start .array-cell {
  width: 58px;
  height: 58px;
  font-size: 30px;
}

.answer-rows {
  display: grid;
  gap: 10px;
  min-height: 0;
  overflow: auto;
}

.binary-rows label {
  display: grid;
  grid-template-columns: 120px 1fr;
  align-items: center;
  gap: 10px;
  color: var(--muted);
  font-size: clamp(18px, 1.55cqw, 25px);
  font-weight: 900;
}

.practice-feedback {
  min-height: 30px;
  color: var(--muted);
  font-size: clamp(18px, 1.4cqw, 24px);
  font-weight: 900;
}

.correct {
  border-color: rgba(21, 153, 87, 0.65);
}

.incorrect {
  border-color: rgba(232, 74, 95, 0.65);
}

.correct .practice-feedback {
  color: var(--green);
}

.incorrect .practice-feedback {
  color: var(--red);
}

.practice-group {
  display: grid;
  grid-template-columns: 90px 1fr;
  gap: 10px;
  align-items: start;
  border-left: 8px solid var(--orange);
  border-radius: 8px;
  padding: 10px 12px;
  background: #fff8ef;
}

.practice-label {
  color: var(--muted);
  font-size: clamp(17px, 1.3cqw, 22px);
  font-weight: 900;
}

.practice-lines {
  display: grid;
  gap: 8px;
}

.answer-rows input,
.binary-rows input {
  min-width: 0;
  border: 2px solid var(--line);
  border-radius: 8px;
  padding: 10px 12px;
  font-weight: 900;
}

.hybrid-layout,
.search-intro {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
  flex: 1;
  min-height: 0;
}

.search-definition {
  display: grid;
  align-content: center;
  gap: 22px;
  padding: 24px;
}

.binary-card {
  align-content: stretch;
}

.binary-rows {
  display: grid;
  gap: 14px;
  align-content: start;
}

.binary-rows label {
  grid-template-columns: 110px 1fr;
}

.nav-zone {
  position: fixed;
  top: 50%;
  width: 74px;
  height: 170px;
  transform: translateY(-50%);
  border: 0;
  background: transparent;
  cursor: pointer;
}

.nav-prev { left: 0; }
.nav-next { right: 0; }

.nav-zone span {
  display: block;
  width: 28px;
  height: 28px;
  border-top: 5px solid rgba(23, 32, 51, 0.38);
  border-left: 5px solid rgba(23, 32, 51, 0.38);
}

.nav-prev span { transform: rotate(-45deg); margin-left: 28px; }
.nav-next span { transform: rotate(135deg); margin-left: 16px; }

.footer {
  position: fixed;
  right: 28px;
  bottom: 22px;
  display: flex;
  align-items: center;
  gap: 16px;
  color: var(--muted);
  font-weight: 900;
}

.footer p { font-size: 18px; }

.dots { display: flex; gap: 7px; }

.dot {
  width: 12px;
  height: 12px;
  border: 0;
  border-radius: 50%;
  background: #cbd5e1;
  cursor: pointer;
}

.dot.active { background: var(--blue); }