:root {
  --bg: #f4f6fb;
  --card-bg: #ffffff;
  --text: #1f2533;
  --text-soft: #6b7285;
  --accent: #4f6df5;
  --accent-dark: #3a54d6;
  --success: #1fa860;
  --fail: #e05252;
  --border: #dde2ee;
  --shadow: 0 8px 24px rgba(31, 37, 51, 0.08);
  --radius: 14px;
  --tile-size: 76px;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: "Pretendard", "Apple SD Gothic Neo", "Malgun Gothic", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
}

/* 게임(왼쪽) + 리더보드(오른쪽) 2단 배치. 좁으면 자동으로 아래로 쌓임 */
.layout {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-start;
  justify-content: center;
  gap: 20px;
  width: 100%;
}

.game {
  flex: 1 1 440px;
  max-width: 480px;
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 30px 24px;
  display: flex;
  flex-direction: column;
  gap: 22px;
}

/* 상단 줄: 목록 링크 + 게임 방법 버튼 */
.top-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.back-link {
  font-size: 0.85rem;
  color: var(--text-soft);
  text-decoration: none;
  transition: color 0.15s ease;
}

.back-link:hover {
  color: var(--accent);
}

.help-btn {
  padding: 5px 12px;
  font-family: inherit;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-soft);
  background: transparent;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  transition: border-color 0.15s ease, color 0.15s ease;
}

.help-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* 상단 */
.game-header {
  text-align: center;
}

.game-header h1 {
  font-size: 2.1rem;
  letter-spacing: -0.02em;
}

.accent {
  color: var(--accent);
}

.subtitle {
  margin-top: 5px;
  color: var(--text-soft);
  font-size: 0.92rem;
}

/* ---------- 점수 / 제한시간 ---------- */
.status-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.98rem;
  font-weight: 700;
  color: var(--text-soft);
  padding: 0 4px;
}

.status-right {
  display: flex;
  align-items: center;
  gap: 10px;
}

.timer {
  font-variant-numeric: tabular-nums;
}

.giveup-btn {
  padding: 3px 12px;
  font-family: inherit;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-soft);
  background: transparent;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  transition: border-color 0.15s ease, color 0.15s ease, opacity 0.15s ease;
}

.giveup-btn:hover:not(:disabled) {
  border-color: var(--fail);
  color: var(--fail);
}

.giveup-btn:disabled {
  opacity: 0.35;
  cursor: default;
}

.timer.warn {
  color: var(--fail);
  animation: blink 1s ease infinite;
}

@keyframes blink {
  50% { opacity: 0.45; }
}

/* ---------- 계산대 (위쪽 빈 상자) ---------- */
.workbench {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 10px;
  padding: 14px 10px;
  background: #eef1fb;
  border-radius: 12px;
}

.bench-box {
  width: 64px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text);
  border: 2px dashed #c3cbe4;
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.6);
  transition: border-color 0.12s ease, background 0.12s ease, transform 0.12s ease;
}

.bench-box.filled {
  border-style: solid;
  border-color: var(--accent);
  background: #fff;
  cursor: pointer;
}

.bench-box.filled:hover {
  transform: translateY(-2px);
}

.bench-op-box {
  width: 46px;
  height: 46px;
  border-radius: 50%;
  font-size: 1.3rem;
  color: var(--accent-dark);
}

.bench-eq {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--text-soft);
}

.bench-result {
  border-color: #c3cbe4;
}

.bench-result.showing {
  border-style: solid;
  border-color: var(--success);
  background: rgba(31, 168, 96, 0.1);
  color: var(--success);
  animation: pop-in 0.18s ease;
}

/* ---------- 게임 시작 버튼 ---------- */
.start-btn {
  padding: 14px 40px;
  font-family: inherit;
  font-size: 1.25rem;
  font-weight: 700;
  color: #fff;
  background: var(--accent);
  border: none;
  border-radius: 14px;
  box-shadow: 0 6px 16px rgba(79, 109, 245, 0.3);
  cursor: pointer;
  transition: background 0.15s ease, transform 0.12s ease, box-shadow 0.12s ease;
}

.start-btn:hover {
  background: var(--accent-dark);
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(79, 109, 245, 0.4);
}

.start-btn:active {
  transform: translateY(0);
}

/* ---------- 숫자 타일 ---------- */
.board {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 12px;
  min-height: calc(var(--tile-size) + 8px);
  flex-wrap: wrap;
}

.tile-btn {
  min-width: var(--tile-size);
  height: var(--tile-size);
  padding: 0 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: inherit;
  font-size: 1.9rem;
  font-weight: 700;
  color: var(--text);
  background: linear-gradient(160deg, #ffffff, #eef1fb);
  border: 2px solid var(--border);
  border-radius: 14px;
  box-shadow: 0 3px 8px rgba(31, 37, 51, 0.07);
  cursor: pointer;
  user-select: none;
  transition: transform 0.12s ease, box-shadow 0.12s ease,
    border-color 0.12s ease, background 0.12s ease;
}

.tile-btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 14px rgba(79, 109, 245, 0.18);
}

.tile-btn.selected {
  border-color: var(--accent);
  background: rgba(79, 109, 245, 0.12);
  color: var(--accent-dark);
  transform: translateY(-3px);
  box-shadow: 0 6px 14px rgba(79, 109, 245, 0.25);
}

.tile-btn.fraction {
  font-size: 1.15rem;
}

/* 빈 슬롯 — 타일이 위로 올라간 자리를 그대로 유지 (레이아웃 고정) */
.tile-empty {
  min-width: var(--tile-size);
  height: var(--tile-size);
  border: 2px dashed var(--border);
  border-radius: 14px;
  opacity: 0.5;
  pointer-events: none;
}

/* 진짜 분수 모양: 분자 / 가로줄 / 분모 */
.frac {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  vertical-align: middle;
  line-height: 1.2;
  margin: 0 2px;
}

.frac .fnum {
  border-bottom: 2px solid currentColor;
  padding: 0 5px 1px;
}

.frac .fden {
  padding: 1px 5px 0;
}

.tile-btn.deal {
  animation: deal-in 0.35s ease backwards;
}

.tile-btn.deal:nth-child(2) { animation-delay: 0.06s; }
.tile-btn.deal:nth-child(3) { animation-delay: 0.12s; }
.tile-btn.deal:nth-child(4) { animation-delay: 0.18s; }

@keyframes deal-in {
  from {
    opacity: 0;
    transform: translateY(14px) scale(0.9);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

@keyframes pop-in {
  0% { transform: scale(0.6); }
  60% { transform: scale(1.12); }
  100% { transform: scale(1); }
}

/* ---------- 연산자 버튼 ---------- */
.ops {
  display: flex;
  justify-content: center;
  gap: 14px;
}

.op-btn {
  width: 54px;
  height: 54px;
  border-radius: 50%;
  font-family: inherit;
  font-size: 1.45rem;
  font-weight: 700;
  color: var(--accent-dark);
  background: linear-gradient(160deg, #ffffff, #eef1fb);
  border: 2px solid var(--border);
  box-shadow: 0 3px 8px rgba(31, 37, 51, 0.07);
  cursor: pointer;
  user-select: none;
  transition: transform 0.12s ease, box-shadow 0.12s ease,
    border-color 0.12s ease, background 0.12s ease, opacity 0.12s ease;
}

.op-btn:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: 0 6px 14px rgba(79, 109, 245, 0.18);
}

.op-btn:disabled {
  opacity: 0.35;
  cursor: default;
}

.op-btn.selected {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.message .frac,
.answer .frac {
  font-size: 0.82em;
  line-height: 1.1;
}

.message .frac .fnum,
.answer .frac .fnum {
  border-bottom-width: 1.5px;
  padding: 0 3px 1px;
}

.message .frac .fden,
.answer .frac .fden {
  padding: 1px 3px 0;
}

/* ---------- 정답 보기 ---------- */
.answer {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 5px;
  padding: 12px 16px;
  background: #fdf6e3;
  border: 1.5px dashed #e5c96b;
  border-radius: 10px;
}

.answer.hidden {
  display: none;
}

.answer-step {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.98rem;
  font-weight: 600;
  color: #8a6d1a;
}

.answer-no {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: #e5c96b;
  color: #fff;
  font-size: 0.75rem;
  flex-shrink: 0;
}

/* ---------- 결과 / 버튼 ---------- */
.result-area {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.message {
  font-size: 1.05rem;
  font-weight: 600;
  min-height: 1.5em;
}

.message.success {
  color: var(--success);
}

.message.fail {
  color: var(--fail);
}

.button-row {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: center;
}

.ghost-btn {
  padding: 10px 18px;
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-soft);
  background: transparent;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  cursor: pointer;
  transition: border-color 0.15s ease, color 0.15s ease, opacity 0.15s ease;
}

.ghost-btn:hover:not(:disabled) {
  border-color: var(--text-soft);
  color: var(--text);
}

.ghost-btn:disabled {
  opacity: 0.4;
  cursor: default;
}

.newgame-btn {
  padding: 10px 26px;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 700;
  color: #fff;
  background: var(--accent);
  border: none;
  border-radius: 10px;
  box-shadow: 0 4px 12px rgba(79, 109, 245, 0.28);
  cursor: pointer;
  transition: background 0.15s ease, transform 0.12s ease;
}

.newgame-btn:hover {
  background: var(--accent-dark);
  transform: translateY(-2px);
}

.newgame-btn:active {
  transform: translateY(0);
}

.hidden {
  display: none;
}

/* ---------- 리더보드 (오른쪽 사이드 패널) ---------- */
.leaderboard {
  flex: 1 1 260px;
  max-width: 320px;
  align-self: stretch;
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 22px 18px;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.lb-title {
  text-align: center;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text);
}

/* 순위권 진입 시 뜨는 이름 입력 팝업 */
.modal-overlay {
  position: fixed;
  inset: 0;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  background: rgba(31, 37, 51, 0.5);
  animation: overlay-in 0.15s ease;
}

.modal-overlay.hidden {
  display: none;
}

.modal-box {
  width: 100%;
  max-width: 340px;
  padding: 26px 24px;
  background: var(--card-bg);
  border-radius: 16px;
  box-shadow: 0 20px 50px rgba(31, 37, 51, 0.35);
  text-align: center;
  animation: modal-in 0.2s ease;
}

.lb-entry-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text);
}

.modal-sub {
  margin-top: 4px;
  margin-bottom: 16px;
  font-size: 0.9rem;
  color: var(--text-soft);
}

.lb-skip {
  margin-top: 12px;
  font-family: inherit;
  font-size: 0.85rem;
  color: var(--text-soft);
  background: none;
  border: none;
  cursor: pointer;
  text-decoration: underline;
}

.lb-skip:hover {
  color: var(--text);
}

/* 게임 방법 팝업 — 여러 페이지 */
.howto-box {
  max-width: 400px;
}

.howto-pages {
  margin: 14px 0 10px;
}

.howto-page {
  display: none;
  flex-direction: column;
  align-items: center;
  gap: 14px;
}

.howto-page.active {
  display: flex;
  animation: howto-fade 0.2s ease;
}

@keyframes howto-fade {
  from { opacity: 0; transform: translateX(8px); }
  to { opacity: 1; transform: translateX(0); }
}

.howto-img {
  width: 100%;
  padding: 14px 10px;
  background: #f7f9ff;
  border: 1px solid var(--border);
  border-radius: 12px;
}

.howto-svg,
.howto-img svg {
  width: 100%;
  height: auto;
  display: block;
}

.howto-cap {
  font-size: 0.95rem;
  line-height: 1.5;
  color: var(--text);
  min-height: 3em;
}

.howto-dots {
  display: flex;
  justify-content: center;
  gap: 7px;
  margin-bottom: 16px;
}

.howto-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--border);
  transition: background 0.15s ease, transform 0.15s ease;
}

.howto-dot.active {
  background: var(--accent);
  transform: scale(1.25);
}

.howto-nav {
  display: flex;
  gap: 10px;
  justify-content: center;
}

.howto-nav .ghost-btn,
.howto-nav .newgame-btn {
  min-width: 88px;
}

@keyframes overlay-in {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes modal-in {
  from { opacity: 0; transform: translateY(12px) scale(0.96); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

.lb-form {
  display: flex;
  gap: 8px;
}

#lb-name {
  flex: 1;
  min-width: 0;
  padding: 10px 12px;
  font-family: inherit;
  font-size: 1rem;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  outline: none;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

#lb-name:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(79, 109, 245, 0.15);
}

#lb-save {
  padding: 0 20px;
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  color: #fff;
  background: var(--accent);
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: background 0.15s ease;
}

#lb-save:hover {
  background: var(--accent-dark);
}

.lb-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.lb-row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 12px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.98rem;
}

.lb-row.mine {
  border-color: var(--accent);
  background: rgba(79, 109, 245, 0.08);
  font-weight: 700;
}

.lb-rank {
  width: 28px;
  text-align: center;
  font-weight: 700;
  color: var(--text-soft);
  flex-shrink: 0;
}

.lb-row .lb-name {
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.lb-row .lb-score {
  font-weight: 700;
  color: var(--accent-dark);
  font-variant-numeric: tabular-nums;
}

.lb-empty {
  text-align: center;
  color: var(--text-soft);
  font-size: 0.92rem;
  padding: 10px 0;
}

.lb-status {
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-soft);
  min-height: 1.1em;
}

/* 반응형: 좁은 화면 */
@media (max-width: 440px) {
  :root {
    --tile-size: 62px;
  }

  .game {
    padding: 22px 14px;
  }

  .game-header h1 {
    font-size: 1.7rem;
  }

  .workbench {
    gap: 6px;
    padding: 12px 6px;
  }

  .bench-box {
    width: 54px;
    height: 54px;
    font-size: 1.25rem;
  }

  .bench-op-box {
    width: 40px;
    height: 40px;
    font-size: 1.15rem;
  }

  .bench-eq {
    font-size: 1.3rem;
  }

  .tile-btn {
    font-size: 1.55rem;
    padding: 0 10px;
    border-radius: 12px;
  }

  .tile-btn.fraction {
    font-size: 0.95rem;
  }

  .op-btn {
    width: 48px;
    height: 48px;
    font-size: 1.3rem;
  }
}