* { box-sizing: border-box; }

/* 라이트 테마 (기본) */
body {
  --bg: #f3f4f6;
  --panel: #ffffff;
  --panel-border: #d9dce1;
  --text: #1f2328;
  --muted: #6b7280;
  --btn-bg: #5b8def;
  --btn-bg-hover: #4a7bdb;
  --btn-text: #ffffff;
  --btn-disabled-bg: #e5e7eb;
  --btn-disabled-text: #9aa1ad;
  --input-bg: #ffffff;
  --input-border: #c9cdd4;
  --accent: #3b6fd4;
  --xl-bg: #ffffff;
  --xl-grid: #d4d4d4;
  --xl-head-bg: #e9ebee;
  --xl-head-border: #c6c6c6;
  --xl-head-text: #555555;
  --xl-text: #1f1f1f;
  --xl-green: #217346;
  --xl-btnface: #e8eaed;
  --xl-btnface-hover: #dcdfe4;
  --xl-btnborder: #aeb3bb;
  --xl-titlebar-bg: #217346;
  --xl-titlebar-text: #ffffff;
  --xl-ribbon-bg: #f3f2f1;
  /* 돌 = 조건부 서식 셀 (엑셀 "좋음"/"보통" 스타일) */
  --xf-me-bg: #c6efce;
  --xf-me-tx: #276b24;
  --xf-op-bg: #ffeb9c;
  --xf-op-tx: #9c6500;
  /* 일반 모드 오목판 */
  --board-bg: #d8a35f;
  --board-line: #8a6234;
}

/* 다크 테마 */
body[data-theme="dark"] {
  --bg: #0f1117;
  --panel: #1a1d27;
  --panel-border: #2a2e3a;
  --text: #e8e8ec;
  --muted: #9096a6;
  --btn-bg: #5b8def;
  --btn-bg-hover: #4a7bdb;
  --btn-text: #ffffff;
  --btn-disabled-bg: #2a2e3a;
  --btn-disabled-text: #6b7180;
  --input-bg: #0f1117;
  --input-border: #2a2e3a;
  --accent: #5b8def;
  --xl-bg: #212226;
  --xl-grid: #3a3d44;
  --xl-head-bg: #2b2e35;
  --xl-head-border: #454952;
  --xl-head-text: #b8bcc6;
  --xl-text: #e8e8ec;
  --xl-green: #4fbe8a;
  --xl-btnface: #3a3d44;
  --xl-btnface-hover: #454952;
  --xl-btnborder: #555a64;
  --xl-titlebar-bg: #1f2124;
  --xl-titlebar-text: #c8ccd4;
  --xl-ribbon-bg: #26282d;
  --xf-me-bg: #2a5c3e;
  --xf-me-tx: #7ee2a3;
  --xf-op-bg: #4a4420;
  --xf-op-tx: #e8d377;
  --board-bg: #a9793f;
  --board-line: #6e4e26;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Pretendard, Roboto, sans-serif;
}

#app {
  width: 100%;
  max-width: 560px;
  padding: 24px;
}

header h1 {
  text-align: center;
  margin: 0 0 24px;
  font-size: 28px;
}

#btn-theme, #btn-stealth {
  position: fixed;
  z-index: 20;
  top: 14px;
  width: 38px;
  height: 38px;
  padding: 0;
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 50%;
  font-size: 16px;
  cursor: pointer;
  line-height: 1;
}

#btn-theme { right: 14px; }
#btn-stealth { right: 60px; }

/* 게임(시트) 화면에서는 제목 표시줄에 녹아들게 축소 */
body.in-sheet #btn-theme, body.in-sheet #btn-stealth {
  top: 3px;
  width: 24px;
  height: 24px;
  font-size: 12px;
  background: transparent;
  border: none;
}

body.in-sheet #btn-theme { right: 10px; }
body.in-sheet #btn-stealth { right: 40px; }

/* 월루모드: 게임 필수 요소 외 전부 숨김 */
body.stealth h1,
body.stealth .hint,
body.stealth .divider { display: none; }

body.stealth #btn-theme,
body.stealth #btn-stealth { opacity: 0.4; }

body.stealth #btn-theme:hover,
body.stealth #btn-stealth:hover { opacity: 1; }

.hidden { display: none; }

.card {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 20px;
  margin-bottom: 16px;
}

.card h2 { margin: 0 0 4px; font-size: 18px; }

.hint {
  color: var(--muted);
  font-size: 13px;
  margin: 4px 0 14px;
}

.divider {
  text-align: center;
  color: var(--muted);
  font-size: 13px;
  margin: 12px 0;
}

input.code-input {
  display: block;
  width: 100%;
  padding: 12px 14px;
  font-size: 20px;
  letter-spacing: 4px;
  text-align: center;
  background: var(--input-bg);
  border: 1px solid var(--input-border);
  border-radius: 8px;
  color: var(--text);
  margin-bottom: 10px;
}

input.code-input:focus {
  outline: none;
  border-color: var(--btn-bg);
}

button {
  width: 100%;
  padding: 12px 14px;
  font-size: 15px;
  font-weight: 600;
  border: none;
  border-radius: 8px;
  background: var(--btn-bg);
  color: var(--btn-text);
  cursor: pointer;
}

button:hover { background: var(--btn-bg-hover); }

button:disabled {
  background: var(--btn-disabled-bg);
  color: var(--btn-disabled-text);
  cursor: not-allowed;
}

.code {
  text-align: center;
  font-size: 32px;
  font-weight: 700;
  letter-spacing: 8px;
  background: var(--input-bg);
  border: 1px dashed var(--accent);
  border-radius: 8px;
  padding: 14px;
  color: var(--accent);
}

.status {
  text-align: center;
  color: var(--muted);
  font-size: 14px;
  min-height: 20px;
}

.build-info {
  text-align: center;
  color: var(--muted);
  font-size: 11px;
  opacity: 0.7;
  margin-top: 14px;
}

/* ===== 게임 화면: 브라우저 창 전체를 채우는 가짜 엑셀 ===== */
#screen-game {
  position: fixed;
  inset: 0;
  z-index: 10;
  display: flex;
  flex-direction: column;
  background: var(--xl-bg);
  font-family: "Segoe UI", "Malgun Gothic", sans-serif;
  font-size: 13px;
  color: var(--xl-text);
}

#screen-game.hidden { display: none; }

.xl-titlebar {
  display: flex;
  align-items: center;
  height: 30px;
  flex: none;
  background: var(--xl-titlebar-bg);
  color: var(--xl-titlebar-text);
  font-size: 12px;
}

.xl-qat { width: 130px; padding-left: 12px; letter-spacing: 1px; opacity: 0.9; }
#xl-filename { flex: 1; text-align: center; }
.xl-title-spacer { width: 130px; }

.xl-menubar {
  display: flex;
  align-items: center;
  gap: 2px;
  height: 30px;
  flex: none;
  background: var(--xl-ribbon-bg);
  padding: 0 6px;
  font-size: 12.5px;
}

.xl-menu { padding: 5px 11px; color: var(--xl-text); }

.xl-menu.xl-menu-file {
  background: var(--xl-green);
  color: #fff;
  font-weight: 600;
}

.xl-menu.active {
  font-weight: 600;
  color: var(--xl-green);
  box-shadow: inset 0 -2px 0 var(--xl-green);
}

.xl-toolbar {
  display: flex;
  align-items: center;
  gap: 14px;
  height: 36px;
  flex: none;
  background: var(--xl-ribbon-bg);
  border-bottom: 1px solid var(--xl-head-border);
  padding: 0 12px;
  font-size: 12px;
  color: var(--xl-head-text);
}

.xl-tool-group {
  display: flex;
  align-items: center;
  gap: 6px;
  padding-right: 14px;
  border-right: 1px solid var(--xl-head-border);
}

.xl-tool-group:last-child { border-right: none; }

.xl-fontbox, .xl-sizebox {
  background: var(--xl-bg);
  border: 1px solid var(--xl-head-border);
  border-radius: 2px;
  padding: 2px 8px;
  white-space: nowrap;
}

.xl-tool { padding: 2px 4px; }

.xl-formulabar {
  display: flex;
  align-items: center;
  height: 26px;
  flex: none;
  background: var(--xl-bg);
  border-bottom: 1px solid var(--xl-head-border);
  font-size: 12px;
}

#xl-namebox {
  width: 70px;
  text-align: center;
  border-right: 1px solid var(--xl-head-border);
  color: var(--xl-text);
}

.xl-fx {
  width: 34px;
  text-align: center;
  font-style: italic;
  color: var(--xl-head-text);
  border-right: 1px solid var(--xl-head-border);
}

.xl-formula-input { flex: 1; padding-left: 8px; color: var(--xl-head-text); }

.xl-grid-area { flex: 1 1 auto; overflow: hidden; }

table#sheet {
  border-collapse: collapse;
  table-layout: fixed;
  font-size: 13px;
  color: var(--xl-text);
}

table#sheet th, table#sheet td {
  border: 1px solid var(--xl-grid);
  height: 24px;
  padding: 0 6px;
  text-align: center;
  font-weight: 400;
  overflow: hidden;
  white-space: nowrap;
}

.xl-letters th {
  background: var(--xl-head-bg);
  color: var(--xl-head-text);
  font-size: 12px;
  font-weight: 400;
  width: 90px;
  border-color: var(--xl-head-border);
}

.xl-corner, .xl-rownum {
  background: var(--xl-head-bg);
  color: var(--xl-head-text);
  width: 32px;
  font-size: 12px;
  border-color: var(--xl-head-border) !important;
}

.xl-label { font-weight: 700; }

/* 제목/메모는 진짜 엑셀처럼 빈 옆 셀로 텍스트가 흘러넘침 */
.xl-title-cell, .xl-note, .xl-status-cell {
  text-align: left !important;
  overflow: visible !important;
  position: relative;
  z-index: 1;
}

.xl-title-cell { font-weight: 700; font-size: 14px; }
.xl-note { color: var(--xl-head-text); }

/* 범례 셀 (돌 색의 인게임 설명) */
.xl-legend-me { background: var(--xf-me-bg); color: var(--xf-me-tx); font-size: 12px; }
.xl-legend-op { background: var(--xf-op-bg); color: var(--xf-op-tx); font-size: 12px; }

/* 오목판 셀 (조건부 서식 위장) */
.xl-board-cell { font-size: 11px; }

.xl-board-cell.xf-me { background: var(--xf-me-bg); color: var(--xf-me-tx); font-weight: 600; }
.xl-board-cell.xf-op { background: var(--xf-op-bg); color: var(--xf-op-tx); font-weight: 600; }

/* 마지막 수 = 엑셀 셀 선택 테두리 + fill handle */
.xl-sel {
  position: relative;
  outline: 2px solid var(--xl-green);
  outline-offset: -2px;
}

.xl-sel::after {
  content: "";
  position: absolute;
  right: -2px;
  bottom: -2px;
  width: 5px;
  height: 5px;
  background: var(--xl-green);
  border: 1px solid var(--xl-bg);
}

/* 승리 라인 = 범위 선택풍 하이라이트 */
.xl-range {
  box-shadow: inset 0 0 0 2px var(--xl-green);
  background-image: linear-gradient(rgba(33, 115, 70, 0.18), rgba(33, 115, 70, 0.18));
}

/* 금수 표식 (흑 차례에만, 아주 미세하게) */
.xl-forbid { color: var(--xl-head-text); opacity: 0.5; }

.xl-btn-cell { padding: 2px !important; }

.xl-btn-cell button {
  width: 100%;
  padding: 3px 8px;
  font-size: 12px;
  font-weight: 600;
  background: var(--xl-btnface);
  color: var(--xl-text);
  border: 1px solid var(--xl-btnborder);
  border-radius: 2px;
  cursor: pointer;
}

.xl-btn-cell button:hover { background: var(--xl-btnface-hover); }

.xl-tabs {
  display: flex;
  align-items: center;
  gap: 2px;
  flex: none;
  background: var(--xl-head-bg);
  border-top: 1px solid var(--xl-head-border);
  padding: 0 8px;
  height: 25px;
}

.xl-statusbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex: none;
  height: 22px;
  background: var(--xl-head-bg);
  border-top: 1px solid var(--xl-head-border);
  padding: 0 14px;
  font-size: 11.5px;
  color: var(--xl-head-text);
}

.xl-tab {
  background: var(--xl-bg);
  color: var(--xl-green);
  font-size: 11px;
  font-weight: 600;
  padding: 3px 14px;
  border-left: 1px solid var(--xl-head-border);
  border-right: 1px solid var(--xl-head-border);
  border-bottom: 2px solid var(--xl-green);
  height: 100%;
  display: flex;
  align-items: center;
}

.xl-tab-add {
  color: var(--xl-head-text);
  font-size: 14px;
  padding: 0 8px;
}

/* ===== 월루모드 OFF: 심플 오목판 ===== */
body:not(.stealth) #screen-game {
  position: static;
  background: transparent;
  font-family: inherit;
  font-size: inherit;
  color: var(--text);
}

body:not(.stealth) .xl-titlebar,
body:not(.stealth) .xl-menubar,
body:not(.stealth) .xl-toolbar,
body:not(.stealth) .xl-formulabar,
body:not(.stealth) .xl-grid-area,
body:not(.stealth) .xl-tabs,
body:not(.stealth) .xl-statusbar { display: none; }

body.stealth #game-normal { display: none; }

.turn-indicator {
  text-align: center;
  font-size: 16px;
  font-weight: 600;
  padding: 12px;
  border-radius: 8px;
  background: var(--panel);
  border: 1px solid var(--panel-border);
  margin-bottom: 16px;
}

#board {
  display: grid;
  grid-template-columns: repeat(15, 1fr);
  grid-auto-rows: 1fr;
  width: min(90vw, 512px);
  aspect-ratio: 1;
  margin: 0 auto;
  background: var(--board-bg);
  border-radius: 6px;
  padding: 6px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
}

.bd-cell {
  position: relative;
  cursor: pointer;
  /* 교차선: 셀 중앙을 지나는 가로/세로 1px 선 */
  background-image:
    linear-gradient(var(--board-line), var(--board-line)),
    linear-gradient(var(--board-line), var(--board-line));
  background-size: 100% 1px, 1px 100%;
  background-position: center, center;
  background-repeat: no-repeat;
}

.bd-cell::after {
  content: "";
  position: absolute;
  inset: 12%;
  border-radius: 50%;
}

.bd-cell.s1::after {
  background: radial-gradient(circle at 35% 30%, #555, #0a0a0a 70%);
}

.bd-cell.s2::after {
  background: radial-gradient(circle at 35% 30%, #ffffff, #d8d8d8 75%);
  border: 1px solid #999;
}

.bd-cell.last::before {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  width: 22%;
  height: 22%;
  transform: translate(-50%, -50%);
  border-radius: 50%;
  background: #e74c3c;
  z-index: 1;
}

.bd-cell.win::after {
  box-shadow: 0 0 0 3px #f1c40f;
}

/* 금수 자리 표시 (흑 차례) */
.bd-cell.forbid { cursor: not-allowed; }

.bd-cell.forbid::after {
  content: "✕";
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  font-weight: 700;
  color: #c0392b;
  border-radius: 0;
  inset: 0;
}

#end-area { margin-top: 16px; text-align: center; }

#end-area p {
  font-size: 20px;
  font-weight: 700;
  margin: 0 0 12px;
}

#update-notice {
  position: fixed;
  bottom: 16px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 30;
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--panel);
  border: 1px solid var(--panel-border);
  color: var(--text);
  border-radius: 8px;
  padding: 8px 12px;
  font-size: 13px;
}

#update-notice.hidden { display: none; }

#update-notice button {
  width: auto;
  padding: 4px 10px;
  font-size: 12px;
}