:root {
  --bg: #0f1216;
  --panel: #161a20;
  --panel-2: #1c2129;
  --line: #262c35;
  --fg: #e7ebf0;
  --muted: #93a0b0;
  --accent: #4f8ef7;
  --accent-soft: rgba(79, 142, 247, .16);
  --radius: 8px;
  --topbar-h: 52px;
  color-scheme: dark;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; } /* display 값을 가진 요소의 hidden 속성이 무시되지 않게 */
html, body { height: 100%; margin: 0; }
body {
  background: var(--bg);
  color: var(--fg);
  font-family: "Pretendard", "Apple SD Gothic Neo", -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans KR", sans-serif;
  font-size: 13px;
  overflow: hidden;
}

.app { display: flex; flex-direction: column; height: 100%; }

/* 상단 바 */
.topbar {
  display: flex; align-items: center; gap: 16px;
  height: var(--topbar-h); padding: 0 14px;
  background: var(--panel); border-bottom: 1px solid var(--line);
  flex: 0 0 auto;
}
.brand { display: flex; align-items: center; gap: 7px; user-select: none; }
.brand-mark {
  background: var(--accent); color: #fff; font-weight: 800; letter-spacing: .02em;
  padding: 3px 7px; border-radius: 6px; font-size: 12px;
}
.brand-name { font-weight: 700; letter-spacing: .14em; color: var(--muted); font-size: 12px; }

.file-zone { display: flex; align-items: center; gap: 8px; min-width: 0; }
.file-name {
  color: var(--muted); font-size: 12.5px; max-width: 260px;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.export-zone { margin-left: auto; display: flex; align-items: center; gap: 6px; flex-wrap: wrap; justify-content: flex-end; }
.export-label { color: var(--muted); font-size: 11.5px; margin-right: 2px; letter-spacing: .04em; }

.btn {
  appearance: none; border: 1px solid var(--line); background: var(--panel-2); color: var(--fg);
  padding: 6px 12px; border-radius: var(--radius); font-size: 12.5px; cursor: pointer;
  font-family: inherit; transition: background .12s, border-color .12s, color .12s;
  white-space: nowrap;
}
.btn:hover { background: #232935; border-color: #38414f; }
.btn:active { transform: translateY(1px); }
.btn.ghost { background: transparent; color: var(--muted); }
.btn.export { min-width: 56px; }
.btn.export:hover { border-color: var(--accent); color: #cfe0ff; background: var(--accent-soft); }
.btn.busy { opacity: .55; pointer-events: none; }
#btn-open { background: var(--accent); border-color: var(--accent); color: #fff; font-weight: 600; }
#btn-open:hover { background: #3f7ce4; }

/* 열린 파일 탭 */
.tabs {
  display: flex; gap: 4px; padding: 6px 12px; overflow-x: auto;
  background: var(--panel); border-bottom: 1px solid var(--line); flex: 0 0 auto;
}
.tab {
  display: flex; align-items: center; gap: 6px; padding: 4px 8px 4px 10px;
  border: 1px solid var(--line); border-radius: 6px; background: var(--panel-2);
  color: var(--muted); font-size: 12px; cursor: pointer; white-space: nowrap;
}
.tab.active { color: var(--fg); border-color: var(--accent); background: var(--accent-soft); }
.tab .close { color: var(--muted); border: 0; background: none; cursor: pointer; font-size: 13px; line-height: 1; padding: 0 2px; }
.tab .close:hover { color: #ff8080; }

/* 옵션 바 */
.optionbar {
  display: flex; align-items: center; gap: 14px; flex-wrap: wrap;
  padding: 8px 14px; background: var(--panel-2); border-bottom: 1px solid var(--line); flex: 0 0 auto;
}
.opt { display: flex; align-items: center; gap: 6px; color: var(--muted); font-size: 12px; }
.opt select {
  appearance: none; background: var(--panel); color: var(--fg); border: 1px solid var(--line);
  border-radius: 6px; padding: 4px 24px 4px 8px; font-size: 12px; font-family: inherit; cursor: pointer;
  background-image: linear-gradient(45deg, transparent 50%, var(--muted) 50%), linear-gradient(135deg, var(--muted) 50%, transparent 50%);
  background-position: calc(100% - 13px) 50%, calc(100% - 9px) 50%;
  background-size: 4px 4px, 4px 4px; background-repeat: no-repeat;
}
.opt-group { display: flex; border: 1px solid var(--line); border-radius: 6px; overflow: hidden; }
.seg {
  border: 0; background: var(--panel); color: var(--muted); padding: 5px 10px;
  font-size: 12px; cursor: pointer; font-family: inherit; border-right: 1px solid var(--line);
}
.seg:last-child { border-right: 0; }
.seg.active { background: var(--accent-soft); color: #cfe0ff; }
.counts { margin-left: auto; color: var(--muted); font-size: 11.5px; letter-spacing: .02em; }

/* 작업 영역 */
.workspace { flex: 1 1 auto; display: flex; min-height: 0; }
.pane { min-width: 0; display: flex; }
.editor-pane { flex: 0 0 44%; border-right: 1px solid var(--line); }
.preview-pane { flex: 1 1 auto; background: #0b0d10; }
.workspace.layout-preview .editor-pane,
.workspace.layout-preview .splitter { display: none; }
.workspace.layout-edit .preview-pane,
.workspace.layout-edit .splitter { display: none; }
.workspace.layout-edit .editor-pane { flex: 1 1 auto; border-right: 0; }

#editor {
  width: 100%; height: 100%; resize: none; border: 0; outline: 0;
  background: #12151a; color: #dbe3ec; padding: 16px 18px;
  font-family: "JetBrains Mono", "SFMono-Regular", Menlo, Consolas, monospace;
  font-size: 13px; line-height: 1.7; tab-size: 2;
}
#editor::placeholder { color: #5c6773; }

.splitter { flex: 0 0 5px; cursor: col-resize; background: transparent; }
.splitter:hover { background: var(--accent-soft); }

#preview { width: 100%; height: 100%; border: 0; background: #fff; }

/* 드래그앤드롭 */
.dropzone {
  position: fixed; inset: 0; z-index: 40; background: rgba(10, 13, 18, .8);
  display: flex; align-items: center; justify-content: center;
}
.dropzone-inner {
  border: 2px dashed var(--accent); border-radius: 14px; padding: 44px 64px;
  font-size: 15px; color: #cfe0ff; background: rgba(79, 142, 247, .08);
}

/* 알림 */
.toast {
  position: fixed; left: 50%; bottom: 26px; transform: translateX(-50%);
  background: #21262f; color: var(--fg); border: 1px solid var(--line);
  padding: 9px 16px; border-radius: 999px; font-size: 12.5px; z-index: 50;
  box-shadow: 0 8px 26px rgba(0, 0, 0, .45); max-width: 80vw; text-align: center;
}
.toast.error { border-color: #7a2f34; color: #ffc9cc; }

@media (max-width: 900px) {
  .topbar { height: auto; flex-wrap: wrap; padding: 8px 10px; gap: 8px; }
  .export-zone { margin-left: 0; width: 100%; justify-content: flex-start; }
  .editor-pane { flex-basis: 100%; }
  .workspace { flex-direction: column; }
  .splitter { display: none; }
}