:root {
  --font-size: 20px; --line-height: 1.9; --letter-spacing: 0.02em; --pad: 24px;
  --font-family-default: system-ui, -apple-system, "Segoe UI", "Noto Sans CJK TC", "PingFang TC", sans-serif;
  --font-family: var(--font-family-default);
  --sans: "Microsoft JhengHei", "微軟正黑體", "PingFang TC", "Noto Sans CJK TC", system-ui, sans-serif;
  --ming: "MingLiU", "PMingLiU", "新細明體", "Noto Serif CJK TC", serif;
  --kai: "DFKai-SB", "標楷體", "BiauKai", "Noto Serif CJK TC", serif;
}
html[data-theme="white"] { --bg:#ffffff; --fg:#111827; --muted:#6b7280; --panel:#f4f5f7; --border:#dcdfe4; --accent:#2563eb; }
html[data-theme="paper"] { --bg:#f5ecd7; --fg:#3b2f1e; --muted:#7c6a4d; --panel:#eadfc4; --border:#d8caa8; --accent:#8a6d3b; }
html[data-theme="green"] { --bg:#c7e6c9; --fg:#1f3a24; --muted:#4a6b50; --panel:#b6dab9; --border:#9cc7a0; --accent:#2f6b3a; }
html[data-theme="grey"]  { --bg:#1f2937; --fg:#e5e7eb; --muted:#9ca3af; --panel:#111827; --border:#374151; --accent:#60a5fa; }
html[data-theme="black"] { --bg:#000000; --fg:#c9ced6; --muted:#7c828c; --panel:#0b0b0d; --border:#26282d; --accent:#38bdf8; }

* { box-sizing: border-box; }
/* 一定要有 !important：下面好多 ID 選擇器（#empty-hint / #tts-bar …）自己寫咗 display，
   優先度高過瀏覽器內建嘅 [hidden]{display:none}，會令 hidden 屬性完全失效 */
[hidden] { display: none !important; }
html, body { height: 100%; margin: 0; }
body {
  display: grid; grid-template-rows: auto 1fr auto; height: 100vh;
  background: var(--bg); color: var(--fg); font-family: var(--font-family);
  transition: background .2s, color .2s;
}
#topbar, #statusbar {
  display: flex; align-items: center; gap: 8px; padding: 6px 10px;
  background: var(--panel); border-bottom: 1px solid var(--border);
  position: relative; z-index: 25;      /* 高過 backdrop(20)：面板開住都仲撳得到工具列 */
}
#statusbar { border-top: 1px solid var(--border); border-bottom: none; flex-wrap: wrap; }
.grow { flex: 1; }
#title-block { display: flex; flex-direction: column; min-width: 0; }
#book-title { font-weight: 700; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; max-width: 40vw; }
#chapter-title { font-size: 12px; color: var(--muted); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; max-width: 40vw; }
.ibtn, .pbtn {
  font: inherit; font-size: 14px; color: var(--fg); background: var(--bg);
  border: 1px solid var(--border); border-radius: 8px; padding: 6px 10px; cursor: pointer;
}
.ibtn:hover, .pbtn:hover { border-color: var(--accent); color: var(--accent); }
.pbtn { display: inline-block; width: 100%; margin: 4px 0; }
.ibtn.active, .pbtn.active { border-color: var(--accent); color: var(--accent); background: color-mix(in srgb, var(--accent) 14%, transparent); }
#wake-status { font-size: 11px; color: var(--muted); margin-top: 4px; }

#reader { position: relative; overflow: hidden; min-height: 0; }
#page-wrap { height: 100%; padding: var(--pad); box-sizing: border-box; }
body[data-mode="scroll"] #page-wrap { overflow-y: auto; overscroll-behavior: contain; }
body[data-mode="page"] #page-wrap { overflow: hidden; }
#page-content {
  font-size: var(--font-size); line-height: var(--line-height); letter-spacing: var(--letter-spacing);
  text-align: justify; hyphens: auto;
}
#page-content .para { margin: 0 0 calc(var(--font-size) * .6); text-indent: 2em; word-break: break-word; }
#page-content .para.hl { background: rgba(56, 189, 248, .18); border-radius: 4px; box-shadow: -4px 0 0 rgba(56,189,248,.45); }
#page-content .para.tts-active { background: rgba(250, 204, 21, .18); }
#empty-hint { position: absolute; inset: 0; display: grid; place-items: center; color: var(--muted); pointer-events: none; }

.panel {
  position: fixed; top: var(--topbar-h, 0px); bottom: var(--statusbar-h, 0px); left: 0;
  width: min(88vw, 360px); z-index: 30;   /* 由工具列下面開始：工具列永遠撳得到 */
  background: var(--panel); border-right: 1px solid var(--border); padding: 14px;
  overflow-y: auto; transform: translateX(-102%); transition: transform .22s ease;
}
#toc-panel  { left: auto; right: 0; transform: translateX(102%); border-right: none; border-left: 1px solid var(--border); }
#settings-panel { left: auto; right: 0; transform: translateX(102%); border-right: none; border-left: 1px solid var(--border); }
#marks-panel { left: auto; right: 0; transform: translateX(102%); border-right: none; border-left: 1px solid var(--border); }
.panel.open, #toc-panel.open, #settings-panel.open, #marks-panel.open { transform: none; }   /* 一定要帶 ID：ID 選擇器優先度高過 .panel.open */
.panel h2 { margin: 0 0 10px; font-size: 16px; display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.pclose {
  font: inherit; font-size: 15px; line-height: 1; padding: 4px 9px; cursor: pointer;
  color: var(--fg); background: var(--bg); border: 1px solid var(--border); border-radius: 8px;
}
.pclose:hover { border-color: var(--accent); color: var(--accent); }
#panel-backdrop { position: fixed; inset: var(--topbar-h, 0px) 0 var(--statusbar-h, 0px) 0; z-index: 20; background: rgba(0, 0, 0, .28); }
.panel h3 { margin: 12px 0 4px; font-size: 13px; color: var(--muted); font-weight: 600; }
.row { display: flex; align-items: center; gap: 8px; }
#drop-zone { border: 2px dashed var(--border); border-radius: 10px; padding: 18px; text-align: center; color: var(--muted); margin: 8px 0; }
#drop-zone.over { border-color: var(--accent); color: var(--accent); }
#shelf-list, #toc-list { list-style: none; margin: 8px 0; padding: 0; }
#shelf-list li, #toc-list li { padding: 8px; border-bottom: 1px solid var(--border); cursor: pointer; }
#shelf-list li .meta, #toc-list li .meta { display: block; font-size: 11px; color: var(--muted); }
#shelf-list li.active { border-left: 3px solid var(--accent); }
#toc-list li.lv1 { font-weight: 700; }
#toc-list li.lv2 { padding-left: 20px; }
#toc-list li.current { color: var(--accent); }
#marks-list li .meta { display: block; font-size: 11px; color: var(--muted); }
.mclose { color: #ef4444; border-color: #ef4444; margin-top: 6px; padding: 2px 8px; font-size: 12px; border-radius: 8px; background: var(--bg); cursor: pointer; }
#marks-list li.empty { color: var(--muted); cursor: default; font-size: 13px; }
#btn-addmark.active { border-color: var(--accent); color: var(--accent); }
#btn-del { color: #ef4444; border-color: #ef4444; margin-top: 6px; padding: 2px 8px; font-size: 12px; }
.sgroup { border-top: 1px solid var(--border); padding-top: 6px; }
.swatches { display: flex; gap: 8px; flex-wrap: wrap; }
.swatch { width: 40px; height: 40px; border-radius: 8px; border: 2px solid var(--border); cursor: pointer; }
.swatch.active { outline: 3px solid var(--accent); }

#progress-track { flex: 1; height: 6px; background: var(--border); border-radius: 3px; overflow: hidden; }
#progress-bar { height: 100%; width: 0; background: var(--accent); }
#pos-label { font-size: 12px; color: var(--muted); min-width: 96px; text-align: center; }

#tts-bar {
  position: fixed; left: 50%; transform: translateX(-50%); bottom: 56px; z-index: 25;
  display: flex; gap: 10px; align-items: center; flex-wrap: wrap;
  background: var(--panel); border: 1px solid var(--border); border-radius: 12px; padding: 8px 12px;
  box-shadow: 0 6px 24px rgba(0,0,0,.18); font-size: 12px; max-width: 94vw;
}
#tts-bar .pbtn { width: auto; margin: 0; }
#tts-bar input[type="range"] { width: 90px; }
#toast {
  position: fixed; left: 50%; transform: translateX(-50%); bottom: 16px; z-index: 50;
  background: rgba(17,24,39,.92); color: #f9fafb; padding: 8px 14px; border-radius: 8px; font-size: 13px;
  max-width: 90vw;
}
@media (min-width: 900px) { #book-title, #chapter-title { max-width: 46vw; } }