/* Book study: scoped to one optional skin; no framework or external fonts. */
body[data-skin="book-study"] {
    --bg-page:#f7f5f0; --bg-panel:#fffefb; --bg-panel-hover:#efede6;
    --border-color:#ddd9d0; --border-hover:#9babb9;
    --text-main:#2c3035; --text-muted:#686861; --text-dark:#72766e;
    --primary:#38516c; --primary-light:#38516c; --primary-glow:rgba(56,81,108,.08);
    --book-soft:#e9edf0; --book-red:#a04442; --book-green:#3e6852;
    --color-syl:#7e8999; --color-bll:#a18e83; --color-nk:#a28e64;
    --color-wk:#798f81; --color-sh:#918698;
    font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;
    height:100vh; height:100dvh; padding:16px 24px 18px;
    background:var(--bg-page); color:var(--text-main); color-scheme:light;
}
body.dark-theme[data-skin="book-study"] {
    --bg-page:#191b1d; --bg-panel:#202325; --bg-panel-hover:#2b2f31;
    --border-color:#3b3e40; --border-hover:#8294a8;
    --text-main:#ece9e2; --text-muted:#b5b3ac; --text-dark:#a4a49e;
    --primary:#bbcadb; --primary-light:#bbcadb; --primary-glow:rgba(187,202,219,.08);
    --book-soft:#2c3742; --book-red:#edaaa2; --book-green:#a1c9b0;
    color-scheme:dark;
}
body[data-skin="book-study"] > header {padding:4px 4px 15px;margin-bottom:8px;gap:20px}
body[data-skin="book-study"] .header-title-area h1 {font-size:23px;font-weight:650;letter-spacing:-.04em}
body[data-skin="book-study"] .header-title-area p {font-size:10px;border:0;background:none;color:var(--text-muted);padding:0;margin-top:5px}
body[data-skin="book-study"] .header-meta {gap:8px}
body[data-skin="book-study"] .header-meta button {min-height:36px;border-radius:6px;box-shadow:none}
body[data-skin="book-study"] .ai-nav-btn,
body[data-skin="book-study"] .cloud-sync-btn,
body[data-skin="book-study"] .theme-switch-btn {background:var(--bg-panel)!important;border-color:var(--border-color)!important;color:var(--primary)!important}
body[data-skin="book-study"] .skin-menu {background:var(--bg-panel);border-color:var(--border-color);box-shadow:0 12px 36px #0002}
body[data-skin="book-study"] .skin-option {background:var(--bg-page);border-color:var(--border-color);color:var(--text-main)}
body[data-skin="book-study"] .skin-option.active {border-color:var(--primary);background:var(--book-soft)}
body[data-skin="book-study"] .time-machine-bar {border:0;border-radius:0;background:none!important;margin:0 4px 12px;padding:4px 0;gap:6px;flex-direction:column;align-items:stretch;color:var(--text-muted)}
body[data-skin="book-study"] .time-machine-display {min-height:32px}
body[data-skin="book-study"] .time-machine-date {background:none;border:0;color:var(--primary)}
body[data-skin="book-study"] .time-machine-toggle-btn {display:inline-flex}
body[data-skin="book-study"] .time-machine-controls {display:none}
body[data-skin="book-study"] .time-machine-bar.expanded .time-machine-controls {display:flex;gap:8px;justify-content:flex-end}
body[data-skin="book-study"] .app-layout:not(.focus-mode) {grid-template-columns:240px minmax(0,1fr) 280px;gap:0;position:relative}
body[data-skin="book-study"] .workspace-panel {min-width:0;background:transparent;border:0;border-radius:0;box-shadow:none;padding:14px 18px;overscroll-behavior:contain}
body[data-skin="book-study"] .subject-scroller {padding-left:4px;border-right:1px solid var(--border-color)}
body[data-skin="book-study"] .calendar-panel {padding-right:4px;border-left:1px solid var(--border-color)}
body[data-skin="book-study"] .pending-workspace {background:var(--bg-panel);padding:16px 26px}
body[data-skin="book-study"] .panel-heading {font-size:14px;font-weight:600;border-color:var(--border-color);padding-bottom:16px;margin-bottom:14px;letter-spacing:0}
body[data-skin="book-study"] .global-search-trigger {margin-bottom:22px;border:1px solid var(--border-color);border-radius:6px;background:var(--bg-panel);box-shadow:none;padding:12px}
body[data-skin="book-study"] .search-trigger-left span {font-size:12px!important;font-weight:400!important;line-height:1.6}
body[data-skin="book-study"] .he5500-section {background:none!important;border:0!important;border-bottom:1px solid var(--border-color)!important;border-radius:0;box-shadow:none!important;padding:12px 0!important;margin:0!important}
body[data-skin="book-study"] .he5500-heading {gap:8px;padding:0;font-size:12px;flex-wrap:wrap}
body[data-skin="book-study"] .he5500-heading-title {gap:8px;min-width:0;font-weight:550}
body[data-skin="book-study"] .he5500-heading-icon {background:var(--book-soft)!important;color:var(--primary)!important;width:28px;height:28px;border-radius:5px;flex-shrink:0}
body[data-skin="book-study"] .he5500-heading-count {background:none!important;border:0!important;box-shadow:none!important;padding:0;color:var(--text-muted)!important;font-size:10px!important;font-weight:400!important}
body[data-skin="book-study"] .subject-stack {gap:0;margin-top:8px}
body[data-skin="book-study"] .subject-group {border:0;border-bottom:1px solid var(--border-color);border-radius:0}
body[data-skin="book-study"] .subject-group:last-child {border-bottom:0}
body[data-skin="book-study"] .subject-header-row {padding:14px 0;gap:9px;background:none}
body[data-skin="book-study"] .subject-header-row:hover {background:var(--bg-panel-hover)}
body[data-skin="book-study"] .subject-badge-squircle {background:var(--book-soft);border:0;border-radius:5px;box-shadow:none;width:32px;height:32px;color:var(--primary);font-size:11px}
body[data-skin="book-study"] .subject-header-row .subject-name {font-weight:550}
body[data-skin="book-study"] .middle-review-tab-bar {background:none;border:0;border-bottom:1px solid var(--border-color);border-radius:0;padding:0;gap:20px}
body[data-skin="book-study"] .middle-review-tab-btn {flex:0 1 auto;min-height:44px;border-radius:0;padding:8px 2px;border:0;border-bottom:2px solid transparent;box-shadow:none;background:none;color:var(--text-muted);font-weight:500}
body[data-skin="book-study"] .middle-review-tab-btn.active {background:none;border-bottom-color:var(--primary);color:var(--primary);box-shadow:none}
body[data-skin="book-study"] .middle-review-tab-btn .tab-badge {background:var(--book-soft);color:var(--primary);font-size:10px;font-weight:500}
body[data-skin="book-study"] .today-summary-bar {background:none;border:0;border-radius:0;box-shadow:none;padding:10px 0 18px;gap:12px}
body[data-skin="book-study"] .summary-stat-item {background:none;border:0;border-radius:4px;padding:8px 4px;flex-direction:row;gap:10px;box-shadow:none;justify-content:flex-start;flex-wrap:wrap}
body[data-skin="book-study"] .summary-stat-item::before {display:none}
body[data-skin="book-study"] .summary-stat-item:hover {transform:none;box-shadow:none;background:var(--bg-panel-hover)}
body[data-skin="book-study"] .summary-stat-item.active {background:var(--book-soft);box-shadow:none;border:0}
body[data-skin="book-study"] .stat-lbl {font-weight:400;letter-spacing:0;color:var(--text-muted);font-size:11px}
body[data-skin="book-study"] .stat-val {font-size:20px;font-weight:550;font-family:inherit;color:var(--primary);text-shadow:none}
body[data-skin="book-study"] .stat-val.red {color:var(--book-red)}
body[data-skin="book-study"] .stat-val.green {color:var(--book-green)}
body[data-skin="book-study"] .question-pending-card {background:var(--bg-panel);border:1px solid var(--border-color);box-shadow:none;border-radius:6px;margin-bottom:18px}
body[data-skin="book-study"] .q-card-text-summary {font-size:15px;line-height:1.8;color:var(--text-main);white-space:normal;overflow-wrap:anywhere}
body[data-skin="book-study"] .q-card-section {font-size:11px;background:none;border:0;color:var(--text-muted)}
body[data-skin="book-study"] .q-card-badge-box {padding-top:10px;gap:10px}
body[data-skin="book-study"] .q-card-badge-box .q-badge {background:none!important;border:0!important;border-radius:0;padding:0;font-size:11px;color:var(--text-muted)!important;font-weight:400}
body[data-skin="book-study"] .q-card-badge-box .overdue-badge {color:var(--book-red)!important}
body[data-skin="book-study"] .q-card-question-full,body[data-skin="book-study"] .q-card-answer-box {font-size:16px;line-height:1.85;overflow-wrap:anywhere}
body[data-skin="book-study"] .subject-review-header {background:var(--bg-panel-hover);border:0;border-bottom:1px solid var(--border-color);border-radius:4px;box-shadow:none;padding:14px 12px}
body[data-skin="book-study"] .pending-list-scroll {padding-right:6px}
body[data-skin="book-study"] .exam-countdown-banner {border:0;border-radius:0;background:none;box-shadow:none;padding:0 0 22px;margin-bottom:0;border-bottom:1px solid var(--border-color)}
body[data-skin="book-study"] .countdown-title-badge {background:none;padding:0;color:var(--primary);font-weight:500;font-size:11px}
body[data-skin="book-study"] .countdown-top-row {flex-wrap:wrap;gap:8px}
body[data-skin="book-study"] .countdown-target-date {color:var(--text-muted);font-size:10px;background:none}
body[data-skin="book-study"] .countdown-main-timer {flex-wrap:wrap;gap:12px;margin-top:16px}
body[data-skin="book-study"] .countdown-days-num {font-family:Georgia,serif;font-size:46px;font-weight:400;color:var(--text-main);text-shadow:none}
body[data-skin="book-study"] .countdown-days-unit {color:var(--primary)}
body[data-skin="book-study"] .countdown-sub-hms {background:none;border:0;color:var(--text-muted);padding:0;font-size:10px}
body[data-skin="book-study"] .countdown-hms-num {color:var(--text-muted);font-weight:400}
body[data-skin="book-study"] .countdown-quote {font-size:11px;color:var(--text-muted);margin-top:12px}
body[data-skin="book-study"] .review-dashboard-section {background:none;border:0;border-radius:0;box-shadow:none;padding:22px 0;margin:0;border-bottom:1px solid var(--border-color)}
body[data-skin="book-study"] .review-dashboard-head h3 {font-weight:550;font-size:12px}
body[data-skin="book-study"] .review-dashboard-grid {grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}
body[data-skin="book-study"] :is(.review-dashboard-stat,.review-pressure-card,.review-history-card,.review-date-summary-card) {background:none;border:0;border-radius:0;box-shadow:none;padding:5px 0}
body[data-skin="book-study"] :is(.review-dashboard-stat,.review-pressure-card,.review-history-card,.review-date-summary-card)::before {display:none}
body[data-skin="book-study"] :is(.review-dashboard-stat,.review-pressure-card,.review-history-card,.review-date-summary-card) strong {color:var(--primary);font-size:20px;font-weight:500;font-family:inherit}
body[data-skin="book-study"] :is(.review-stat-red,.review-pressure-card) strong {color:var(--book-red)}
body[data-skin="book-study"] .review-stat-green strong {color:var(--book-green)}
body[data-skin="book-study"] .review-dashboard-head {gap:6px;flex-wrap:wrap}
.book-more-toggle,.book-overview-toggle,.book-overview-close,.book-stat-toggle {display:none}
.book-more,.book-more-items {display:contents}
body[data-skin="book-study"] .book-more {display:block;position:relative}
body[data-skin="book-study"] .book-more-toggle {display:inline-flex;align-items:center;justify-content:center;cursor:pointer;padding:0 12px;font:inherit;font-size:12px}
body[data-skin="book-study"] .book-more-items {display:none;position:absolute;right:0;top:calc(100% + 8px);z-index:1000;min-width:180px;padding:8px;background:var(--bg-panel);border:1px solid var(--border-color);border-radius:8px;box-shadow:0 12px 36px #0002}
body[data-skin="book-study"] .book-more.open .book-more-items {display:grid;gap:6px}
body[data-skin="book-study"] .book-stat-toggle {display:block;background:none;border:0;color:var(--primary);font-size:11px;min-height:32px;padding:0 4px;cursor:pointer;margin-left:auto}
body[data-skin="book-study"] .book-stat-collapsed > :not(.review-dashboard-head) {display:none}
body[data-skin="book-study"] .book-stat-collapsed {padding:10px 0}
body[data-skin="book-study"] .book-stat-collapsed .review-dashboard-head {margin:0}
body[data-skin="book-study"] button:focus-visible {outline:2px solid var(--primary);outline-offset:3px}
@media(min-width:769px) and (max-width:1200px) and (orientation:landscape) {
 body[data-skin="book-study"] .app-layout:not(.focus-mode) {grid-template-columns:210px minmax(0,1fr)}
 body[data-skin="book-study"] .app-layout:not(.focus-mode) .calendar-panel {display:none}
 body[data-skin="book-study"] .app-layout.book-overview-open:not(.focus-mode) .calendar-panel {display:flex;position:absolute;right:0;top:0;bottom:0;width:310px;z-index:50;background:var(--bg-panel);padding:18px;box-shadow:-12px 0 40px #0002}
 body[data-skin="book-study"] .book-overview-toggle,body[data-skin="book-study"] .book-overview-close {display:inline-flex;min-height:36px;align-items:center;font:inherit;font-size:12px;color:var(--primary);background:none;border:1px solid var(--border-color);border-radius:5px;padding:0 10px;cursor:pointer}
}
@media(max-width:768px),(orientation:portrait) and (max-width:1200px) {
 body[data-skin="book-study"] {padding:8px 10px 0!important}
 body[data-skin="book-study"] > header {padding:6px 4px 12px!important;gap:8px!important}
 body[data-skin="book-study"] .header-title-area h1 {font-size:20px}
 body[data-skin="book-study"] .header-title-area p {display:none!important}
 body[data-skin="book-study"] .header-meta {justify-content:flex-start!important;gap:6px!important;flex-wrap:wrap!important;overflow:visible!important}
 body[data-skin="book-study"] .book-more-items {position:fixed;top:var(--book-more-top,130px);left:12px;right:12px;min-width:0}
 body[data-skin="book-study"] .header-meta button {font-size:11px!important;min-height:36px;padding:0 8px!important}
 body[data-skin="book-study"] .time-machine-bar {border:0!important;border-radius:0!important;padding:0 4px!important;margin-bottom:8px!important}
 body[data-skin="book-study"] .app-layout:not(.focus-mode) {grid-template-columns:minmax(0,1fr);gap:0}
 body[data-skin="book-study"] .app-layout:not(.focus-mode) > .workspace-panel {border:0;border-radius:0;padding:16px 12px 90px!important}
 body[data-skin="book-study"] .panel-heading {padding-bottom:12px;font-size:13px}
 body[data-skin="book-study"] .today-summary-bar {gap:6px;padding:8px 0 14px!important}
 body[data-skin="book-study"] .summary-stat-item {flex-direction:column;gap:6px;align-items:flex-start;padding:10px 6px!important}
 body[data-skin="book-study"] .stat-val {font-size:19px}
 body[data-skin="book-study"] .middle-review-tab-bar {gap:12px}
 body[data-skin="book-study"] .middle-review-tab-btn {font-size:11px;padding:8px 0}
 body[data-skin="book-study"] .mobile-tabs {background:var(--bg-panel);border:1px solid var(--border-color);box-shadow:0 -4px 18px #0001}
 body[data-skin="book-study"] .mobile-tab.active {background:var(--book-soft);color:var(--primary)}
}
body[data-skin="book-study"].focus-mode .app-layout {grid-template-columns:minmax(0,1fr)}
body[data-skin="book-study"].focus-mode .pending-workspace {max-width:1080px;width:100%;margin:0 auto}
/* Revised information architecture: two primary columns, overview on demand. */
.book-study-tools,.book-search-slot,.book-overview-shade,.book-materials > h2 {display:none}
body[data-skin="book-study"] .app-layout:not(.focus-mode) {grid-template-columns:240px minmax(0,1fr)}
body[data-skin="book-study"] > header {justify-content:flex-start}
body[data-skin="book-study"] .header-title-area {width:216px;flex-shrink:0}
body[data-skin="book-study"] .book-search-slot {display:block;flex:1;min-width:0}
body[data-skin="book-study"] .book-search-slot .global-search-trigger {max-width:360px;margin:0;min-height:38px;padding:8px 12px}
body[data-skin="book-study"] .book-search-slot .search-trigger-left span {white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
body[data-skin="book-study"] .book-study-tools {display:flex;align-items:flex-start;justify-content:space-between;gap:12px;flex-wrap:wrap;border-bottom:1px solid var(--border-color);padding:0 0 14px;margin-bottom:4px}
body[data-skin="book-study"] .book-study-tools .time-machine-bar {flex:1;min-width:180px;margin:0;padding:0}
body[data-skin="book-study"] .book-study-tools .panel-heading-actions {min-height:32px}
body[data-skin="book-study"] .pending-workspace {padding:26px 40px}
body[data-skin="book-study"] .pending-workspace > :is(.panel-heading,.book-study-tools,.middle-review-tab-bar,.today-summary-bar,.pending-list-scroll) {width:100%;max-width:1040px;margin-left:auto;margin-right:auto}
body[data-skin="book-study"] .pending-workspace > .panel-heading {border:0;margin:0;padding:0 0 6px;font-size:24px;font-weight:500;min-height:40px}
body[data-skin="book-study"] .pending-workspace > .panel-heading svg {display:none}
body[data-skin="book-study"] .book-materials > h2 {display:block;font-size:11px;font-weight:500;color:var(--text-muted);padding:28px 0 10px;letter-spacing:.05em}
body[data-skin="book-study"] .book-materials .he5500-section {padding:16px 0!important}
body[data-skin="book-study"] .book-materials .he5500-heading-title {font-size:12px}
body[data-skin="book-study"] .book-materials .he5500-heading-count {margin-left:36px}
body[data-skin="book-study"] .book-overview-toggle,body[data-skin="book-study"] .book-overview-close {display:inline-flex;min-height:36px;align-items:center;justify-content:center;font:inherit;font-size:12px;border:1px solid var(--border-color);border-radius:5px;padding:0 10px;cursor:pointer}
body[data-skin="book-study"] .app-layout:not(.focus-mode) > .calendar-panel {display:none}
body[data-skin="book-study"] .app-layout.book-overview-open:not(.focus-mode) > .calendar-panel {display:flex;position:absolute;right:0;top:0;bottom:0;width:min(360px,100%);z-index:51;background:var(--bg-panel);padding:22px;border-left:1px solid var(--border-color);box-shadow:-12px 0 40px #0002}
body[data-skin="book-study"] .app-layout.book-overview-open .book-overview-shade {display:block;position:absolute;inset:0;z-index:50;background:#191b1d30;border:0;cursor:pointer}
body[data-skin="book-study"].focus-mode .book-study-tools {display:none}
@media(min-width:769px) and (max-width:1200px) and (orientation:landscape){
 body[data-skin="book-study"] .app-layout:not(.focus-mode) {grid-template-columns:210px minmax(0,1fr)}
 body[data-skin="book-study"] .header-title-area {width:186px}
 body[data-skin="book-study"] .book-search-slot .search-trigger-left span {display:none}
 body[data-skin="book-study"] .book-search-slot {flex:0 0 40px}
 body[data-skin="book-study"] .pending-workspace {padding:22px 28px}
 body[data-skin="book-study"] .header-meta {margin-left:auto}
}
@media(max-width:768px),(orientation:portrait) and (max-width:1200px){
 body[data-skin="book-study"] > header {display:grid!important;grid-template-columns:1fr 40px!important;gap:8px!important}
 body[data-skin="book-study"] .header-title-area {width:auto!important}
 body[data-skin="book-study"] .book-search-slot {display:block}
 body[data-skin="book-study"] .book-search-slot .global-search-trigger {padding:8px;margin:0}
 body[data-skin="book-study"] .book-search-slot .search-trigger-left span {display:none}
 body[data-skin="book-study"] .header-meta {grid-column:1 / -1}
 body[data-skin="book-study"] #skin-btn-text {position:absolute;width:1px;height:1px;padding:0;overflow:hidden;clip-path:inset(50%);white-space:nowrap}
 body[data-skin="book-study"] .skin-picker > button {min-width:38px}
 body[data-skin="book-study"] .header-meta button {min-height:40px}
 body[data-skin="book-study"] .book-overview-toggle {display:none}
 body[data-skin="book-study"] .app-layout:not(.focus-mode) {grid-template-columns:minmax(0,1fr)}
 body[data-skin="book-study"] .app-layout.mobile-tab-calendar > .calendar-panel {position:static;width:100%;display:flex!important;box-shadow:none}
 body[data-skin="book-study"] .book-overview-close {display:none}
 body[data-skin="book-study"] .pending-workspace > .panel-heading {font-size:22px;padding-bottom:8px}
 body[data-skin="book-study"] .book-study-tools {gap:8px;padding-bottom:12px}
 body[data-skin="book-study"] .book-study-tools .time-machine-bar {padding:0!important;margin:0!important}
 body[data-skin="book-study"] .book-study-tools .panel-heading-actions {width:100%;justify-content:flex-end}
}
@media(prefers-reduced-motion:reduce) {body[data-skin="book-study"] *,body[data-skin="book-study"] *::before {transition:none!important;animation:none!important}}