:root {
  color-scheme: light;
  --page: #e8ecea;
  --surface: #fbfaf7;
  --surface-soft: #f0f3f1;
  --surface-strong: #ffffff;
  --panel-glass: rgba(255, 255, 255, 0.84);
  --panel-glass-strong: rgba(255, 255, 255, 0.94);
  --line: rgba(35, 48, 43, 0.14);
  --line-strong: rgba(35, 48, 43, 0.24);
  --text: #17211d;
  --muted: #52605a;
  --subtle: #7b8580;
  --lichess: #56725d;
  --lichess-dark: #1f332c;
  --blue: #3f82b8;
  --green: #5f8d58;
  --red: #ba4b4a;
  --gold: #c99b3d;
  --accent-gold: #d6a642;
  --accent-sage: #6f9372;
  --accent-ink: #17211d;
  --light-square: #f0d9b5;
  --dark-square: #8f6849;
  --move-light: #f2df76;
  --move-dark: #d0b84e;
  --hint: rgba(40, 120, 78, 0.42);
  --shadow: 0 24px 70px rgba(18, 26, 23, 0.18);
  --tight-shadow: 0 10px 28px rgba(18, 26, 23, 0.12);
  --inner-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.72);
  --chrome-height: 142px;
  --workbench-height: calc(100dvh - var(--chrome-height));
  font-family: "Noto Sans SC", "Microsoft YaHei UI", "Segoe UI", system-ui, sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  position: relative;
  isolation: isolate;
  background:
    linear-gradient(135deg, rgba(31, 51, 44, 0.16), rgba(255, 255, 255, 0) 42%),
    linear-gradient(180deg, #eef2ef 0%, var(--page) 46%, #dde3e0 100%);
  color: var(--text);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -2;
  pointer-events: none;
  background:
    linear-gradient(115deg, rgba(23, 33, 29, 0.11) 0%, rgba(23, 33, 29, 0) 38%),
    linear-gradient(315deg, rgba(214, 166, 66, 0.13) 0%, rgba(214, 166, 66, 0) 34%),
    repeating-linear-gradient(90deg, rgba(23, 33, 29, 0.025) 0 1px, transparent 1px 82px),
    repeating-linear-gradient(0deg, rgba(23, 33, 29, 0.018) 0 1px, transparent 1px 82px);
}

button,
input,
textarea {
  font: inherit;
}

button {
  cursor: pointer;
}

.app-shell {
  width: calc(100% - 28px);
  min-height: 100dvh;
  margin: 0 auto;
  padding: 12px 0 14px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  margin-bottom: 10px;
  padding: 12px 16px;
  border: 1px solid rgba(255, 255, 255, 0.22);
  border-radius: 14px;
  background:
    linear-gradient(135deg, rgba(23, 33, 29, 0.95), rgba(45, 66, 57, 0.91)),
    linear-gradient(180deg, rgba(255, 255, 255, 0.09), rgba(255, 255, 255, 0));
  box-shadow: 0 18px 48px rgba(18, 26, 23, 0.22), inset 0 1px 0 rgba(255, 255, 255, 0.14);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.brand-lockup {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 250px;
}

.brand-mark {
  width: 58px;
  height: 58px;
  flex: 0 0 auto;
  border: 1px solid rgba(255, 255, 255, 0.52);
  border-radius: 12px;
  background: #fff;
  object-fit: cover;
  box-shadow:
    0 0 20px rgba(77, 214, 255, 0.24),
    0 0 26px rgba(236, 80, 227, 0.18),
    inset 0 1px 0 rgba(255, 255, 255, 0.85);
}

.eyebrow {
  margin: 0 0 3px;
  color: rgba(242, 213, 143, 0.92);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 0;
  color: #fffef9;
  font-size: clamp(24px, 2.8vw, 34px);
  font-weight: 800;
  line-height: 1.1;
}

h2 {
  margin-bottom: 0;
  font-size: 17px;
  font-weight: 700;
}

h3 {
  margin-bottom: 10px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 700;
}

.top-status {
  display: grid;
  gap: 3px;
  min-width: 260px;
  padding: 9px 12px;
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.11);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.12);
}

.top-status span {
  color: rgba(230, 237, 232, 0.72);
  font-size: 12px;
}

.top-status strong {
  color: #fffef9;
  font-size: 14px;
}

.mode-switch {
  display: inline-grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 4px;
  min-width: 270px;
  padding: 5px;
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.09);
}

.language-switch {
  display: inline-grid;
  grid-template-columns: 1fr 1fr;
  gap: 4px;
  min-width: 150px;
  padding: 5px;
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.09);
}

.mode-button {
  min-height: 34px;
  border: 1px solid transparent;
  border-radius: 6px;
  padding: 0 9px;
  background: transparent;
  color: rgba(238, 244, 240, 0.78);
  font-size: 13px;
  font-weight: 700;
  white-space: nowrap;
}

.language-button {
  min-height: 34px;
  border: 1px solid transparent;
  border-radius: 6px;
  background: transparent;
  color: rgba(238, 244, 240, 0.78);
  font-size: 12px;
  font-weight: 800;
}

.mode-button.active {
  border-color: rgba(255, 255, 255, 0.6);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.96), rgba(234, 238, 235, 0.92));
  color: var(--lichess-dark);
  box-shadow: 0 10px 22px rgba(0, 0, 0, 0.14), inset 0 1px 0 rgba(255, 255, 255, 0.8);
}

.language-button.active {
  border-color: rgba(255, 255, 255, 0.48);
  background: rgba(255, 255, 255, 0.92);
  color: var(--lichess-dark);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.75);
}

.workbench {
  display: grid;
  grid-template-columns: minmax(300px, 0.9fr) minmax(560px, 1.8fr) minmax(300px, 0.9fr);
  gap: 14px;
  align-items: stretch;
}

.panel,
.board-zone {
  height: var(--workbench-height);
  min-height: 0;
  border: 1px solid rgba(255, 255, 255, 0.54);
  border-radius: 14px;
  background: var(--panel-glass);
  box-shadow: var(--shadow), var(--inner-shadow);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

.panel {
  padding: 15px;
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-gutter: stable;
  scrollbar-width: thin;
  scrollbar-color: rgba(35, 48, 43, 0.24) transparent;
}

.panel::-webkit-scrollbar {
  width: 9px;
}

.panel::-webkit-scrollbar-thumb {
  border: 2px solid transparent;
  border-radius: 999px;
  background: rgba(35, 48, 43, 0.28);
  background-clip: content-box;
}

.panel-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 14px;
}

.panel-heading.compact {
  margin-bottom: 9px;
}

.panel-heading.compact span {
  min-width: 26px;
  height: 22px;
  display: inline-grid;
  place-items: center;
  border-radius: 999px;
  background: rgba(31, 51, 44, 0.08);
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}

.field {
  display: grid;
  gap: 7px;
  margin-bottom: 11px;
}

.field span,
.side-picker > span {
  color: var(--muted);
  font-size: 13px;
  font-weight: 700;
}

textarea,
input {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.88);
  color: var(--text);
  outline: none;
  box-shadow: inset 0 1px 2px rgba(18, 26, 23, 0.05);
}

textarea {
  min-height: 220px;
  resize: vertical;
  padding: 10px 11px;
  line-height: 1.45;
}

input {
  height: 40px;
  padding: 0 10px;
}

textarea:focus,
input:focus {
  border-color: var(--blue);
  box-shadow: 0 0 0 3px rgba(63, 130, 184, 0.18), inset 0 1px 2px rgba(18, 26, 23, 0.05);
}

.button-row,
.action-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 9px;
}

.primary-button,
.secondary-button,
.ghost-button,
.file-button,
.segmented {
  min-height: 38px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  padding: 0 12px;
  color: var(--text);
  font-weight: 700;
  text-decoration: none;
  background: linear-gradient(180deg, #ffffff, #edf1ee);
  transition: border-color 120ms ease, box-shadow 120ms ease, transform 120ms ease;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.72), 0 8px 18px rgba(18, 26, 23, 0.08);
}

.primary-button {
  border-color: rgba(68, 111, 55, 0.78);
  background: linear-gradient(180deg, #89ad63, #4f7c45);
  color: #fff;
  text-shadow: 0 1px 0 rgba(0, 0, 0, 0.22);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.28), 0 12px 24px rgba(62, 107, 55, 0.27);
}

.secondary-button,
.file-button {
  background: linear-gradient(180deg, #ffffff, #e8eee9);
}

.ghost-button {
  min-height: 32px;
  background: rgba(255, 255, 255, 0.58);
  color: var(--lichess);
}

.primary-button:hover,
.secondary-button:hover,
.ghost-button:hover,
.file-button:hover,
.segmented:hover {
  border-color: var(--blue);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.78), 0 10px 22px rgba(63, 130, 184, 0.16);
  transform: translateY(-1px);
}

.file-button input {
  position: absolute;
  inline-size: 1px;
  block-size: 1px;
  opacity: 0;
  pointer-events: none;
}

.divider {
  height: 1px;
  margin: 16px 0;
  background: var(--line);
}

.side-picker {
  display: grid;
  gap: 9px;
}

.side-picker div {
  display: grid;
  grid-template-columns: 1fr 1fr;
  overflow: hidden;
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.58);
}

.segmented {
  border: 0;
  border-radius: 0;
  background: transparent;
  color: var(--muted);
}

.segmented.active {
  background: linear-gradient(180deg, #5f7d62, #365447);
  color: #fff;
}

.note {
  margin: 14px 0 0;
  color: var(--subtle);
  font-size: 12px;
  line-height: 1.45;
}

.current-task[data-tone="error"] {
  color: #8b2f24;
}

.saved-studies {
  display: grid;
  gap: 12px;
}

.prep-panel {
  display: grid;
  gap: 14px;
}

.database-status {
  display: grid;
  gap: 6px;
  padding: 11px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.72);
}

.database-status strong {
  color: var(--text);
  font-size: 12px;
}

.database-status span {
  color: var(--muted);
  font-size: 12px;
  line-height: 1.45;
}

.prep-common-replies {
  display: grid;
  gap: 9px;
  margin-top: 4px;
  padding: 11px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.72);
}

.prep-common-replies h3 {
  margin: 0;
  color: var(--text);
  font-size: 13px;
}

.prep-common-replies > p {
  margin: 0;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.4;
}

.prep-common-replies ol {
  display: grid;
  gap: 7px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.prep-common-replies li {
  margin: 0;
}

.prep-common-replies button {
  position: relative;
  overflow: hidden;
  display: grid;
  grid-template-columns: 24px minmax(46px, 0.8fr) minmax(58px, 1fr) minmax(0, 2.3fr);
  gap: 7px;
  align-items: center;
  width: 100%;
  min-height: 34px;
  padding: 6px 7px;
  border: 1px solid rgba(35, 48, 43, 0.1);
  border-radius: 7px;
  background: rgba(255, 255, 255, 0.62);
  color: inherit;
  text-align: left;
  cursor: pointer;
}

.prep-common-replies button::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: var(--prep-share, 0%);
  background: rgba(77, 140, 111, 0.14);
  pointer-events: none;
}

.prep-common-replies button:hover {
  border-color: rgba(31, 51, 44, 0.22);
  background: rgba(255, 255, 255, 0.9);
}

.prep-common-replies button > span,
.prep-common-replies button strong,
.prep-common-replies button code,
.prep-common-replies button em {
  position: relative;
  z-index: 1;
}

.prep-common-replies button > span {
  display: inline-grid;
  place-items: center;
  width: 20px;
  height: 20px;
  border-radius: 999px;
  background: rgba(31, 51, 44, 0.08);
  color: var(--muted);
  font-size: 11px;
  font-weight: 800;
}

.prep-common-replies strong {
  color: var(--text);
  font-size: 14px;
}

.prep-common-replies code {
  padding: 2px 6px;
  border-radius: 999px;
  background: rgba(35, 48, 43, 0.07);
  color: var(--muted);
  font-family: "Inter", "Segoe UI", system-ui, sans-serif;
  font-size: 11px;
}

.prep-common-replies em {
  min-width: 0;
  color: var(--subtle);
  font-size: 11px;
  font-style: normal;
  line-height: 1.3;
}

.prep-common-replies i {
  display: none;
}

.prep-report-list {
  display: grid;
  gap: 14px;
  max-height: 620px;
  overflow-y: auto;
  padding-right: 4px;
  scrollbar-gutter: stable;
}

.prep-report-group {
  display: grid;
  gap: 8px;
}

.prep-report-group h3 {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin: 0;
  color: var(--text);
  font-size: 13px;
}

.prep-report-group h3 span {
  color: var(--muted);
  font-size: 12px;
}

.prep-report-item {
  display: grid;
  gap: 8px;
  padding: 10px;
  border: 1px solid var(--line);
  border-left: 4px solid var(--blue);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.72);
}

.prep-report-item[data-tone="weak"] {
  border-left-color: #b06c3d;
}

.prep-report-item[data-tone="gap"] {
  border-left-color: #8b4f5d;
}

.prep-report-position,
.prep-report-main {
  display: grid;
  gap: 3px;
}

.prep-report-position > span,
.prep-report-main > span {
  color: var(--subtle);
  font-size: 11px;
  font-weight: 800;
}

.prep-report-position strong {
  color: var(--text);
  font-size: 12px;
  line-height: 1.35;
}

.prep-report-main {
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: end;
}

.prep-report-main > span {
  grid-column: 1 / -1;
}

.prep-report-main strong {
  color: var(--text);
  font-size: 18px;
  line-height: 1.1;
}

.prep-report-main code {
  align-self: center;
  padding: 2px 6px;
  border-radius: 999px;
  background: rgba(35, 48, 43, 0.07);
  color: var(--muted);
  font-family: "Inter", "Segoe UI", system-ui, sans-serif;
  font-size: 11px;
}

.prep-report-item p {
  margin: 0;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.45;
}

.prep-report-item em {
  color: var(--muted);
  font-size: 12px;
  font-style: normal;
}

.saved-list {
  display: grid;
  gap: 10px;
  max-height: calc((54px * 3) + (12px * 2) + 46px);
  min-height: 0;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: 12px 14px 34px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(244, 247, 245, 0.74);
  scrollbar-gutter: stable;
  scrollbar-width: thin;
  scrollbar-color: rgba(35, 48, 43, 0.24) transparent;
}

.saved-list::-webkit-scrollbar,
.endgame-lesson-list::-webkit-scrollbar {
  width: 9px;
}

.saved-list::-webkit-scrollbar-thumb,
.endgame-lesson-list::-webkit-scrollbar-thumb {
  border: 2px solid transparent;
  border-radius: 999px;
  background: rgba(35, 48, 43, 0.28);
  background-clip: content-box;
}

.saved-study {
  display: grid;
  gap: 3px;
  width: 100%;
  height: 54px;
  flex: 0 0 54px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 8px 9px;
  background: rgba(255, 255, 255, 0.82);
  color: var(--text);
  text-align: left;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.6);
  transition: background 120ms ease, border-color 120ms ease, transform 120ms ease;
}

.saved-study strong {
  overflow: hidden;
  font-size: 13px;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.saved-study span {
  color: var(--subtle);
  font-size: 11px;
}

.saved-study.active {
  border-color: rgba(214, 166, 66, 0.72);
  background: linear-gradient(90deg, rgba(214, 166, 66, 0.22), rgba(255, 255, 255, 0.75));
  box-shadow: inset 3px 0 0 var(--accent-gold);
}

.saved-study:hover {
  border-color: rgba(63, 130, 184, 0.34);
  background: rgba(255, 255, 255, 0.9);
  transform: translateY(-1px);
}

.rename-field {
  margin-bottom: 0;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.72);
}

.rename-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 74px;
  gap: 8px;
}

.rename-row .secondary-button {
  min-height: 40px;
}

.board-zone {
  display: grid;
  grid-template-rows: auto auto minmax(0, 1fr) auto;
  gap: 10px;
  padding: 14px;
  overflow: hidden;
  background:
    linear-gradient(145deg, rgba(255, 255, 255, 0.88), rgba(240, 244, 241, 0.74)),
    var(--panel-glass);
}

.feedback {
  min-height: 42px;
  display: flex;
  align-items: center;
  margin-bottom: 0;
  padding: 9px 12px;
  border: 1px solid rgba(95, 141, 88, 0.28);
  border-radius: 8px;
  background: rgba(243, 248, 237, 0.84);
  color: #3f6939;
  line-height: 1.35;
}

.feedback[data-tone="error"] {
  border-color: rgba(195, 61, 50, 0.25);
  background: #fff0ee;
  color: #8f2119;
}

.current-line-panel {
  display: grid;
  gap: 7px;
  min-height: 54px;
  padding: 9px 11px;
  border: 1px solid rgba(35, 48, 43, 0.13);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.72);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.66);
}

.current-line-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.current-line-head span {
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
}

.current-line-actions {
  display: inline-flex;
  align-items: center;
  gap: 12px;
}

.link-button {
  min-height: 24px;
  border: 0;
  border-radius: 0;
  padding: 0;
  background: transparent;
  color: var(--blue);
  box-shadow: none;
  font-size: 12px;
  font-weight: 800;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.link-button:hover {
  color: var(--lichess-dark);
}

.current-line {
  max-height: 42px;
  margin: 0;
  overflow-y: auto;
  color: var(--text);
  font-family: "Segoe UI", "Noto Sans SC", system-ui, sans-serif;
  font-size: 13px;
  line-height: 1.45;
  scrollbar-width: thin;
}

.board-slot {
  position: relative;
  min-height: 0;
  display: grid;
  place-items: center;
  container-type: size;
}

.board-frame {
  width: min(100cqw, 100cqh);
  max-width: 100%;
  max-height: 100%;
  min-width: 0;
  aspect-ratio: 1;
  margin: 0 auto;
  padding: 10px;
  border: 1px solid rgba(35, 48, 43, 0.17);
  border-radius: 14px;
  background:
    linear-gradient(145deg, rgba(23, 33, 29, 0.12), rgba(255, 255, 255, 0.66)),
    linear-gradient(180deg, rgba(214, 166, 66, 0.11), rgba(63, 130, 184, 0.08));
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.78), 0 18px 42px rgba(18, 26, 23, 0.16);
}

.board-wrap {
  display: grid;
  grid-template-columns: 22px 1fr;
  grid-template-rows: 1fr 22px;
  width: 100%;
  height: 100%;
  padding: 0;
}

.board {
  grid-column: 2;
  grid-row: 1;
  display: grid;
  grid-template-columns: repeat(8, minmax(0, 1fr));
  width: 100%;
  height: 100%;
  overflow: hidden;
  border-radius: 8px;
  box-shadow: 0 12px 34px rgba(70, 52, 34, 0.26);
  touch-action: none;
}

.board.is-wrong {
  animation: wrongShake 260ms ease-in-out;
}

.rank-labels {
  grid-column: 1;
  grid-row: 1;
  display: grid;
  grid-template-rows: repeat(8, minmax(0, 1fr));
  align-items: center;
  justify-items: center;
  color: rgba(31, 51, 44, 0.72);
  font-size: 12px;
  font-weight: 700;
}

.file-labels {
  grid-column: 2;
  grid-row: 2;
  display: grid;
  grid-template-columns: repeat(8, minmax(0, 1fr));
  align-items: center;
  justify-items: center;
  color: rgba(31, 51, 44, 0.72);
  font-size: 12px;
  font-weight: 700;
}

.square {
  position: relative;
  display: grid;
  place-items: center;
  width: 100%;
  aspect-ratio: 1;
  border: 0;
  border-radius: 0;
  padding: 0;
}

.square.light {
  background: var(--light-square);
}

.square.dark {
  background: var(--dark-square);
}

.square.selected.light {
  background: #f6e17a;
}

.square.selected.dark {
  background: #c9a248;
}

.square.last.light {
  background: var(--move-light);
}

.square.last.dark {
  background: var(--move-dark);
}

.square.hint::after {
  content: "";
  position: absolute;
  width: 34%;
  height: 34%;
  border-radius: 50%;
  background: var(--hint);
}

.square.hint.occupied::after {
  inset: 7%;
  width: auto;
  height: auto;
  border: 6px solid var(--hint);
  background: transparent;
}

.square.selected::before {
  content: "";
  position: absolute;
  inset: 0;
  background: rgba(255, 255, 0, 0.18);
}

.square.legal-target::after {
  content: "";
  position: absolute;
  z-index: 2;
  width: 32%;
  height: 32%;
  border-radius: 999px;
  background: rgba(23, 33, 29, 0.28);
  pointer-events: none;
}

.square.legal-target.occupied::after {
  inset: 7%;
  width: auto;
  height: auto;
  border: 5px solid rgba(23, 33, 29, 0.28);
  background: transparent;
}

.square.drag-source .piece {
  opacity: 0;
}

.piece {
  position: relative;
  z-index: 1;
  width: 100%;
  height: 100%;
  display: block;
  background-position: center;
  background-repeat: no-repeat;
  background-size: 92%;
  filter: drop-shadow(0 1px 1px rgba(0, 0, 0, 0.32));
}

.piece-drag-ghost {
  position: fixed;
  left: 0;
  top: 0;
  z-index: 30;
  width: var(--drag-piece-size, 64px);
  height: var(--drag-piece-size, 64px);
  pointer-events: none;
  transform: translate(-50%, -50%);
  will-change: transform;
  filter: drop-shadow(0 14px 18px rgba(0, 0, 0, 0.28));
}

.promotion-picker {
  position: absolute;
  left: 50%;
  bottom: 18px;
  z-index: 20;
  display: grid;
  gap: 8px;
  width: min(360px, calc(100% - 32px));
  padding: 10px;
  border: 1px solid rgba(35, 48, 43, 0.2);
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.94);
  box-shadow: 0 18px 40px rgba(18, 26, 23, 0.22), inset 0 1px 0 rgba(255, 255, 255, 0.76);
  transform: translateX(-50%);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
}

.promotion-picker > span {
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
  text-align: center;
}

.promotion-picker > div {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 7px;
}

.promotion-choice {
  display: grid;
  gap: 3px;
  justify-items: center;
  min-height: 78px;
  border: 1px solid rgba(214, 166, 66, 0.38);
  border-radius: 8px;
  padding: 5px 4px 7px;
  background: linear-gradient(180deg, #fffdf7, #efe6cf);
  color: var(--text);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.72), 0 7px 16px rgba(70, 52, 34, 0.11);
}

.promotion-choice .piece {
  width: 46px;
  height: 46px;
}

.promotion-choice strong {
  font-size: 12px;
}

.promotion-choice:hover {
  border-color: var(--blue);
  transform: translateY(-1px);
}

.piece-wK { background-image: url("assets/piece/cburnett/wK.svg"); }
.piece-wQ { background-image: url("assets/piece/cburnett/wQ.svg"); }
.piece-wR { background-image: url("assets/piece/cburnett/wR.svg"); }
.piece-wB { background-image: url("assets/piece/cburnett/wB.svg"); }
.piece-wN { background-image: url("assets/piece/cburnett/wN.svg"); }
.piece-wP { background-image: url("assets/piece/cburnett/wP.svg"); }
.piece-bK { background-image: url("assets/piece/cburnett/bK.svg"); }
.piece-bQ { background-image: url("assets/piece/cburnett/bQ.svg"); }
.piece-bR { background-image: url("assets/piece/cburnett/bR.svg"); }
.piece-bB { background-image: url("assets/piece/cburnett/bB.svg"); }
.piece-bN { background-image: url("assets/piece/cburnett/bN.svg"); }
.piece-bP { background-image: url("assets/piece/cburnett/bP.svg"); }

.move-strip {
  min-height: 42px;
  max-height: 42px;
  display: flex;
  flex-wrap: nowrap;
  gap: 7px;
  align-items: center;
  margin-top: 0;
  padding: 10px 11px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.64);
  overflow-x: auto;
  overflow-y: hidden;
  scrollbar-width: thin;
}

.move-strip span {
  flex: 0 0 auto;
  color: var(--muted);
  font-size: 13px;
}

.move-strip .mine {
  color: #3f6939;
  font-weight: 700;
}

.move-strip .opponent {
  color: var(--text);
}

.current-task {
  min-height: 56px;
  margin-bottom: 13px;
  color: var(--text);
  line-height: 1.45;
}

.target-pill {
  display: inline-flex;
  align-items: center;
  width: fit-content;
  min-height: 28px;
  margin: -2px 0 10px;
  padding: 6px 10px;
  border: 1px solid rgba(140, 105, 35, 0.22);
  border-radius: 8px;
  background: rgba(255, 248, 229, 0.86);
  color: #744d08;
  font-size: 12px;
  font-weight: 800;
}

.target-pill[data-target="draw"] {
  border-color: rgba(45, 113, 98, 0.24);
  background: rgba(229, 247, 241, 0.86);
  color: #245f53;
}

.live-dot {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--green);
  font-size: 12px;
  font-weight: 700;
}

.live-dot::before {
  content: "";
  width: 7px;
  height: 7px;
  border-radius: 999px;
  background: var(--green);
}

.stats-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 9px;
  margin-bottom: 16px;
}

.stats-grid div {
  min-height: 68px;
  display: grid;
  align-content: center;
  gap: 3px;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.68);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.58);
}

.stats-grid strong {
  color: var(--lichess-dark);
  font-size: 22px;
}

.stats-grid span {
  color: var(--subtle);
  font-size: 12px;
}

.answer-box {
  margin-bottom: 15px;
}

.answers {
  display: grid;
  gap: 7px;
}

.answer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  min-height: 39px;
  border: 1px solid rgba(214, 166, 66, 0.35);
  border-radius: 8px;
  padding: 0 11px;
  background: rgba(255, 248, 228, 0.82);
  color: var(--text);
  font-weight: 700;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.6);
}

.answer span {
  color: var(--subtle);
  font-size: 12px;
}

.branch-label {
  margin: 0 0 2px;
  color: var(--lichess);
  font-size: 12px;
  font-weight: 800;
}

.opponent-choice {
  border-color: rgba(63, 130, 184, 0.4);
  background: rgba(235, 244, 251, 0.88);
}

.empty,
.muted {
  margin: 0;
  color: var(--subtle);
  font-size: 13px;
  line-height: 1.45;
}

.wide {
  grid-column: 1 / -1;
}

.engine-card {
  display: grid;
  gap: 11px;
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid var(--line);
}

.engine-status {
  min-height: 42px;
  margin: 0;
  padding: 9px 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.68);
  color: var(--text);
  font-size: 13px;
  line-height: 1.45;
}

.engine-profiles {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.engine-profile {
  min-height: 48px;
  display: grid;
  align-content: center;
  gap: 2px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 7px 8px;
  background: rgba(255, 255, 255, 0.72);
  color: var(--text);
  text-align: left;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.58);
  transition: background 120ms ease, border-color 120ms ease, transform 120ms ease;
}

.engine-profile strong {
  font-size: 12px;
}

.engine-profile span {
  color: var(--subtle);
  font-size: 11px;
}

.engine-profile.active {
  border-color: rgba(95, 141, 88, 0.8);
  background: linear-gradient(180deg, rgba(241, 248, 230, 0.96), rgba(222, 239, 213, 0.96));
  color: #3f6939;
}

.engine-profile:hover {
  border-color: rgba(63, 130, 184, 0.34);
  background: rgba(255, 255, 255, 0.9);
  transform: translateY(-1px);
}

.engine-actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 9px;
}

.engine-note {
  margin: 0;
  color: var(--subtle);
  font-size: 11px;
  line-height: 1.45;
}

.hidden {
  display: none !important;
}

.endgame-panel {
  display: grid;
  gap: 12px;
}

.endgame-category-list,
.endgame-lesson-list {
  display: grid;
  gap: 8px;
}

.endgame-lesson-list {
  max-height: min(58vh, calc((54px * 8) + (8px * 7) + 24px));
  min-height: 0;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: 10px 12px 28px 0;
  scrollbar-gutter: stable;
  scrollbar-width: thin;
  scrollbar-color: rgba(35, 48, 43, 0.24) transparent;
}

.endgame-category,
.endgame-lesson {
  width: 100%;
  min-height: 54px;
  display: grid;
  gap: 3px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.72);
  color: var(--text);
  padding: 9px 10px;
  text-align: left;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.58);
  transition: background 120ms ease, border-color 120ms ease, transform 120ms ease;
}

.endgame-category strong,
.endgame-lesson strong {
  font-size: 13px;
}

.endgame-category span,
.endgame-lesson em {
  color: var(--subtle);
  font-size: 11px;
  font-style: normal;
  line-height: 1.35;
}

.endgame-lesson {
  grid-template-columns: 28px 1fr;
  align-items: center;
}

.endgame-lesson span {
  width: 24px;
  height: 24px;
  display: inline-grid;
  place-items: center;
  border-radius: 999px;
  background: rgba(31, 51, 44, 0.08);
  color: var(--muted);
  font-size: 11px;
  font-weight: 700;
}

.endgame-lesson strong,
.endgame-lesson em {
  grid-column: 2;
}

.endgame-category.active,
.endgame-lesson.active {
  border-color: rgba(63, 130, 184, 0.62);
  background: linear-gradient(90deg, rgba(63, 130, 184, 0.15), rgba(255, 255, 255, 0.78));
  box-shadow: inset 3px 0 0 var(--blue);
}

.endgame-category:hover,
.endgame-lesson:hover {
  border-color: rgba(214, 166, 66, 0.45);
  background: rgba(255, 255, 255, 0.88);
  transform: translateY(-1px);
}

.lesson-card {
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.66);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.58);
}

.lesson-card h3 {
  margin-bottom: 5px;
  color: var(--text);
  font-size: 15px;
}

.lesson-goal {
  margin-bottom: 10px;
  color: var(--lichess);
  font-size: 12px;
  font-weight: 700;
}

.lesson-source {
  margin: -3px 0 10px;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.35;
}

.lesson-card dl {
  display: grid;
  gap: 6px;
  margin: 0;
}

.lesson-card dt {
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}

.lesson-card dd {
  margin: 0 0 5px;
  color: var(--text);
  font-size: 13px;
  line-height: 1.5;
}

.answer-note {
  margin: 0;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.45;
}

body.locale-en {
  font-family: "Inter", "Segoe UI", system-ui, sans-serif;
}

body.locale-en .topbar {
  grid-template-columns: minmax(170px, 0.8fr) minmax(250px, 1fr) minmax(150px, 0.55fr) minmax(230px, 0.9fr);
  display: grid;
}

body.locale-en .mode-switch,
body.locale-en .language-switch {
  width: 100%;
  min-width: 0;
}

body.locale-en .mode-button,
body.locale-en .language-button,
body.locale-en .primary-button,
body.locale-en .secondary-button,
body.locale-en .ghost-button,
body.locale-en .file-button,
body.locale-en .link-button {
  white-space: normal;
  overflow-wrap: anywhere;
  line-height: 1.18;
}

body.locale-en .mode-button {
  white-space: nowrap;
  overflow-wrap: normal;
  font-size: 12px;
}

body.locale-en .button-row,
body.locale-en .action-grid,
body.locale-en .engine-actions {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

body.locale-en .action-grid .primary-button,
body.locale-en .action-grid .secondary-button {
  min-height: 44px;
  padding-inline: 8px;
}

body.locale-en .stats-grid span,
body.locale-en .engine-profile strong,
body.locale-en .engine-profile span,
body.locale-en .endgame-category strong,
body.locale-en .endgame-category span,
body.locale-en .endgame-lesson strong,
body.locale-en .endgame-lesson em,
body.locale-en .lesson-card dd,
body.locale-en .lesson-source,
body.locale-en .current-task,
body.locale-en .engine-status {
  overflow-wrap: anywhere;
  hyphens: auto;
}

body.locale-en .endgame-lesson {
  min-height: 68px;
  align-items: start;
}

body.locale-en .endgame-lesson strong {
  line-height: 1.25;
}

body.locale-en .endgame-lesson em,
body.locale-en .endgame-category span {
  line-height: 1.32;
}

body.locale-en .lesson-card dd {
  font-size: 12.5px;
  line-height: 1.48;
}

body.locale-en .top-status {
  min-width: 0;
}

body.locale-en .brand-lockup {
  min-width: 0;
}

@keyframes wrongShake {
  0%,
  100% {
    transform: translateX(0);
    box-shadow: 0 7px 22px rgba(70, 52, 34, 0.3);
  }
  25% {
    transform: translateX(-5px);
    box-shadow: 0 0 0 4px rgba(195, 61, 50, 0.22);
  }
  75% {
    transform: translateX(5px);
    box-shadow: 0 0 0 4px rgba(195, 61, 50, 0.22);
  }
}

@media (max-width: 1180px) {
  :root {
    --workbench-height: auto;
  }

  .workbench {
    grid-template-columns: 1fr;
  }

  .panel,
  .board-zone {
    height: auto;
    overflow: visible;
  }

  .board-zone {
    order: -1;
  }

  .board-frame {
    width: min(100%, 760px);
    max-height: none;
    min-width: 0;
  }

  textarea {
    min-height: 165px;
  }

  .endgame-lesson-list {
    max-height: 420px;
  }
}

@media (max-width: 680px) {
  .app-shell {
    width: calc(100% - 16px);
    padding: 10px 0 16px;
  }

  .topbar {
    align-items: stretch;
    flex-direction: column;
  }

  .brand-lockup {
    min-width: 0;
  }

  .top-status {
    min-width: 0;
  }

  .mode-switch {
    width: 100%;
    min-width: 0;
  }

  .language-switch {
    width: 100%;
    min-width: 0;
  }

  body.locale-en .topbar {
    display: flex;
  }

  .panel,
  .board-zone {
    padding: 11px;
  }

  .button-row,
  .action-grid,
  .stats-grid,
  .engine-profiles,
  .engine-actions {
    grid-template-columns: 1fr;
  }

  .piece {
    font-size: clamp(24px, 10vw, 44px);
  }
}