:root {
  --bg: #f4f6f7;
  --panel: #ffffff;
  --panel-soft: #eef3f5;
  --ink: #17212b;
  --muted: #64717f;
  --border: #d9e1e6;
  --accent: #2d5f82;
  --accent-strong: #1f4e70;
  --accent-soft: #e5f0f7;
  --accent-2: #c58a2a;
  --danger: #a33a36;
  --shadow: 0 16px 36px rgba(24, 39, 51, 0.08);
  --radius: 8px;
  font-family: Inter, "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
}

body[data-theme="forest"] {
  --bg: #f4f7f3;
  --panel-soft: #edf4ef;
  --accent: #17694b;
  --accent-strong: #0f4f38;
  --accent-soft: #e2f1ea;
  --accent-2: #b7791f;
}

body[data-theme="plum"] {
  --bg: #f7f5f8;
  --panel-soft: #f1edf5;
  --accent: #6d4a8d;
  --accent-strong: #573977;
  --accent-soft: #efe7f5;
  --accent-2: #b36b2c;
}

body[data-theme="dark-slate"] {
  --bg: #10151d;
  --panel: #171f2a;
  --panel-soft: #202b38;
  --ink: #edf3f8;
  --muted: #9ba9b6;
  --border: #2c3947;
  --accent: #8fb7ff;
  --accent-strong: #b9d1ff;
  --accent-soft: #24354d;
  --accent-2: #f0b85c;
  --danger: #ff8f89;
  --shadow: 0 18px 40px rgba(0, 0, 0, 0.26);
}

body[data-theme="dark-moss"] {
  --bg: #0f1714;
  --panel: #17231f;
  --panel-soft: #20312a;
  --ink: #edf7f1;
  --muted: #9eb3a8;
  --border: #2c4038;
  --accent: #7fd7a9;
  --accent-strong: #b4f2d0;
  --accent-soft: #223d32;
  --accent-2: #d7ba72;
  --danger: #ff9a91;
  --shadow: 0 18px 42px rgba(0, 0, 0, 0.28);
}

body[data-theme="dark-ember"] {
  --bg: #17130f;
  --panel: #241d17;
  --panel-soft: #312720;
  --ink: #f8f1ea;
  --muted: #b6a79a;
  --border: #44362b;
  --accent: #f0b85c;
  --accent-strong: #ffdca0;
  --accent-soft: #45331e;
  --accent-2: #8fc7ff;
  --danger: #ff938b;
  --shadow: 0 18px 42px rgba(0, 0, 0, 0.3);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--ink);
}

button,
input,
select,
textarea {
  font: inherit;
}

button {
  cursor: pointer;
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.icon-defs {
  display: none;
}

.icon {
  width: 18px;
  height: 18px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  flex: 0 0 auto;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.login-screen {
  display: grid;
  place-items: center;
  min-height: 100vh;
  padding: 20px;
}

.login-card {
  display: grid;
  gap: 14px;
  width: min(100%, 360px);
  padding: 22px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: var(--shadow);
}

.login-brand {
  margin-bottom: 4px;
}

.form-status {
  min-height: 22px;
  margin: 0;
  color: var(--danger);
  line-height: 1.5;
  word-break: break-word;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 68px;
  padding: 12px 22px;
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--panel) 92%, transparent);
  backdrop-filter: blur(14px);
}

.user-area {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 10px;
  min-width: 150px;
}

.user-area span {
  color: var(--muted);
  font-size: 13px;
  font-weight: 700;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 176px;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: var(--radius);
  background: var(--accent);
  color: #fff;
  font-weight: 800;
}

body[data-theme^="dark"] .brand-mark {
  color: #10151d;
}

.brand strong {
  display: block;
  line-height: 1.1;
  font-size: 18px;
  letter-spacing: 0;
}

.brand span:last-child {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-size: 12px;
}

.page-tabs {
  display: flex;
  gap: 8px;
  padding: 4px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--panel-soft);
}

.page-tab {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-width: 78px;
  min-height: 34px;
  padding: 0 12px;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: var(--muted);
}

.page-tab.is-active {
  background: var(--panel);
  color: var(--accent-strong);
  box-shadow: 0 1px 5px rgba(25, 38, 48, 0.13);
}

.app-shell {
  width: min(1120px, calc(100vw - 28px));
  margin: 18px auto 38px;
}

.view-panel {
  display: none;
}

.view-panel.is-active {
  display: block;
}

.study-view {
  max-width: 850px;
  margin: 0 auto;
}

.practice-card,
.answer-card,
.reference-card,
.score-card,
.settings-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: var(--shadow);
}

.practice-card,
.answer-card,
.reference-card,
.score-card {
  padding: 20px;
  margin-bottom: 14px;
}

.practice-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
}

.badges {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.badge {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent-strong);
  font-size: 13px;
  font-weight: 700;
}

.badge-secondary {
  background: color-mix(in srgb, var(--accent-2) 18%, var(--panel));
  color: color-mix(in srgb, var(--accent-2) 82%, var(--ink));
}

.badge-muted {
  background: var(--panel-soft);
  color: var(--muted);
}

.nav-controls {
  display: flex;
  gap: 8px;
}

.icon-button {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--ink);
}

.icon-button:hover {
  border-color: color-mix(in srgb, var(--accent) 45%, var(--border));
  color: var(--accent-strong);
}

.counter-line {
  margin-top: 20px;
  color: var(--muted);
  font-size: 13px;
}

h1 {
  margin: 10px 0 12px;
  line-height: 1.35;
  font-size: 30px;
  letter-spacing: 0;
}

.source-line {
  color: var(--muted);
  font-size: 13px;
  word-break: break-word;
}

.cloze-box {
  margin-top: 16px;
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--panel-soft);
  line-height: 1.9;
  word-break: break-word;
}

.blank-chip {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  padding: 0 10px;
  margin: 0 3px;
  border: 1px solid color-mix(in srgb, var(--accent) 45%, var(--border));
  border-radius: 999px;
  background: var(--panel);
  color: var(--accent-strong);
  font-weight: 800;
  white-space: nowrap;
}

.surface-title {
  margin-bottom: 12px;
  font-weight: 800;
}

.blank-inputs {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  margin-bottom: 12px;
}

.blank-field,
.field-label {
  display: grid;
  gap: 7px;
  color: var(--muted);
  font-size: 13px;
}

.blank-field label,
.field-label span {
  font-weight: 700;
}

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

.hint-button {
  min-width: 66px;
  height: 40px;
  padding: 0 12px;
  border: 1px solid color-mix(in srgb, var(--accent) 34%, var(--border));
  border-radius: var(--radius);
  background: var(--accent-soft);
  color: var(--accent-strong);
  font-weight: 700;
}

.hint-text {
  padding: 9px 10px;
  border: 1px solid color-mix(in srgb, var(--accent-2) 32%, var(--border));
  border-radius: var(--radius);
  background: color-mix(in srgb, var(--accent-2) 12%, var(--panel));
  color: color-mix(in srgb, var(--accent-2) 78%, var(--ink));
  line-height: 1.55;
}

input,
select,
textarea {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--ink);
  outline: none;
}

input,
select {
  height: 40px;
  padding: 0 12px;
}

textarea {
  display: block;
  min-height: 170px;
  resize: vertical;
  padding: 13px 14px;
  line-height: 1.7;
}

input:focus,
select:focus,
textarea:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 18%, transparent);
}

.action-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 12px;
}

.primary-button,
.secondary-button,
.ghost-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 40px;
  padding: 0 14px;
  border-radius: var(--radius);
  border: 1px solid transparent;
}

.primary-button {
  background: var(--accent);
  color: #fff;
}

body[data-theme^="dark"] .primary-button {
  color: #10151d;
}

.primary-button:hover {
  background: var(--accent-strong);
}

.secondary-button {
  border-color: color-mix(in srgb, var(--accent) 35%, var(--border));
  background: var(--accent-soft);
  color: var(--accent-strong);
}

.ghost-button {
  border-color: var(--border);
  background: var(--panel);
  color: var(--muted);
}

.reference-card pre {
  margin: 0;
  white-space: pre-wrap;
  word-break: break-word;
  line-height: 1.75;
  font-family: inherit;
}

.score-head {
  display: flex;
  align-items: baseline;
  gap: 12px;
}

.score-head strong {
  font-size: 34px;
  color: var(--accent-strong);
}

.score-head span {
  color: var(--muted);
  font-weight: 700;
}

#scoreFeedback {
  margin: 8px 0 14px;
  line-height: 1.65;
}

.score-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.score-grid > div {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px;
  background: var(--panel-soft);
}

.score-grid h2 {
  margin: 0 0 8px;
  font-size: 15px;
  letter-spacing: 0;
}

.score-grid ul {
  margin: 0;
  padding-left: 18px;
  color: var(--muted);
  line-height: 1.65;
}

.score-suggestion {
  margin: 12px 0 0;
  padding: 10px 12px;
  border-left: 4px solid var(--accent-2);
  background: color-mix(in srgb, var(--accent-2) 14%, var(--panel));
  color: color-mix(in srgb, var(--accent-2) 78%, var(--ink));
}

.score-card.has-error .score-head strong,
.score-card.has-error #scoreFeedback {
  color: var(--danger);
}

.settings-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(300px, 0.9fr);
  gap: 14px;
}

.settings-card {
  padding: 18px;
}

.settings-card.env-card {
  grid-column: 2;
}

.settings-card.admin-card {
  grid-column: 1 / -1;
}

.settings-card > * + * {
  margin-top: 12px;
}

.segmented {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  padding: 3px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--panel-soft);
}

.segment {
  min-height: 34px;
  padding: 0 10px;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: var(--muted);
}

.segment.is-active {
  background: var(--panel);
  color: var(--accent-strong);
  box-shadow: 0 1px 5px rgba(25, 38, 48, 0.12);
}

.search-box {
  position: relative;
  display: block;
}

.search-box .icon {
  position: absolute;
  left: 12px;
  top: 11px;
  color: var(--muted);
}

.search-box input {
  padding-left: 38px;
}

.stats-strip {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}

.stats-strip div {
  padding: 10px 8px;
  border-radius: var(--radius);
  background: var(--panel-soft);
  text-align: center;
}

.stats-strip span {
  display: block;
  font-size: 21px;
  font-weight: 800;
  color: var(--accent-strong);
}

.stats-strip small {
  display: block;
  margin-top: 2px;
  color: var(--muted);
  font-size: 12px;
}

.chapter-list {
  display: grid;
  gap: 8px;
}

.chapter-item {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 10px;
  width: 100%;
  min-height: 42px;
  padding: 8px 10px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  background: transparent;
  color: var(--ink);
  text-align: left;
}

.chapter-item:hover,
.chapter-item.is-active {
  border-color: color-mix(in srgb, var(--accent) 32%, var(--border));
  background: var(--accent-soft);
}

.chapter-item small {
  color: var(--muted);
}

.theme-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.theme-section-title {
  margin: 14px 0 8px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 800;
}

.theme-choice {
  display: flex;
  align-items: center;
  gap: 10px;
  min-height: 44px;
  padding: 0 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--ink);
  text-align: left;
}

.theme-choice span {
  width: 18px;
  height: 18px;
  border-radius: 999px;
  background: var(--swatch);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--swatch) 18%, transparent);
}

.theme-choice.is-active {
  border-color: var(--accent);
  background: var(--accent-soft);
  color: var(--accent-strong);
}

.env-status {
  min-height: 22px;
  margin: 10px 0 0;
  color: var(--muted);
  line-height: 1.5;
  word-break: break-word;
}

.env-readonly {
  display: grid;
  gap: 8px;
}

.env-readonly div {
  display: grid;
  grid-template-columns: 76px minmax(0, 1fr);
  align-items: center;
  gap: 10px;
  min-height: 42px;
  padding: 9px 10px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--panel-soft);
}

.env-readonly span {
  color: var(--muted);
  font-size: 13px;
}

.env-readonly strong {
  color: var(--ink);
  font-size: 14px;
  word-break: break-word;
}

.admin-form {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr) auto;
  align-items: end;
  gap: 10px;
}

.admin-users {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.user-pill {
  min-height: 34px;
  padding: 0 11px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--panel-soft);
  color: var(--ink);
}

.user-pill:hover {
  border-color: color-mix(in srgb, var(--accent) 38%, var(--border));
  color: var(--accent-strong);
}

.is-hidden {
  display: none;
}

@media (max-width: 880px) {
  .app-shell {
    width: min(100% - 20px, 760px);
  }

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

  .settings-card.env-card {
    grid-column: auto;
  }

  .settings-card.admin-card {
    grid-column: auto;
  }

  .admin-form {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 620px) {
  .topbar {
    align-items: stretch;
    flex-direction: column;
    padding: 12px;
  }

  .page-tabs {
    width: 100%;
    grid-template-columns: repeat(2, 1fr);
  }

  .user-area {
    width: 100%;
    justify-content: space-between;
  }

  .page-tab {
    flex: 1;
  }

  .practice-card,
  .answer-card,
  .reference-card,
  .score-card,
  .settings-card {
    padding: 14px;
  }

  .practice-top {
    flex-direction: column;
  }

  .nav-controls {
    width: 100%;
    justify-content: flex-end;
  }

  h1 {
    font-size: 24px;
  }

  .blank-inputs,
  .score-grid,
  .theme-grid {
    grid-template-columns: 1fr;
  }

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

  .action-row > button {
    flex: 1 1 120px;
  }
}