:root {
  --bg: #f6f8fb;
  --panel: #ffffff;
  --ink: #172033;
  --muted: #667085;
  --line: #d9e0ea;
  --blue: #175c9e;
  --blue-soft: #eaf3fb;
  --green: #0d7a3a;
  --green-soft: #e6f4ea;
  --red: #b42318;
  --red-soft: #fff0ee;
  --yellow: #fff4cc;
  --focus: #2f6fed;
  --snb-width: 260px;
  --snb-collapsed-width: 0px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: "Malgun Gothic", "Segoe UI", Arial, sans-serif;
  font-size: 15px;
  letter-spacing: 0;
}

button,
input,
select {
  font: inherit;
}

button {
  border: 1px solid var(--line);
  background: #fff;
  color: var(--ink);
  min-height: 36px;
  padding: 7px 11px;
  border-radius: 6px;
  cursor: pointer;
}

button:hover {
  border-color: #9db5d0;
  background: #f8fbff;
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.48;
  background: #f3f5f8;
  color: #8a94a6;
}

button:disabled:hover {
  border-color: var(--line);
  background: #f3f5f8;
}

button:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

.setup-screen {
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin-right: var(--snb-width);
  padding: 24px;
  background:
    linear-gradient(180deg, rgba(255,255,255,0.74), rgba(246,248,251,0.96)),
    var(--bg);
}

.setup-screen[hidden],
.login-screen[hidden],
.saved-review-screen[hidden] {
  display: none;
}

body.session-active .setup-screen,
body.session-active .login-screen {
  display: none;
}

.setup-panel {
  width: min(820px, 100%);
  display: grid;
  grid-template-columns: minmax(0, 1fr) 330px;
  gap: 22px;
  align-items: stretch;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 24px;
  box-shadow: 0 24px 70px rgba(23, 32, 51, 0.12);
}

.setup-preview {
  width: min(980px, 100%);
  margin-top: 16px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 18px;
  box-shadow: 0 14px 42px rgba(23, 32, 51, 0.08);
}

.setup-preview-head {
  margin-bottom: 12px;
}

.setup-preview-head h2 {
  margin: 3px 0 4px;
  font-size: 20px;
}

.preview-list {
  display: grid;
  gap: 10px;
}

.preview-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  background: #fff;
  display: flex;
  flex-direction: column;
  height: 158px;
  overflow: hidden;
}

.preview-card-head {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 8px;
}

.preview-card-head span {
  color: var(--muted);
  font-size: 12px;
}

.preview-card-meta {
  margin-top: auto;
  color: var(--muted);
  font-size: 12px;
}

.preview-card > .text-en,
.preview-card > .text-ko {
  display: -webkit-box;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.preview-card > .text-en {
  -webkit-line-clamp: 2;
}

.preview-card > .text-ko {
  -webkit-line-clamp: 2;
}

.preview-pagination {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 8px;
  margin-top: 14px;
  flex-wrap: wrap;
}

.preview-pagination span {
  min-width: 72px;
  text-align: center;
  color: var(--muted);
  font-weight: 800;
}

.page-numbers {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  justify-content: center;
}

.page-numbers button,
.preview-pagination .page-icon {
  min-width: 34px;
  padding: 0 9px;
}

.page-numbers .active {
  background: var(--blue);
  border-color: var(--blue);
  color: #fff;
  font-weight: 800;
}

.auth-panel {
  width: min(820px, 100%);
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(320px, 420px);
  gap: 14px;
  align-items: center;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px 18px;
  margin-bottom: 16px;
  box-shadow: 0 12px 36px rgba(23, 32, 51, 0.08);
}

.auth-panel h2 {
  margin: 3px 0 4px;
  font-size: 20px;
}

.auth-form {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.auth-form button {
  min-height: 36px;
}

.user-meta {
  margin: 3px 0 0;
  color: var(--muted);
  font-size: 12px;
}

.login-screen {
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin-right: var(--snb-width);
  padding: 24px;
  background: var(--bg);
}

.setup-copy {
  display: flex;
  flex-direction: column;
  justify-content: center;
  border-right: 1px solid var(--line);
  padding-right: 22px;
}

.setup-copy h1 {
  margin: 6px 0 10px;
  font-size: 32px;
  line-height: 1.18;
}

.setup-copy p:last-child {
  margin: 0;
  color: var(--muted);
  line-height: 1.6;
}

.setup-form {
  display: grid;
  gap: 15px;
}

.field-help {
  margin: 0;
  color: var(--muted);
  font-size: 12px;
}

.multi-select {
  position: relative;
}

.multi-select-button {
  width: 100%;
  text-align: left;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.multi-select-button::after {
  content: "⌄";
  color: var(--muted);
  font-size: 15px;
}

.multi-select-menu {
  position: absolute;
  z-index: 20;
  inset: calc(100% + 6px) 0 auto 0;
  max-height: 260px;
  overflow: auto;
  padding: 8px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 6px;
  box-shadow: 0 14px 40px rgba(23, 32, 51, 0.16);
}

.multi-option,
.check-row {
  display: flex;
  align-items: center;
  gap: 8px;
}

.multi-option {
  min-height: 32px;
  padding: 5px 6px;
  border-radius: 5px;
  font-size: 13px;
  cursor: pointer;
}

.multi-option:hover {
  background: #f4f8fc;
}

.multi-option input,
.check-row input {
  width: 16px;
  min-height: 16px;
  flex: 0 0 16px;
}

.check-row {
  color: #344054;
  font-size: 13px;
}

.start-btn {
  min-height: 44px;
}

.saved-review-screen {
  min-height: 100vh;
  margin-right: var(--snb-width);
  padding: 24px;
  background: var(--bg);
}

body.session-active .saved-review-screen {
  display: none;
}

.saved-review-panel {
  width: min(980px, 100%);
  margin: 0 auto;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 22px;
  box-shadow: 0 18px 54px rgba(23, 32, 51, 0.1);
}

.saved-review-header {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: flex-start;
  margin-bottom: 16px;
}

.saved-review-header h1 {
  margin: 4px 0 8px;
  font-size: 28px;
}

.saved-review-actions {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.app-shell {
  display: block;
  min-height: 0;
}

body.session-active .app-shell {
  display: block;
  min-height: 100vh;
}

body.session-active.snb-collapsed .app-shell {
  display: block;
}

.sidebar {
  position: fixed;
  inset: 0 0 0 auto;
  z-index: 40;
  width: var(--snb-width);
  overflow: auto;
  background: var(--panel);
  border-left: 1px solid var(--line);
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 14px;
  min-height: 100vh;
}

body:not(.session-active) .session-only {
  display: none !important;
}

.sidebar-auth {
  display: grid;
  gap: 6px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfcfe;
}

.sidebar-auth strong {
  font-size: 17px;
}

.sidebar-auth span {
  color: var(--muted);
  font-size: 12px;
}

.brand,
.toolbar,
.toolbar-actions,
.control-row {
  display: flex;
  align-items: center;
}

.brand {
  justify-content: space-between;
  gap: 12px;
}

.brand h1 {
  margin: 0;
  font-size: 22px;
  line-height: 1.2;
}

.brand p,
.eyebrow {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.icon-btn {
  width: 38px;
  min-width: 38px;
  padding: 0;
  font-size: 22px;
  line-height: 1;
}

.snb-toggle {
  position: sticky;
  top: 12px;
  z-index: 25;
}

.side-nav {
  display: grid;
  gap: 6px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  padding: 10px 0;
}

.side-nav-item {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  justify-content: flex-start;
  min-height: 38px;
}

.side-nav-item.active {
  background: var(--blue);
  color: #fff;
  border-color: var(--blue);
  font-weight: 800;
}

.side-icon {
  display: inline-grid;
  place-items: center;
  width: 22px;
  min-width: 22px;
  font-weight: 900;
}

body.snb-collapsed .sidebar {
  width: var(--snb-collapsed-width);
  min-height: 0;
  padding: 0;
  overflow: visible;
  border-left: 0;
  background: transparent;
  align-items: flex-start;
}

body.snb-collapsed .brand {
  display: block;
  width: 0;
}

body.snb-collapsed .snb-toggle {
  position: fixed;
  top: 16px;
  right: 16px;
  z-index: 70;
  background: #fff;
  box-shadow: 0 8px 24px rgba(23, 32, 51, 0.14);
}

body.snb-collapsed .brand > div,
body.snb-collapsed #resetStatsBtn,
body.snb-collapsed .sidebar-auth,
body.snb-collapsed .side-nav,
body.snb-collapsed .side-label,
body.snb-collapsed .sidebar > .control-block,
body.snb-collapsed .sidebar > .segmented,
body.snb-collapsed .sidebar > .stats-grid,
body.snb-collapsed .sidebar > .control-row,
body.snb-collapsed .sidebar > .question-list {
  display: none;
}

body.snb-collapsed .side-nav {
  width: 100%;
  border: 0;
}

body.snb-collapsed .side-nav-item {
  justify-content: center;
  padding: 0;
}

.danger {
  color: var(--red);
}

.danger-button {
  border-color: #f2a6a0;
  color: var(--red);
  background: #fff;
  font-weight: 800;
  white-space: nowrap;
}

.danger-button:hover {
  border-color: var(--red);
  background: var(--red-soft);
}

.control-block {
  display: grid;
  gap: 6px;
}

.control-block label {
  color: #344054;
  font-weight: 700;
  font-size: 13px;
}

select,
input {
  width: 100%;
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 7px 10px;
  background: #fff;
  color: var(--ink);
}

.segmented {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  border: 1px solid var(--line);
  border-radius: 6px;
  overflow: hidden;
}

.segmented button {
  border: 0;
  border-right: 1px solid var(--line);
  border-radius: 0;
  min-height: 34px;
  padding: 6px;
  font-size: 13px;
}

.segmented button:last-child {
  border-right: 0;
}

.segmented .active {
  background: var(--blue);
  color: #fff;
  font-weight: 700;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  border: 1px solid var(--line);
  border-radius: 6px;
  overflow: hidden;
}

.stats-grid div {
  padding: 10px 6px;
  text-align: center;
  border-right: 1px solid var(--line);
  background: #fbfcfe;
}

.stats-grid div:last-child {
  border-right: 0;
}

.stats-grid span {
  display: block;
  font-weight: 800;
  font-size: 18px;
}

.stats-grid small {
  display: block;
  margin-top: 2px;
  color: var(--muted);
  font-size: 11px;
}

.control-row {
  gap: 8px;
}

.control-row button {
  flex: 1;
}

.question-list {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 6px;
  overflow: auto;
  padding-right: 2px;
}

.q-jump {
  min-height: 34px;
  padding: 0;
  font-size: 12px;
  border-radius: 5px;
}

.q-jump.active {
  background: var(--blue);
  border-color: var(--blue);
  color: #fff;
  font-weight: 800;
}

.q-jump.correct {
  border-color: #8fd3a8;
  background: var(--green-soft);
}

.q-jump.wrong {
  border-color: #f2a6a0;
  background: var(--red-soft);
}

.q-jump.bookmarked::after {
  content: "★";
  margin-left: 2px;
  color: #c68500;
}

.main-panel {
  display: none;
  margin-right: var(--snb-width);
  padding: 22px;
  min-width: 0;
}

body.session-active .main-panel {
  display: block;
}

body.snb-collapsed .setup-screen,
body.snb-collapsed .login-screen,
body.snb-collapsed .saved-review-screen,
body.snb-collapsed .main-panel {
  margin-right: var(--snb-collapsed-width);
}

.toolbar {
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 14px;
}

.toolbar h2 {
  margin: 3px 0 0;
  font-size: 26px;
  line-height: 1.2;
}

.toolbar-actions {
  gap: 8px;
}

.session-strip {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px 14px;
  margin-bottom: 14px;
}

.session-strip > div:first-child {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: center;
  margin-bottom: 9px;
}

#progressCount {
  font-size: 18px;
}

#sessionSummary {
  color: var(--muted);
  font-size: 13px;
  text-align: right;
}

.progress-track {
  height: 8px;
  background: #e9eef5;
  border-radius: 999px;
  overflow: hidden;
}

.progress-fill {
  width: 0%;
  height: 100%;
  background: var(--blue);
  transition: width 160ms ease;
}

.question-area {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
}

.view-panel[hidden] {
  display: none;
}

.review-view {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 18px;
}

.review-header h2 {
  margin: 4px 0 8px;
  font-size: 25px;
}

.review-header p:last-child {
  color: var(--muted);
  margin: 0 0 14px;
}

.review-actions {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}

.result-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 10px;
}

.result-tile {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px;
  background: #fbfcfe;
}

.result-tile strong {
  display: block;
  font-size: 24px;
  margin-bottom: 4px;
}

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

.review-list {
  display: grid;
  gap: 10px;
}

.review-list.compact {
  max-height: 320px;
  overflow: auto;
  margin-top: 12px;
}

.review-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  background: #fff;
}

.review-card.selectable {
  cursor: pointer;
  transition: border-color 140ms ease, box-shadow 140ms ease, background 140ms ease;
}

.review-card.selectable:hover {
  border-color: #9db5d0;
}

.review-card.selectable:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 3px;
}

.review-card.correct {
  border-color: #8fd3a8;
  background: var(--green-soft);
}

.review-card.wrong {
  border-color: #f2a6a0;
  background: var(--red-soft);
}

.review-card.selectable.is-selected {
  border-color: var(--blue);
  box-shadow: 0 0 0 2px rgba(23, 92, 158, 0.2), 0 10px 24px rgba(23, 32, 51, 0.08);
}

.review-card.wrong.selectable.is-selected {
  border-color: var(--blue);
  background: linear-gradient(0deg, rgba(234, 243, 251, 0.6), rgba(234, 243, 251, 0.6)), var(--red-soft);
}

.review-card-head {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: flex-start;
  margin-bottom: 8px;
}

.review-card-title {
  font-weight: 800;
}

.review-card-meta {
  color: var(--muted);
  font-size: 12px;
  margin-top: 2px;
}

.review-card .text-en,
.review-card .text-ko {
  font-weight: 500;
}

.review-card-explanation {
  margin-top: 10px;
  padding: 9px 10px;
  border-radius: 6px;
  background: var(--yellow);
  color: #5b3b00;
  font-size: 13px;
  line-height: 1.5;
}

.review-card-answer {
  margin-top: 10px;
  padding: 9px 10px;
  border-radius: 6px;
  background: var(--yellow);
  color: #5b3b00;
  font-weight: 800;
}

.review-card-actions {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin-top: 10px;
}

.empty-review {
  border: 1px dashed var(--line);
  border-radius: 8px;
  padding: 28px 14px;
  text-align: center;
  color: var(--muted);
  background: #fbfcfe;
}

.question-text {
  padding: 16px 18px;
  border-bottom: 2px solid #1f4e79;
  background: #f4f6f8;
}

.text-en {
  color: #687386;
  font-weight: 700;
  line-height: 1.45;
}

.text-ko {
  margin-top: 6px;
  color: #111827;
  font-weight: 700;
  line-height: 1.5;
}

.multi-hint {
  padding: 8px 18px;
  color: #475467;
  border-bottom: 1px solid var(--line);
  background: #fbfdff;
  font-size: 13px;
}

.multi-hint.important {
  background: #fff8df;
  color: #7a4b00;
  font-weight: 800;
}

.options {
  display: grid;
}

.option {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 10px;
  padding: 11px 18px;
  border-bottom: 1px solid var(--line);
  cursor: pointer;
}

.option:hover {
  background: #f7fbff;
}

.option input {
  width: 18px;
  min-height: 18px;
  margin: 2px auto 0;
}

.option.selected {
  background: var(--blue-soft);
}

.option.correct {
  background: var(--green-soft);
}

.option.incorrect {
  background: var(--red-soft);
}

.option-letter {
  font-weight: 800;
  margin-right: 4px;
}

.option .text-en,
.option .text-ko {
  font-weight: 500;
}

.option.correct .text-en,
.option.correct .text-ko {
  color: var(--green);
  font-weight: 800;
}

.answer-bar {
  display: flex;
  gap: 8px;
  padding: 14px 18px;
  background: #fff;
  border-bottom: 1px solid var(--line);
}

.nav-text {
  min-width: 96px;
}

.primary {
  background: var(--blue);
  color: #fff;
  border-color: var(--blue);
  font-weight: 800;
}

.primary:hover {
  background: #0f4c81;
  border-color: #0f4c81;
}

.result-panel {
  padding: 12px 18px;
  background: var(--yellow);
  color: #5b3b00;
  font-weight: 700;
  line-height: 1.5;
}

.result-panel.good {
  background: var(--green-soft);
  color: var(--green);
}

.result-panel.bad {
  background: var(--red-soft);
  color: var(--red);
}

.empty-state {
  padding: 40px 18px;
  color: var(--muted);
  text-align: center;
}

.float-scroll {
  position: fixed;
  right: calc(var(--snb-width) + 18px);
  bottom: 18px;
  z-index: 35;
  display: grid;
  gap: 8px;
}

body.snb-collapsed .float-scroll {
  right: 18px;
}

.float-scroll button {
  width: 38px;
  min-width: 38px;
  height: 38px;
  padding: 0;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 8px 24px rgba(23, 32, 51, 0.14);
  font-weight: 900;
}

@media (max-width: 900px) {
  body.session-active .app-shell {
    display: block;
  }

  body.session-active.snb-collapsed .app-shell {
    display: block;
  }

  .setup-panel {
    grid-template-columns: 1fr;
  }

  .auth-panel {
    grid-template-columns: 1fr;
  }

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

  .setup-copy {
    border-right: 0;
    border-bottom: 1px solid var(--line);
    padding-right: 0;
    padding-bottom: 18px;
  }

  .sidebar {
    width: var(--snb-width);
    min-height: 100vh;
    border-left: 1px solid var(--line);
    border-bottom: 0;
  }

  body.snb-collapsed .sidebar {
    width: var(--snb-collapsed-width);
    align-items: flex-start;
  }

  body.snb-collapsed .side-label {
    display: none;
  }

  body.snb-collapsed .side-nav {
    display: none;
  }

  .question-list {
    max-height: 132px;
  }

  .main-panel {
    padding: 14px;
  }
}

@media (max-width: 560px) {
  :root {
    --snb-width: min(280px, 82vw);
  }

  .setup-screen,
  .login-screen,
  .saved-review-screen,
  .main-panel,
  body.snb-collapsed .setup-screen,
  body.snb-collapsed .login-screen,
  body.snb-collapsed .saved-review-screen,
  body.snb-collapsed .main-panel {
    margin-right: 0;
  }

  .setup-screen {
    padding: 14px;
  }

  .sidebar {
    padding: 14px 10px;
    box-shadow: -16px 0 40px rgba(23, 32, 51, 0.16);
  }

  body.snb-collapsed .sidebar {
    box-shadow: none;
  }

  .setup-panel {
    padding: 18px;
  }

  .setup-preview {
    padding: 14px;
  }

  .preview-card-head {
    display: grid;
  }

  .preview-card {
    height: 178px;
  }

  .saved-review-screen {
    padding: 14px;
  }

  .login-screen {
    padding: 14px;
  }

  .saved-review-panel {
    padding: 16px;
  }

  .saved-review-header {
    display: grid;
  }

  .saved-review-actions {
    display: grid;
    grid-template-columns: 1fr;
  }

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

  .setup-copy h1 {
    font-size: 25px;
  }

  .toolbar {
    align-items: flex-start;
  }

  .toolbar h2 {
    font-size: 21px;
  }

  .answer-bar {
    display: grid;
    grid-template-columns: 1fr 1fr;
  }

  .answer-bar .primary,
  .answer-bar #clearBtn,
  .answer-bar #explainBtn {
    grid-column: span 2;
  }

  .session-strip > div:first-child {
    display: grid;
  }

  #sessionSummary {
    text-align: left;
  }

  .question-list {
    grid-template-columns: repeat(4, 1fr);
  }

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

  .review-card-head {
    display: grid;
  }
}