@import url("https://fonts.googleapis.com/css2?family=IBM+Plex+Sans:wght@400;500;600;700&display=swap");

:root {
  --font-scale: 1;
  --font-family: "IBM Plex Sans", "Segoe UI", sans-serif;
  --accent: #77808a;
  --accent-strong: #5b6470;
  --accent-soft: rgba(119, 128, 138, 0.18);
  --bg: #edeae3;
  --bg-elevated: rgba(255, 255, 255, 0.76);
  --bg-elevated-strong: rgba(255, 255, 255, 0.9);
  --bg-muted: rgba(245, 242, 236, 0.82);
  --border: rgba(30, 39, 50, 0.08);
  --border-strong: rgba(30, 39, 50, 0.12);
  --text: #17202a;
  --text-soft: #586271;
  --text-faint: #7d8692;
  --shadow: 0 24px 60px rgba(21, 29, 38, 0.08);
  --shadow-soft: 0 12px 28px rgba(21, 29, 38, 0.05);
  --success: #2f7d5d;
  --danger: #9a4c4c;
  --warning: #a87e3d;
}

:root[data-theme="dark"] {
  --bg: #11161d;
  --bg-elevated: rgba(21, 28, 37, 0.82);
  --bg-elevated-strong: rgba(24, 32, 42, 0.94);
  --bg-muted: rgba(18, 24, 32, 0.84);
  --border: rgba(255, 255, 255, 0.08);
  --border-strong: rgba(255, 255, 255, 0.14);
  --text: #eef3f8;
  --text-soft: #bac3cf;
  --text-faint: #7f8b99;
  --shadow: 0 30px 70px rgba(0, 0, 0, 0.34);
  --shadow-soft: 0 14px 32px rgba(0, 0, 0, 0.22);
  --success: #67c39a;
  --danger: #f08c87;
  --warning: #d6ac63;
}

* {
  box-sizing: border-box;
}

html {
  font-size: calc(16px * var(--font-scale));
}

body {
  margin: 0;
  min-height: 100vh;
  overflow-x: hidden;
  overflow-anchor: none;
  font-family: var(--font-family);
  color: var(--text);
  background:
    radial-gradient(circle at top left, var(--accent-soft), transparent 24%),
    radial-gradient(circle at bottom right, rgba(145, 153, 162, 0.14), transparent 22%),
    linear-gradient(180deg, var(--bg), color-mix(in srgb, var(--bg) 76%, black 3%));
  background-attachment: fixed;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 72px 72px;
  mask-image: radial-gradient(circle at center, black 25%, transparent 85%);
  opacity: 0.28;
}

button,
input,
textarea {
  font: inherit;
}

button {
  cursor: pointer;
  border: 0;
  background: none;
  color: inherit;
}

a {
  color: inherit;
}

#app {
  min-height: 100vh;
}

.app-shell {
  position: relative;
  --sidebar-width: 356px;
  --sidebar-slot: var(--sidebar-width);
  display: grid;
  grid-template-columns: var(--sidebar-slot) minmax(0, 1fr);
  min-height: 100vh;
}

.app-shell.sidebar-collapsed {
  --sidebar-slot: 24px;
}

.app-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(8, 11, 16, 0.42);
  opacity: 0;
  pointer-events: none;
  transition: opacity 180ms ease;
  z-index: 36;
}

.app-shell.sidebar-open .app-backdrop,
.app-shell.settings-open .app-backdrop {
  opacity: 1;
  pointer-events: auto;
}

.sidebar {
  position: sticky;
  top: 0;
  width: var(--sidebar-width);
  height: 100dvh;
  padding: 1.1rem 1rem 1rem;
  border-right: 1px solid var(--border);
  background: linear-gradient(180deg, var(--bg-elevated-strong), var(--bg-elevated));
  backdrop-filter: blur(18px);
  overflow: hidden;
  transition: transform 180ms ease;
  z-index: 42;
}

.app-shell.sidebar-collapsed .sidebar {
  transform: translateX(calc(-1 * (var(--sidebar-width) - 18px)));
}

.sidebar-float-toggle {
  position: fixed;
  top: 1.35rem;
  left: calc(var(--sidebar-slot) - 14px);
  transform: none;
  width: 2rem;
  height: 2.8rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: color-mix(in srgb, var(--bg-elevated-strong) 82%, transparent);
  backdrop-filter: blur(20px);
  box-shadow: var(--shadow-soft);
  z-index: 34;
  transition:
    left 180ms ease,
    transform 180ms ease,
    background 180ms ease;
}

.sidebar-float-toggle:hover {
  transform: scale(1.03);
}

.sidebar-inner {
  display: grid;
  grid-template-rows: auto minmax(0, 1fr);
  gap: 1rem;
  height: 100%;
}

.sidebar-pin,
.sidebar-scroll {
  display: grid;
  gap: 1rem;
}

.sidebar-pin {
  position: relative;
  z-index: 1;
}

.sidebar-scroll {
  min-height: 0;
  overflow-y: auto;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
  touch-action: pan-y;
  padding-right: 0.12rem;
}

.main-panel {
  min-width: 0;
  padding: 1.1rem;
}

.topbar {
  position: sticky;
  top: 1rem;
  z-index: 20;
  margin-bottom: 1rem;
  padding: 1rem 1.1rem;
  border: 1px solid var(--border);
  border-radius: 28px;
  background:
    linear-gradient(180deg, color-mix(in srgb, var(--bg-elevated-strong) 86%, transparent), color-mix(in srgb, var(--bg-elevated) 74%, transparent));
  backdrop-filter: blur(24px) saturate(1.15);
  box-shadow: 0 18px 42px rgba(12, 18, 26, 0.08);
  transition:
    transform 220ms ease,
    opacity 220ms ease,
    background 180ms ease;
}

.topbar.is-hidden {
  transform: translateY(calc(-100% - 1.5rem));
  opacity: 0;
}

.topbar-main,
.topbar-left,
.topbar-actions,
.nav-shortcuts,
.hero-actions,
.metric-grid,
.chip-row,
.article-actions,
.nav-links,
.settings-actions,
.track-info,
.range-row,
.settings-topline {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.topbar-main {
  justify-content: space-between;
}

.topbar-left {
  min-width: 0;
}

.topbar-actions {
  position: relative;
  justify-content: flex-end;
  flex-wrap: wrap;
}

.topbar-title {
  margin: 0;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
}

.topbar-subtitle,
.muted {
  color: var(--text-soft);
}

.topbar-subtitle {
  margin: 0.55rem 0 0;
  max-width: 72ch;
  font-size: 0.92rem;
}

.meta-pills,
.accent-grid,
.hero-stats,
.course-grid,
.bookmark-strip,
.track-list,
.settings-grid,
.search-results,
.quiz-list {
  display: grid;
  gap: 1rem;
}

.meta-pills {
  grid-template-columns: repeat(auto-fit, minmax(160px, max-content));
  margin-top: 0.85rem;
}

.meta-pill,
.tone-pill,
.chip {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  width: fit-content;
  padding: 0.42rem 0.72rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: color-mix(in srgb, var(--accent-soft) 40%, transparent);
  color: var(--text-soft);
  font-size: 0.78rem;
  font-weight: 600;
}

.surface,
.surface-muted,
.metric-card,
.level-nav-card,
.level-card,
.bookmark-card,
.search-result-card,
.quiz-card,
.rail-card,
.settings-section,
.brand-lockup {
  border: 1px solid var(--border);
  border-radius: 26px;
  background: var(--bg-elevated);
  box-shadow: var(--shadow-soft);
}

.surface,
.surface-muted,
.metric-card,
.level-card,
.bookmark-card,
.quiz-card,
.rail-card,
.settings-section {
  padding: 1.05rem;
}

.surface-muted,
.brand-lockup {
  background: color-mix(in srgb, var(--bg-muted) 88%, transparent);
}

.brand-lockup {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.9rem;
  align-items: center;
  padding: 1rem;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 3rem;
  height: 3rem;
  border-radius: 18px;
  background: linear-gradient(160deg, var(--accent), var(--accent-strong));
  color: white;
  font-weight: 700;
  letter-spacing: 0.08em;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.22);
}

.eyebrow {
  margin: 0 0 0.28rem;
  color: var(--text-faint);
  text-transform: uppercase;
  letter-spacing: 0.14em;
  font-size: 0.72rem;
  font-weight: 700;
}

.brand-lockup h1,
.hero h1,
.section-head h2,
.lesson-header h1,
.quiz-header h1,
.settings-head h2 {
  margin: 0;
  letter-spacing: -0.03em;
}

.search-input,
.topbar-search-input,
.settings-input,
.settings-range,
.quiz-option input {
  width: 100%;
}

.search-input,
.topbar-search-input,
.settings-input {
  padding: 0.9rem 1rem;
  border: 1px solid var(--border);
  border-radius: 18px;
  background: color-mix(in srgb, var(--bg-elevated-strong) 86%, transparent);
  color: var(--text);
  outline: none;
}

.search-input:focus,
.topbar-search-input:focus,
.settings-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px color-mix(in srgb, var(--accent-soft) 64%, transparent);
}

.nav-shortcuts {
  flex-wrap: wrap;
}

.shortcut-btn,
.icon-btn,
.button,
.button-secondary,
.button-ghost,
.button-danger,
.mini-btn,
.outline-button,
.upload-label {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 0.95rem;
  border-radius: 16px;
  border: 1px solid var(--border);
  background: color-mix(in srgb, var(--bg-elevated-strong) 88%, transparent);
  color: var(--text);
  transition:
    transform 150ms ease,
    border-color 150ms ease,
    background 150ms ease;
}

.icon-btn {
  width: 2.85rem;
  height: 2.85rem;
  padding: 0;
  flex: 0 0 auto;
}

.icon-btn svg,
.sidebar-float-toggle svg {
  width: 1.1rem;
  height: 1.1rem;
}

.shortcut-btn,
.button,
.button-secondary,
.button-ghost,
.button-danger,
.mini-btn {
  font-weight: 600;
}

.shortcut-btn:hover,
.icon-btn:hover,
.button:hover,
.button-secondary:hover,
.button-ghost:hover,
.button-danger:hover,
.mini-btn:hover,
.outline-button:hover,
.upload-label:hover {
  transform: translateY(-1px);
  border-color: var(--border-strong);
}

.button,
.mini-btn {
  background: linear-gradient(160deg, var(--accent), var(--accent-strong));
  color: white;
  border-color: transparent;
}

.mini-btn-outline {
  background: color-mix(in srgb, var(--bg-elevated-strong) 92%, transparent);
  color: var(--text);
  border-color: var(--border);
}

.button-secondary {
  background: color-mix(in srgb, var(--accent-soft) 58%, transparent);
  border-color: color-mix(in srgb, var(--accent) 45%, var(--border));
}

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

.button-danger {
  background: color-mix(in srgb, var(--danger) 20%, transparent);
  color: var(--danger);
  border-color: color-mix(in srgb, var(--danger) 24%, var(--border));
}

.level-nav-card {
  padding: 0.9rem;
}

.level-nav-card.is-active {
  border-color: color-mix(in srgb, var(--accent) 55%, var(--border));
  background: color-mix(in srgb, var(--accent-soft) 28%, var(--bg-elevated));
}

.level-nav-head,
.level-card-head,
.bookmark-card-head,
.search-result-head,
.quiz-card-head,
.section-head,
.settings-head,
.settings-label,
.bookmark-row,
.quiz-side-panel,
.score-row {
  display: flex;
  justify-content: space-between;
  gap: 0.8rem;
}

.level-nav-head {
  align-items: flex-start;
}

.level-nav-main {
  display: grid;
  gap: 0.4rem;
  text-align: left;
  min-width: 0;
}

.level-nav-main strong,
.level-card h3,
.bookmark-card h3,
.quiz-card h3 {
  letter-spacing: -0.02em;
}

.level-nav-main strong,
.search-result-card strong {
  font-size: 0.95rem;
}

.level-progress,
.track-bar,
.score-bar {
  position: relative;
  height: 0.58rem;
  overflow: hidden;
  border-radius: 999px;
  background: color-mix(in srgb, var(--text-faint) 18%, transparent);
}

.level-progress {
  margin-top: 0.8rem;
}

.level-progress-fill,
.track-fill,
.score-fill {
  position: absolute;
  inset: 0 auto 0 0;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--accent), var(--accent-strong));
}

.module-group {
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}

.module-title {
  margin: 0 0 0.6rem;
  font-size: 0.84rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-faint);
}

.submodule-group + .submodule-group {
  margin-top: 0.75rem;
}

.submodule-title {
  margin: 0 0 0.45rem;
  font-size: 0.9rem;
  color: var(--text-soft);
}

.lesson-row,
.bookmark-row,
.search-result-card {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 0.6rem;
  align-items: center;
}

.lesson-row + .lesson-row {
  margin-top: 0.4rem;
}

.lesson-link,
.search-result-main,
.bookmark-card-main {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  min-width: 0;
  text-align: left;
}

.lesson-link {
  padding: 0.62rem 0.7rem;
  border-radius: 14px;
}

.lesson-link:hover,
.lesson-link.is-current {
  background: color-mix(in srgb, var(--accent-soft) 42%, transparent);
}

.bookmark-btn {
  width: 2.3rem;
  height: 2.3rem;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-faint);
}

.bookmark-btn.is-active {
  color: var(--accent-strong);
  background: color-mix(in srgb, var(--accent-soft) 46%, transparent);
}

.status-dot {
  flex: 0 0 auto;
  width: 0.75rem;
  height: 0.75rem;
  border-radius: 999px;
  border: 2px solid color-mix(in srgb, var(--text-faint) 50%, transparent);
}

.status-dot.is-complete {
  background: var(--success);
  border-color: var(--success);
}

.status-dot.is-current {
  border-color: var(--accent-strong);
  background: color-mix(in srgb, var(--accent) 70%, white 12%);
}

.sidebar-footer {
  padding: 1rem;
}

.topbar-search {
  position: relative;
  display: flex;
  align-items: center;
  gap: 0.65rem;
}

.topbar-search-input {
  width: 0;
  opacity: 0;
  padding-inline: 0;
  pointer-events: none;
  transition:
    width 180ms ease,
    opacity 180ms ease,
    padding 180ms ease;
}

.topbar-search.is-open .topbar-search-input {
  width: min(320px, 46vw);
  opacity: 1;
  padding-inline: 1rem;
  pointer-events: auto;
}

.topbar-search-popover {
  position: absolute;
  top: calc(100% + 0.8rem);
  right: 0;
  width: min(460px, calc(100vw - 2rem));
  padding: 1rem;
  border: 1px solid var(--border);
  border-radius: 24px;
  background:
    linear-gradient(180deg, color-mix(in srgb, var(--bg-elevated-strong) 86%, transparent), color-mix(in srgb, var(--bg-elevated) 74%, transparent));
  backdrop-filter: blur(26px) saturate(1.15);
  box-shadow: var(--shadow);
}

.search-results-compact {
  gap: 0.75rem;
}

.view {
  display: grid;
  gap: 1rem;
  overflow-anchor: none;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(280px, 0.85fr);
  gap: 1rem;
  padding: 1.2rem;
}

.hero-copy {
  display: grid;
  gap: 0.85rem;
}

.hero-copy h1 {
  font-size: clamp(2rem, 4vw, 3.4rem);
}

.hero-quote {
  margin: 0;
  max-width: 28ch;
  font-size: clamp(1.05rem, 2vw, 1.35rem);
  line-height: 1.45;
  color: var(--text-soft);
}

.hero-last-card {
  display: grid;
  gap: 0.35rem;
  max-width: 28rem;
  cursor: pointer;
}

.hero-last-card strong {
  font-size: 1.03rem;
  letter-spacing: -0.02em;
}

.metric-grid {
  flex-wrap: wrap;
}

.metric-card {
  min-width: 160px;
  flex: 1 1 180px;
}

.metric-label {
  margin: 0;
  color: var(--text-faint);
  font-size: 0.84rem;
}

.metric-value {
  margin: 0.28rem 0 0;
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: -0.04em;
}

.section-progress-label,
.track-progress-label {
  color: var(--text-soft);
  font-size: 0.92rem;
  font-weight: 600;
}

.section-head {
  align-items: flex-end;
  margin-bottom: 1rem;
}

.section-head p,
.level-card p,
.bookmark-card p,
.search-result-card p,
.rail-card p,
.settings-section p,
.quiz-header p,
.quiz-card p {
  margin: 0.3rem 0 0;
  color: var(--text-soft);
  line-height: 1.55;
}

.progress-track,
.bookmark-panel {
  padding: 1.1rem;
}

.progress-track .track-list {
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  align-items: stretch;
}

.progress-track .track-row {
  display: grid;
  grid-template-rows: minmax(0, 1fr) auto;
  gap: 1rem;
  padding: 1.2rem;
  border: 1px solid var(--border);
  border-radius: 22px;
  background: color-mix(in srgb, var(--bg-elevated-strong) 82%, transparent);
  box-shadow: var(--shadow-soft);
}

.track-row-link {
  cursor: pointer;
  transition:
    transform 160ms ease,
    border-color 160ms ease,
    background 160ms ease;
}

.track-row-link:hover,
.track-row-link:focus-visible {
  transform: translateY(-2px);
  border-color: color-mix(in srgb, var(--accent) 45%, var(--border));
  outline: none;
}

.track-info {
  justify-content: space-between;
}

.track-info.compact {
  align-items: flex-start;
}

.track-card-copy {
  display: grid;
  align-content: start;
  gap: 0.45rem;
}

.track-card-copy strong {
  display: block;
}

.track-progress-box {
  display: grid;
  gap: 0.45rem;
}

.track-progress-top {
  display: flex;
  justify-content: flex-end;
}

.track-actions {
  display: flex;
  justify-content: flex-start;
}

.sidebar-footer .track-row + .track-row {
  padding-top: 0.9rem;
  border-top: 1px solid var(--border);
}

.course-grid {
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

.level-card {
  display: grid;
  gap: 0.9rem;
}

.level-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
}

.level-card-progress {
  color: var(--text-soft);
  font-size: 0.92rem;
  font-weight: 600;
}

.level-card-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem 1.2rem;
  color: var(--text-soft);
  font-size: 0.92rem;
}

.bookmark-strip {
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.bookmark-card-title-row {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  min-width: 0;
}

.bookmark-card-title-row h3 {
  margin: 0;
}

.bookmark-card-link {
  position: relative;
  cursor: pointer;
  transition:
    transform 160ms ease,
    border-color 160ms ease;
}

.bookmark-card-link:hover,
.bookmark-card-link:focus-visible {
  transform: translateY(-2px);
  border-color: color-mix(in srgb, var(--accent) 45%, var(--border));
  outline: none;
}

.bookmark-card-link .bookmark-card-head {
  position: relative;
  z-index: 1;
}

.empty-state {
  padding: 1rem;
  border: 1px dashed var(--border);
  border-radius: 22px;
  color: var(--text-soft);
  background: color-mix(in srgb, var(--bg-elevated) 74%, transparent);
}

.lesson-layout,
.quiz-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) 320px;
  gap: 1rem;
}

.lesson-header,
.quiz-header {
  display: grid;
  gap: 0.9rem;
  margin-bottom: 1rem;
}

.lesson-header-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.9rem;
}

.lesson-header h1,
.quiz-header h1 {
  font-size: clamp(1.6rem, 2.5vw, 2.5rem);
}

.lesson-bookmark-btn {
  width: 2.8rem;
  height: 2.8rem;
  flex: 0 0 auto;
}

.lesson-bookmark-btn svg {
  width: 1.08rem;
  height: 1.08rem;
}

.lesson-article {
  display: grid;
  gap: 1rem;
  line-height: 1.75;
}

.lesson-article h1,
.lesson-article h2,
.lesson-article h3,
.lesson-article h4 {
  margin: 0.4rem 0 0;
  letter-spacing: -0.03em;
  scroll-margin-top: 7rem;
}

.lesson-article p,
.lesson-article ul,
.lesson-article ol,
.lesson-article blockquote,
.lesson-article pre,
.lesson-article .table-wrap {
  margin: 0;
}

.lesson-article ul,
.lesson-article ol {
  padding-left: 1.2rem;
}

.lesson-article blockquote {
  padding: 1rem 1.1rem;
  border-left: 4px solid var(--accent);
  border-radius: 18px;
  background: color-mix(in srgb, var(--accent-soft) 38%, transparent);
}

.lesson-article code {
  padding: 0.18rem 0.35rem;
  border-radius: 8px;
  background: color-mix(in srgb, var(--bg-muted) 90%, transparent);
  font-size: 0.92em;
}

.lesson-article pre {
  padding: 1rem;
  overflow: auto;
  border-radius: 20px;
  background: color-mix(in srgb, var(--bg-muted) 92%, transparent);
}

.lesson-article table {
  width: 100%;
  border-collapse: collapse;
}

.lesson-article th,
.lesson-article td {
  padding: 0.8rem;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
  text-align: left;
}

.lesson-article th {
  color: var(--text-soft);
  font-size: 0.84rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.lesson-footer {
  display: grid;
  gap: 1rem;
  margin-top: 1rem;
}

.nav-links {
  flex-wrap: wrap;
}

.nav-card {
  flex: 1 1 240px;
  display: grid;
  gap: 0.35rem;
  padding: 0.9rem 1rem;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: color-mix(in srgb, var(--bg-elevated) 88%, transparent);
  text-align: left;
}

.lesson-rail {
  display: grid;
  gap: 1rem;
  align-self: start;
  position: sticky;
  top: 6.8rem;
}

.outline-list {
  display: grid;
  gap: 0.55rem;
}

.outline-button {
  justify-content: flex-start;
  text-align: left;
}

.outline-button[data-level="3"] {
  padding-left: 1.3rem;
}

.outline-button[data-level="4"] {
  padding-left: 1.7rem;
}

.quiz-layout {
  align-items: start;
}

.quiz-side {
  display: grid;
  gap: 1rem;
  position: sticky;
  top: 6.8rem;
}

.quiz-side-panel {
  flex-direction: column;
  align-items: stretch;
}

.quiz-list {
  gap: 1rem;
}

.quiz-card {
  display: grid;
  gap: 1rem;
}

.quiz-card.is-correct {
  border-color: color-mix(in srgb, var(--success) 45%, var(--border));
}

.quiz-card.is-wrong {
  border-color: color-mix(in srgb, var(--danger) 35%, var(--border));
}

.quiz-options {
  display: grid;
  gap: 0.6rem;
}

.quiz-option {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.75rem;
  align-items: start;
  padding: 0.8rem 0.9rem;
  border: 1px solid var(--border);
  border-radius: 18px;
  background: color-mix(in srgb, var(--bg-elevated-strong) 80%, transparent);
}

.quiz-option.is-selected {
  border-color: color-mix(in srgb, var(--accent) 52%, var(--border));
  background: color-mix(in srgb, var(--accent-soft) 34%, transparent);
}

.quiz-option.is-correct {
  border-color: color-mix(in srgb, var(--success) 55%, var(--border));
  background: color-mix(in srgb, var(--success) 14%, transparent);
}

.quiz-option.is-wrong {
  border-color: color-mix(in srgb, var(--danger) 38%, var(--border));
  background: color-mix(in srgb, var(--danger) 11%, transparent);
}

.quiz-feedback {
  padding: 0.9rem 1rem;
  border-radius: 18px;
}

.quiz-feedback.good {
  background: color-mix(in srgb, var(--success) 15%, transparent);
  color: var(--success);
}

.quiz-feedback.bad {
  background: color-mix(in srgb, var(--danger) 15%, transparent);
  color: var(--danger);
}

.score-pill {
  padding: 0.45rem 0.7rem;
  border-radius: 999px;
  background: color-mix(in srgb, var(--accent-soft) 38%, transparent);
  color: var(--text-soft);
  font-size: 0.8rem;
  font-weight: 700;
}

.settings-panel {
  position: fixed;
  top: 0;
  right: 0;
  width: min(420px, 100vw);
  height: 100vh;
  padding: 1rem;
  transform: translateX(104%);
  transition: transform 180ms ease;
  z-index: 45;
}

.app-shell.settings-open .settings-panel {
  transform: translateX(0);
}

.settings-panel-inner {
  height: 100%;
  overflow: auto;
  padding: 0.25rem;
  border-radius: 30px;
  background:
    linear-gradient(180deg, color-mix(in srgb, var(--bg-elevated-strong) 78%, transparent), color-mix(in srgb, var(--bg-elevated) 70%, transparent));
  backdrop-filter: blur(28px) saturate(1.12);
  border: 1px solid color-mix(in srgb, white 14%, var(--border));
  box-shadow: var(--shadow);
}

.settings-head {
  align-items: center;
  margin-bottom: 1rem;
}

.settings-grid {
  gap: 1rem;
}

.settings-section {
  display: grid;
  gap: 0.9rem;
  background: transparent;
  backdrop-filter: blur(24px) saturate(1.1);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.08),
    var(--shadow-soft);
}

.settings-label {
  align-items: baseline;
}

.range-value {
  color: var(--text-soft);
  font-weight: 600;
}

.settings-range {
  accent-color: var(--accent);
}

.accent-grid {
  grid-template-columns: repeat(auto-fit, minmax(116px, 1fr));
}

.accent-button {
  display: grid;
  gap: 0.55rem;
  justify-items: start;
  padding: 0.9rem;
  border-radius: 18px;
  border: 1px solid var(--border);
  background: color-mix(in srgb, var(--bg-elevated-strong) 86%, transparent);
}

.accent-button.is-active {
  border-color: color-mix(in srgb, var(--accent) 55%, var(--border));
  box-shadow: 0 0 0 4px color-mix(in srgb, var(--accent-soft) 48%, transparent);
}

.accent-swatch {
  width: 100%;
  height: 1rem;
  border-radius: 999px;
}

.hidden-input {
  display: none;
}

.settings-note {
  padding: 0.75rem 0.9rem;
  border-radius: 16px;
  background: color-mix(in srgb, var(--accent-soft) 34%, transparent);
}

.search-result-card-compact {
  border-radius: 20px;
  background: color-mix(in srgb, var(--bg-elevated-strong) 84%, transparent);
}

.toast {
  position: fixed;
  right: 1rem;
  bottom: 1rem;
  min-width: 220px;
  max-width: 360px;
  padding: 0.85rem 1rem;
  border-radius: 18px;
  border: 1px solid var(--border);
  background: color-mix(in srgb, var(--bg-elevated-strong) 92%, transparent);
  box-shadow: var(--shadow);
  transform: translateY(1rem);
  opacity: 0;
  pointer-events: none;
  transition:
    transform 160ms ease,
    opacity 160ms ease;
  z-index: 50;
}

.toast.is-visible {
  transform: translateY(0);
  opacity: 1;
}

.mobile-only {
  display: none;
}

@media (max-width: 1120px) {
  .app-shell {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: fixed;
    left: 0;
    top: 0;
    width: min(392px, 92vw);
    height: 100dvh;
    transform: translateX(-105%);
    transition: transform 180ms ease;
    box-shadow: var(--shadow);
  }

  .app-shell.sidebar-collapsed .sidebar {
    transform: translateX(-105%);
  }

  .app-shell.sidebar-open .sidebar {
    transform: translateX(0);
  }

  .sidebar-float-toggle {
    display: none;
  }

  .mobile-only {
    display: inline-flex;
  }
}

@media (max-width: 980px) {
  .hero,
  .lesson-layout,
  .quiz-layout {
    grid-template-columns: 1fr;
  }

  .lesson-rail,
  .quiz-side {
    position: static;
  }
}

@media (max-width: 720px) {
  .main-panel {
    padding: 0.8rem;
  }

  .topbar {
    top: 0.8rem;
    border-radius: 24px;
  }

  .hero,
  .surface,
  .surface-muted,
  .metric-card,
  .level-card,
  .bookmark-card,
  .quiz-card,
  .rail-card,
  .settings-section {
    padding: 0.95rem;
  }

  .topbar-actions,
  .hero-actions,
  .article-actions,
  .settings-actions,
  .level-actions,
  .nav-shortcuts,
  .nav-links {
    flex-wrap: wrap;
  }

  .topbar-main {
    flex-wrap: wrap;
  }

  .topbar-search.is-open .topbar-search-input {
    width: min(100vw - 8rem, 320px);
  }

  .topbar-search-popover {
    right: -0.3rem;
  }

  .lesson-header-top {
    align-items: center;
  }

  .brand-lockup {
    grid-template-columns: 1fr;
  }

  .brand-mark {
    width: 2.7rem;
    height: 2.7rem;
  }
}