:root {
  --bg: #f7f9fc;
  --surface: #ffffff;
  --surface-soft: #f4f7fb;
  --surface-tint: #eef7f6;
  --text: #142235;
  --text-strong: #0d1b2e;
  --muted: #627189;
  --line: #e2e8f0;
  --line-strong: #d3dce8;
  --accent: #137a72;
  --accent-strong: #0e665f;
  --accent-soft: #e8f5f3;
  --blue: #2b5fb3;
  --danger: #b42318;
  --warning: #a15c00;
  --shadow-sm: 0 2px 8px rgba(15, 34, 58, 0.04);
  --shadow: 0 10px 30px rgba(15, 34, 58, 0.07);
  --shadow-lg: 0 24px 60px rgba(15, 34, 58, 0.10);
  --radius-sm: 10px;
  --radius: 16px;
  --radius-lg: 24px;
  --content: 1280px;
}

:root.dark {
  --bg: #0d1420;
  --surface: #121c2a;
  --surface-soft: #172334;
  --surface-tint: #102725;
  --text: #e7edf5;
  --text-strong: #f8fbff;
  --muted: #a4b1c2;
  --line: #263448;
  --line-strong: #33435b;
  --accent: #4cc7b6;
  --accent-strong: #79ddcf;
  --accent-soft: #14312e;
  --blue: #79a7ef;
  --danger: #ff8c84;
  --warning: #f0bb70;
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.16);
  --shadow: 0 12px 32px rgba(0, 0, 0, 0.24);
  --shadow-lg: 0 26px 70px rgba(0, 0, 0, 0.30);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  background: var(--bg);
}

body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(circle at 20% -10%, rgba(19, 122, 114, 0.05), transparent 32rem),
    var(--bg);
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 15px;
  line-height: 1.55;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

body::selection {
  background: rgba(19, 122, 114, 0.18);
}

a {
  color: inherit;
  text-decoration: none;
}

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

button {
  cursor: pointer;
}

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

img,
svg {
  max-width: 100%;
}

h1,
h2,
h3,
h4 {
  color: var(--text-strong);
  letter-spacing: -0.025em;
}

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

h2 {
  margin-bottom: 12px;
  font-size: clamp(22px, 2vw, 30px);
  line-height: 1.2;
}

h3 {
  margin-bottom: 9px;
  font-size: 17px;
  line-height: 1.3;
}

p {
  margin-bottom: 12px;
}

.container {
  width: min(var(--content), calc(100% - 48px));
  margin: 0 auto;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--surface) 94%, transparent);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(18px) saturate(140%);
}

.nav {
  min-height: 76px;
  display: flex;
  align-items: center;
  gap: 18px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  flex: 0 0 auto;
  color: var(--text-strong);
  font-size: 16px;
  font-weight: 850;
  letter-spacing: -0.03em;
}

.brand::before {
  content: "N";
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  border: 1px solid #cce3e0;
  border-radius: 10px;
  background: linear-gradient(145deg, #eef9f7, #dcefeb);
  color: var(--accent-strong);
  font-size: 14px;
  font-weight: 950;
}

.navlinks {
  display: flex;
  align-items: center;
  gap: 3px;
  flex: 1;
  min-width: 0;
  overflow-x: auto;
  scrollbar-width: none;
}

.navlinks::-webkit-scrollbar {
  display: none;
}

.navlinks a {
  padding: 9px 11px;
  border-radius: 9px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 750;
  white-space: nowrap;
  transition: background 140ms ease, color 140ms ease;
}

.navlinks a:hover,
.navlinks a:focus-visible {
  background: var(--surface-soft);
  color: var(--text-strong);
}

.navright {
  display: flex;
  align-items: center;
  gap: 8px;
  flex: 0 0 auto;
}

.avatar {
  width: 38px;
  height: 38px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: var(--surface-soft);
  color: var(--text-strong);
  font-weight: 900;
}

.page {
  padding: 46px 0 86px;
}

.section {
  padding: 34px 0;
}

.title {
  max-width: 980px;
  margin: 8px 0 16px;
  color: var(--text-strong);
  font-size: clamp(34px, 5vw, 56px);
  line-height: 1.02;
  letter-spacing: -0.045em;
}

.eyebrow {
  margin-bottom: 8px;
  color: var(--accent-strong);
  font-size: 11px;
  font-weight: 900;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.muted {
  color: var(--muted);
}

.small {
  font-size: 13px;
}


.catalog-head {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 34px;
  align-items: end;
  margin-bottom: 42px;
}

.lead {
  max-width: 780px;
  margin: 0;
  color: var(--muted);
  font-size: 17px;
  line-height: 1.7;
}

.catalog-count {
  display: grid;
  min-width: 150px;
  gap: 2px;
  padding: 20px 24px;
  text-align: left;
}

.catalog-count strong {
  color: var(--text-strong);
  font-size: 34px;
  line-height: 1;
}

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

.topic-section {
  padding: 4px 0 48px;
}

.section-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 20px;
}

.section-heading h2 {
  margin-bottom: 0;
}

.topic-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
}

.topic-card {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  gap: 14px;
  align-items: center;
  min-height: 92px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  text-align: left;
  box-shadow: var(--shadow-sm);
  transition: border-color 160ms ease, transform 160ms ease, box-shadow 160ms ease;
}

.topic-card:hover,
.topic-card:focus-visible {
  border-color: #bdd8d4;
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}

.topic-card strong {
  display: block;
  color: var(--text-strong);
  font-size: 14px;
}

.topic-card small {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-size: 12px;
}

.topic-icon {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  border-radius: 11px;
  background: var(--accent-soft);
  color: var(--accent-strong);
  font-size: 16px;
}

.topic-arrow {
  color: var(--muted);
  font-size: 18px;
}

.catalog-tools {
  padding: 24px;
  margin: 4px 0 46px;
}

.catalog-checks {
  grid-column: 1 / -1;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  padding-top: 4px;
}

.catalog-results {
  padding-bottom: 54px;
}

@media (max-width: 1050px) {
  .topic-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (max-width: 760px) {
  .catalog-head {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .catalog-count {
    display: flex;
    align-items: baseline;
    gap: 10px;
    width: fit-content;
  }

  .topic-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .section-heading {
    align-items: start;
    flex-direction: column;
    gap: 8px;
  }
}

@media (max-width: 520px) {
  .topic-grid {
    grid-template-columns: 1fr;
  }

  .catalog-tools {
    padding: 18px;
  }
}

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
}

.hero {
  padding: clamp(30px, 5vw, 56px);
  border: 1px solid #dfe9e8;
  border-radius: var(--radius-lg);
  background:
    linear-gradient(145deg, rgba(255, 255, 255, 0.98), rgba(246, 251, 250, 0.98)),
    var(--surface);
  box-shadow: var(--shadow);
}

.split {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.grid {
  display: grid;
  gap: 20px;
}

.g2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.g3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.g4 {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.kpis {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
}

.stat {
  padding: 22px;
}

.stat .num {
  margin: 2px 0 4px;
  color: var(--text-strong);
  font-size: 30px;
  font-weight: 900;
  letter-spacing: -0.04em;
}

.btn {
  min-height: 42px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 9px 15px;
  border: 1px solid var(--line-strong);
  border-radius: 10px;
  background: var(--surface);
  color: var(--text-strong);
  font-size: 13px;
  font-weight: 800;
  box-shadow: 0 1px 2px rgba(15, 34, 58, 0.03);
  transition: transform 120ms ease, border-color 120ms ease, box-shadow 120ms ease, background 120ms ease;
}

.btn:hover {
  border-color: #bfcbd9;
  box-shadow: var(--shadow-sm);
  transform: translateY(-1px);
}

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

.btn.primary:hover {
  background: var(--accent-strong);
  border-color: var(--accent-strong);
}

.btn.ghost {
  background: transparent;
  box-shadow: none;
}

.btn:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible,
a:focus-visible {
  outline: 3px solid rgba(19, 122, 114, 0.20);
  outline-offset: 2px;
}

.progress {
  height: 7px;
  overflow: hidden;
  border-radius: 999px;
  background: var(--surface-soft);
}

.progress > span {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--accent), #39a497);
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-height: 30px;
  padding: 5px 9px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-soft);
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
}

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

.notice {
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface-soft);
  color: var(--text);
}

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

.list-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 16px 18px;
  border: 1px solid var(--line);
  border-radius: 13px;
  background: var(--surface);
  transition: border-color 130ms ease, box-shadow 130ms ease, transform 130ms ease;
}

.list-item:hover {
  border-color: #cbd6e3;
  box-shadow: var(--shadow-sm);
  transform: translateY(-1px);
}

.field {
  display: grid;
  gap: 8px;
}

.field label {
  color: var(--text-strong);
  font-size: 13px;
  font-weight: 800;
}

.field input,
.field select,
.field textarea {
  width: 100%;
  border: 1px solid var(--line-strong);
  border-radius: 11px;
  background: var(--surface);
  color: var(--text);
  padding: 12px 13px;
  transition: border-color 120ms ease, box-shadow 120ms ease;
}

.field input:hover,
.field select:hover,
.field textarea:hover {
  border-color: #b9c6d5;
}

.field textarea {
  resize: vertical;
  min-height: 120px;
  line-height: 1.65;
}

.form {
  display: grid;
  gap: 18px;
}

.auth {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 44px 20px;
  background:
    radial-gradient(circle at 50% -10%, rgba(19, 122, 114, 0.07), transparent 30rem),
    var(--bg);
}


.auth-card-pro {
  width: min(560px, 100%);
  padding: 42px;
  border-radius: 24px;
  box-shadow: var(--shadow-lg);
}

.auth-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 10px;
}

.auth-brand-mark {
  width: 46px;
  height: 46px;
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  border: 1px solid #cce3e0;
  border-radius: 14px;
  background: linear-gradient(145deg, #eef9f7, #dcefeb);
  color: var(--accent-strong);
  font-size: 18px;
  font-weight: 950;
}

.auth-header h1 {
  margin: 2px 0 0;
  font-size: clamp(28px, 4vw, 38px);
  line-height: 1.08;
}

.auth-intro {
  max-width: 48ch;
  margin-bottom: 26px;
  font-size: 15px;
}

.google-btn {
  width: 100%;
  justify-content: center;
  min-height: 48px;
  border-color: var(--line-strong);
  font-weight: 850;
}

.google-btn:hover {
  border-color: #aebdce;
  background: var(--surface-soft);
}

.google-mark {
  width: 22px;
  height: 22px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: var(--surface);
  font-size: 12px;
  font-weight: 950;
}

.auth-divider {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 22px 0 4px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.auth-divider::before,
.auth-divider::after {
  content: '';
  height: 1px;
  flex: 1;
  background: var(--line);
}

.auth-divider span {
  padding: 0 2px;
}

.auth-submit {
  width: 100%;
  min-height: 48px;
  margin-top: 4px;
}

.auth-links {
  margin-top: 22px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  font-size: 14px;
}

.auth-links a {
  color: var(--blue);
  font-weight: 750;
}

@media (max-width: 620px) {
  .auth-card-pro {
    padding: 28px 22px;
    border-radius: 20px;
  }
}

.auth-card {
  width: min(560px, 100%);
  padding: clamp(28px, 5vw, 44px);
  border-radius: 24px;
  box-shadow: var(--shadow-lg);
}

.two {
  display: grid;
  grid-template-columns: 290px minmax(0, 1fr);
  gap: 24px;
}

.sidebar {
  position: sticky;
  top: 98px;
  height: max-content;
  padding: 18px;
}

.lesson {
  max-width: 960px;
  margin: 0 auto;
  padding: clamp(28px, 5vw, 58px);
}

.markdown {
  color: #27384c;
  font-size: 18px;
  line-height: 1.85;
}

:root.dark .markdown {
  color: var(--text);
}

.markdown p {
  margin: 0 0 20px;
}

.markdown h2,
.markdown h3 {
  margin: 34px 0 12px;
}

.markdown ul,
.markdown ol {
  padding-left: 24px;
  margin-bottom: 22px;
}

.markdown li {
  margin: 8px 0;
}

.choices {
  display: grid;
  gap: 12px;
}

.choice {
  width: 100%;
  padding: 16px 17px;
  border: 1px solid var(--line-strong);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  text-align: left;
  transition: border-color 120ms ease, background 120ms ease, transform 120ms ease;
}

.choice:hover {
  border-color: #b7c6d7;
  transform: translateY(-1px);
}

.choice.selected {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.brain {
  min-height: 480px;
  overflow: hidden;
  border: 1px solid #172333;
  border-radius: 20px;
  background: #071016;
  box-shadow: var(--shadow-lg);
}

.brain svg {
  display: block;
  width: 100%;
  min-height: 480px;
}

.brain circle {
  fill: #124039;
  stroke: #61d4c3;
  stroke-width: 0.55;
}

.brain circle.active {
  fill: #43c7b6;
}

.lab {
  padding: 18px;
  overflow: hidden;
  border: 1px solid #172333;
  border-radius: 18px;
  background: #071016;
}

.lab svg {
  width: 100%;
  height: 240px;
}

.searchbox {
  width: 100%;
  padding: 16px 18px;
  border: 1px solid var(--line-strong);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  font-size: 15px;
}

.mobile-menu {
  display: none;
}

.footer {
  padding: 34px 0;
  border-top: 1px solid var(--line);
  background: var(--surface);
  color: var(--muted);
  font-size: 13px;
}

.week {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 12px;
  margin: 22px 0 10px;
}

.week-day {
  display: grid;
  justify-items: center;
  gap: 8px;
  color: var(--muted);
  font-size: 11px;
}

.week-dot {
  width: 30px;
  height: 30px;
  border: 1px solid var(--line);
  border-radius: 9px;
  background: var(--surface-soft);
}

.week-dot.active {
  border-color: var(--accent);
  background: var(--accent);
  box-shadow: 0 0 0 4px rgba(19, 122, 114, 0.09);
}

.flash-review {
  display: grid;
  gap: 16px;
  margin-top: 20px;
  padding: 22px;
  border: 1px solid #dce9e7;
  border-radius: 16px;
  background: linear-gradient(145deg, #ffffff, #f3f9f8);
}

.navlinks.open {
  display: flex;
  position: absolute;
  top: 72px;
  left: 16px;
  right: 16px;
  z-index: 60;
  flex-wrap: wrap;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--surface);
  box-shadow: var(--shadow-lg);
}

.source-link {
  cursor: pointer;
}

code {
  padding: 2px 6px;
  border-radius: 6px;
  background: var(--surface-soft);
  color: var(--text-strong);
  font-size: 0.9em;
}

hr {
  border: 0;
  border-top: 1px solid var(--line);
  margin: 28px 0;
}

.hide {
  display: none !important;
}

@media (max-width: 1120px) {
  .navlinks {
    display: none;
  }

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

  .kpis,
  .g4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 900px) {
  .container {
    width: min(100% - 34px, var(--content));
  }

  .g3,
  .g2 {
    grid-template-columns: 1fr;
  }

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

  .sidebar {
    position: static;
  }

  .hero .split,
  .split {
    align-items: flex-start;
    flex-direction: column;
  }

  .page {
    padding-top: 32px;
  }
}

@media (max-width: 640px) {
  .container {
    width: min(100% - 24px, var(--content));
  }

  .nav {
    min-height: 64px;
    gap: 10px;
  }

  .brand {
    font-size: 15px;
  }

  .brand::before {
    width: 32px;
    height: 32px;
  }

  .navright .btn {
    min-height: 38px;
    padding: 8px 10px;
  }

  .title {
    font-size: clamp(32px, 11vw, 46px);
  }

  .hero {
    padding: 28px 22px;
    border-radius: 18px;
  }

  .kpis,
  .g4 {
    grid-template-columns: 1fr 1fr;
    gap: 10px;
  }

  .stat {
    padding: 17px;
  }

  .stat .num {
    font-size: 25px;
  }

  .lesson {
    padding: 24px 19px;
  }

  .markdown {
    font-size: 16px;
    line-height: 1.78;
  }

  .brain,
  .brain svg {
    min-height: 380px;
  }

  .auth-card {
    padding: 25px 20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  * {
    scroll-behavior: auto !important;
    animation: none !important;
    transition: none !important;
  }
}

.course-card { min-height: 300px; }
.course-card h3 { margin-top: 14px; margin-bottom: 9px; }
.catalog-results { scroll-margin-top: 24px; }

.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 1000;
  padding: 9px 13px;
  border-radius: 9px;
  background: var(--text-strong);
  color: var(--surface);
  transform: translateY(-160%);
  transition: transform 120ms ease;
}

.skip-link:focus {
  transform: translateY(0);
}

.not-found,
.error-panel {
  max-width: 820px;
  margin: 8vh auto 0;
  padding: clamp(30px, 6vw, 64px);
}

.not-found-code {
  color: var(--accent);
  font-size: clamp(62px, 11vw, 120px);
  font-weight: 950;
  line-height: .9;
  letter-spacing: -.06em;
  margin-bottom: 18px;
}

.error-reference {
  display: inline-block;
  margin: 4px 0 22px;
  padding: 8px 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface-soft);
  color: var(--muted);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 12px;
}

.toast {
  position: fixed;
  right: 20px;
  bottom: 20px;
  z-index: 200;
  max-width: min(420px, calc(100vw - 40px));
  padding: 12px 14px;
  border: 1px solid var(--line-strong);
  border-radius: 11px;
  background: var(--text-strong);
  color: #fff;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  pointer-events: none;
  transform: translateY(10px);
  transition: opacity 140ms ease, transform 140ms ease;
}

.toast.success,
.toast.error,
.toast.info {
  opacity: 1;
  transform: translateY(0);
}

.toast.success {
  background: var(--accent-strong);
}

.toast.error {
  background: #7a1f19;
}

@media (max-width: 640px) {
  .toast {
    right: 12px;
    bottom: 12px;
    max-width: calc(100vw - 24px);
  }
}



.lesson-audio-controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  margin: 0 0 30px;
  padding: 18px 20px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: linear-gradient(180deg, var(--surface), var(--surface-soft));
}

.lesson-audio-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  flex: 0 0 auto;
}

.lesson-audio-controls .btn {
  flex: 0 0 auto;
  white-space: nowrap;
}

.lesson-audio-controls .btn.secondary {
  background: var(--surface-soft);
  color: var(--ink);
  border-color: var(--line-strong);
}

@media (max-width: 620px) {
  .lesson-audio-controls {
    align-items: flex-start;
    flex-direction: column;
  }

  .lesson-audio-buttons {
    display: grid;
    grid-template-columns: 1fr;
    width: 100%;
  }

  .lesson-audio-controls .btn {
    width: 100%;
  }
}

.lesson-audio-picker {
  display: flex;
  align-items: end;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 14px;
}
.lesson-audio-picker label {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 12px;
  font-weight: 700;
  color: var(--muted, #667085);
}
.lesson-audio-picker select {
  min-width: 260px;
  max-width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--border, #dce3ea);
  border-radius: 10px;
  background: var(--surface, #fff);
  color: var(--text, #15202b);
}
@media (max-width: 700px) {
  .lesson-audio-picker { align-items: stretch; }
  .lesson-audio-picker select { min-width: 0; width: 100%; }
  .lesson-audio-buttons { width: 100%; }
  .lesson-audio-buttons .btn { flex: 1; }
}