:root {
  --bg: #ffffff;
  --text: #101010;
  --muted: #525252;
  --line: #e8e8e8;
  --surface: #ffffff;
  --soft-bg: #f8f8f8;
  --body-copy: #303030;
  --card-shadow: 0 8px 18px rgba(10, 10, 10, 0.04);
  --glow: radial-gradient(circle at 20% 0%, rgba(18, 18, 18, 0.06), transparent 48%);
  --max-width: 980px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Inter", "Helvetica Neue", Helvetica, Arial, sans-serif;
}

body[data-theme="dark"] {
  --bg: #0f1113;
  --text: #eceef1;
  --muted: #a4acb7;
  --line: #2a3038;
  --surface: #14181d;
  --soft-bg: #1a2028;
  --body-copy: #d2d8e0;
  --card-shadow: 0 12px 26px rgba(0, 0, 0, 0.25);
  --glow: radial-gradient(circle at 20% 0%, rgba(110, 136, 255, 0.14), transparent 52%);
}

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

.site-wrap {
  max-width: var(--max-width);
  margin: 0 auto;
  min-height: 100vh;
  display: grid;
  grid-template-columns: 200px 1fr;
}

.sidebar {
  border-right: 1px solid var(--line);
  padding: 2.25rem 1.25rem;
}

.brand-logo {
  width: 100px;
  height: 100px;
  display: block;
  object-fit: contain;
  margin: 0 auto 0.75rem;
}

.brand {
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  margin: 0 0 2rem;
  text-align: center;
}

.nav-list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 0.35rem;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.35rem 0.25rem;
  border-radius: 7px;
  color: var(--muted);
  transition: color 120ms ease, background-color 120ms ease;
}

.nav-link:hover {
  color: var(--text);
  background: var(--soft-bg);
}

.nav-link.active {
  color: var(--text);
  font-weight: 500;
  background: var(--soft-bg);
}

.icon {
  width: 20px;
  height: 20px;
  stroke: currentColor;
  stroke-width: 1.7;
  fill: none;
  flex-shrink: 0;
}

.content {
  padding: 2.25rem 2rem 3rem;
  max-width: 700px;
  position: relative;
}

.content::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 240px;
  background: var(--glow);
  pointer-events: none;
}

.content > * {
  position: relative;
  z-index: 1;
}

.theme-toggle {
  margin: 0.8rem auto 0;
  width: 2.2rem;
  height: 2.2rem;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--text);
  border-radius: 999px;
  padding: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

.theme-toggle:hover {
  background: var(--soft-bg);
}

.toggle-icon {
  font-size: 0.98rem;
  line-height: 1;
}

.toggle-sun {
  display: inline-block;
}

.toggle-moon {
  display: none;
}

body[data-theme="dark"] .toggle-sun {
  display: none;
}

body[data-theme="dark"] .toggle-moon {
  display: inline-block;
}

.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;
}

.eyebrow {
  font-size: 0.74rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 0.85rem;
}

h1 {
  margin: 0;
  font-size: clamp(1.15rem, 0.8vw + 0.95rem, 1.45rem);
  font-weight: 600;
  line-height: 1.1;
}

.intro {
  margin-top: 1rem;
  max-width: 44ch;
  color: var(--body-copy);
  line-height: 1.55;
}

.intro-note {
  margin: 0.65rem 0 0;
  font-size: 0.84rem;
  color: var(--muted);
  letter-spacing: 0.01em;
}

.hero-actions {
  margin-top: 1rem;
}

.primary-cta {
  display: inline-block;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--text);
  padding: 0.52rem 0.8rem;
  border-radius: 9px;
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  transition: transform 140ms ease, box-shadow 140ms ease, background-color 140ms ease;
}

.primary-cta:hover {
  transform: translateY(-1px);
  box-shadow: var(--card-shadow);
  background: var(--soft-bg);
}

.posts {
  margin-top: 2rem;
  display: grid;
  gap: 1.2rem;
}

.archive-list {
  margin-top: 2rem;
  display: grid;
  gap: 0.9rem;
}

.archive-item {
  border: 1px solid var(--line);
  background: var(--surface);
  border-radius: 12px;
  padding: 0.95rem 1rem;
  transition: transform 140ms ease, box-shadow 140ms ease, border-color 140ms ease;
}

.archive-item p {
  margin: 0;
  color: var(--body-copy);
  line-height: 1.5;
}

.post-card {
  border: 1px solid var(--line);
  background: var(--surface);
  border-radius: 14px;
  padding: 1rem 1.05rem;
  transition: transform 140ms ease, box-shadow 140ms ease, border-color 140ms ease;
}

.post-card:hover,
.archive-item:hover {
  transform: translateY(-2px);
  box-shadow: var(--card-shadow);
  border-color: color-mix(in srgb, var(--line) 70%, var(--text) 30%);
}

.post-meta {
  margin: 0;
  font-size: 0.73rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}

.post-title {
  margin: 0.45rem 0 0.35rem;
  font-size: 1.04rem;
  font-weight: 600;
}

.post-card p {
  margin: 0;
  color: var(--body-copy);
  line-height: 1.5;
}

.vocab-section {
  margin-top: 1rem;
}

.vocab-subtitle {
  margin: 0 0 0.5rem;
  font-size: 0.92rem;
  letter-spacing: 0.02em;
}

.vocab-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.vocab-table th,
.vocab-table td {
  text-align: left;
  border-bottom: 1px solid var(--line);
  padding: 0.45rem 0.35rem;
  color: var(--body-copy);
}

.vocab-table th {
  color: var(--text);
  font-weight: 600;
}

.vocab-playbar {
  margin-top: 0.75rem;
}

.play-full-list-btn {
  appearance: none;
  -webkit-appearance: none;
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.42rem 0.85rem 0.42rem 0.45rem;
  border: 1px solid var(--line);
  border-radius: 11px;
  background: var(--surface);
  color: var(--text);
  font-family: inherit;
  font-size: 0.76rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  line-height: 1.2;
  cursor: pointer;
  transition:
    transform 160ms ease,
    box-shadow 160ms ease,
    border-color 160ms ease,
    background-color 160ms ease,
    color 160ms ease;
}

.play-full-list-btn:hover {
  transform: translateY(-2px);
  border-color: color-mix(in srgb, var(--line) 55%, var(--text) 45%);
  background: var(--soft-bg);
  box-shadow: 0 10px 22px rgba(0, 0, 0, 0.1);
}

body[data-theme="dark"] .play-full-list-btn:hover {
  box-shadow: 0 12px 30px rgba(0, 0, 0, 0.38);
}

.play-full-list-btn:focus-visible {
  outline: 2px solid color-mix(in srgb, var(--text) 55%, transparent);
  outline-offset: 2px;
}

.play-full-list-btn:active {
  transform: translateY(0);
}

.play-full-list-btn.is-playing {
  border-color: color-mix(in srgb, var(--line) 45%, var(--text) 55%);
  background: color-mix(in srgb, var(--soft-bg) 65%, var(--surface) 35%);
}

.play-full-list-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.35rem;
  height: 1.55rem;
  border-radius: 4px;
  background: var(--soft-bg);
  border: 1px solid var(--line);
  flex-shrink: 0;
  transition:
    transform 160ms ease,
    border-color 160ms ease,
    background-color 160ms ease;
}

.play-full-list-btn:hover .play-full-list-icon {
  transform: scale(1.06);
  border-color: color-mix(in srgb, var(--line) 40%, var(--text) 60%);
}

.play-full-list-btn.is-playing .play-full-list-icon {
  background: var(--surface);
}

.play-full-list-svg {
  width: 15px;
  height: 15px;
  display: block;
  margin-left: 2px;
}

.play-full-list-label {
  padding-right: 0.1rem;
}

.play-full-list-btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.vocab-play-col {
  display: none;
}

.vocab-play-col::after {
  content: "▶";
  font-size: 0.62rem;
  opacity: 0.45;
  letter-spacing: 0;
}

.vocab-play-cell {
  display: none;
}

.play-row-btn {
  appearance: none;
  -webkit-appearance: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  transition: transform 120ms ease, background-color 120ms ease, box-shadow 120ms ease;
  display: none;
}

.play-row-btn:hover {
  background: var(--soft-bg);
  transform: scale(1.04);
  box-shadow: var(--card-shadow);
}

.play-row-btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
  transform: none;
}

.play-icon-sm {
  font-size: 0.62rem;
  line-height: 1;
  display: inline-block;
  transform: translateX(0.5px);
}

.vocab-list {
  margin: 0.8rem 0 0;
  padding-left: 1.15rem;
  display: grid;
  grid-template-columns: repeat(2, minmax(120px, 1fr));
  gap: 0.2rem 1rem;
  color: var(--body-copy);
}

.vocab-list li {
  font-size: 0.92rem;
  line-height: 1.45;
}

.quiz-link {
  display: inline-block;
  margin-top: 0.85rem;
  font-size: 0.84rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--text);
  border-bottom: 1px solid var(--text);
  padding-bottom: 0.08rem;
}

.quiz-link:hover {
  color: var(--text);
  border-bottom-color: var(--body-copy);
}

.about-block {
  margin-top: 2rem;
  max-width: 55ch;
  line-height: 1.65;
  color: var(--body-copy);
}

.about-block a {
  text-decoration: underline;
  text-decoration-color: color-mix(in srgb, var(--muted) 50%, var(--text) 50%);
  text-underline-offset: 0.18em;
}

.about-block a:hover {
  text-decoration-color: var(--text);
}

.study-flow {
  margin-top: 2.4rem;
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: color-mix(in srgb, var(--surface) 78%, var(--soft-bg) 22%);
}

.section-title {
  margin: 0;
  font-size: 1.18rem;
  font-weight: 600;
  line-height: 1.25;
}

.section-intro {
  margin: 0.7rem 0 0;
  max-width: 52ch;
  color: var(--body-copy);
  line-height: 1.55;
}

.study-flow-steps {
  margin: 1rem 0 0;
  padding-left: 1.35rem;
  max-width: 42ch;
  color: var(--body-copy);
  line-height: 1.65;
}

.study-flow-steps li {
  margin: 0.5rem 0;
  padding-left: 0.15rem;
}

.study-flow-steps li::marker {
  color: var(--muted);
  font-weight: 600;
}

.study-flow-soon {
  color: var(--muted);
  font-style: italic;
  margin-right: 0.25rem;
}

.site-footer {
  margin-top: 2.5rem;
  padding-top: 1rem;
  border-top: 1px solid var(--line);
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.footer-logo {
  width: 52px;
  height: 52px;
  object-fit: contain;
}

.footer-nav {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.footer-nav a {
  font-size: 0.86rem;
  color: var(--muted);
}

.footer-nav a:hover {
  color: var(--text);
}

.social-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.82rem;
  color: var(--muted);
}

.social-link:hover {
  color: var(--text);
}

.social-icon {
  width: 14px;
  height: 14px;
  fill: currentColor;
  flex-shrink: 0;
}

.copyright {
  margin: 0 0 0 auto;
  font-size: 0.78rem;
  color: var(--muted);
}

@media (max-width: 800px) {
  .site-wrap {
    grid-template-columns: 1fr;
  }

  .sidebar {
    border-right: 0;
    border-bottom: 1px solid var(--line);
    padding-bottom: 1rem;
  }

  .nav-list {
    grid-auto-flow: column;
    grid-auto-columns: max-content;
    gap: 0.7rem;
  }

  .content {
    padding: 1.4rem 1.1rem 2rem;
  }

  .copyright {
    margin-left: 0;
    width: 100%;
  }
}