:root {
  --color-gold: #FFC629;
  --color-black: #1f2933;
  --color-gray: #6b7280;
  --color-heading: #111827;
  --color-white: #FFFFFF;
  --radius: 12px;
  --shadow: 0 2px 8px rgba(45, 41, 38, 0.08);
}

* { box-sizing: border-box; }
html, body { height: 100%; }

body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Inter, Arial, sans-serif;
  color: var(--color-black);
  background: var(--color-white);
  line-height: 1.6;
}

.muted { color: var(--color-gray); }
h1, h2, h3, h4 { color: var(--color-heading); }
.site-hero__title { color: var(--color-heading); }

header {
  background: var(--color-white);
  color: var(--color-black);
  padding: 16px 0;
  border-bottom: 1px solid var(--color-gray);
}

nav.nav-desktop {
  display: flex;
  justify-content: center;
  gap: 1rem;
  background: var(--color-white);
  border-bottom: 1px solid var(--color-gray);
  padding: 8px 0;
}

nav.nav-desktop a {
  color: var(--color-black);
  text-decoration: none;
  padding: 4px 8px;
  border-radius: var(--radius);
}

nav.nav-desktop a:hover { background: rgba(178, 180, 178, 0.2); }

.container {
  max-width: 960px;
  margin: 2rem auto;
  padding: 0 1rem;
}

.section { margin-top: 24px; margin-bottom: 24px; }
.section-lg { margin-top: 32px; margin-bottom: 32px; }

.cards-row { display: grid; grid-template-columns: 1fr; gap: 16px; }
@media (min-width: 700px) { .cards-row { grid-template-columns: 1fr 1fr; } }

.card {
  background: var(--color-white);
  border: 1px solid var(--color-gray);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
  margin-bottom: 16px;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 28px rgba(45, 41, 38, 0.10);
  transition: transform .2s ease, box-shadow .3s ease;
}

button, .btn {
  appearance: none;
  border: 1px solid var(--color-gold);
  background: var(--color-gold);
  color: var(--color-black);
  cursor: pointer;
  border-radius: var(--radius);
  padding: 12px 16px;
  font-weight: 600;
  transition: background .15s ease, transform .08s ease, box-shadow .2s ease;
}

button:hover, .btn:hover { background: #E6B225; box-shadow: 0 8px 18px rgba(45, 41, 38, 0.12); transform: translateY(-1px) scale(1.01); }
button:active, .btn:active { transform: translateY(0) scale(0.99); box-shadow: 0 4px 12px rgba(45, 41, 38, 0.08); }
button:focus-visible, .btn:focus-visible { outline: 3px solid var(--color-gold); outline-offset: 2px; }
button:disabled, .btn:disabled { opacity: .6; cursor: not-allowed; }

.btn-ghost {
  background: #EEF0F3;
  border-color: #EEF0F3;
  color: var(--color-black);
}

.btn-ghost:hover { background: #E5E7EB; }

.toast {
  position: fixed;
  top: 16px;
  left: 50%;
  transform: translateX(-50%);
  padding: 10px 16px;
  border-radius: 999px;
  color: #fff;
  font-weight: 700;
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.15);
  z-index: 1000;
  pointer-events: none;
  animation: toastPop 1.1s ease forwards;
}

.toast.correct { background: #16a34a; }
.toast.incorrect { background: #dc2626; }

@keyframes toastPop {
  0% { opacity: 0; transform: translate(-50%, -6px) scale(0.96); }
  12%, 80% { opacity: 1; transform: translate(-50%, 0) scale(1); }
  100% { opacity: 0; transform: translate(-50%, -6px) scale(0.98); }
}

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

.progress {
  width: 100%;
  height: 8px;
  background: rgba(178, 180, 178, 0.35);
  border-radius: 999px;
}

.progress-fill {
  width: 0%;
  height: 100%;
  background: var(--color-gold);
  border-radius: 999px;
  transition: width .35s cubic-bezier(.2, .7, .2, 1);
}

.answer {
  display: block;
  width: 100%;
  text-align: left;
  margin: 12px 0;
  background: var(--color-gold);
  color: var(--color-black);
  border: 1px solid var(--color-gold);
  border-radius: var(--radius);
  padding: 12px 14px;
  transition: background .15s ease, box-shadow .2s ease, transform .08s ease;
}

.answer:hover { filter: brightness(0.98); box-shadow: 0 8px 18px rgba(45, 41, 38, 0.12); transform: translateY(-1px); }
.answer:focus-visible { outline: 3px solid var(--color-gold); outline-offset: 2px; }

.mobile-nav { display: none; }

:focus-visible { outline: 3px solid var(--color-gold); outline-offset: 2px; }

@media (max-width: 768px) {
  nav.nav-desktop { display: none; }
  .mobile-nav {
    display: flex;
    justify-content: space-around;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--color-white);
    border-top: 1px solid var(--color-gray);
    padding: 8px 0;
  }
  .mobile-nav a {
    text-decoration: none;
    color: var(--color-black);
    padding: 8px 12px;
  }
  .container { padding: 0 1rem; }
  button, .btn { width: 100%; }
}

.site-header {
  background: var(--color-white);
  color: var(--color-black);
  border-bottom: 2px solid var(--color-gold);
  position: sticky;
  top: 0;
  z-index: 50;
  box-shadow: 0 2px 8px rgba(45, 41, 38, 0.04);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  max-width: 900px;
  margin: 0 auto;
  padding: 10px 16px;
}

.site-title { font-weight: 700; font-size: 18px; letter-spacing: .2px; }
.site-nav { display: flex; gap: 16px; }
.site-nav__link { color: var(--color-black); text-decoration: none; padding: 6px 8px; border-radius: 8px; border-bottom: 2px solid transparent; }
.site-nav__link:hover { background: rgba(178, 180, 178, 0.20); }
.site-nav__link:focus-visible { outline: 3px solid var(--color-gold); outline-offset: 2px; }
.site-nav__link.is-active { font-weight: 700; border-bottom-color: var(--color-gold); }
.site-header__right { display: flex; align-items: center; gap: 16px; }
.site-user { font-weight: 600; font-size: .95rem; color: var(--color-black); min-height: 1.2em; }
.site-user:empty { display: none; }

.site-nav__button {
  border: none;
  background: transparent;
  color: inherit;
  font: inherit;
  cursor: pointer;
  padding: 6px 8px;
  border-radius: 8px;
  border-bottom: 2px solid transparent;
  transition: background .15s ease;
}

.site-nav__button:hover { background: rgba(178, 180, 178, 0.20); }

.site-hero { background: var(--color-white); border-bottom: 1px solid var(--color-gray); }
.site-hero .container { padding-top: 32px; padding-bottom: 32px; }
.site-hero__title { margin: 0 0 10px 0; font-size: clamp(28px, 4.5vw, 44px); letter-spacing: -0.2px; color: var(--color-black); }
.site-hero__tag { margin: 0 0 16px 0; color: var(--color-gray); font-size: clamp(14px, 2.4vw, 18px); }
.site-hero__cta { display: inline-block; }

@media (max-width: 768px) {
  .site-header__inner { flex-direction: column; align-items: stretch; }
  .site-header__right { width: 100%; flex-direction: column; align-items: stretch; gap: 8px; }
  .site-nav { flex-direction: column; gap: 8px; }
  .site-nav__link { display: block; padding: 10px 12px; }
}

.site-footer { margin-top: 32px; padding: 16px 0; background: var(--color-white); border-top: 1px solid var(--color-gray); color: var(--color-gray); font-size: .9rem; text-align: center; }
.site-footer__inner { max-width: 900px; margin: 0 auto; padding: 0 16px; }

.fade-slide { animation: fadeSlide .4s ease both; }
@keyframes fadeSlide { from { opacity: 0; transform: translateY(-4px); } to { opacity: 1; transform: translateY(0); } }

.results-toolbar { display: flex; gap: 12px; align-items: center; justify-content: space-between; margin: 16px 0; flex-wrap: wrap; }
.result-item .term { margin: .25rem 0 .5rem 0; font-size: 1.1rem; font-weight: 700; }
.result-item.card { padding: 14px 16px; }
.result-item .definition { margin: .25rem 0; display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.your-answer { color: #dc2626; }
.badge { display: inline-flex; align-items: center; line-height: 1.2; padding: 2px 8px; border-radius: 999px; font-size: 12px; font-weight: 700; color: #fff; }
.badge.correct { background: #16a34a; }
.badge.incorrect { background: #dc2626; }
.pill { display: inline-flex; align-items: center; line-height: 1.2; padding: 2px 8px; border-radius: 999px; font-size: 12px; font-weight: 600; }
.pill.high_frequency { background: #e8f6eb; color: #1f7a32; }
.pill.basic { background: #fff4df; color: #8a5a00; }
.pill.common { background: #e8eafc; color: #283593; }
.pill.advanced { background: #fdecec; color: #8a1c1c; }

#resultsRoot > .card:first-child { display: grid; grid-template-columns: 1fr auto; gap: 8px 16px; align-items: center; }
#resultsRoot > .card:first-child h1 { grid-column: 1 / -1; margin-bottom: 4px; }
#resultsRoot > .card:first-child > p { grid-column: 1; display: flex; gap: 16px; align-items: baseline; flex-wrap: wrap; margin: .25rem 0; }
#resultsRoot > .card:first-child .results-actions { grid-column: 2; display: flex; gap: 8px; justify-content: flex-end; }
#resultsRoot > .card:first-child > .row { grid-column: 1 / -1; justify-content: space-between; flex-wrap: wrap; }
#resultsRoot > .card:first-child > .row .pill { flex: 1 1 0; text-align: center; min-width: 0; }

@media (max-width: 768px) {
  #resultsRoot > .card:first-child { grid-template-columns: 1fr; }
  #resultsRoot > .card:first-child .results-actions { grid-column: 1; justify-content: flex-start; }
}

.login-page { min-height: 100%; display: flex; flex-direction: column; background: var(--color-white); }
.login-main { flex: 1; display: flex; justify-content: center; padding: 48px 0; }
.login-card { max-width: 420px; width: 100%; display: flex; flex-direction: column; gap: 20px; }
.login-form { display: flex; flex-direction: column; gap: 16px; margin-top: 8px; }
.form-field { display: flex; flex-direction: column; gap: 6px; }
.form-label { font-size: .9rem; font-weight: 600; color: var(--color-black); }
.form-field input {
  padding: 12px 14px;
  border-radius: var(--radius);
  border: 1px solid var(--color-gray);
  font-size: 1rem;
  color: var(--color-black);
  background: var(--color-white);
}

.form-field input:focus-visible { outline: 3px solid var(--color-gold); outline-offset: 2px; }
.login-error { min-height: 1.2em; color: #dc2626; font-weight: 500; }
.login-submit { width: 100%; }
.login-switch { text-align: center; margin: 0; }
.login-switch a { font-weight: 600; color: var(--color-black); }

.profile-card { display: flex; flex-direction: column; gap: 20px; }
.profile-details {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px;
  margin: 0;
}

.profile-detail {
  border: 1px solid var(--color-gray);
  border-radius: var(--radius);
  padding: 14px 16px;
  background: var(--color-white);
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.profile-detail dt {
  margin: 0;
  font-size: .8rem;
  text-transform: uppercase;
  letter-spacing: .05em;
  color: var(--color-gray);
}

.profile-detail dd {
  margin: 0;
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--color-black);
}

.profile-actions { display: flex; gap: 12px; }

@media (max-width: 640px) {
  .login-main { padding: 32px 0; }
  .profile-details { grid-template-columns: 1fr; }
  .profile-actions { flex-direction: column; }
  .profile-actions .btn { width: 100%; }
}

.learn-toolbar { display: flex; gap: 12px; align-items: center; justify-content: space-between; flex-wrap: wrap; margin: 16px 0; }
.learn-tabs {
  --tab-count: 5;
  --tab-gap: 8px;
  --tab-width: calc((100% - (var(--tab-count) - 1) * var(--tab-gap)) / var(--tab-count));
  --underline-index: 0;
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: var(--tab-gap);
  position: relative;
}

.learn-tabs::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: calc((var(--tab-width) + var(--tab-gap)) * var(--underline-index));
  width: var(--tab-width);
  height: 3px;
  border-radius: 999px;
  background: var(--color-gold);
  transition: left 0.22s cubic-bezier(0.4, 0, 0.2, 1);
}

.learn-tabs .btn {
  width: 100%;
  transition: color .22s cubic-bezier(0.4, 0, 0.2, 1), background-color .22s cubic-bezier(0.4, 0, 0.2, 1), box-shadow .22s cubic-bezier(0.4, 0, 0.2, 1);
}

.learn-tabs .btn .tab-count {
  display: inline-block;
  margin-left: 4px;
  opacity: 1;
  transition: opacity .22s cubic-bezier(0.4, 0, 0.2, 1);
}

.learn-tabs .btn .tab-count.is-updating { opacity: 0; }
.learn-tabs:has(button:nth-child(1).is-active) { --underline-index: 0; }
.learn-tabs:has(button:nth-child(2).is-active) { --underline-index: 1; }
.learn-tabs:has(button:nth-child(3).is-active) { --underline-index: 2; }
.learn-tabs:has(button:nth-child(4).is-active) { --underline-index: 3; }
.learn-tabs:has(button:nth-child(5).is-active) { --underline-index: 4; }

@media (max-width: 640px) {
  .learn-tabs { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .learn-tabs::after { display: none; }
}

.learn-list { display: flex; flex-direction: column; gap: 12px; }
.learn-row { padding: 14px 16px; border: 1px solid var(--color-gray); border-radius: var(--radius); background: var(--color-white); box-shadow: var(--shadow); display: flex; gap: 12px; justify-content: space-between; align-items: flex-start; }
.learn-row .term { font-weight: 700; font-size: 1rem; margin: 0; }
.learn-row .definition { margin: .25rem 0 0 0; display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.learn-actions { display: flex; gap: 8px; align-items: center; }

@media (max-width: 768px) {
  .learn-row { flex-direction: column; }
  .learn-actions { width: 100%; justify-content: space-between; }
}

.word-card .term { font-weight: 700; }
.word-card .part-of-speech { color: var(--color-gray); margin-left: 6px; font-size: .95rem; }
.word-card .definition { color: var(--color-black); }
.range-indicator { transition: opacity .22s cubic-bezier(0.4, 0, 0.2, 1); }
.range-indicator.is-updating { opacity: 0; }

:where(.learn-list .learn-row.fade-slide, .result-item.fade-slide) { animation-delay: 0ms; }
:where(.learn-list .learn-row.fade-slide, .result-item.fade-slide):nth-child(2) { animation-delay: 50ms; }
:where(.learn-list .learn-row.fade-slide, .result-item.fade-slide):nth-child(3) { animation-delay: 100ms; }
:where(.learn-list .learn-row.fade-slide, .result-item.fade-slide):nth-child(4) { animation-delay: 150ms; }
:where(.learn-list .learn-row.fade-slide, .result-item.fade-slide):nth-child(5) { animation-delay: 200ms; }
:where(.learn-list .learn-row.fade-slide, .result-item.fade-slide):nth-child(6) { animation-delay: 250ms; }
:where(.learn-list .learn-row.fade-slide, .result-item.fade-slide):nth-child(7) { animation-delay: 300ms; }
:where(.learn-list .learn-row.fade-slide, .result-item.fade-slide):nth-child(8) { animation-delay: 350ms; }
:where(.learn-list .learn-row.fade-slide, .result-item.fade-slide):nth-child(n+9) { animation-delay: 400ms; }

@media print {
  .site-header, .site-footer, .results-toolbar, .results-actions, .btn, .btn-ghost { display: none !important; }
  .container { max-width: 100%; margin: 0; padding: 0; }
  .card { box-shadow: none; border: 1px solid #000; break-inside: avoid; page-break-inside: avoid; }
}

.quiz-progress { margin: 10px 0; }
.question-block { animation: fadeSlide .35s ease both; }

@keyframes correctPulse {
  0% { box-shadow: 0 0 0 0 rgba(34, 197, 94, .45); }
  60% { box-shadow: 0 0 0 6px rgba(34, 197, 94, .0); }
  100% { box-shadow: 0 0 0 0 rgba(34, 197, 94, 0); }
}

@keyframes wrongPulse {
  0% { box-shadow: 0 0 0 0 rgba(220, 38, 38, .4); }
  60% { box-shadow: 0 0 0 6px rgba(220, 38, 38, .0); }
  100% { box-shadow: 0 0 0 0 rgba(220, 38, 38, 0); }
}

.answer.correct-flash { animation: correctPulse 0.24s cubic-bezier(0.4, 0, 0.2, 1); }
.answer.wrong-flash { animation: wrongPulse 0.26s cubic-bezier(0.4, 0, 0.2, 1); }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
}