/* Reusable components: cards, buttons, badges, tabs, progress, flashcards */

/* ---------- Page heading ---------- */

.page-head {
  margin-bottom: var(--space-6);
}
.page-head h1 {
  font-size: var(--text-2xl);
  letter-spacing: -0.01em;
}
.page-head .lead {
  color: var(--color-text-soft);
  max-width: 60ch;
  margin-top: var(--space-2);
}
.page-head .en {
  color: var(--color-text-faint);
  font-style: italic;
}

.breadcrumb {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
  font-size: var(--text-sm);
  color: var(--color-text-soft);
}
.breadcrumb a { color: var(--color-text-soft); }
.breadcrumb a:hover { color: var(--color-accent-strong); }

/* ---------- Buttons ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  font-weight: 600;
  font-size: var(--text-sm);
  color: var(--color-text);
  background: var(--color-surface);
  border-color: var(--color-border);
  transition: transform var(--duration-fast), background var(--duration-fast),
    box-shadow var(--duration-fast), color var(--duration-fast);
}
.btn:hover { transform: translateY(-1px); box-shadow: var(--shadow-sm); }
.btn:active { transform: translateY(0); }

.btn--primary {
  background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-strong) 100%);
  color: white;
  border-color: transparent;
}
.btn--warm {
  background: var(--color-warm);
  color: white;
}
.btn--ghost {
  background: transparent;
  border-color: var(--color-border);
}
.btn--danger {
  background: transparent;
  color: oklch(55% 0.18 25);
  border-color: oklch(75% 0.12 25);
}
.btn--sm { padding: var(--space-1) var(--space-3); font-size: var(--text-xs); }
.btn--lg { padding: var(--space-3) var(--space-6); font-size: var(--text-base); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; transform: none; box-shadow: none; }

.btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

/* ---------- Surface card ---------- */

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  box-shadow: var(--shadow-sm);
}

/* ---------- Badges / chips ---------- */

.badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 0.15em 0.7em;
  border-radius: var(--radius-pill);
  font-size: var(--text-xs);
  font-weight: 600;
  background: var(--color-surface-2);
  color: var(--color-text-soft);
}
.badge--level { background: var(--color-accent-soft); color: var(--color-accent-strong); }
.badge--new { background: var(--status-new-soft); color: var(--status-new); }
.badge--learning { background: var(--status-learning-soft); color: oklch(45% 0.13 70); }
.badge--known { background: var(--status-known-soft); color: oklch(42% 0.12 155); }

/* ---------- Progress bar ---------- */

.progress {
  --pct: 0%;
  height: 10px;
  width: 100%;
  background: var(--color-surface-3);
  border-radius: var(--radius-pill);
  overflow: hidden;
}
.progress__fill {
  height: 100%;
  width: var(--pct);
  border-radius: inherit;
  background: linear-gradient(90deg, var(--color-accent) 0%, var(--status-known) 100%);
  transition: width var(--duration-slow) var(--ease-out-expo);
}
.progress--ring {
  width: 84px;
  height: 84px;
  border-radius: 50%;
  background: conic-gradient(var(--status-known) var(--pct), var(--color-surface-3) 0);
  display: grid;
  place-items: center;
}
.progress--ring::after {
  content: attr(data-label);
  width: 60px;
  height: 60px;
  border-radius: 50%;
  background: var(--color-surface);
  display: grid;
  place-items: center;
  font-weight: 700;
  font-size: var(--text-sm);
  color: var(--color-text);
}

/* ---------- Dashboard ---------- */

.dash-hero {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: var(--space-5);
  margin-bottom: var(--space-6);
}
.dash-hero__main {
  position: relative;
  overflow: hidden;
  padding: var(--space-6);
  border-radius: var(--radius-lg);
  background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-strong) 100%);
  color: white;
  box-shadow: var(--shadow-md);
}
.dash-hero__main h1 { color: white; font-size: var(--text-2xl); }
.dash-hero__main p { opacity: 0.9; margin-top: var(--space-2); max-width: 40ch; }
.dash-hero__main .btn { margin-top: var(--space-5); }
.dash-hero__main::after {
  content: "";
  position: absolute;
  right: -40px;
  bottom: -60px;
  width: 220px;
  height: 220px;
  border-radius: 50%;
  background: oklch(100% 0 0 / 0.12);
}

.stat-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-3);
}
.stat {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  box-shadow: var(--shadow-sm);
}
.stat__num {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 700;
}
.stat__label { color: var(--color-text-faint); font-size: var(--text-sm); }

.today-card { display: flex; flex-direction: column; gap: var(--space-3); }
.today-list { list-style: none; padding: 0; display: grid; gap: var(--space-2); }
.today-list li {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-surface-2);
}
.today-list li.done { opacity: 0.6; }
.today-list .task-check {
  width: 22px; height: 22px;
  border-radius: 6px;
  border: 2px solid var(--color-border);
  display: grid; place-items: center;
  flex-shrink: 0;
}
.today-list li.done .task-check {
  background: var(--status-known);
  border-color: var(--status-known);
  color: white;
}

/* ---------- Topic grid (editorial, not uniform) ---------- */

.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 260px), 1fr));
  gap: var(--space-4);
}
.topic-card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  padding: var(--space-5);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  color: var(--color-text);
  transition: transform var(--duration-fast) var(--ease-out-expo),
    box-shadow var(--duration-fast);
  overflow: hidden;
}
.topic-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
.topic-card__emoji {
  font-size: 2.2rem;
  width: 60px; height: 60px;
  display: grid; place-items: center;
  border-radius: var(--radius-md);
  background: var(--color-surface-2);
}
.topic-card__title { font-size: var(--text-lg); }
.topic-card__title small { display: block; color: var(--color-text-faint); font-weight: 400; font-style: italic; }
.topic-card__meta { display: flex; gap: var(--space-3); color: var(--color-text-soft); font-size: var(--text-sm); }
.topic-card__foot { margin-top: auto; }

/* ---------- Topic detail tabs ---------- */

.tabs {
  display: inline-flex;
  gap: var(--space-1);
  padding: var(--space-1);
  background: var(--color-surface-2);
  border-radius: var(--radius-pill);
  margin-bottom: var(--space-5);
}
.tab {
  border: none;
  background: transparent;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-pill);
  font-weight: 600;
  color: var(--color-text-soft);
}
.tab[aria-selected="true"] {
  background: var(--color-surface);
  color: var(--color-accent-strong);
  box-shadow: var(--shadow-sm);
}

/* ---------- Word / structure list rows ---------- */

.entry-list { display: grid; gap: var(--space-3); }
.entry {
  display: grid;
  grid-template-columns: 6px 1fr auto;
  gap: var(--space-4);
  align-items: center;
  padding: var(--space-4);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}
.entry__stripe { align-self: stretch; border-radius: var(--radius-pill); background: var(--status-new); }
.entry[data-status="learning"] .entry__stripe { background: var(--status-learning); }
.entry[data-status="known"] .entry__stripe { background: var(--status-known); }
.entry__en { font-weight: 600; font-size: var(--text-lg); }
.entry__ipa { color: var(--color-accent-strong); font-size: var(--text-sm); margin-left: var(--space-2); }
.entry__pos { color: var(--color-text-faint); font-size: var(--text-xs); font-style: italic; margin-left: var(--space-2); }
.entry__vi { color: var(--color-text-soft); }
.entry__ex { color: var(--color-text-faint); font-size: var(--text-sm); margin-top: var(--space-1); }
.entry__ex b { color: var(--color-text-soft); font-weight: 600; }
.entry__actions { display: flex; gap: var(--space-2); }

.struct {
  padding: var(--space-5);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-left: 5px solid var(--color-warm);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}
.struct[data-status="known"] { border-left-color: var(--status-known); }
.struct[data-status="learning"] { border-left-color: var(--status-learning); }
.struct__pattern {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  background: var(--color-surface-2);
  display: inline-block;
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-sm);
}
.struct__explain { color: var(--color-text-soft); margin: var(--space-3) 0; }
.struct__examples { list-style: none; padding: 0; display: grid; gap: var(--space-2); }
.struct__examples li {
  padding-left: var(--space-4);
  border-left: 2px solid var(--color-border);
}
.struct__examples .en { font-weight: 600; }
.struct__examples .vi { color: var(--color-text-faint); font-size: var(--text-sm); }
.struct__actions { margin-top: var(--space-4); }

/* ---------- Flashcard study — split-screen slider ---------- */

.study {
  max-width: 880px;
  margin-inline: auto;
}
.study__progress {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  margin-bottom: var(--space-4);
  color: var(--color-text-soft);
  font-size: var(--text-sm);
}
.study__progress .progress { flex: 1; }

/* Stage holds the split card + vertical indicator side by side */
.stage {
  display: grid;
  grid-template-columns: 1fr 84px;
  gap: var(--space-4);
  margin-bottom: var(--space-5);
}

/* The card: a button so it's keyboard-focusable. Perspective enables the 3D flip. */
.flashcard {
  position: relative;
  width: 100%;
  height: 380px;
  cursor: pointer;
  border: none;
  padding: 0;
  background: none;
  perspective: 1800px;
}

/* Inner wrapper rotates for the "lật bài" (flip) effect on click. */
.flashcard__inner {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
  transition: transform var(--duration-slow) var(--ease-out-expo);
}
.flashcard.is-flipped .flashcard__inner { transform: rotateY(180deg); }

/* Front & back faces of the flip. */
.flashcard__face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}
.flashcard__face--front { background: var(--color-surface); }
.flashcard__face--back {
  transform: rotateY(180deg);
  display: flex;
  flex-direction: column;
  justify-content: safe center; /* căn giữa khi vừa, dồn lên đầu khi tràn để cuộn được */
  gap: var(--space-3);
  padding: var(--space-6);
  background: linear-gradient(150deg, var(--color-accent-soft) 0%, var(--color-surface) 70%);
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
}

/* Front face = split into two halves (template look). */
.flashcard__half {
  position: absolute;
  top: 0;
  height: 100%;
  width: 50%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: var(--space-3);
  padding: var(--space-6);
  will-change: transform;
}
.flashcard__half--left {
  left: 0;
  align-items: flex-start;
  text-align: left;
  background: linear-gradient(150deg, var(--color-accent-strong) 0%, oklch(38% 0.10 220) 100%);
  color: white;
}
.flashcard__half--right {
  right: 0;
  align-items: stretch;
  justify-content: flex-start;
  text-align: left;
  background: var(--color-surface);
  border-left: 1px solid var(--color-border);
}

/* Card-change effect: halves slide in from opposite vertical directions. */
@keyframes halfFromTop {
  from { transform: translateY(-105%); }
  to   { transform: translateY(0); }
}
@keyframes halfFromBottom {
  from { transform: translateY(105%); }
  to   { transform: translateY(0); }
}
.flashcard[data-anim="next"] .flashcard__half--left,
.flashcard[data-anim="in"] .flashcard__half--left {
  animation: halfFromTop var(--duration-slow) var(--ease-out-expo) both;
}
.flashcard[data-anim="next"] .flashcard__half--right,
.flashcard[data-anim="in"] .flashcard__half--right {
  animation: halfFromBottom var(--duration-slow) var(--ease-out-expo) both;
}
.flashcard[data-anim="prev"] .flashcard__half--left {
  animation: halfFromBottom var(--duration-slow) var(--ease-out-expo) both;
}
.flashcard[data-anim="prev"] .flashcard__half--right {
  animation: halfFromTop var(--duration-slow) var(--ease-out-expo) both;
}

/* Decorative oversized index watermark on the left panel */
.flashcard__watermark {
  position: absolute;
  right: -0.1em;
  bottom: -0.28em;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 10rem;
  line-height: 1;
  color: oklch(100% 0 0 / 0.10);
  pointer-events: none;
}

.flashcard__kicker {
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.14em;
  opacity: 0.8;
}
.flashcard__word {
  font-family: var(--font-display);
  font-size: clamp(2rem, 1.2rem + 3vw, 3.2rem);
  line-height: 1.05;
}
.flashcard__pattern {
  font-family: var(--font-display);
  font-size: clamp(1.3rem, 0.9rem + 1.6vw, 2rem);
  line-height: 1.15;
}
.flashcard__ipa { color: oklch(92% 0.04 200); font-size: var(--text-lg); }
.flashcard__pos { font-style: italic; font-size: var(--text-sm); opacity: 0.85; }

.flashcard__count {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  color: var(--color-text-faint);
}
.flashcard__count b { color: var(--color-accent-strong); }
.flashcard__hint { color: var(--color-text-faint); font-size: var(--text-sm); }

/* Front-face "common phrases" list (vocab) */
.flashcard__usage { margin-top: var(--space-2); }
.flashcard__usage-label {
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--color-accent-strong);
  margin-bottom: var(--space-2);
}
.flashcard__usage ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: var(--space-2);
}
.flashcard__usage li {
  position: relative;
  padding-left: 1.1em;
  color: var(--color-text);
  font-size: var(--text-base);
  line-height: 1.35;
}
.flashcard__usage li::before {
  content: "“";
  position: absolute;
  left: 0;
  top: 0.05em;
  color: var(--color-accent);
  font-family: var(--font-display);
  font-weight: 700;
}
.flashcard__flip-hint {
  margin-top: auto;
  padding-top: var(--space-3);
  color: var(--color-text-faint);
  font-size: var(--text-xs);
}
.flashcard__formula {
  font-family: var(--font-display);
  font-size: var(--text-base);
  background: var(--color-surface-2);
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-sm);
}

/* Back face (answer side) */
.flashcard__vi { font-size: var(--text-xl); color: var(--color-text); font-weight: 600; }
.flashcard__ex { color: var(--color-text-soft); font-size: var(--text-sm); }
.flashcard__ex b { color: var(--color-accent-strong); }

/* Vertical slider indicator (right of the card) */
.vslider {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-2) 0;
}
.vslider__btn {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text);
  font-size: 1.1rem;
  display: grid;
  place-items: center;
  transition: background var(--duration-fast), transform var(--duration-fast);
}
.vslider__btn:hover:not(:disabled) { background: var(--color-accent-soft); transform: translateY(-2px); }
.vslider__btn:disabled { opacity: 0.35; cursor: not-allowed; }
.vslider__count {
  font-family: var(--font-display);
  text-align: center;
  line-height: 1;
}
.vslider__count .cur { display: block; font-size: var(--text-2xl); color: var(--color-accent-strong); }
.vslider__count .sep { display: block; width: 26px; height: 2px; background: var(--color-border); margin: var(--space-2) auto; }
.vslider__count .total { display: block; font-size: var(--text-base); color: var(--color-text-faint); }
.vslider__ticks {
  display: flex;
  flex-direction: column;
  gap: 5px;
  align-items: center;
}
.vslider__tick {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-surface-3);
  transition: background var(--duration-fast), height var(--duration-fast);
}
.vslider__tick.is-current { height: 18px; border-radius: var(--radius-pill); background: var(--color-accent); }
.vslider__tick.is-known { background: var(--status-known); }
.vslider__tick.is-learning { background: var(--status-learning); }

.study__controls { display: flex; gap: var(--space-3); justify-content: center; }
.study__nav { display: flex; justify-content: space-between; margin-top: var(--space-4); }
.study__hintbar { text-align: center; color: var(--color-text-faint); font-size: var(--text-xs); margin-top: var(--space-3); }
.study__done {
  text-align: center;
  padding: var(--space-8) var(--space-5);
}
.study__done .big { font-size: 3rem; }

/* ---------- Plan timeline ---------- */

.plan-week { margin-bottom: var(--space-6); }
.plan-week__head {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-bottom: var(--space-4);
}
.plan-week__head h2 { font-size: var(--text-lg); }
.plan-week__head .progress { flex: 1; max-width: 240px; }

.plan-days { display: grid; gap: var(--space-3); }
.plan-day {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: var(--space-4);
  align-items: start;
  padding: var(--space-4);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  transition: border-color var(--duration-fast);
}
.plan-day.done { border-color: var(--status-known); background: var(--status-known-soft); }
.plan-day__num {
  display: grid; place-items: center;
  width: 46px; height: 46px;
  border-radius: var(--radius-md);
  background: var(--color-surface-2);
  font-family: var(--font-display);
  font-weight: 700;
}
.plan-day.done .plan-day__num { background: var(--status-known); color: white; }
.plan-day__title { font-weight: 600; }
.plan-day__tasks { list-style: none; padding: 0; margin-top: var(--space-2); display: grid; gap: var(--space-1); color: var(--color-text-soft); font-size: var(--text-sm); }
.plan-day__tasks li::before { content: "›"; color: var(--color-accent); margin-right: var(--space-2); }
.plan-day__tasks a { color: var(--color-accent-strong); }

/* ---------- Settings ---------- */

.setting-block {
  display: grid;
  gap: var(--space-3);
  padding: var(--space-5);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  margin-bottom: var(--space-4);
}
.setting-block h2 { font-size: var(--text-lg); }
.setting-block p { color: var(--color-text-soft); font-size: var(--text-sm); }

.toast {
  position: fixed;
  left: 50%;
  bottom: var(--space-6);
  transform: translateX(-50%) translateY(20px);
  background: var(--color-text);
  color: var(--color-bg);
  padding: var(--space-3) var(--space-5);
  border-radius: var(--radius-pill);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--duration-normal), transform var(--duration-normal) var(--ease-out-expo);
  z-index: 50;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

.empty {
  text-align: center;
  padding: var(--space-8);
  color: var(--color-text-faint);
}

/* ---------- Tenses reference ---------- */

.tense-group { margin-bottom: var(--space-6); }
.tense-group__title {
  font-size: var(--text-xl);
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-2);
  border-bottom: 2px solid var(--color-border);
}
.tense-group__title .en { color: var(--color-text-faint); font-weight: 400; font-style: italic; font-size: var(--text-base); }

.tense-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 330px), 1fr));
  gap: var(--space-4);
}
.tense-card {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  padding: var(--space-5);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-top: 4px solid var(--color-accent);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}
.tense-card[data-status="known"] { border-top-color: var(--status-known); }
.tense-card[data-status="learning"] { border-top-color: var(--status-learning); }
.tense-card__head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-3);
}
.tense-card__head h3 { font-size: var(--text-lg); }
.tense-card__head .en { color: var(--color-text-faint); font-weight: 400; font-style: italic; font-size: var(--text-sm); }

.tense-card__formulas { display: grid; gap: var(--space-2); }
.tense-formula {
  font-family: var(--font-display);
  background: var(--color-surface-2);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
}
.tense-formula .sign {
  display: inline-grid;
  place-items: center;
  width: 1.4em; height: 1.4em;
  border-radius: 50%;
  margin-right: var(--space-2);
  font-weight: 700;
  color: white;
}
.sign--pos { background: var(--status-known); }
.sign--neg { background: var(--color-warm); }
.sign--q { background: var(--color-accent); }

.tense-card__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-4);
}
.tense-block h4 {
  font-size: var(--text-sm);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-accent-strong);
  margin-bottom: var(--space-2);
}
.tense-usage, .tense-mistakes { margin: 0; padding-left: 1.1em; color: var(--color-text-soft); font-size: var(--text-sm); display: grid; gap: var(--space-1); }
.tense-block--warn h4 { color: oklch(55% 0.16 50); }

.signal-row { display: flex; flex-wrap: wrap; gap: var(--space-2); }
.signal-chip {
  background: var(--color-accent-soft);
  color: var(--color-accent-strong);
  padding: 0.15em 0.7em;
  border-radius: var(--radius-pill);
  font-size: var(--text-xs);
  font-weight: 600;
}

.tense-examples { list-style: none; margin: 0; padding: 0; display: grid; gap: var(--space-2); }
.tense-examples li { padding-left: var(--space-3); border-left: 2px solid var(--color-border); }
.tense-examples .en { display: block; font-weight: 600; }
.tense-examples .vi { display: block; color: var(--color-text-faint); font-size: var(--text-sm); }

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

/* ---------- Responsive ---------- */

@media (max-width: 760px) {
  .dash-hero { grid-template-columns: 1fr; }
  /* Stack the split card vertically; indicator goes horizontal below */
  .stage { grid-template-columns: 1fr; }
  .flashcard { height: 460px; }
  .flashcard__half { width: 100%; height: 50%; }
  .flashcard__half--left { top: 0; }
  .flashcard__half--right { top: 50%; right: 0; border-left: none; border-top: 1px solid var(--color-border); }
  .flashcard__watermark { font-size: 7rem; }
  .vslider {
    flex-direction: row;
    justify-content: center;
    gap: var(--space-4);
  }
  .vslider__count { display: flex; align-items: center; gap: var(--space-2); }
  .vslider__count .sep { width: 16px; margin: 0 var(--space-1); }
  .vslider__ticks { flex-direction: row; }
  .vslider__tick.is-current { height: 6px; width: 18px; }

  /* Touch targets: nút đủ lớn để chạm thoải mái */
  .btn { min-height: 44px; }
  .btn--sm { min-height: 36px; }
  .study__controls { width: 100%; }
  .study__controls .btn { flex: 1; }
  .vslider__btn { width: 48px; height: 48px; }
}
@media (max-width: 520px) {
  .entry { grid-template-columns: 6px 1fr; }
  .entry__actions { grid-column: 2; justify-content: flex-start; flex-wrap: wrap; }
  .dash-hero__main .btn { width: 100%; }
  .page-head h1 { overflow-wrap: anywhere; }
}