/* ============================================================
   Ui.css — bundled styles for Components/Shared/Ui (primitives)
   and Components/Shared/Domain (composites).
   Loaded once from App.razor.
   Tokens: see app.css. Helpers: see CommonShared.css.
============================================================ */

/* ===== PRIMITIVES ===== */

/* Button -------------------------------------------------- */
.ui-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 0 18px;
    height: 40px;
    border: 1px solid transparent;
    border-radius: var(--radius-input, 8px);
    font: 500 14px/1 var(--font-primary);
    cursor: pointer;
    user-select: none;
    background: transparent;
    color: var(--text-900);
    transition: transform var(--motion-instant) var(--ease-out),
                background var(--motion-fast) var(--ease-out),
                box-shadow var(--motion-fast) var(--ease-out),
                border-color var(--motion-fast) var(--ease-out);
}
.ui-btn:active:not(:disabled) { transform: scale(0.97); }
.ui-btn:focus-visible { outline: none; box-shadow: var(--shadow-focus); }
.ui-btn:disabled { opacity: 0.55; cursor: not-allowed; }

.ui-btn--sm { height: 32px; padding: 0 12px; font-size: 13px; }
.ui-btn--md { height: 40px; }

.ui-btn--primary { background: var(--primary-600); color: #fff; }
.ui-btn--primary:hover:not(:disabled) { background: var(--primary-800); }

.ui-btn--ghost { background: transparent; color: var(--text-900); }
.ui-btn--ghost:hover:not(:disabled) { background: var(--bg-muted, var(--divider)); }

.ui-btn--outline { background: transparent; color: var(--primary-600); border-color: var(--primary-600); }
.ui-btn--outline:hover:not(:disabled) { background: var(--primary-50); }

.ui-btn--destructive { background: var(--danger); color: #fff; }
.ui-btn--destructive:hover:not(:disabled) { background: #b91c1c; }

.ui-btn--loading { color: transparent; pointer-events: none; position: relative; }
.ui-btn--loading::after {
    content: "";
    position: absolute;
    inset: 0;
    margin: auto;
    width: 16px; height: 16px;
    border: 2px solid currentColor;
    border-radius: 50%;
    border-top-color: transparent;
    color: #fff;
    animation: ui-spin 0.7s linear infinite;
}
.ui-btn--ghost.ui-btn--loading::after,
.ui-btn--outline.ui-btn--loading::after { color: var(--primary-600); }
@keyframes ui-spin { to { transform: rotate(360deg); } }

.ui-btn__icon { display: inline-flex; line-height: 0; }

/* Card ---------------------------------------------------- */
.ui-card {
    background: var(--surface);
    border: var(--border-hairline, 0.5px) solid var(--border-subtle, var(--border));
    border-radius: var(--radius-card, 12px);
    padding: var(--card-padding, 20px);
    color: var(--text-900);
}
.ui-card--hoverable {
    transition: transform var(--motion-fast) var(--ease-out),
                box-shadow var(--motion-fast) var(--ease-out);
    cursor: pointer;
}
.ui-card--hoverable:hover { transform: translateY(-2px); box-shadow: var(--shadow-hover); }
.ui-card__header { margin-bottom: 12px; }
.ui-card__footer { margin-top: 16px; padding-top: 12px; border-top: 1px solid var(--divider); }

/* Badge --------------------------------------------------- */
.ui-badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 2px 10px;
    border-radius: var(--radius-pill, 999px);
    font: 500 12px/1.4 var(--font-primary);
    white-space: nowrap;
}
.ui-badge--sm { font-size: 11px; padding: 1px 8px; }

.ui-badge--neutral  { background: var(--divider); color: var(--text-700); }
.ui-badge--info     { background: var(--info-bg); color: var(--info); }
.ui-badge--success  { background: var(--success-bg); color: var(--success); }
.ui-badge--warning  { background: var(--warning-bg); color: var(--warning); }
.ui-badge--danger   { background: var(--danger-bg); color: var(--danger); }
.ui-badge--brand    { background: var(--primary-100); color: var(--primary-600); }

/* Skeleton ------------------------------------------------ */
.ui-skeleton { /* defined in CommonShared.css as .u-skeleton; alias here */
    background: linear-gradient(90deg,
        var(--bg-muted, #F1EFE8) 25%,
        rgba(255,255,255,0.5) 50%,
        var(--bg-muted, #F1EFE8) 75%);
    background-size: 200% 100%;
    animation: u-shimmer 1.5s var(--ease-linear) infinite;
    border-radius: var(--radius-md);
    display: block;
}
.ui-skeleton--text { height: 14px; }
.ui-skeleton--avatar { border-radius: 50%; width: 40px; height: 40px; }
.ui-skeleton--card { height: 140px; border-radius: var(--radius-card, 12px); }

/* ProgressBar --------------------------------------------- */
.ui-progress {
    width: 100%;
    height: 8px;
    background: var(--divider);
    border-radius: var(--radius-pill, 999px);
    overflow: hidden;
}
.ui-progress__fill {
    height: 100%;
    background: var(--primary-500);
    border-radius: inherit;
    transition: width var(--motion-slower) var(--ease-out);
}
.ui-progress--success .ui-progress__fill { background: var(--success); }
.ui-progress--warning .ui-progress__fill { background: var(--warning); }
.ui-progress--danger  .ui-progress__fill { background: var(--danger); }

/* Modal --------------------------------------------------- */
.ui-modal-backdrop {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.5);
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
    z-index: var(--z-modal, 9999);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 16px;
    animation: ui-fade-in var(--motion-fast) var(--ease-out) both;
}
.ui-modal {
    background: var(--surface);
    border-radius: var(--radius-card, 12px);
    box-shadow: var(--shadow-modal);
    max-width: min(540px, calc(100vw - 32px));
    width: 100%;
    max-height: calc(100vh - 32px);
    overflow: auto;
    animation: ui-modal-in var(--motion-base) var(--ease-out) both;
}
@keyframes ui-fade-in { from { opacity: 0; } to { opacity: 1; } }
@keyframes ui-modal-in {
    from { opacity: 0; transform: scale(0.96); }
    to   { opacity: 1; transform: scale(1); }
}
.ui-modal__header {
    display: flex; align-items: center; justify-content: space-between;
    padding: 18px 20px; border-bottom: 1px solid var(--divider);
}
.ui-modal__title { font: 500 16px/1.4 var(--font-primary); margin: 0; }
.ui-modal__close {
    background: transparent; border: none; cursor: pointer;
    padding: 4px; border-radius: var(--radius-md);
    color: var(--text-500); transition: background var(--motion-fast);
}
.ui-modal__close:hover { background: var(--divider); color: var(--text-900); }
.ui-modal__body { padding: 20px; }
.ui-modal__footer {
    display: flex; justify-content: flex-end; gap: 8px;
    padding: 14px 20px; border-top: 1px solid var(--divider);
}

/* Drawer -------------------------------------------------- */
.ui-drawer-backdrop {
    position: fixed; inset: 0;
    background: rgba(15, 23, 42, 0.4);
    z-index: var(--z-modal, 9999);
    animation: ui-fade-in var(--motion-fast) var(--ease-out) both;
}
.ui-drawer {
    position: fixed;
    top: 0; bottom: 0;
    width: min(420px, 92vw);
    background: var(--surface);
    box-shadow: var(--shadow-modal);
    z-index: calc(var(--z-modal, 9999) + 1);
    display: flex; flex-direction: column;
    overflow: hidden;
}
.ui-drawer--right { right: 0; animation: ui-drawer-in-right var(--motion-slow) var(--ease-out) both; }
.ui-drawer--left  { left: 0;  animation: ui-drawer-in-left  var(--motion-slow) var(--ease-out) both; }
@keyframes ui-drawer-in-right { from { transform: translateX(100%); } to { transform: translateX(0); } }
@keyframes ui-drawer-in-left  { from { transform: translateX(-100%); } to { transform: translateX(0); } }
.ui-drawer__header {
    display: flex; align-items: center; justify-content: space-between;
    padding: 18px 20px; border-bottom: 1px solid var(--divider);
}
.ui-drawer__title { font: 500 16px/1.4 var(--font-primary); margin: 0; }
.ui-drawer__body { flex: 1 1 auto; overflow: auto; padding: 18px 20px; }
.ui-drawer__footer { padding: 14px 20px; border-top: 1px solid var(--divider); }

/* Tabs ---------------------------------------------------- */
.ui-tabs {
    display: flex; flex-direction: column; gap: 16px;
}
.ui-tabs__list {
    position: relative;
    display: inline-flex;
    gap: 4px;
    border-bottom: 1px solid var(--divider);
}
.ui-tabs__btn {
    background: transparent; border: none; cursor: pointer;
    padding: 10px 14px;
    font: 500 14px/1.2 var(--font-primary);
    color: var(--text-500);
    border-radius: 8px 8px 0 0;
    transition: color var(--motion-fast) var(--ease-out),
                background var(--motion-fast) var(--ease-out);
}
.ui-tabs__btn:hover { color: var(--text-900); background: var(--divider); }
.ui-tabs__btn--active { color: var(--primary-600); }
.ui-tabs__indicator {
    position: absolute;
    bottom: -1px;
    height: 2px;
    background: var(--primary-600);
    border-radius: 2px 2px 0 0;
    transition: transform var(--motion-base) var(--ease-out),
                width var(--motion-base) var(--ease-out);
}
.ui-tabs__panel { padding: 4px 0; }

/* Toast --------------------------------------------------- */
.ui-toast-container {
    position: fixed;
    bottom: 24px;
    right: 24px;
    z-index: calc(var(--z-modal, 9999) + 10);
    display: flex; flex-direction: column;
    gap: 10px;
    pointer-events: none;
}
.ui-toast {
    pointer-events: auto;
    min-width: 280px;
    max-width: 380px;
    padding: 12px 16px;
    border-radius: var(--radius-input, 8px);
    background: var(--surface);
    box-shadow: var(--shadow-modal);
    border: 1px solid var(--border-subtle, var(--border));
    display: flex; align-items: flex-start; gap: 10px;
    animation: ui-toast-in var(--motion-base) var(--ease-out) both;
    color: var(--text-900);
}
.ui-toast--leaving { animation: ui-toast-out var(--motion-fast) var(--ease-in) both; }
@keyframes ui-toast-in {
    from { opacity: 0; transform: translateY(20px); }
    to   { opacity: 1; transform: translateY(0); }
}
@keyframes ui-toast-out {
    from { opacity: 1; transform: translateY(0); }
    to   { opacity: 0; transform: translateY(20px); }
}
.ui-toast__icon { font-size: 18px; line-height: 1; flex-shrink: 0; padding-top: 2px; }
.ui-toast--success .ui-toast__icon { color: var(--success); }
.ui-toast--info    .ui-toast__icon { color: var(--info); }
.ui-toast--warning .ui-toast__icon { color: var(--warning); }
.ui-toast--danger  .ui-toast__icon { color: var(--danger); }
.ui-toast__body { flex: 1; font: 400 14px/1.5 var(--font-primary); }
.ui-toast__close {
    background: transparent; border: none; cursor: pointer;
    color: var(--text-500); padding: 0 4px; line-height: 1;
}
.ui-toast__close:hover { color: var(--text-900); }

/* ===== COMPOSITES ===== */

/* StatCard ------------------------------------------------ */
.ui-stat {
    background: var(--surface);
    border: 1px solid var(--border-subtle, var(--border));
    border-radius: var(--radius-card, 12px);
    padding: 16px 18px;
    display: flex; flex-direction: column;
    gap: 6px;
}
.ui-stat__label { font: 400 12px/1.4 var(--font-primary); color: var(--text-500); }
.ui-stat__value { font: 500 24px/1.2 var(--font-heading); color: var(--text-900); }
.ui-stat__hint  { font: 400 12px/1.4 var(--font-primary); color: var(--text-500); }
.ui-stat--accent { border-left: 3px solid var(--primary-600); padding-left: 16px; }

/* TopicIcon ----------------------------------------------- */
.ui-topic-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px; height: 40px;
    border-radius: 10px;
    font-size: 18px;
    flex-shrink: 0;
}
.ui-topic-icon--sm { width: 32px; height: 32px; font-size: 14px; border-radius: 8px; }
.ui-topic-icon--lg { width: 48px; height: 48px; font-size: 20px; border-radius: 12px; }

.ui-topic-icon--amber  { background: var(--c-amber-bg);  color: var(--c-amber-fg); }
.ui-topic-icon--blue   { background: var(--c-blue-bg);   color: var(--c-blue-fg); }
.ui-topic-icon--purple { background: var(--c-purple-bg); color: var(--c-purple-fg); }
.ui-topic-icon--pink   { background: var(--c-pink-bg);   color: var(--c-pink-fg); }
.ui-topic-icon--coral  { background: var(--c-coral-bg);  color: var(--c-coral-fg); }
.ui-topic-icon--teal   { background: var(--c-teal-bg);   color: var(--c-teal-fg); }
.ui-topic-icon--green  { background: var(--c-green-bg);  color: var(--c-green-fg); }

/* TestCard ------------------------------------------------ */
.ui-test-card {
    background: var(--surface);
    border: 1px solid var(--border-subtle, var(--border));
    border-radius: var(--radius-card, 12px);
    padding: 18px;
    display: flex; flex-direction: column;
    gap: 12px;
    transition: transform var(--motion-fast) var(--ease-out),
                box-shadow var(--motion-fast) var(--ease-out);
    cursor: pointer;
    position: relative;
}
.ui-test-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-hover); }
.ui-test-card__header {
    display: flex; align-items: flex-start; justify-content: space-between; gap: 10px;
}
.ui-test-card__title { font: 500 15px/1.4 var(--font-heading); margin: 0; }
.ui-test-card__meta { font: 400 12px/1.4 var(--font-primary); color: var(--text-500); }
.ui-test-card__progress { margin-top: auto; }

/* LessonCard ---------------------------------------------- */
.ui-lesson-card {
    background: var(--surface);
    border: 1px solid var(--border-subtle, var(--border));
    border-radius: var(--radius-card, 12px);
    padding: 16px;
    display: flex; align-items: center; gap: 14px;
    transition: transform var(--motion-fast) var(--ease-out),
                box-shadow var(--motion-fast) var(--ease-out);
}
.ui-lesson-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-hover); }
.ui-lesson-card__num {
    display: inline-flex; align-items: center; justify-content: center;
    width: 32px; height: 32px;
    border-radius: 50%;
    font: 500 13px/1 var(--font-primary);
    flex-shrink: 0;
}
.ui-lesson-card__body { flex: 1; min-width: 0; }
.ui-lesson-card__title { font: 500 14px/1.4 var(--font-heading); margin: 0 0 4px; }
.ui-lesson-card__sub { font: 400 12px/1.4 var(--font-primary); color: var(--text-500); }
.ui-lesson-card__check { color: var(--success); font-size: 18px; flex-shrink: 0; }

/* VocabCard ----------------------------------------------- */
.ui-vocab-card {
    background: var(--surface);
    border: 1px solid var(--border-subtle, var(--border));
    border-radius: var(--radius-card, 12px);
    padding: 16px;
    transition: transform var(--motion-fast) var(--ease-out),
                box-shadow var(--motion-fast) var(--ease-out);
}
.ui-vocab-card:hover { transform: translateY(-1px); box-shadow: var(--shadow-hover); }
.ui-vocab-card__head { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.ui-vocab-card__word { font: 500 18px/1.3 var(--font-heading); margin: 0; }
.ui-vocab-card__ipa { font: 400 13px/1.4 var(--font-primary); color: var(--text-500); }
.ui-vocab-card__audio {
    background: var(--primary-50); border: none; cursor: pointer;
    width: 32px; height: 32px; border-radius: 50%;
    color: var(--primary-600); display: inline-flex; align-items: center; justify-content: center;
    transition: background var(--motion-fast);
}
.ui-vocab-card__audio:hover { background: var(--primary-100); }
.ui-vocab-card__audio.is-playing { animation: u-pulse-once 600ms var(--ease-in-out) infinite; }
.ui-vocab-card__meaning { font: 400 14px/1.5 var(--font-primary); color: var(--text-700); margin: 8px 0 4px; }
.ui-vocab-card__example { font: italic 400 13px/1.5 var(--font-primary); color: var(--text-500); }

/* SkillHero ----------------------------------------------- */
.ui-skill-hero {
    background: var(--surface);
    border: 1px solid var(--border-subtle, var(--border));
    border-radius: var(--radius-card, 12px);
    padding: 24px;
    display: flex; align-items: center; gap: 18px;
    border-left: 4px solid var(--primary-600);
}
.ui-skill-hero__title { font: 500 22px/1.3 var(--font-heading); margin: 0 0 4px; }
.ui-skill-hero__sub { font: 400 14px/1.5 var(--font-primary); color: var(--text-500); margin: 0; }
.ui-skill-hero__stats { margin-left: auto; display: flex; gap: 18px; }
.ui-skill-hero__stat { text-align: right; }
.ui-skill-hero__stat-v { font: 500 18px/1.2 var(--font-heading); color: var(--text-900); }
.ui-skill-hero__stat-l { font: 400 12px/1.4 var(--font-primary); color: var(--text-500); }

/* FilterBar ----------------------------------------------- */
.ui-filter-bar {
    display: flex; align-items: center; gap: 12px;
    padding: 12px 0;
}
.ui-filter-bar__search {
    position: relative;
    flex: 1; max-width: 320px;
}
.ui-filter-bar__search input {
    width: 100%;
    height: 38px;
    padding: 0 14px 0 36px;
    border: 1px solid var(--border-subtle, var(--border));
    border-radius: var(--radius-input, 8px);
    background: var(--surface);
    font: 400 14px/1 var(--font-primary);
    transition: border-color var(--motion-fast), box-shadow var(--motion-fast);
}
.ui-filter-bar__search input:focus { outline: none; border-color: var(--primary-500); box-shadow: var(--shadow-focus); }
.ui-filter-bar__search-icon {
    position: absolute; left: 12px; top: 50%; transform: translateY(-50%);
    color: var(--text-500); pointer-events: none;
}
.ui-filter-bar__chips { display: flex; gap: 6px; }
.ui-filter-bar__chip {
    padding: 6px 12px;
    border: 1px solid var(--border-subtle, var(--border));
    border-radius: var(--radius-pill, 999px);
    background: var(--surface);
    color: var(--text-700);
    font: 500 13px/1 var(--font-primary);
    cursor: pointer;
    transition: background var(--motion-fast), color var(--motion-fast), border-color var(--motion-fast);
}
.ui-filter-bar__chip:hover { background: var(--bg-muted, var(--divider)); }
.ui-filter-bar__chip--active { background: var(--primary-100); color: var(--primary-600); border-color: var(--primary-100); }
.ui-filter-bar__count { font: 400 13px/1.4 var(--font-primary); color: var(--text-500); margin-left: auto; }

/* EmptyState / ErrorState --------------------------------- */
.ui-state {
    display: flex; flex-direction: column; align-items: center; text-align: center;
    padding: 40px 24px;
    gap: 8px;
    animation: u-fade-up var(--motion-slow) var(--ease-out) both;
}
.ui-state__icon {
    font-size: 40px;
    color: var(--text-500);
    margin-bottom: 8px;
    line-height: 1;
}
.ui-state--error .ui-state__icon { color: var(--danger); }
.ui-state__title { font: 500 16px/1.4 var(--font-heading); margin: 0; }
.ui-state__sub { font: 400 13px/1.6 var(--font-primary); color: var(--text-500); margin: 0; max-width: 360px; }
.ui-state__actions { display: flex; gap: 8px; margin-top: 12px; }

/* StreakPill ---------------------------------------------- */
.ui-streak-pill {
    display: inline-flex; align-items: center; gap: 8px;
    padding: 8px 16px;
    background: var(--c-amber-bg);
    color: var(--c-amber-fg);
    border: 1px solid color-mix(in srgb, var(--c-amber-fg, #BA7517) 18%, transparent);
    border-radius: var(--radius-pill, 999px);
    font: 500 13px/1.3 var(--font-primary);
    box-shadow: 0 1px 2px rgba(186, 117, 23, 0.08);
}
.ui-streak-pill__dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--success-token, #3B6D11);
    box-shadow: 0 0 0 3px rgba(99, 153, 34, 0.18);
    flex-shrink: 0;
    animation: streak-pulse 2.4s var(--ease-out) infinite;
}
.ui-streak-pill__count {
    font-weight: 600;
    color: var(--text-primary, #1A1A18);
    font-size: 14px;
    letter-spacing: -0.01em;
}
.ui-streak-pill__suffix {
    color: var(--c-amber-fg, #BA7517);
    font-size: 12.5px;
}
.ui-streak-pill.is-bumped { animation: u-pulse-once 400ms var(--ease-spring); }
@keyframes streak-pulse {
    0%, 100% { box-shadow: 0 0 0 3px rgba(99, 153, 34, 0.18); }
    50%      { box-shadow: 0 0 0 6px rgba(99, 153, 34, 0.10); }
}

/* ============================================================
   ModuleSwitcher — segmented control 4 tabs (Aptis/VSTEP/TOEIC/IELTS)
   Per master prompt: only 6px colored dot, NOT colored pill.
============================================================ */
.module-switcher {
    display: inline-flex;
    align-items: center;
    gap: 2px;
    padding: 3px;
    background: var(--bg-muted, #F1EFE8);
    border-radius: var(--radius-pill, 999px);
    border: 1px solid var(--border-subtle, rgba(0,0,0,0.06));
    font-family: var(--font-sans, 'Inter', sans-serif);
}

.module-switcher__tab {
    position: relative;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 6px 12px;
    border-radius: var(--radius-pill, 999px);
    color: var(--text-secondary, #5F5E5A);
    text-decoration: none;
    font: 500 13px/1 var(--font-sans);
    cursor: pointer;
    transition: background var(--motion-fast) var(--ease-out),
                color var(--motion-fast) var(--ease-out),
                transform var(--motion-instant) var(--ease-out);
}

.module-switcher__tab:hover {
    color: var(--text-primary, #1A1A18);
    background: transparent;
}

.module-switcher__tab:active {
    transform: scale(0.97);
}

.module-switcher__tab.is-active {
    background: var(--bg-surface, #FFFFFF);
    color: var(--text-primary, #1A1A18);
    box-shadow: 0 1px 2px rgba(0,0,0,0.04);
}

.module-switcher__dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    flex-shrink: 0;
    background: var(--text-tertiary);
    transition: transform var(--motion-fast) var(--ease-spring);
}

.module-switcher__tab.is-active .module-switcher__dot {
    transform: scale(1.3);
}

.module-switcher__label {
    line-height: 1;
}

@media (max-width: 768px) {
    .module-switcher__label {
        display: none;
    }
    .module-switcher__tab {
        padding: 6px 8px;
    }
}

/* ============================================================
   Motion patterns — count-up, breathing submit, dot fill,
   filter exit/enter, fade-up, draw-line.
============================================================ */

/* Count-up wrapper — number container fades + slides as it changes.
   Pair with JS that toggles .is-changing while updating textContent. */
.u-count-up {
    display: inline-block;
    transition: transform var(--motion-base) var(--ease-out),
                opacity var(--motion-base) var(--ease-out);
    font-variant-numeric: tabular-nums;
}
.u-count-up.is-changing {
    opacity: 0.6;
    transform: translateY(-2px);
}

/* Auto-stagger fallback — for grids that can't set inline style="--i: N".
   CommonShared.css's .u-stagger expects --i; this nth-child variant
   activates only when also tagged .u-stagger--auto. */
.u-stagger--auto > *:nth-child(1) { --i: 0; }
.u-stagger--auto > *:nth-child(2) { --i: 1; }
.u-stagger--auto > *:nth-child(3) { --i: 2; }
.u-stagger--auto > *:nth-child(4) { --i: 3; }
.u-stagger--auto > *:nth-child(5) { --i: 4; }
.u-stagger--auto > *:nth-child(6) { --i: 5; }
.u-stagger--auto > *:nth-child(7) { --i: 6; }
.u-stagger--auto > *:nth-child(8) { --i: 7; }
.u-stagger--auto > *:nth-child(9) { --i: 8; }
.u-stagger--auto > *:nth-child(10) { --i: 9; }
.u-stagger--auto > *:nth-child(n+11) { --i: 10; }

/* Question dot — used in question navigator panel */
.u-q-dot {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 6px;
    border: 1px solid var(--border-subtle);
    background: var(--bg-surface);
    color: var(--text-secondary);
    font: 500 13px/1 var(--font-sans);
    cursor: pointer;
    transition: background var(--motion-fast) var(--ease-out),
                border-color var(--motion-fast) var(--ease-out),
                color var(--motion-fast) var(--ease-out),
                transform var(--motion-fast) var(--ease-spring);
}
.u-q-dot:hover { border-color: var(--border-default); }
.u-q-dot.is-current { border-color: var(--brand-primary); border-width: 2px; }
.u-q-dot.is-answered {
    background: var(--success-bg-token);
    border-color: transparent;
    color: var(--success-token);
}
.u-q-dot.is-just-answered { transform: scale(1.15); }
.u-q-dot.is-flagged::after {
    content: "";
    position: absolute;
    top: 4px; right: 4px;
    width: 6px; height: 6px;
    border-radius: 50%;
    background: var(--warning-token);
}

/* Filter exit/enter — for grids whose contents are filtered live */
.u-filter-exit {
    animation: u-fade-out var(--motion-fast) var(--ease-in) forwards;
}
@keyframes u-fade-out {
    from { opacity: 1; transform: translateY(0); }
    to   { opacity: 0; transform: translateY(-8px); }
}

/* Tab underline slide indicator — shared marker style */
.u-tabs-indicator {
    position: absolute;
    bottom: 0;
    left: 0;
    height: 2px;
    background: var(--brand-primary);
    border-radius: 2px 2px 0 0;
    transform-origin: left center;
    transition: transform var(--motion-base) var(--ease-out),
                width var(--motion-base) var(--ease-out);
    will-change: transform, width;
}

/* Draw-line — for roadmap connectors that animate stroke on mount */
@keyframes u-draw-line {
    from { stroke-dashoffset: 100%; }
    to   { stroke-dashoffset: 0; }
}
.u-draw-line {
    stroke-dasharray: 100%;
    animation: u-draw-line var(--motion-celebrate) var(--ease-out) both;
}

/* Avatar overlay on hover (Profile page) */
.u-avatar-overlay {
    position: relative;
    overflow: hidden;
}
.u-avatar-overlay::after {
    content: "Đổi ảnh";
    position: absolute;
    inset: 0;
    display: flex; align-items: center; justify-content: center;
    background: rgba(0,0,0,0.45);
    color: #fff;
    font: 500 12px/1 var(--font-sans);
    opacity: 0;
    transition: opacity var(--motion-fast) var(--ease-out);
}
.u-avatar-overlay:hover::after { opacity: 1; }

/* Page transition — apply to <main> wrapper for subtle route fade */
.u-page-enter {
    animation: u-page-in var(--motion-slow) var(--ease-out) both;
}
@keyframes u-page-in {
    from { opacity: 0; transform: translateY(4px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* ============================================================
   SkillTile — 4-tile skill landing (Tests/By part/Tips/Pick).
   Per master prompt §7.3: 4 thẻ + icon container 4 màu.
============================================================ */
.ui-skill-tile {
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
    gap: 16px;
    padding: 18px 20px;
    background: var(--bg-surface, #FFFFFF);
    border: var(--border-hairline, 0.5px) solid var(--border-subtle, rgba(0,0,0,0.08));
    border-radius: var(--radius-card, 12px);
    color: inherit;
    text-decoration: none;
    text-align: left;
    cursor: pointer;
    font: inherit;
    width: 100%;
    transition: transform var(--motion-fast) var(--ease-out),
                box-shadow var(--motion-fast) var(--ease-out),
                border-color var(--motion-fast) var(--ease-out);
}
.ui-skill-tile:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
    border-color: var(--border-default);
}
.ui-skill-tile:active {
    transform: scale(0.99);
    transition-duration: var(--motion-instant);
}
.ui-skill-tile:focus-visible {
    outline: none;
    box-shadow: var(--shadow-focus);
}

.ui-skill-tile__icon {
    width: 44px;
    height: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 12px;
    font-size: 20px;
    flex-shrink: 0;
}
.ui-skill-tile--blue   .ui-skill-tile__icon { background: var(--c-blue-bg);   color: var(--c-blue-fg); }
.ui-skill-tile--amber  .ui-skill-tile__icon { background: var(--c-amber-bg);  color: var(--c-amber-fg); }
.ui-skill-tile--pink   .ui-skill-tile__icon { background: var(--c-pink-bg);   color: var(--c-pink-fg); }
.ui-skill-tile--teal   .ui-skill-tile__icon { background: var(--c-teal-bg);   color: var(--c-teal-fg); }
.ui-skill-tile--purple .ui-skill-tile__icon { background: var(--c-purple-bg); color: var(--c-purple-fg); }
.ui-skill-tile--coral  .ui-skill-tile__icon { background: var(--c-coral-bg);  color: var(--c-coral-fg); }
.ui-skill-tile--green  .ui-skill-tile__icon { background: var(--c-green-bg);  color: var(--c-green-fg); }

.ui-skill-tile__body { min-width: 0; }
.ui-skill-tile__title { font: 500 15px/1.3 var(--font-sans); margin: 0 0 4px; color: var(--text-primary); }
.ui-skill-tile__sub   { font: 400 13px/1.45 var(--font-sans); margin: 0; color: var(--text-secondary); }

.ui-skill-tile__stat {
    text-align: right;
    display: flex;
    flex-direction: column;
    gap: 2px;
    flex-shrink: 0;
}
.ui-skill-tile__stat-v {
    font: 500 18px/1.1 var(--font-sans);
    color: var(--brand-primary);
    font-variant-numeric: tabular-nums;
}
.ui-skill-tile__stat-l { font: 400 11px/1.3 var(--font-sans); color: var(--text-tertiary); }

.ui-skill-tile-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 14px;
}

/* ============================================================
   VocabCard 3D flip variant — apply .ui-vocab-card--flip
   to make the card flip on hover (or .is-flipped via JS).
   Front face: word + IPA + meaning. Back face: example + synonyms.
============================================================ */
.ui-vocab-card--flip {
    position: relative;
    perspective: 1000px;
    background: transparent;
    border: none;
    padding: 0;
    min-height: 180px;
}
.ui-vocab-card--flip > .ui-vocab-card__inner {
    position: relative;
    width: 100%;
    height: 100%;
    min-height: inherit;
    transition: transform var(--motion-slow) var(--ease-out);
    transform-style: preserve-3d;
}
.ui-vocab-card--flip:hover > .ui-vocab-card__inner,
.ui-vocab-card--flip.is-flipped > .ui-vocab-card__inner {
    transform: rotateY(180deg);
}
.ui-vocab-card__face {
    position: absolute;
    inset: 0;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
    background: var(--bg-surface);
    border: var(--border-hairline) solid var(--border-subtle);
    border-radius: var(--radius-card);
    padding: 16px;
    display: flex;
    flex-direction: column;
    gap: 6px;
}
.ui-vocab-card__face--back {
    transform: rotateY(180deg);
    background: var(--brand-primary-soft);
}

/* ============================================================
   Lesson roadmap — connector line between numbered cards.
   Apply .ui-roadmap to a vertical stack of .ui-roadmap__step.
============================================================ */
.ui-roadmap {
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 14px;
}
.ui-roadmap::before {
    content: "";
    position: absolute;
    top: 24px;
    bottom: 24px;
    left: 19px;
    width: 2px;
    background: linear-gradient(
        to bottom,
        var(--border-default) 50%,
        transparent 0
    );
    background-size: 2px 8px;
    background-repeat: repeat-y;
    z-index: 0;
}

.ui-roadmap__step {
    position: relative;
    z-index: 1;
    display: grid;
    grid-template-columns: 40px 1fr auto;
    align-items: center;
    gap: 14px;
    background: var(--bg-surface);
    border: var(--border-hairline) solid var(--border-subtle);
    border-radius: var(--radius-card);
    padding: 14px 18px 14px 14px;
    transition: transform var(--motion-fast) var(--ease-out),
                box-shadow var(--motion-fast) var(--ease-out);
}
.ui-roadmap__step:hover { transform: translateY(-1px); box-shadow: var(--shadow-hover); }

.ui-roadmap__num {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font: 500 13px/1 var(--font-sans);
    flex-shrink: 0;
    background: var(--bg-muted);
    color: var(--text-secondary);
}
.ui-roadmap__step--intro    .ui-roadmap__num { background: var(--bg-muted);    color: var(--text-secondary); }
.ui-roadmap__step--core     .ui-roadmap__num { background: var(--c-blue-bg);   color: var(--c-blue-fg); }
.ui-roadmap__step--speaking .ui-roadmap__num { background: var(--c-coral-bg);  color: var(--c-coral-fg); }
.ui-roadmap__step--listening .ui-roadmap__num{ background: var(--c-teal-bg);   color: var(--c-teal-fg); }
.ui-roadmap__step--reading  .ui-roadmap__num { background: var(--c-amber-bg);  color: var(--c-amber-fg); }
.ui-roadmap__step--writing  .ui-roadmap__num { background: var(--c-pink-bg);   color: var(--c-pink-fg); }
.ui-roadmap__step--mock     .ui-roadmap__num { background: var(--c-green-bg);  color: var(--c-green-fg); }
.ui-roadmap__step--done     .ui-roadmap__num { background: var(--success-bg-token); color: var(--success-token); }

.ui-roadmap__body { min-width: 0; }
.ui-roadmap__title { font: 500 14px/1.4 var(--font-sans); margin: 0 0 2px; color: var(--text-primary); }
.ui-roadmap__sub   { font: 400 12px/1.4 var(--font-sans); margin: 0; color: var(--text-tertiary); }
.ui-roadmap__check { color: var(--success-token); font-size: 18px; flex-shrink: 0; }

/* Stagger entry on the roadmap mounting */
.ui-roadmap.u-stagger > .ui-roadmap__step {
    opacity: 0;
    animation: u-fade-up var(--motion-base) var(--ease-out) forwards;
    animation-delay: calc(var(--i, 0) * var(--stagger-base));
}

/* ============================================================
   Question navigator panel polish — drawer-friendly shared rules
   that replace ad-hoc styling in DoTestQuestionPanel.shared.css.
   Activate by adding class .qpanel-v2 on the drawer root.
============================================================ */
.qpanel-v2 .qpanel-v2__filters {
    position: relative;
    display: inline-flex;
    gap: 4px;
    border-bottom: 1px solid var(--border-subtle);
    margin-bottom: 12px;
}
.qpanel-v2 .qpanel-v2__filter {
    background: transparent;
    border: 0;
    padding: 8px 12px;
    font: 500 13px/1.2 var(--font-sans);
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: 8px 8px 0 0;
    transition: color var(--motion-fast) var(--ease-out),
                background var(--motion-fast) var(--ease-out);
}
.qpanel-v2 .qpanel-v2__filter:hover { color: var(--text-primary); background: var(--bg-muted); }
.qpanel-v2 .qpanel-v2__filter.is-active { color: var(--brand-primary); }

.qpanel-v2 .qpanel-v2__filter-indicator {
    position: absolute;
    bottom: -1px;
    left: 0;
    height: 2px;
    background: var(--brand-primary);
    border-radius: 2px 2px 0 0;
    transition: transform var(--motion-base) var(--ease-out),
                width var(--motion-base) var(--ease-out);
    will-change: transform, width;
}

.qpanel-v2 .qpanel-v2__grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(40px, 1fr));
    gap: 8px;
    padding: 4px 0 16px;
}

.qpanel-v2 .qpanel-v2__submit {
    width: 100%;
    height: 44px;
    border-radius: var(--radius-input);
    border: 1px solid var(--border-default);
    background: var(--bg-surface);
    color: var(--text-secondary);
    font: 500 14px/1 var(--font-sans);
    cursor: pointer;
    transition: background var(--motion-fast) var(--ease-out),
                color var(--motion-fast) var(--ease-out),
                border-color var(--motion-fast) var(--ease-out);
}
.qpanel-v2 .qpanel-v2__submit.is-ready {
    background: var(--brand-primary);
    color: var(--text-on-brand);
    border-color: var(--brand-primary);
    animation: u-breathe 1.6s var(--ease-in-out) infinite;
}
.qpanel-v2 .qpanel-v2__submit:hover { background: var(--brand-primary-dark); color: var(--text-on-brand); }

/* ============================================================
   Empty state illustration — line-art monochrome line drawing
   that respects --text-tertiary so it sits softly behind text.
============================================================ */
.ui-empty-illustration {
    width: 96px;
    height: 96px;
    color: var(--text-tertiary);
    margin: 0 auto 12px;
    opacity: 0.7;
}
.ui-empty-illustration svg {
    width: 100%;
    height: 100%;
    stroke: currentColor;
    fill: none;
    stroke-width: 1.5;
    stroke-linecap: round;
    stroke-linejoin: round;
}

/* ============================================================
   Profile inline-edit hints (master prompt §7.11)
============================================================ */
.ui-input-edit {
    position: relative;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    width: 100%;
}
.ui-input-edit input {
    flex: 1;
    height: 38px;
    padding: 0 36px 0 12px;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-input);
    background: var(--bg-surface);
    color: var(--text-primary);
    font: 400 14px/1 var(--font-sans);
    transition: border-color var(--motion-fast), box-shadow var(--motion-fast);
}
.ui-input-edit input:hover { border-color: var(--border-default); }
.ui-input-edit input:focus {
    outline: none;
    border-color: var(--brand-primary);
    box-shadow: var(--shadow-focus);
}
.ui-input-edit__pencil {
    position: absolute;
    right: 10px;
    color: var(--text-tertiary);
    pointer-events: none;
    transition: opacity var(--motion-fast) var(--ease-out);
}
.ui-input-edit input:focus + .ui-input-edit__pencil { opacity: 0; }

.ui-copy-button {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 4px 10px;
    background: var(--bg-muted);
    color: var(--text-secondary);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-input);
    font: 500 12px/1 var(--font-sans);
    cursor: pointer;
    transition: background var(--motion-fast) var(--ease-out),
                color var(--motion-fast) var(--ease-out);
}
.ui-copy-button:hover { background: var(--brand-primary-soft); color: var(--brand-primary); }
.ui-copy-button.is-copied { background: var(--success-bg-token); color: var(--success-token); border-color: var(--success-bg-token); }
.ui-copy-button.is-copied::after { content: " ✓"; }

.ui-mono {
    font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
    font-size: 0.92em;
}