/* ─────────────────────────────────────────────────────────────────────
 * ui-components.css — Reusable UI primitives.
 * Depends on: design-tokens.css (must be loaded first).
 *
 * Brand palette "Đỏ–Đất nung" (2026-07-01): deep red var(--color-primary) (primary) ·
 * terracotta #B45A3C (accent) · slate (secondary) · amber/green (states) · gray (neutrals).
 * No rose/pink, no teal/emerald/cyan, no blue/purple.
 * ───────────────────────────────────────────────────────────────────── */

/* ════════════════════════════════════════════════════════════════════
 * PAGE HEADER
 * ════════════════════════════════════════════════════════════════════ */
.page-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    gap: var(--space-4);
    flex-wrap: wrap;
    padding-bottom: var(--space-5);
    margin-bottom: var(--space-6);
    border-bottom: 1px solid var(--color-border);
}
.page-title {
    font-size: var(--fs-h1-desktop);
    font-weight: var(--fw-bold);
    color: var(--color-ink);
    margin: 0;
    letter-spacing: var(--tracking-tight);
    line-height: var(--lh-tight);
}
.page-subtitle {
    font-size: var(--fs-body);
    color: var(--color-muted);
    margin: var(--space-2) 0 0;
    line-height: var(--lh-normal);
}
.section-title {
    font-size: var(--fs-h2-desktop);
    font-weight: var(--fw-bold);
    color: var(--color-ink);
    margin: 0 0 var(--space-2);
    letter-spacing: var(--tracking-tight);
}
.section-subtitle {
    font-size: var(--fs-body);
    color: var(--color-muted);
    margin: 0 0 var(--space-5);
}
.eyebrow {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: var(--fs-small);
    font-weight: var(--fw-bold);
    color: var(--color-primary);
    letter-spacing: var(--tracking-mono);
    text-transform: uppercase;
    margin-bottom: var(--space-3);
}

@media (max-width: 768px) {
    .page-title    { font-size: var(--fs-h1-mobile); }
    .section-title { font-size: var(--fs-h2-mobile); }
}

/* ════════════════════════════════════════════════════════════════════
 * BUTTONS
 * ════════════════════════════════════════════════════════════════════ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    height: var(--btn-h-md);
    padding: 0 var(--btn-px-md);
    border-radius: var(--radius-md);
    border: 1.5px solid transparent;
    font-family: var(--font-sans);
    font-size: var(--fs-small);
    font-weight: var(--fw-bold);
    line-height: 1;
    letter-spacing: var(--tracking-normal);
    cursor: pointer;
    text-decoration: none;
    transition: all var(--dur-base) var(--ease);
    user-select: none;
    white-space: nowrap;
}
.btn:focus-visible { outline: none; box-shadow: var(--shadow-focus); }
.btn:disabled, .btn[aria-disabled="true"] {
    opacity: .55; cursor: not-allowed; pointer-events: none;
}
.btn i, .btn .fa, .btn .fas, .btn .far { font-size: 0.95em; }

/* Sizes */
.btn-sm { height: var(--btn-h-sm); padding: 0 var(--btn-px-sm); font-size: var(--fs-micro); }
.btn-md { height: var(--btn-h-md); padding: 0 var(--btn-px-md); }
.btn-lg { height: var(--btn-h-lg); padding: 0 var(--btn-px-lg); font-size: var(--fs-body); }

/* Variants — RED primary */
.btn-primary {
    background: var(--color-primary);
    color: var(--color-on-dark);
    border-color: var(--color-primary);
    box-shadow: 0 4px 12px rgba(185, 28, 28, .22);
}
.btn-primary:hover:not(:disabled) {
    background: var(--color-primary-hover);
    border-color: var(--color-primary-hover);
    color: var(--color-on-dark);
    transform: translateY(-1px);
    box-shadow: 0 6px 18px rgba(185, 28, 28, .30);
}

/* Secondary — navy (cool contrast to the red primary) */
.btn-secondary {
    background: var(--color-secondary);
    color: var(--color-on-dark);
    border-color: var(--color-secondary);
    box-shadow: 0 4px 12px rgba(30, 58, 138, .22);
}
.btn-secondary:hover:not(:disabled) {
    background: var(--color-secondary-hover);
    border-color: var(--color-secondary-hover);
    color: var(--color-on-dark);
    transform: translateY(-1px);
}

/* Outline (neutral) */
.btn-outline {
    background: var(--color-surface);
    color: var(--color-text);
    border-color: var(--color-border);
}
.btn-outline:hover:not(:disabled) {
    border-color: var(--color-primary);
    color: var(--color-primary);
    transform: translateY(-1px);
}

/* Ghost */
.btn-ghost {
    background: transparent;
    color: var(--color-text);
    border-color: transparent;
}
.btn-ghost:hover:not(:disabled) {
    background: var(--color-soft);
    color: var(--color-text);
}

/* Danger — restyled as AMBER warning (no red allowed in brand) */
.btn-danger {
    background: var(--color-warning);
    color: var(--color-on-dark);
    border-color: var(--color-warning);
    box-shadow: 0 4px 12px rgba(245, 158, 11, .22);
}
.btn-danger:hover:not(:disabled) {
    background: var(--color-warning);
    border-color: var(--color-warning);
    color: var(--color-on-dark);
    transform: translateY(-1px);
}

/* Success — GREEN (color-correct). KHÔNG dùng --color-secondary vì secondary là hồng/đỏ. */
.btn-success {
    background: var(--color-correct, var(--color-correct));
    color: var(--color-on-dark);
    border-color: var(--color-correct, var(--color-correct));
}
.btn-success:hover:not(:disabled) {
    background: var(--color-correct-deep, var(--color-correct-deep));
    border-color: var(--color-correct-deep, var(--color-correct-deep));
    color: var(--color-on-dark);
    transform: translateY(-1px);
}

/* Accent — terracotta (AI / premium / special) */
.btn-accent {
    background: var(--color-accent);
    color: var(--color-on-dark);
    border-color: var(--color-accent);
    box-shadow: 0 4px 12px rgba(180, 90, 60, .22);
}
.btn-accent:hover:not(:disabled) {
    background: var(--color-accent-hover);
    border-color: var(--color-accent-hover);
    color: var(--color-on-dark);
    transform: translateY(-1px);
}

/* Locked — gray, non-actionable visual */
.btn-locked {
    background: var(--color-locked-soft);
    color: var(--color-locked-deep);
    border-color: var(--color-border);
    cursor: not-allowed;
}
.btn-locked:hover { transform: none; }

.btn-pill { border-radius: var(--radius-pill); }
.btn-block { width: 100%; }

.btn-group { display: inline-flex; gap: var(--space-2); flex-wrap: wrap; }

/* ════════════════════════════════════════════════════════════════════
 * CARDS
 * ════════════════════════════════════════════════════════════════════ */
.ui-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-6);
    transition: border-color var(--dur-base) var(--ease),
                box-shadow var(--dur-base) var(--ease),
                transform var(--dur-base) var(--ease);
}
.ui-card-hover:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}
.ui-card-flat { box-shadow: none; }
.ui-card-elevated { box-shadow: var(--shadow-md); border-color: transparent; }

/* Premium card (red accent) */
.ui-card-premium {
    background: linear-gradient(135deg, var(--color-accent-soft), var(--color-surface));
    border-color: var(--color-accent);
}

/* Locked card */
.ui-card-locked {
    background: var(--color-locked-soft);
    border-color: var(--color-border);
    color: var(--color-locked-deep);
}
.ui-card-locked .ui-card-title { color: var(--color-locked-deep); }

.ui-card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-3);
    padding-bottom: var(--space-4);
    margin-bottom: var(--space-4);
    border-bottom: 1px solid var(--color-line);
}
.ui-card-title {
    font-size: var(--fs-h4);
    font-weight: var(--fw-semibold);
    color: var(--color-ink);
    margin: 0;
    letter-spacing: var(--tracking-tight);
}
.ui-card-subtitle {
    font-size: var(--fs-small);
    color: var(--color-muted);
    margin: var(--space-1) 0 0;
}
.ui-card-body {}
.ui-card-footer {
    display: flex;
    justify-content: flex-end;
    gap: var(--space-2);
    padding-top: var(--space-4);
    margin-top: var(--space-4);
    border-top: 1px solid var(--color-line);
}

/* ── Icon tile ──────────────────────────────────────────────────────────────
 * FA icon centered in a soft tone-colored rounded square (brand icon style).
 * Replaces emoji-as-icon across cards/sections/tiles. Tone = brand palette.
 * Default = neutral; add --primary/secondary/accent/warning/locked for color.
 * When placed inside a hovering link/button/.ui-card-hover, the tile fills with
 * the solid tone + white icon (matches the vocab "Chọn chế độ học" cards).
 * Usage: <span class="ui-icon-tile ui-icon-tile--primary"><i class="fas fa-book-open"></i></span>
 */
.ui-icon-tile {
    display: inline-flex; align-items: center; justify-content: center;
    flex-shrink: 0;
    width: 48px; height: 48px;
    border-radius: var(--radius-md);
    background: var(--color-soft);
    color: var(--color-muted);
    font-size: 20px; line-height: 1;
    transition: background var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
}
.ui-icon-tile.is-sm { width: 40px; height: 40px; font-size: 17px; }
.ui-icon-tile.is-lg { width: 56px; height: 56px; font-size: 24px; }
.ui-icon-tile--primary   { background: var(--color-primary-soft);   color: var(--color-primary); }
.ui-icon-tile--secondary { background: var(--color-secondary-soft); color: var(--color-secondary); }
.ui-icon-tile--accent    { background: var(--color-accent-soft);    color: var(--color-accent); }
.ui-icon-tile--warning   { background: var(--color-warning-soft);   color: var(--color-warning); }
.ui-icon-tile--locked    { background: var(--color-locked-soft);    color: var(--color-locked-deep); }
:where(a, button, .ui-card-hover, .ui-icon-tile-fillon):hover .ui-icon-tile--primary   { background: var(--color-primary);   color: var(--color-on-dark); }
:where(a, button, .ui-card-hover, .ui-icon-tile-fillon):hover .ui-icon-tile--secondary { background: var(--color-secondary); color: var(--color-on-dark); }
:where(a, button, .ui-card-hover, .ui-icon-tile-fillon):hover .ui-icon-tile--accent    { background: var(--color-accent);    color: var(--color-on-dark); }
:where(a, button, .ui-card-hover, .ui-icon-tile-fillon):hover .ui-icon-tile--warning   { background: var(--color-warning);   color: var(--color-on-dark); }
:where(a, button, .ui-card-hover, .ui-icon-tile-fillon):hover .ui-icon-tile--locked    { background: var(--color-locked);    color: var(--color-on-dark); }

/* ════════════════════════════════════════════════════════════════════
 * FORMS
 * ════════════════════════════════════════════════════════════════════ */
.form-group {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
    margin-bottom: var(--space-4);
}
.form-label {
    font-size: var(--fs-small);
    font-weight: var(--fw-semibold);
    color: var(--color-text);
    line-height: 1.3;
}
.form-label .form-required { color: var(--color-warning); margin-left: 2px; }
.form-help {
    font-size: var(--fs-micro);
    color: var(--color-muted);
    margin-top: var(--space-1);
}

.form-control {
    display: block;
    width: 100%;
    height: var(--input-h);
    padding: 0 var(--input-px);
    font-family: var(--font-sans);
    font-size: var(--fs-body);
    line-height: 1.4;
    color: var(--color-text);
    background: var(--color-surface);
    border: 1.5px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: border-color var(--dur-base) var(--ease),
                box-shadow var(--dur-base) var(--ease);
}
/* Placeholder: dùng token để luôn nhìn rõ ở cả sáng/tối (mặc định trình duyệt quá tối trên nền dark). */
.form-control::placeholder { color: var(--color-mute2); opacity: 1; }
textarea.form-control {
    height: auto;
    min-height: 96px;
    padding: var(--space-3) var(--input-px);
    line-height: var(--lh-normal);
    resize: vertical;
}
select.form-control {
    appearance: none;
    background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'><path d='M1 1l5 5 5-5' stroke='%2364748B' stroke-width='1.5' fill='none' stroke-linecap='round' stroke-linejoin='round'/></svg>");
    background-repeat: no-repeat;
    background-position: right 14px center;
    padding-right: 36px;
}

.form-control:hover { border-color: var(--color-mute2); }
.form-control:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: var(--shadow-focus);
}
.form-control:disabled { background: var(--color-soft); cursor: not-allowed; }
/* Nền tối: bootstrap '.form-control:focus{background-color:var(--bs-body-bg);color:var(--bs-body-color)}' thắng
   (quy tắc trên không khai nền/chữ) ⇒ ô đang gõ thành nền TRẮNG chữ đen. Chỉ áp ở tối — nền sáng không đổi. */
html[data-user-theme="dark"] .form-control:focus { background-color: var(--color-surface); color: var(--color-text); }
@media (prefers-color-scheme: dark) {
    html[data-user-theme="system"] .form-control:focus { background-color: var(--color-surface); color: var(--color-text); }
}

.form-control.is-invalid { border-color: var(--color-warning); }
.form-control.is-invalid:focus { box-shadow: 0 0 0 3px rgba(245, 158, 11, .22); }
.form-error {
    font-size: var(--fs-micro);
    color: var(--color-warning-deep);
    margin-top: var(--space-1);
    display: flex;
    align-items: center;
    gap: 6px;
}

.form-check {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    cursor: pointer;
    font-size: var(--fs-small);
}
.form-check input[type="checkbox"],
.form-check input[type="radio"] {
    width: 18px; height: 18px; accent-color: var(--color-primary);
}

/* ════════════════════════════════════════════════════════════════════
 * TABLES
 * ════════════════════════════════════════════════════════════════════ */
.ui-table-wrap {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
}
.ui-table {
    width: 100%;
    border-collapse: collapse;
    font-size: var(--fs-small);
}
.ui-table thead th {
    background: var(--color-soft);
    color: var(--color-muted);
    font-weight: var(--fw-bold);
    font-size: var(--fs-micro);
    text-transform: uppercase;
    letter-spacing: var(--tracking-wide);
    padding: var(--space-3) var(--space-4);
    text-align: left;
    border-bottom: 1px solid var(--color-border);
}
.ui-table tbody td {
    padding: var(--space-4);
    border-bottom: 1px solid var(--color-line);
    color: var(--color-text);
    vertical-align: middle;
}
.ui-table tbody tr:last-child td { border-bottom: none; }
.ui-table tbody tr:hover td { background: var(--color-bg); }
.ui-table .ui-table-actions { display: flex; gap: var(--space-2); justify-content: flex-end; }

.ui-table-empty {
    text-align: center;
    padding: var(--space-12) var(--space-6);
    color: var(--color-muted);
    font-size: var(--fs-small);
}

/* ════════════════════════════════════════════════════════════════════
 * BADGES — only primary/secondary/accent/warning/muted
 * ════════════════════════════════════════════════════════════════════ */
.badge {
    display: inline-flex;
    align-items: center;
    gap: 5px;
    padding: 3px 10px;
    border-radius: var(--radius-pill);
    font-family: var(--font-mono);
    font-size: var(--fs-micro);
    font-weight: var(--fw-bold);
    line-height: 1.4;
    letter-spacing: var(--tracking-wide);
    background: var(--color-soft);
    color: var(--color-muted);
}
.badge-primary   { background: var(--color-primary-soft);   color: var(--color-primary-hover); }
.badge-secondary { background: var(--color-secondary-soft); color: var(--color-secondary-hover); }
.badge-accent    { background: var(--color-accent-soft);    color: var(--color-accent-hover); }
.badge-warning   { background: var(--color-warning-soft);   color: var(--color-warning-deep); }
.badge-locked    { background: var(--color-locked-soft);    color: var(--color-locked-deep); }
.badge-muted     { background: var(--color-soft);           color: var(--color-muted); }
.badge-dark      { background: var(--color-inverse-surface);            color: var(--color-on-dark); }
/* Legacy aliases — point at brand-appropriate colors */
.badge-success   { background: var(--color-correct-soft, var(--color-correct-soft)); color: var(--color-correct-deep, var(--color-correct-deep)); }
.badge-danger    { background: var(--color-warning-soft);   color: var(--color-warning-deep); }
.badge-info      { background: var(--color-accent-soft);    color: var(--color-accent-hover); }

/* "Premium" badge utility — pink */
.badge-premium {
    background: var(--color-accent);
    color: var(--color-on-dark);
}

/* ════════════════════════════════════════════════════════════════════
 * ALERTS
 * ════════════════════════════════════════════════════════════════════ */
.ui-alert {
    display: flex;
    gap: var(--space-3);
    padding: var(--space-4) var(--space-5);
    border-radius: var(--radius-md);
    border-left: 4px solid var(--color-accent);
    background: var(--color-accent-soft);
    color: var(--color-accent-deep);
    font-size: var(--fs-small);
    line-height: var(--lh-normal);
    margin-bottom: var(--space-4);
}
.ui-alert i { margin-top: 2px; flex-shrink: 0; }
.ui-alert-success { border-color: var(--color-correct, var(--color-correct)); background: var(--color-correct-soft, var(--color-correct-soft)); color: var(--color-correct-deep, var(--color-correct-deep)); }
.ui-alert-warning { border-color: var(--color-warning);   background: var(--color-warning-soft);   color: var(--color-warning-deep); }
.ui-alert-locked  { border-color: var(--color-locked);    background: var(--color-locked-soft);    color: var(--color-locked-deep); }
/* Legacy: "danger" → warning (no red) */
.ui-alert-danger  { border-color: var(--color-warning);   background: var(--color-warning-soft);   color: var(--color-warning-deep); }
.ui-alert-info    { border-color: var(--color-accent);    background: var(--color-accent-soft);    color: var(--color-accent-deep); }

/* ════════════════════════════════════════════════════════════════════
 * UTILITIES
 * ════════════════════════════════════════════════════════════════════ */
.ui-link {
    color: var(--color-primary);
    text-decoration: none;
    font-weight: var(--fw-semibold);
    border-bottom: 1px solid transparent;
    transition: border-color var(--dur-fast) var(--ease);
}
.ui-link:hover { border-color: var(--color-primary); color: var(--color-primary-hover); }

.ui-divider {
    height: 1px;
    background: var(--color-border);
    margin: var(--space-6) 0;
    border: none;
}

.ui-stack-2 > * + * { margin-top: var(--space-2); }
.ui-stack-3 > * + * { margin-top: var(--space-3); }
.ui-stack-4 > * + * { margin-top: var(--space-4); }
.ui-stack-6 > * + * { margin-top: var(--space-6); }

.ui-text-muted   { color: var(--color-muted); }
.ui-text-mono    { font-family: var(--font-mono); }
.ui-text-center  { text-align: center; }

/* Premium / Locked state helpers */
.is-premium { color: var(--color-accent); }
.is-locked  { color: var(--color-locked); }
.is-success { color: var(--color-correct, var(--color-correct)); }

/* ════════════════════════════════════════════════════════════════════
 * PAGE SHELL — khung nội dung rộng thống nhất mọi trang
 * ════════════════════════════════════════════════════════════════════ */
.page-shell {
    width: 100%;
    max-width: var(--page-w, 1200px);
    margin-inline: auto;
    padding: var(--space-6) var(--space-5);
}
.page-shell-narrow { max-width: 760px; }
@media (max-width: 640px) { .page-shell { padding: var(--space-5) var(--space-4); } }

/* ════════════════════════════════════════════════════════════════════
 * MODAL (.ui-modal-* — prefix ui- để KHÔNG đụng .modal của Bootstrap)
 * ════════════════════════════════════════════════════════════════════ */
.ui-modal-overlay {
    position: fixed; inset: 0; z-index: var(--z-modal, 1050);
    display: none; align-items: center; justify-content: center;
    padding: var(--space-5);
    background: color-mix(in srgb, var(--color-ink) 55%, transparent);
    -webkit-backdrop-filter: blur(4px); backdrop-filter: blur(4px);
}
.ui-modal-overlay.is-open { display: flex; }
.ui-modal {
    width: 100%; max-width: 480px;
    max-height: calc(100vh - var(--space-12));
    display: flex; flex-direction: column; overflow: hidden;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    animation: ui-modal-in .22s var(--ease);
}
@keyframes ui-modal-in { from { opacity: 0; transform: translateY(12px) scale(.98); } to { opacity: 1; transform: none; } }
.ui-modal-sm { max-width: 384px; }
.ui-modal-lg { max-width: 720px; }
.ui-modal-header {
    display: flex; align-items: center; justify-content: space-between; gap: var(--space-3);
    padding: var(--space-5) var(--space-5) var(--space-4);
    border-bottom: 1px solid var(--color-line);
}
.ui-modal-title { font-size: var(--fs-h4); font-weight: var(--fw-bold); color: var(--color-ink); margin: 0; }
.ui-modal-close {
    flex-shrink: 0; width: 32px; height: 32px; border-radius: var(--radius-sm);
    border: none; background: transparent; color: var(--color-muted); cursor: pointer;
    display: inline-flex; align-items: center; justify-content: center; font-size: 15px;
    transition: background var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
}
.ui-modal-close:hover { background: var(--color-soft); color: var(--color-ink); }
.ui-modal-body { padding: var(--space-5); overflow-y: auto; color: var(--color-text); font-size: var(--fs-small); line-height: var(--lh-normal); }
.ui-modal-footer {
    display: flex; align-items: center; justify-content: flex-end; gap: var(--space-3);
    padding: var(--space-4) var(--space-5); border-top: 1px solid var(--color-line);
}
/* Alert/confirm — icon giữa */
.ui-modal-alert { max-width: 420px; text-align: center; }
.ui-modal-alert .ui-modal-body { padding: var(--space-6) var(--space-6) var(--space-2); }
.ui-modal-alert .ui-modal-footer { justify-content: center; border-top: none; padding-top: var(--space-2); }
.ui-modal-alert__icon {
    width: 56px; height: 56px; margin: 0 auto var(--space-4); border-radius: var(--radius-pill);
    display: flex; align-items: center; justify-content: center; font-size: 24px;
    background: var(--color-primary-soft); color: var(--color-primary);
}
.ui-modal-alert__icon[data-tone="warning"] { background: var(--color-warning-soft); color: var(--color-warning-deep); }
.ui-modal-alert__icon[data-tone="success"] { background: var(--color-correct-soft, var(--color-correct-soft)); color: var(--color-correct-deep, var(--color-correct-deep)); }

/* ════════════════════════════════════════════════════════════════════
 * TABS (.ui-tabs / .ui-tab)
 * ════════════════════════════════════════════════════════════════════ */
.ui-tabs {
    display: flex; gap: 0; overflow-x: auto;
    border-bottom: 1px solid var(--color-border);
    margin-bottom: var(--space-5);
}
.ui-tab {
    flex-shrink: 0; display: inline-flex; align-items: center; gap: var(--space-2);
    padding: var(--space-3) var(--space-4); margin-bottom: -1px;
    border: none; background: transparent; cursor: pointer; text-decoration: none;
    font-size: var(--fs-small); font-weight: var(--fw-semibold); color: var(--color-muted);
    border-bottom: 2px solid transparent;
    transition: color var(--dur-fast) var(--ease), border-color var(--dur-fast) var(--ease);
}
.ui-tab:hover { color: var(--color-text); }
.ui-tab.is-active { color: var(--color-primary); border-bottom-color: var(--color-primary); }

/* ════════════════════════════════════════════════════════════════════
 * PAGINATION (.ui-pagination)
 * ════════════════════════════════════════════════════════════════════ */
.ui-pagination {
    display: flex; flex-wrap: wrap; align-items: center; justify-content: center;
    gap: var(--space-1); margin: var(--space-6) 0;
}
.ui-pagination a, .ui-pagination span {
    min-width: 38px; height: 38px; padding: 0 var(--space-3);
    display: inline-flex; align-items: center; justify-content: center;
    border: 1px solid var(--color-border); border-radius: var(--radius-md);
    background: var(--color-surface); color: var(--color-text);
    font-size: var(--fs-small); font-weight: var(--fw-semibold); text-decoration: none;
    transition: all var(--dur-fast) var(--ease);
}
.ui-pagination a:hover { border-color: var(--color-primary); color: var(--color-primary); }
.ui-pagination .is-active { background: var(--color-primary); border-color: var(--color-primary); color: var(--color-on-dark); }
.ui-pagination .is-disabled { opacity: .5; pointer-events: none; }

/* ════════════════════════════════════════════════════════════════════
 * EMPTY STATE (.ui-empty)
 * ════════════════════════════════════════════════════════════════════ */
.ui-empty {
    display: flex; flex-direction: column; align-items: center; text-align: center;
    padding: var(--space-12) var(--space-6); color: var(--color-muted);
}
.ui-empty__icon {
    width: 64px; height: 64px; margin-bottom: var(--space-4); border-radius: var(--radius-pill);
    display: flex; align-items: center; justify-content: center; font-size: 28px;
    background: var(--color-soft); color: var(--color-mute2);
}
.ui-empty__title { font-size: var(--fs-h4); font-weight: var(--fw-bold); color: var(--color-ink); margin: 0 0 var(--space-2); }
.ui-empty__hint { max-width: 380px; margin: 0 0 var(--space-4); font-size: var(--fs-small); color: var(--color-muted); line-height: var(--lh-normal); }

/* ════════════════════════════════════════════════════════════════════
 * BUTTON STATES — active + loading (unified site-wide, request §6)
 * ════════════════════════════════════════════════════════════════════ */
.btn:active:not(:disabled) { transform: translateY(0) scale(.985); }

/* Loading — hide the label, show a spinner, block clicks.
 * JS: btn.classList.add('is-loading') while an async action runs. */
.btn.is-loading { color: transparent !important; pointer-events: none; position: relative; }
.btn.is-loading::after {
    content: ""; position: absolute;
    width: 1em; height: 1em; top: calc(50% - .5em); left: calc(50% - .5em);
    border: 2px solid var(--color-on-dark); border-right-color: transparent;
    border-radius: 50%;
    animation: ui-btn-spin .6s linear infinite;
}
.btn-outline.is-loading::after,
.btn-ghost.is-loading::after,
.btn-locked.is-loading::after { border-color: var(--color-primary); border-right-color: transparent; }
@keyframes ui-btn-spin { to { transform: rotate(360deg); } }

/* ════════════════════════════════════════════════════════════════════
 * NAVIGATION ACTIONS — unified Back / Continue / Retry / Results / Start
 * ONE layout + ONE icon convention for every learning / quiz / lesson /
 * detail page. Back is always the subdued button, never louder than the
 * primary CTA. Prefer the PHP partial: templates/components/page-nav.php
 *   Back      → .btn .btn-ghost .btn-prev    + <i class="fas fa-arrow-left">
 *   Continue  → .btn .btn-primary .btn-next  + <i class="fas fa-arrow-right"> (icon last)
 *   Retry     → .btn .btn-outline            + <i class="fas fa-rotate-right">
 *   Results   → .btn .btn-primary            + <i class="fas fa-flag-checkered">
 *   Start     → .btn .btn-primary .btn-lg    + <i class="fas fa-play">
 * ════════════════════════════════════════════════════════════════════ */
.ui-nav-actions {
    display: flex; align-items: center; justify-content: space-between;
    gap: var(--space-3); flex-wrap: wrap;
    margin-top: var(--space-6);
    padding-top: var(--space-5);
    border-top: 1px solid var(--color-line);
}
.ui-nav-actions--flush  { border-top: none; padding-top: 0; }
.ui-nav-actions--end    { justify-content: flex-end; }
.ui-nav-actions--center { justify-content: center; }
.ui-nav-actions__group  { display: inline-flex; align-items: center; gap: var(--space-2); flex-wrap: wrap; }

/* Directional micro-nudge on hover — back nudges left, next nudges right.
 * Replaces the scattered per-page translateX(-2px/2px/3px) values. */
.btn-prev:hover:not(:disabled) { transform: translateX(-2px); }
.btn-next:hover:not(:disabled) { transform: translateX(2px); }
/* Coloured CTAs keep their vertical lift AND nudge right. */
.btn-primary.btn-next:hover:not(:disabled),
.btn-secondary.btn-next:hover:not(:disabled),
.btn-accent.btn-next:hover:not(:disabled),
.btn-success.btn-next:hover:not(:disabled) { transform: translate(2px, -1px); }

/* Sticky bottom lesson nav — pins the Back/Next bar on long pages. */
.ui-nav-actions--sticky {
    position: sticky; bottom: 0; z-index: var(--z-sticky, 200);
    padding: var(--space-3) var(--space-4);
    padding-bottom: calc(var(--space-3) + env(safe-area-inset-bottom, 0px));
    background: color-mix(in srgb, var(--color-surface) 92%, transparent);
    -webkit-backdrop-filter: blur(10px); backdrop-filter: blur(10px);
    border-top: 1px solid var(--color-border);
}

@media (max-width: 560px) {
    .ui-nav-actions .btn        { flex: 1 1 auto; }   /* full-width friendly on phones */
    .ui-nav-actions__group .btn { flex: 1 1 auto; }
}