/* =============================================
   Grade-Wise Learning — styles
   Builds on the CSS variables defined in style.css
   ============================================= */

/* Unit pages use the full screen width (capped so lines stay readable on huge monitors) */
.ul-main { max-width: 1480px; padding-top: 1.2rem; }
.header-inner.ul-wide { max-width: 1480px; }

.ul-notice {
    background: #FFF3E0;
    color: #E65100;
    border: 2px solid #FFE0B2;
    border-radius: var(--radius-sm);
    padding: 0.8rem 1.2rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    text-align: center;
}

.ul-muted { color: var(--gray); font-size: 0.86rem; line-height: 1.5; }
.ul-block { width: 100%; margin-top: 0.6rem; }

/* ===== Catalog (units home) =====
   The hierarchy is Grade → Unit → Topics, so a grade heading rules across the
   page and each unit card lists the topics that live inside it. */
.ul-grade-nav {
    display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem;
    margin-bottom: 1.6rem;
}
.ul-grade-pill {
    font-family: var(--font-main); font-weight: 700; font-size: 0.95rem;
    color: var(--purple); background: var(--white);
    border: 2px solid var(--border); border-radius: 999px;
    padding: 0.4rem 1.1rem; text-decoration: none;
    box-shadow: var(--shadow-sm); transition: var(--transition);
}
.ul-grade-pill:hover, .ul-grade-pill:focus-visible {
    border-color: var(--purple); background: var(--purple-light); color: var(--purple-dark);
}
.ul-grade-pill.is-active {
    background: var(--purple); border-color: var(--purple); color: var(--white);
}
/* Shares the row with the grade pills but does something else: it leaves the
   page instead of filtering it, so it gets its own colour rather than passing
   as a fourth grade. */
.ul-marathon-pill {
    background: var(--green); border-color: var(--green); color: var(--white);
    margin-left: 0.4rem;
}
.ul-marathon-pill:hover, .ul-marathon-pill:focus-visible {
    background: #0c8f6f; border-color: #0c8f6f; color: var(--white);
}

.ul-grade-block { margin-bottom: 2rem; }
.ul-grade-heading {
    display: flex; align-items: center; gap: 0.9rem;
    font-family: var(--font-main); font-weight: 800; font-size: 1.25rem;
    color: var(--dark); margin-bottom: 1rem;
}
.ul-grade-heading::after {
    content: ''; flex: 1; height: 3px; border-radius: 2px; background: var(--border);
}

/* Sits above the grade tabs and stays put whichever grade is chosen, because
   it isn't one of them. */
.ul-anygrade-note {
    font-family: var(--font-body); font-size: 0.88rem; color: var(--gray);
    margin: -0.6rem 0 0.9rem;
}

.ul-catalog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.1rem;
}

/* The card is a container rather than one big <a>, because an anchor can't
   contain anchors and each topic needs its own link. Clicking anywhere on the
   card still opens the unit: the title link stretches an invisible overlay
   across it, and the topic links sit above that overlay. */
.ul-catalog-card {
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
    background: white;
    border-radius: var(--radius);
    padding: 1.2rem 1.3rem;
    color: inherit;
    box-shadow: var(--shadow-sm);
    border: 3px solid transparent;
    transition: var(--transition);
}
.ul-catalog-card:not(.ul-catalog-card-disabled):hover {
    box-shadow: var(--shadow);
    border-color: var(--purple);
}
.ul-catalog-card-disabled {
    opacity: 0.55;
    cursor: default;
}

.ul-catalog-head { display: flex; align-items: center; gap: 0.8rem; }
.ul-catalog-emoji { font-size: 2rem; line-height: 1; }
.ul-catalog-kicker {
    display: block; font-family: var(--font-main); font-weight: 800; font-size: 0.68rem;
    color: var(--purple); text-transform: uppercase; letter-spacing: 0.6px;
}
.ul-catalog-title {
    display: block; font-family: var(--font-main); font-weight: 800; font-size: 1.2rem;
    line-height: 1.25; color: var(--dark); text-decoration: none;
}
a.ul-catalog-title {
    color: var(--purple);
    text-decoration: underline;
    text-decoration-thickness: 2px;
    text-underline-offset: 3px;
    text-decoration-color: rgba(108, 99, 255, 0.35);
}
a.ul-catalog-title:hover { color: var(--purple-dark); text-decoration-color: var(--purple-dark); }
/* the overlay that makes the whole card open the unit */
a.ul-catalog-title::after { content: ''; position: absolute; inset: 0; z-index: 1; border-radius: var(--radius); }
.ul-catalog-desc { font-size: 0.85rem; color: var(--gray); line-height: 1.4; }

.ul-catalog-topics { border-top: 1.5px solid var(--border); padding-top: 0.7rem; }
.ul-catalog-topics-label {
    font-family: var(--font-main); font-weight: 800; font-size: 0.72rem;
    color: var(--gray); text-transform: uppercase; letter-spacing: 0.4px; margin-bottom: 0.45rem;
}
.ul-catalog-topic-list {
    margin: 0; padding-left: 1.15rem;
    font-size: 0.85rem; line-height: 1.75; color: var(--gray); font-weight: 600;
}
.ul-catalog-topic-list li { margin-bottom: 0.15rem; }
/* these read as links on sight, not only on hover */
.ul-catalog-topic-list a {
    position: relative; z-index: 2;   /* above the card-wide overlay */
    color: var(--purple);
    text-decoration: underline;
    text-decoration-thickness: 1.5px;
    text-underline-offset: 3px;
    text-decoration-color: rgba(108, 99, 255, 0.45);
    border-radius: var(--radius-xs); padding: 0.05rem 0.25rem; margin-left: -0.25rem;
    transition: var(--transition);
}
.ul-catalog-topic-list a:hover {
    color: var(--purple-dark);
    background: var(--purple-light);
    text-decoration-color: var(--purple-dark);
}
.ul-catalog-topic-list a:focus-visible {
    outline: 3px solid rgba(108,99,255,0.5); outline-offset: 1px;
}
.ul-catalog-cta {
    position: relative; z-index: 2;   /* above the card-wide overlay */
    margin-top: auto; align-self: flex-start;
    font-family: var(--font-main); font-weight: 800;
    font-size: 0.9rem; color: var(--purple); text-decoration: none;
}
.ul-catalog-cta:hover { text-decoration: underline; }
.ul-catalog-badge {
    margin-top: auto; display: inline-block; align-self: flex-start;
    font-size: 0.7rem; font-weight: 800;
    background: var(--border); color: var(--gray); padding: 0.15rem 0.6rem; border-radius: 20px;
    text-transform: uppercase; letter-spacing: 0.3px;
}

/* ===== Page heading ===== */
.ul-crumbs {
    display: flex; flex-wrap: wrap; gap: 0.45rem; align-items: center;
    font-family: var(--font-main); font-size: 0.82rem; font-weight: 600; color: var(--gray);
    margin-bottom: 0.5rem;
}
.ul-crumbs a { color: var(--purple); text-decoration: none; }
.ul-crumbs a:hover { text-decoration: underline; }
.ul-crumbs [aria-current] { color: var(--dark); }

.ul-page-head { margin-bottom: 1.2rem; }
.ul-page-head h1 { font-family: var(--font-main); font-size: 1.9rem; font-weight: 800; color: var(--dark); line-height: 1.25; }
.ul-page-head p { color: var(--gray); font-size: 0.98rem; margin-top: 0.2rem; }

/* ===== Buttons ===== */
.ul-next-btn {
    background: linear-gradient(135deg, var(--purple), #8e87ff);
    color: white; border: none; border-radius: 50px; padding: 0.75rem 1.6rem;
    font-family: var(--font-main); font-weight: 700; font-size: 0.98rem; cursor: pointer;
    transition: var(--transition);
}
.ul-next-btn:hover { transform: translateY(-2px); box-shadow: 0 6px 18px rgba(108,99,255,0.35); }
.ul-next-btn:focus-visible, .ul-prev-btn:focus-visible, .ul-tile:focus-visible, .ul-dot:focus-visible,
.ul-skip-btn:focus-visible, .ul-side-link:focus-visible, .ul-check-btn-lg:focus-visible {
    outline: 3px solid rgba(108,99,255,0.5); outline-offset: 3px;
}

.ul-prev-btn {
    background: white; border: 2px solid var(--border); color: var(--gray);
    border-radius: 50px; padding: 0.65rem 1.25rem; font-family: var(--font-main); font-weight: 700;
    font-size: 0.9rem; cursor: pointer; transition: var(--transition);
}
.ul-prev-btn:hover { border-color: var(--purple); color: var(--purple); }

.ul-skip-btn {
    background: none; border: none; color: var(--gray); cursor: pointer; padding: 0.6rem 0.4rem;
    font-family: var(--font-main); font-weight: 700; font-size: 0.9rem;
}
.ul-skip-btn:hover { color: var(--purple); text-decoration: underline; }

/* ===== Progress bar & score ring ===== */
.ul-bar { flex: 1; height: 10px; background: var(--border); border-radius: 20px; overflow: hidden; min-width: 60px; }
.ul-bar-fill { height: 100%; background: var(--purple); border-radius: 20px; transition: width 0.4s ease; }

.ul-ring { position: relative; flex-shrink: 0; }
.ul-ring svg { width: 100%; height: 100%; display: block; }
.ul-ring-md { width: 96px; height: 96px; }
.ul-ring-lg { width: 150px; height: 150px; }
.ul-ring-track { fill: none; stroke: var(--border); stroke-width: 9; }
.ul-ring-fill { fill: none; stroke: var(--green); stroke-width: 9; stroke-linecap: round; transition: stroke-dasharray 0.5s ease; }
.ul-ring-text { position: absolute; inset: 0; display: flex; flex-direction: column; align-items: center; justify-content: center; }
.ul-ring-num { font-family: var(--font-main); font-weight: 800; font-size: 1.6rem; color: var(--dark); line-height: 1; }
.ul-ring-lg .ul-ring-num { font-size: 2.6rem; }
.ul-ring-label { font-size: 0.7rem; font-weight: 800; color: var(--gray); text-transform: uppercase; letter-spacing: 0.5px; }

/* ===== Unit overview ===== */
.ul-ov-bar {
    display: flex; align-items: center; gap: 0.6rem 2rem; flex-wrap: wrap;
    background: white; border: 2px solid var(--border); border-radius: var(--radius);
    padding: 0.9rem 1.4rem; margin-bottom: 1.2rem;
}
.ul-ov-stat { display: flex; align-items: baseline; gap: 0.35rem; color: var(--gray); font-weight: 700; font-size: 0.9rem; }
.ul-ov-num { font-family: var(--font-main); font-weight: 800; font-size: 1.5rem; color: var(--dark); }
.ul-ov-progress { flex: 1; min-width: 180px; display: flex; }

/* Tiles stay compact — a unit can hold many topics, and this list is for
   picking one, not for reading the lesson from. */
.ul-topic-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 0.8rem;
}
.ul-topic-card {
    display: flex; flex-direction: column; gap: 0.7rem;
    background: white; border: 2px solid var(--border); border-top: 5px solid var(--topic-color);
    border-radius: 14px; padding: 0.85rem 1rem; text-decoration: none; color: inherit;
    transition: var(--transition);
}
.ul-topic-card:hover { border-color: var(--purple); border-top-color: var(--topic-color); box-shadow: var(--shadow); transform: translateY(-3px); }
.ul-topic-card:focus-visible { outline: 3px solid rgba(108,99,255,0.5); outline-offset: 3px; }
.ul-topic-head { display: flex; align-items: center; gap: 0.6rem; }
.ul-topic-code {
    width: 30px; height: 30px; border-radius: 8px; background: var(--dark); color: white; flex-shrink: 0;
    display: flex; align-items: center; justify-content: center; font-family: var(--font-main); font-weight: 800; font-size: 0.85rem;
}
.ul-topic-emoji { font-size: 1.5rem; line-height: 1; }
.ul-topic-title { font-family: var(--font-main); font-weight: 800; font-size: 1rem; color: var(--dark); line-height: 1.3; }
.ul-topic-meta { font-size: 0.78rem; color: var(--gray); font-weight: 700; }
.ul-topic-foot { display: flex; align-items: center; gap: 0.6rem; flex-wrap: wrap; border-top: 1.5px solid var(--border); padding-top: 0.6rem; }
.ul-topic-progress { display: flex; align-items: center; gap: 0.5rem; flex: 1 1 100%; font-size: 0.8rem; font-weight: 700; color: var(--gray); }
.ul-topic-status { font-size: 0.78rem; font-weight: 800; padding: 0.15rem 0.6rem; border-radius: 20px; background: var(--bg); color: var(--gray); }
.ul-status-in-progress { background: #FFF8E1; color: #A67C00; }
.ul-status-finished { background: #E8F5E9; color: #2E7D32; }
.ul-topic-cta { margin-left: auto; font-family: var(--font-main); font-weight: 800; color: var(--purple); font-size: 0.92rem; }

/* ===== Two-column topic layout ===== */
.ul-layout {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 320px;
    gap: 1.4rem;
    align-items: start;
}
.ul-layout-main { min-width: 0; }
.ul-side-sticky { position: sticky; top: 92px; display: flex; flex-direction: column; gap: 1rem; }

.ul-panel {
    background: white; border: 2px solid var(--border); border-radius: var(--radius);
    padding: 1.4rem 1.6rem; margin-bottom: 1.2rem;
}
.ul-side-card { background: white; border: 2px solid var(--border); border-radius: 14px; padding: 1rem 1.1rem; }
.ul-side-title { font-family: var(--font-main); font-weight: 800; font-size: 0.95rem; color: var(--dark); margin-bottom: 0.7rem; }

.ul-h2 { font-family: var(--font-main); font-weight: 800; font-size: 1.2rem; color: var(--dark); margin: 1.6rem 0 0.8rem; }
.ul-h2-flush { margin-top: 0; margin-bottom: 0.2rem; }
.ul-kicker {
    font-family: var(--font-main); font-weight: 800; font-size: 0.78rem; color: var(--purple);
    text-transform: uppercase; letter-spacing: 0.5px; margin-bottom: 0.4rem;
}

.ul-score-row { display: flex; align-items: center; gap: 1rem; margin-bottom: 0.5rem; }
.ul-big-num { font-family: var(--font-main); font-weight: 800; font-size: 2rem; color: var(--dark); line-height: 1; }
.ul-big-num span { font-size: 1rem; color: var(--gray); }

.ul-topic-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 0.2rem; }
.ul-topic-list a {
    display: flex; align-items: center; gap: 0.5rem; padding: 0.45rem 0.55rem; border-radius: 8px;
    text-decoration: none; color: var(--dark); font-size: 0.88rem; font-weight: 700;
}
.ul-topic-list a:hover { background: var(--bg); }
.ul-topic-list a.current { background: var(--purple-light); color: var(--purple); }
.ul-tl-title { flex: 1; }
.ul-tl-count { font-size: 0.75rem; color: var(--gray); font-weight: 700; }

/* ===== Lesson page ===== */
.ul-intro-panel { border-left: 6px solid var(--purple); }
.ul-lesson-blurb { color: var(--dark); font-size: 1.05rem; line-height: 1.7; margin: 0; }

.ul-concept-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
    gap: 1rem;
    align-items: start;
}
.ul-concept { background: white; border: 2px solid var(--border); border-radius: 14px; padding: 1rem 1.1rem; }
.ul-concept-text { display: flex; gap: 0.6rem; align-items: flex-start; font-size: 1rem; line-height: 1.6; color: var(--dark); font-weight: 600; }
.ul-concept-num {
    flex-shrink: 0; width: 28px; height: 28px; border-radius: 50%; background: var(--purple); color: white;
    display: flex; align-items: center; justify-content: center;
    font-family: var(--font-main); font-weight: 800; font-size: 0.85rem; margin-top: 0.05rem;
}

.ul-examples { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 1rem; }
.ul-example-card { background: white; border: 2px solid var(--border); border-radius: 14px; padding: 1rem 1.1rem; }
.ul-example-label {
    font-family: var(--font-main); font-size: 0.72rem; font-weight: 800;
    color: var(--teal-dark); text-transform: uppercase; letter-spacing: 0.4px; margin-bottom: 0.4rem;
}
.ul-example-prompt { font-size: 1.05rem; margin-bottom: 0.5rem; font-family: Georgia, serif; line-height: 1.8; }
.ul-example-steps { font-size: 0.88rem; color: var(--gray); line-height: 1.55; margin: 0 0 0.5rem; padding-left: 1.2rem; }
.ul-example-answer { font-family: var(--font-main); font-weight: 800; color: var(--green); font-size: 0.95rem; }

.ul-lesson-end {
    display: flex; align-items: center; justify-content: space-between; gap: 1rem; flex-wrap: wrap;
    margin-top: 1.4rem; background: var(--purple-light); border-radius: var(--radius); padding: 1rem 1.4rem;
    color: var(--dark); font-size: 0.98rem;
}

/* ===== Topic menu (learn or practise?) ===== */
.ul-choice-grid {
    display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 1rem; margin-top: 1.2rem;
}
.ul-choice {
    display: flex; flex-direction: column; align-items: flex-start; gap: 0.45rem;
    background: white; border: 2px solid var(--border); border-radius: var(--radius);
    padding: 1.6rem 1.4rem; cursor: pointer; text-align: left;
    font-family: var(--font-body); color: inherit; transition: var(--transition);
}
.ul-choice:hover { border-color: var(--purple); box-shadow: var(--shadow); transform: translateY(-3px); }
.ul-choice:focus-visible { outline: 3px solid rgba(108,99,255,0.5); outline-offset: 3px; }
.ul-choice-emoji { font-size: 2.2rem; line-height: 1; }
.ul-choice-title { font-family: var(--font-main); font-weight: 800; font-size: 1.35rem; color: var(--dark); }
.ul-choice-desc { font-size: 0.92rem; color: var(--gray); line-height: 1.5; }
.ul-choice-cta {
    margin-top: auto; padding-top: 0.7rem;
    font-family: var(--font-main); font-weight: 800; font-size: 0.95rem; color: var(--purple);
}
.ul-choice-practice { border-top: 6px solid var(--purple); }

.ul-back-link {
    background: none; border: none; padding: 0 0 0.7rem; cursor: pointer;
    font-family: var(--font-main); font-weight: 700; font-size: 0.9rem; color: var(--gray);
}
.ul-back-link:hover { color: var(--purple); }
.ul-back-link:focus-visible { outline: 3px solid rgba(108,99,255,0.5); outline-offset: 3px; border-radius: 6px; }

/* ===== Question page ===== */
.ul-part-banner {
    background: #FFF3E0; color: #9a4a00; border: 2px dashed #FFCC80; border-radius: var(--radius-sm);
    padding: 0.8rem 1.1rem; font-weight: 700; font-size: 0.95rem; line-height: 1.5; margin-bottom: 1rem;
}

.ul-q-panel { padding: 1.6rem 2rem 1.8rem; min-height: 420px; }
.ul-q-panel.is-correct { border-color: #9be3c8; }
.ul-q-panel.is-close   { border-color: #F0C94A; }
.ul-q-panel.is-wrong   { border-color: #ffb3b3; }

.ul-q-top { display: flex; align-items: center; gap: 0.8rem; flex-wrap: wrap; margin-bottom: 1.2rem; }
.ul-q-count { font-family: var(--font-main); font-weight: 800; font-size: 1.1rem; color: var(--dark); }
.ul-q-count span { color: var(--gray); font-weight: 600; }
.ul-chip {
    display: inline-flex; align-items: center; gap: 0.3rem;
    font-family: var(--font-main); font-weight: 700; font-size: 0.8rem; padding: 0.25rem 0.75rem;
    border-radius: 20px; background: var(--bg); color: var(--purple); border: 1.5px solid var(--border);
}
.ul-q-stars { margin-left: auto; color: var(--orange); letter-spacing: 2px; font-size: 1rem; }

.ul-q-prompt-lg {
    font-family: Georgia, serif; font-size: 1.6rem; line-height: 1.8; color: var(--dark);
    margin-bottom: 1.6rem; max-width: 60ch;
}
.ul-q-prompt-lg .ul-frac { font-size: 1.15em; }

.ul-tiles { display: flex; flex-wrap: wrap; gap: 0.8rem; margin-bottom: 1.2rem; }
.ul-tile {
    min-width: 130px; min-height: 64px; padding: 0.6rem 1.4rem;
    background: white; border: 2.5px solid var(--border); border-radius: 14px; cursor: pointer;
    font-family: var(--font-main); font-weight: 700; font-size: 1.2rem; color: var(--dark);
    box-shadow: 0 3px 0 var(--border); transition: var(--transition);
}
.ul-tiles-symbols .ul-tile { min-width: 96px; font-family: system-ui, sans-serif; font-size: 2rem; font-weight: 800; }
.ul-tile:hover:not(:disabled) { border-color: var(--purple); background: var(--purple-light); }
.ul-tile.selected { border-color: var(--purple); background: var(--purple); color: white; box-shadow: 0 3px 0 var(--purple-dark); }
.ul-tile:disabled { cursor: default; opacity: 0.55; }
.ul-tile.is-correct { opacity: 1; border-color: var(--green); background: #E8F5E9; color: #1b6b3a; box-shadow: 0 3px 0 #9be3c8; }
.ul-tile.is-wrong { opacity: 1; border-color: var(--coral); background: #FCE4EC; color: #C62828; box-shadow: 0 3px 0 #ffb3b3; text-decoration: line-through; }

/* ordering questions: each tile carries the position the student gave it */
.ul-tiles-order { align-items: stretch; }
.ul-tile-order { position: relative; min-width: 104px; padding-top: 1.1rem; }
.ul-tile-order .ul-tile-face { display: block; }
.ul-tile-rank {
    position: absolute; top: 5px; left: 50%; transform: translateX(-50%);
    min-width: 20px; height: 20px; padding: 0 5px; border-radius: 10px; line-height: 20px;
    font-family: var(--font-main); font-weight: 800; font-size: 0.72rem;
    color: var(--gray); background: var(--bg);
}
.ul-tile-rank:empty { background: none; }
.ul-tile-order.selected .ul-tile-rank { background: white; color: var(--purple); }
.ul-tile-order.is-correct .ul-tile-rank { background: white; color: #1b6b3a; }
.ul-tile-order.is-wrong .ul-tile-rank { background: white; color: #C62828; }
.ul-tile-order.is-wrong { text-decoration: none; }

.ul-input-row { display: flex; flex-direction: column; gap: 0.35rem; margin-bottom: 0.4rem; max-width: 360px; }
.ul-input-label { font-family: var(--font-main); font-weight: 700; font-size: 0.85rem; color: var(--gray); }
.ul-answer-input-lg {
    border: 2.5px solid var(--border); border-radius: 12px; padding: 0.8rem 1rem;
    font-size: 1.4rem; font-family: var(--font-main); font-weight: 700; color: var(--dark);
    background: var(--bg); outline: none; transition: var(--transition);
}
.ul-answer-input-lg:focus { border-color: var(--purple); background: white; box-shadow: 0 0 0 4px rgba(108,99,255,0.15); }
.ul-answer-input-lg:disabled { background: #f8f9ff; color: var(--gray); }
.ul-input-help { font-size: 0.82rem; color: var(--gray); margin-bottom: 1.1rem; }

.ul-warn {
    background: #FFF8E1; color: #7a5c00; border: 1.5px solid #F0C94A; border-radius: 10px;
    padding: 0.6rem 0.9rem; font-size: 0.9rem; font-weight: 600; margin-bottom: 1rem; max-width: 60ch;
}

.ul-q-actions { display: flex; align-items: center; gap: 0.8rem; flex-wrap: wrap; }
.ul-check-btn-lg {
    background: linear-gradient(135deg, #10AC84, #2BB3A9); color: white; border: none; border-radius: 12px;
    padding: 0.85rem 2.2rem; font-family: var(--font-main); font-weight: 800; font-size: 1.05rem; cursor: pointer;
    box-shadow: 0 4px 0 #0b8a69; transition: var(--transition);
}
.ul-check-btn-lg:hover:not(:disabled) { transform: translateY(-2px); }
.ul-check-btn-lg:disabled { opacity: 0.45; cursor: not-allowed; box-shadow: none; }
.ul-hint-btn {
    background: var(--yellow); color: #7a5c00; border: none; border-radius: 20px; padding: 0.5rem 1rem;
    font-family: var(--font-main); font-weight: 700; font-size: 0.85rem; cursor: pointer;
}
.ul-hint-box {
    margin-top: 1rem; background: #FFFBEA; border: 1.5px dashed #F0C94A; border-radius: 10px;
    padding: 0.8rem 1rem; font-size: 0.92rem; color: #7a5c00; line-height: 1.55; max-width: 70ch;
}

.ul-fb { border-radius: 14px; padding: 1.1rem 1.3rem; border: 2px solid; margin-top: 0.4rem; }
.ul-fb-correct { background: #effcf6; border-color: #9be3c8; }
.ul-fb-close   { background: #FFFBEA; border-color: #F0C94A; }
.ul-fb-wrong   { background: #fff6f6; border-color: #ffc2c2; }
.ul-fb-title { font-family: var(--font-main); font-weight: 800; font-size: 1.2rem; margin-bottom: 0.4rem; }
.ul-fb-correct .ul-fb-title { color: #1b6b3a; }
.ul-fb-close   .ul-fb-title { color: #8a6500; }
.ul-fb-wrong   .ul-fb-title { color: #b3261e; }
.ul-fb-msg { margin: 0 0 0.6rem; font-size: 0.95rem; line-height: 1.55; color: var(--dark); }
.ul-fb-answer { font-size: 1rem; margin-bottom: 0.7rem; color: var(--dark); }
.ul-fb-answer strong { font-family: var(--font-main); font-size: 1.2rem; }
.ul-fb-solution { background: white; border-radius: 10px; padding: 0.8rem 1rem; margin-bottom: 0.9rem; }
.ul-fb-sol-title { font-family: var(--font-main); font-weight: 800; font-size: 0.85rem; color: var(--purple); text-transform: uppercase; letter-spacing: 0.4px; margin-bottom: 0.3rem; }
.ul-fb-solution ol { margin: 0; padding-left: 1.3rem; }
.ul-fb-solution li { font-size: 0.95rem; line-height: 1.6; color: var(--dark); margin-bottom: 0.2rem; }
.ul-fb-actions { display: flex; gap: 0.7rem; flex-wrap: wrap; align-items: center; margin-top: 0.4rem; }

.ul-pager-nav { display: flex; justify-content: space-between; align-items: center; gap: 0.8rem; }

/* sidebar: stats + question map */
.ul-stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 0.5rem; margin-bottom: 0.9rem; }
.ul-stat-tile { background: var(--bg); border-radius: 10px; padding: 0.55rem 0.3rem; text-align: center; }
.ul-stat-num { font-family: var(--font-main); font-weight: 800; font-size: 1.35rem; color: var(--dark); line-height: 1.1; }
.ul-stat-num span { font-size: 0.8rem; color: var(--gray); }
.ul-stat-label { font-size: 0.7rem; font-weight: 800; color: var(--gray); text-transform: uppercase; letter-spacing: 0.3px; }

.ul-map-group + .ul-map-group { margin-top: 0.7rem; }
.ul-map-label { font-size: 0.75rem; font-weight: 800; color: var(--gray); margin-bottom: 0.35rem; }
.ul-map { display: grid; grid-template-columns: repeat(5, 1fr); gap: 0.4rem; }
.ul-dot {
    width: 100%; aspect-ratio: 1; max-width: 44px; border-radius: 10px; border: 2px solid var(--border);
    background: white; color: var(--gray); cursor: pointer; padding: 0;
    font-family: var(--font-main); font-weight: 700; font-size: 0.85rem; transition: var(--transition);
    display: inline-flex; align-items: center; justify-content: center;
}
.ul-dot:hover { border-color: var(--purple); color: var(--purple); }
.ul-dot.current { border-color: var(--purple); box-shadow: 0 0 0 3px rgba(108,99,255,0.25); color: var(--purple); }
.ul-dot-correct { background: #E8F5E9; border-color: #10AC84; color: #2E7D32; }
.ul-dot-close   { background: #FFF8E1; border-color: #F0C94A; color: #A67C00; }
.ul-dot-wrong   { background: #FCE4EC; border-color: var(--coral); color: #C62828; }

.ul-legend { display: flex; flex-wrap: wrap; gap: 0.3rem 0.8rem; margin-top: 0.8rem; font-size: 0.74rem; color: var(--gray); font-weight: 700; }
.ul-legend span { display: inline-flex; align-items: center; gap: 0.3rem; }
.ul-legend i { width: 12px; height: 12px; border-radius: 4px; border: 2px solid var(--border); background: white; display: inline-block; }

.ul-side-links { display: flex; flex-direction: column; gap: 0.2rem; padding: 0.6rem; }
.ul-side-link {
    text-align: left; background: none; border: none; border-radius: 8px; padding: 0.55rem 0.6rem; cursor: pointer;
    font-family: var(--font-main); font-weight: 700; font-size: 0.9rem; color: var(--dark);
}
.ul-side-link:hover { background: var(--bg); color: var(--purple); }

/* ===== Results page ===== */
.ul-results-hero { display: flex; align-items: center; gap: 1.8rem; flex-wrap: wrap; }
.ul-results-body { flex: 1; min-width: 240px; }
.ul-results-title { font-family: var(--font-main); font-weight: 800; font-size: 1.5rem; color: var(--dark); margin-bottom: 0.6rem; }
.ul-results-chips { display: flex; flex-wrap: wrap; gap: 0.4rem; margin-bottom: 0.9rem; }
.ul-results-chips .ul-status-correct { background: #E8F5E9; color: #2E7D32; border-color: #9be3c8; }
.ul-results-chips .ul-status-close { background: #FFF8E1; color: #A67C00; border-color: #F0C94A; }
.ul-results-chips .ul-status-wrong { background: #FCE4EC; color: #C62828; border-color: #ffb3b3; }

.ul-review-list { display: flex; flex-direction: column; gap: 0.4rem; margin-top: 0.8rem; }
.ul-review-row {
    display: grid; grid-template-columns: 40px minmax(0, 1fr) auto auto; align-items: center; gap: 1rem;
    background: white; border: 1.5px solid var(--border); border-radius: 12px; padding: 0.55rem 0.9rem;
    text-align: left; cursor: pointer; font: inherit; color: var(--dark); transition: var(--transition);
}
.ul-review-row:hover { border-color: var(--purple); background: #fafaff; }
.ul-review-row .ul-dot { pointer-events: none; }
.ul-review-prompt { font-family: Georgia, serif; font-size: 0.98rem; line-height: 1.7; }
.ul-review-answer { font-size: 0.88rem; color: var(--gray); white-space: nowrap; }
.ul-review-status { font-family: var(--font-main); font-size: 0.8rem; font-weight: 800; white-space: nowrap; color: var(--gray); }
.ul-review-status.ul-status-correct { color: #2E7D32; }
.ul-review-status.ul-status-close { color: #A67C00; }
.ul-review-status.ul-status-wrong { color: #C62828; }

/* ===== Fraction rendering ===== */
.ul-frac {
    display: inline-flex;
    flex-direction: row;
    align-items: center;
    vertical-align: middle;
    margin: 0 0.15rem;
    font-family: var(--font-main);
    font-weight: 700;
    line-height: 1;
}
.ul-frac-stack {
    display: inline-flex;
    flex-direction: column;
    align-items: center;
}
.ul-frac-stack .ul-frac-num, .ul-frac-stack .ul-frac-den { padding: 0 0.15rem; }
.ul-frac-stack .ul-frac-num { border-bottom: 2px solid var(--dark); padding-bottom: 2px; }
.ul-frac-stack .ul-frac-den { padding-top: 2px; }
.ul-frac-whole { font-weight: 800; margin-right: 0.15rem; }

/* A fraction raised to a power. The brackets are drawn as their own elements
   so they can be sized to the fraction, and the exponent is a flex item pinned
   to the top — `vertical-align: super` would measure from the line's baseline,
   which a two-storey fraction has already dragged down. */
.ul-pow-group { display: inline-flex; align-items: stretch; vertical-align: middle; }
.ul-pow-paren {
    display: flex; align-items: center;
    font-family: Georgia, serif; font-size: 1.75em; font-weight: 400;
    color: var(--gray); line-height: 0.85;
}
.ul-pow {
    align-self: flex-start; margin-left: 0.04em;
    font-family: var(--font-main); font-weight: 800; font-size: 0.62em;
    line-height: 1.1;
}

/* ===== Key-concept visuals ===== */
.ul-visual { margin-top: 0.8rem; background: var(--bg); border-radius: 10px; padding: 1rem; }
.ul-visual-caption {
    margin-top: 0.8rem; text-align: center; font-size: 0.92rem; line-height: 1.8; color: var(--dark);
    background: white; border-radius: 8px; padding: 0.5rem 0.8rem; white-space: pre-line;
}
.ul-visual-caption-steps { text-align: left; max-width: 520px; margin-left: auto; margin-right: auto; }

/* pizzas */
.ul-vis-row { display: flex; align-items: center; justify-content: center; gap: 1.2rem; flex-wrap: wrap; }
.ul-vis-item { display: flex; flex-direction: column; align-items: center; gap: 0.3rem; }
.ul-vis-label { font-size: 1.15rem; }
.ul-vis-sub { font-size: 0.8rem; color: var(--gray); font-weight: 700; }
.ul-vis-sign {
    width: 48px; height: 48px; border-radius: 50%; background: var(--purple); color: white;
    display: flex; align-items: center; justify-content: center;
    font-family: system-ui, sans-serif; font-weight: 800; font-size: 1.8rem; line-height: 1; box-shadow: var(--shadow-sm);
}
.ul-vis-sign-unknown { background: var(--light-gray); }
.ul-vis-note { text-align: center; font-size: 0.85rem; font-weight: 700; color: var(--gray); line-height: 1.7; margin-bottom: 0.5rem; }
.ul-vis-info {
    background: white; border: 2px dashed var(--purple-light); border-radius: 10px;
    padding: 0.7rem 1rem; max-width: 520px; margin: 0 auto;
}
.ul-vis-info-title { font-family: var(--font-main); font-weight: 800; color: var(--purple); margin-bottom: 0.3rem; text-align: center; }
.ul-vis-info-line { font-size: 0.88rem; line-height: 1.6; color: var(--dark); padding: 0.1rem 0; }
.ul-vis-info-line strong { color: var(--purple); font-size: 1rem; }
.ul-vis-step-arrow { text-align: center; font-size: 1.3rem; color: var(--purple); margin: 0.4rem 0 0.2rem; }
.ul-pizza { width: 110px; height: 110px; }
.ul-pz-plate { fill: white; stroke: #dfe4f7; stroke-width: 1; }
.ul-pz-on { fill: #FFC857; stroke: #E09F3E; stroke-width: 1.5; }
.ul-pz-off { fill: #eef1fb; stroke: #cfd6f0; stroke-width: 1; stroke-dasharray: 3 2; }
.ul-pz-pepperoni { fill: #D1495B; }
.ul-pz-crust { fill: none; stroke: #D9A05B; stroke-width: 2.5; }

/* fraction bars */
.ul-vbars { display: flex; flex-direction: column; gap: 0.35rem; max-width: 520px; margin: 0 auto; }
.ul-vrow { display: flex; align-items: center; gap: 0.7rem; }
.ul-vlabel { width: 72px; flex-shrink: 0; text-align: right; font-size: 1.05rem; white-space: nowrap; }
.ul-vbar {
    flex: 1; display: flex; height: 34px; border: 2px solid var(--dark); border-radius: 6px;
    overflow: hidden; background: white;
}
.ul-vseg { flex: 1; border-right: 1.5px solid var(--dark); }
.ul-vseg:last-child { border-right: none; }
.ul-vnote { margin-left: calc(72px + 0.7rem); font-size: 0.78rem; font-weight: 700; color: var(--gray); }

/* number line race */
.ul-nl { padding: 6rem 1.8rem 3.4rem; }
.ul-nl-track { position: relative; height: 6px; background: var(--dark); border-radius: 3px; }
.ul-nl-tick { position: absolute; top: -8px; width: 3px; height: 22px; background: var(--dark); transform: translateX(-50%); border-radius: 2px; }
.ul-nl-tick span {
    position: absolute; top: 26px; left: 50%; transform: translateX(-50%); white-space: nowrap;
    font-family: var(--font-main); font-weight: 800; font-size: 0.82rem; color: var(--dark);
}
.ul-nl-half { height: 30px; top: -12px; background: var(--purple); }
.ul-nl-half span { top: 32px; color: var(--purple); font-size: 1rem; }
.ul-nl-zone {
    position: absolute; top: 58px; width: 50%; text-align: center; white-space: nowrap;
    font-family: var(--font-main); font-weight: 700; font-size: 0.72rem; color: var(--gray);
}
.ul-nl-zone-less { left: 0; }
.ul-nl-zone-more { left: 50%; }
.ul-nl-point { position: absolute; top: 3px; transform: translateX(-50%); }
.ul-nl-dot { position: absolute; left: 50%; top: 0; width: 16px; height: 16px; border-radius: 50%; border: 3px solid white; transform: translate(-50%, -50%); box-shadow: 0 1px 4px rgba(0,0,0,0.25); }
.ul-nl-label {
    position: absolute; left: 50%; bottom: 14px; transform: translateX(-50%);
    background: white; border: 2px solid; border-radius: 8px; padding: 0.15rem 0.35rem; font-size: 0.95rem;
}
.ul-nl-runner { position: absolute; left: 50%; bottom: 74px; transform: translateX(-50%); font-size: 1.8rem; line-height: 1; }

/* signed number line (negatives on the left, positives on the right) */
.ul-sl { padding: 5.6rem 2rem 3.6rem; }
.ul-sl-track { position: relative; height: 6px; background: var(--dark); border-radius: 3px; }
.ul-sl-tick { position: absolute; top: -7px; width: 2px; height: 20px; background: var(--dark); transform: translateX(-50%); border-radius: 2px; }
.ul-sl-tick span {
    position: absolute; top: 24px; left: 50%; transform: translateX(-50%); white-space: nowrap;
    font-family: var(--font-main); font-weight: 700; font-size: 0.74rem; color: var(--gray);
}
.ul-sl-zero { height: 30px; top: -12px; width: 3px; background: var(--purple); }
.ul-sl-zero span { top: 30px; color: var(--purple); font-weight: 800; font-size: 0.86rem; }
.ul-sl-zone {
    position: absolute; top: 52px; text-align: center; white-space: nowrap;
    font-family: var(--font-main); font-weight: 700; font-size: 0.72rem; color: var(--gray);
}
.ul-sl-zone-neg { left: 0; }
.ul-sl-zone-pos { right: 0; }
.ul-sl-point { position: absolute; top: 3px; transform: translateX(-50%); }
.ul-sl-dot { position: absolute; left: 50%; top: 0; width: 15px; height: 15px; border-radius: 50%; border: 3px solid white; transform: translate(-50%, -50%); box-shadow: 0 1px 4px rgba(0,0,0,0.25); }
.ul-sl-label {
    position: absolute; left: 50%; bottom: 16px; transform: translateX(-50%);
    background: white; border: 2px solid; border-radius: 8px; padding: 0.1rem 0.4rem;
    font-family: var(--font-main); font-weight: 700; font-size: 0.9rem; white-space: nowrap;
}
/* stagger every second label onto a second row above the line, so neighbouring
   points don't collide with each other or with the tick numbers below */
.ul-sl-point-low .ul-sl-label { bottom: 48px; }
.ul-sl-point-low .ul-sl-label::after {
    content: ""; position: absolute; left: 50%; top: 100%; width: 2px; height: 28px;
    background: var(--border); transform: translateX(-50%);
}

/* A unit's topics bundled under a group heading. With thirteen of them a flat
   list reads as one long run of links, so the heading names what they are and
   the list splits into columns rather than pushing the card metres tall. */
.ul-catalog-group + .ul-catalog-group { margin-top: 0.7rem; }
.ul-catalog-group-name {
    font-family: var(--font-main); font-weight: 800; font-size: 0.82rem;
    color: var(--dark); margin-bottom: 0.35rem;
}
.ul-catalog-topic-list.is-split { columns: 2; column-gap: 1.1rem; }
.ul-catalog-topic-list.is-split li { break-inside: avoid; }

@media (max-width: 420px) {
    .ul-catalog-topic-list.is-split { columns: 1; }
}

/* ===== sign in / sign up ===== */
.ul-account-wrap { display: flex; justify-content: center; padding: 1rem 0 3rem; }
.ul-account-card {
    width: 100%; max-width: 440px; background: var(--white);
    border: 2px solid var(--border); border-radius: var(--radius);
    box-shadow: var(--shadow); padding: 2rem 1.75rem;
}
.ul-account-emoji { font-size: 2.4rem; line-height: 1; margin-bottom: 0.5rem; }
.ul-account-card h1 {
    font-family: var(--font-main); font-weight: 800; font-size: 1.5rem;
    color: var(--dark); margin: 0 0 0.4rem;
}
.ul-account-card > p {
    font-family: var(--font-body); color: var(--gray); font-size: 0.95rem;
    line-height: 1.5; margin: 0 0 1.25rem;
}

.ul-account-tabs { display: flex; gap: 0.4rem; margin-bottom: 1.25rem; }
.ul-account-tabs button {
    flex: 1; padding: 0.6rem 0.5rem; cursor: pointer;
    font-family: var(--font-main); font-weight: 700; font-size: 0.85rem;
    color: var(--gray); background: var(--bg);
    border: 2px solid transparent; border-radius: var(--radius-sm);
    transition: var(--transition);
}
.ul-account-tabs button.is-active {
    background: var(--purple-light); border-color: var(--purple); color: var(--purple-dark);
}

.ul-account-form { display: flex; flex-direction: column; }
/* display:flex above would otherwise beat the [hidden] attribute and show both
   the sign-in and sign-up forms at once */
.ul-account-form[hidden] { display: none; }
.ul-account-form label {
    font-family: var(--font-main); font-weight: 700; font-size: 0.82rem;
    color: var(--dark); margin-bottom: 0.35rem;
}
.ul-account-form input {
    font-family: var(--font-body); font-size: 1.05rem; font-weight: 600;
    padding: 0.7rem 0.85rem; margin-bottom: 0.3rem;
    border: 2px solid var(--border); border-radius: var(--radius-sm);
    background: var(--white); color: var(--dark); transition: var(--transition);
}
.ul-account-form input:focus {
    outline: none; border-color: var(--purple); box-shadow: 0 0 0 4px var(--purple-light);
}
/* PIN entry reads as a PIN, not a sentence */
.ul-account-form input[inputmode="numeric"] {
    letter-spacing: 0.5em; text-align: center; max-width: 9rem;
}
.ul-account-hint {
    font-family: var(--font-body); font-size: 0.78rem; color: var(--light-gray);
    margin-bottom: 1rem;
}
.ul-account-error {
    font-family: var(--font-body); font-weight: 700; font-size: 0.85rem;
    color: var(--coral); background: #fff0f0; border: 2px solid var(--coral);
    border-radius: var(--radius-sm); padding: 0.55rem 0.7rem; margin: 0.25rem 0 0.9rem;
}
.ul-account-btn {
    display: inline-block; text-align: center; text-decoration: none; cursor: pointer;
    font-family: var(--font-main); font-weight: 800; font-size: 0.95rem;
    padding: 0.8rem 1.2rem; margin-top: 0.5rem;
    color: var(--white); background: var(--purple);
    border: none; border-radius: var(--radius-sm); transition: var(--transition);
}
.ul-account-btn:hover { background: var(--purple-dark); }
.ul-account-btn:disabled { opacity: 0.6; cursor: default; }
.ul-account-link {
    background: none; border: none; cursor: pointer; padding: 0.8rem 0.5rem;
    font-family: var(--font-main); font-weight: 700; font-size: 0.9rem;
    color: var(--gray); text-decoration: underline;
}
.ul-account-actions { display: flex; align-items: center; gap: 0.75rem; flex-wrap: wrap; }
.ul-account-foot {
    font-family: var(--font-body); font-size: 0.8rem; color: var(--light-gray);
    line-height: 1.5; margin: 1.25rem 0 0; padding-top: 1rem;
    border-top: 2px solid var(--border);
}
.ul-account-foot a { color: var(--purple); }

@media (max-width: 480px) {
    .ul-account-card { padding: 1.5rem 1.15rem; }
}

/* sign rules ("two negatives make a positive") */
.ul-rules { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 0.6rem; }
.ul-rule {
    display: grid; grid-template-columns: 1fr auto auto; align-items: center; gap: 0.5rem;
    background: white; border: 2px solid var(--border); border-radius: 12px; padding: 0.6rem 0.8rem;
}
.ul-rule-expr { font-family: var(--font-main); font-weight: 700; font-size: 0.95rem; }
.ul-rule-arrow { color: var(--light-gray); font-weight: 800; }
.ul-rule-result {
    font-family: var(--font-main); font-weight: 900; font-size: 1.3rem; line-height: 1;
    width: 30px; height: 30px; border-radius: 50%; display: grid; place-items: center;
}
.ul-rule-result.is-pos { background: #E8F5E9; color: #1b6b3a; }
.ul-rule-result.is-neg { background: #FCE4EC; color: #C62828; }
.ul-rule-note { grid-column: 1 / -1; font-size: 0.78rem; color: var(--gray); }

/* ===== Pages that hold more than one problem ===== */
.ul-page-label {
    font-family: var(--font-main); font-weight: 800; font-size: 0.85rem; color: var(--gray);
    text-transform: uppercase; letter-spacing: 0.5px; margin-bottom: 0.6rem;
}
.ul-q-shared { min-height: 0; margin-bottom: 1rem; }
.ul-page-foot { display: flex; justify-content: flex-end; margin-bottom: 0.4rem; }

/* ===== Worked chains =====
   One row per problem, laid out the way the worksheet lays it out: the problem,
   then a blank for each line of working with its label printed underneath. */
.ul-chain {
    display: flex; align-items: flex-start; flex-wrap: wrap; gap: 0.3rem 0.45rem;
    font-family: Georgia, serif; font-size: 1.3rem; color: var(--dark);
    margin-bottom: 0.9rem;
}
.ul-chain-prompt { padding-top: 0.45rem; white-space: nowrap; }
.ul-chain-prompt .ul-frac { font-size: 1.05em; }
.ul-chain-eq { padding-top: 0.45rem; color: var(--gray); }

.ul-chain-step { display: inline-flex; flex-direction: column; align-items: center; gap: 0.15rem; }
.ul-chain-boxes { display: inline-flex; align-items: center; gap: 0.25rem; }
.ul-chain-join { font-family: var(--font-main); font-weight: 800; font-size: 1.05rem; color: var(--gray); }

.ul-chain-label {
    font-family: var(--font-main); font-weight: 700; font-size: 0.7rem; color: var(--gray);
    text-transform: uppercase; letter-spacing: 0.3px; text-align: center; line-height: 1.3;
}
.ul-chain-mark { font-size: 0.95rem; margin-right: 0.15rem; vertical-align: -1px; }
.ul-chain-step.is-correct .ul-chain-label { color: #1b6b3a; }
.ul-chain-step.is-form    .ul-chain-label { color: #8a6500; }
.ul-chain-step.is-wrong   .ul-chain-label { color: #b3261e; }

.ul-chain-input {
    width: 88px; text-align: center;
    border: 2.5px solid var(--border); border-radius: 10px; padding: 0.4rem 0.35rem;
    font-family: var(--font-main); font-weight: 700; font-size: 1.05rem; color: var(--dark);
    background: white; outline: none; transition: var(--transition);
}
.ul-chain-input:focus { border-color: var(--purple); box-shadow: 0 0 0 4px rgba(108,99,255,0.15); }

/* A marked box keeps what the student wrote, with the mark around it. */
.ul-chain-value {
    display: inline-flex; align-items: center; justify-content: center;
    min-width: 88px; padding: 0.35rem 0.4rem; border-radius: 10px;
    border: 2.5px solid transparent;
}
.ul-chain-value.is-correct { border-color: #9be3c8; background: #effcf6; }
.ul-chain-value.is-form    { border-color: #F0C94A; background: #FFFBEA; }
.ul-chain-value.is-wrong,
.ul-chain-value.is-blank   { border-color: #ffb3b3; background: #fff6f6; }

/* What each wrong line actually wanted. */
.ul-chain-faults { list-style: none; margin: 0 0 0.9rem; padding: 0; display: grid; gap: 0.4rem; }
.ul-chain-fault {
    display: grid; grid-template-columns: 150px minmax(0, 1fr); gap: 0.2rem 0.8rem;
    background: #fff6f6; border: 1.5px solid #ffd4d4; border-radius: 10px; padding: 0.55rem 0.8rem;
}
.ul-chain-fault-step {
    font-family: var(--font-main); font-weight: 800; font-size: 0.78rem; color: #b3261e;
    text-transform: uppercase; letter-spacing: 0.3px;
}
.ul-chain-fault-why { font-size: 0.9rem; line-height: 1.55; color: var(--dark); }
.ul-chain-fault-why em { display: block; color: var(--gray); font-size: 0.85rem; margin-top: 0.15rem; }

/* The worked example at the top of the page. */
.ul-sample {
    background: #F3F1FF; border: 2px dashed #C9C2FF; border-radius: var(--radius-sm);
    padding: 0.9rem 1.1rem 0.6rem; margin-bottom: 1.1rem;
}
.ul-sample-label {
    font-family: var(--font-main); font-weight: 800; font-size: 0.78rem; color: var(--purple-dark);
    text-transform: uppercase; letter-spacing: 0.4px; margin-bottom: 0.6rem;
}
.ul-chain-sample { margin-bottom: 0.4rem; }
.ul-chain-sample .ul-chain-value { border-color: #D9D4FF; background: white; }

/* A problem sharing a page is a numbered row, not a page of its own. */
.ul-q-top-slim { margin-bottom: 0.7rem; gap: 0.5rem; }
.ul-q-num { font-family: var(--font-main); font-weight: 800; font-size: 1.05rem; color: var(--gray); }

/* The second action on the account card — a teacher's way through to the
   class view, which should not out-shout "keep learning". */
.ul-account-btn-alt {
    background: var(--white); color: var(--purple);
    border: 2px solid var(--purple); box-shadow: none;
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
    .ul-layout { grid-template-columns: minmax(0, 1fr); }
    .ul-q-panel { min-height: 0; }
    .ul-side-sticky { position: static; display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
}

@media (max-width: 640px) {
    .ul-main { padding-left: 1rem; padding-right: 1rem; }
    .ul-page-head h1 { font-size: 1.45rem; }
    .ul-topic-grid { grid-template-columns: minmax(0, 1fr); }
    .ul-concept-grid, .ul-examples { grid-template-columns: minmax(0, 1fr); }
    .ul-panel { padding: 1rem; }
    .ul-q-panel { padding: 1.1rem 1rem 1.3rem; min-height: 0; }
    .ul-q-prompt-lg { font-size: 1.25rem; }
    .ul-q-stars { margin-left: 0; }
    .ul-tiles { gap: 0.5rem; }
    .ul-tile { flex: 1 1 0; min-width: 0; font-size: 1.05rem; padding: 0.5rem; }
    .ul-tiles-symbols .ul-tile { font-size: 1.7rem; }
    .ul-input-row { max-width: none; }
    .ul-check-btn-lg { width: 100%; }
    .ul-fb-actions .ul-next-btn { width: 100%; }
    .ul-review-row { grid-template-columns: 36px minmax(0, 1fr); gap: 0.3rem 0.7rem; }
    .ul-review-answer, .ul-review-status { grid-column: 2; }
    .ul-concept { padding: 0.8rem 0.7rem; }
    .ul-visual { padding: 0.7rem 0.5rem; }
    .ul-vis-row { gap: 0.5rem; flex-wrap: nowrap; }
    .ul-pizza { width: 84px; height: 84px; }
    .ul-vis-sign { width: 36px; height: 36px; font-size: 1.4rem; flex-shrink: 0; }
    .ul-vlabel { width: 44px; font-size: 0.95rem; }
    .ul-vrow { gap: 0.4rem; }
    .ul-vnote { margin-left: 0; text-align: center; }
    .ul-nl { padding-left: 1.2rem; padding-right: 1.6rem; }
    .ul-sl { padding: 4rem 1.4rem 3.4rem; }
    .ul-sl-label { font-size: 0.78rem; padding: 0.05rem 0.25rem; }
    .ul-sl-tick span { font-size: 0.66rem; }
    .ul-tile-order { flex: 0 1 auto; min-width: 74px; padding: 1.1rem 0.6rem 0.5rem; }
    .ul-chain { font-size: 1.1rem; gap: 0.25rem 0.3rem; }
    .ul-chain-prompt { white-space: normal; }
    .ul-chain-input, .ul-chain-value { width: 70px; min-width: 70px; font-size: 0.95rem; }
    .ul-chain-label { font-size: 0.62rem; }
    .ul-chain-fault { grid-template-columns: minmax(0, 1fr); }
}

/* Quiet "sign in to save" nudge in the practice sidebar */
.ul-signin-hint {
    font-size: 0.82rem; line-height: 1.45; color: var(--gray);
}
.ul-signin-hint a {
    color: var(--purple); font-weight: 700; text-decoration: underline;
    text-underline-offset: 2px;
}
.ul-signin-hint a:hover { color: var(--purple-dark); }