:root {
    color-scheme: light;
    --ink: #16233a;
    --muted: #607089;
    --line: #dce3ec;
    --brand: #2257a6;
    --brand-dark: #183f79;
    --danger: #a32929;
    --success: #1d6846;
    --surface: #ffffff;
    --background: #f4f7fb;
}

* { box-sizing: border-box; }
body {
    margin: 0;
    color: var(--ink);
    background: var(--background);
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    line-height: 1.5;
}
a { color: var(--brand); }
.site-header {
    background: #132c52;
    color: white;
    padding: .9rem 0;
}
.site-header a { color: white; text-decoration: none; }
.container { width: min(1080px, calc(100% - 2rem)); margin: 0 auto; }
.header-row, .actions, .admin-nav { display: flex; align-items: center; gap: .75rem; flex-wrap: wrap; }
.header-row { justify-content: space-between; }
.student-header-actions { justify-content: space-between; width: 100%; }
.confirmation-control { position: relative; }
.confirmation-control > summary { list-style: none; }
.confirmation-control > summary::-webkit-details-marker { display: none; }
.confirmation-panel {
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: .5rem;
    box-shadow: 0 8px 24px rgba(19, 44, 82, .2);
    color: var(--ink);
    padding: .8rem;
    position: absolute;
    right: 0;
    top: calc(100% + .5rem);
    width: min(290px, calc(100vw - 2rem));
    z-index: 20;
}
.confirmation-panel p { margin: 0 2rem .65rem 0; }
.confirmation-close {
    line-height: 1;
    padding: .25rem .45rem;
    position: absolute;
    right: .45rem;
    top: .45rem;
}
main { padding: 2rem 0 3rem; }
.card {
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: .65rem;
    box-shadow: 0 4px 18px rgba(19, 44, 82, .05);
    padding: 1.25rem;
}
.narrow { max-width: 520px; margin: 2rem auto; }
h1 { margin-top: 0; font-size: 1.65rem; }
label { display: block; font-weight: 650; margin: .85rem 0 .35rem; }
input, select, textarea {
    width: 100%;
    border: 1px solid #afbac9;
    border-radius: .4rem;
    padding: .65rem .75rem;
    font: inherit;
}
textarea { min-height: 8rem; resize: vertical; }
select { background: white; }
button, .button {
    display: inline-block;
    border: 0;
    border-radius: .4rem;
    background: var(--brand);
    color: white;
    cursor: pointer;
    font: inherit;
    font-weight: 650;
    padding: .6rem .9rem;
    text-decoration: none;
}
button:hover, .button:hover { background: var(--brand-dark); }
.button.secondary, button.secondary { color: var(--ink); background: #e7edf5; }
.button.danger, button.danger { background: var(--danger); }
.inline-form { display: inline; }
.inline-form button { width: auto; }
.field-error, .alert-error { color: var(--danger); }
.alert { border-radius: .4rem; margin-bottom: 1rem; padding: .75rem 1rem; }
.alert-error { background: #fff0f0; border: 1px solid #efc6c6; }
.alert-success { color: var(--success); background: #ecf8f2; border: 1px solid #bfe2cf; }
.alert-info { color: var(--ink); background: #eef5ff; border: 1px solid #c9d8ee; }
.muted { color: var(--muted); }
[hidden] { display: none !important; }
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; }
th, td { border-bottom: 1px solid var(--line); padding: .75rem .5rem; text-align: left; vertical-align: top; }
.status { font-weight: 650; }
.status.disabled { color: var(--danger); }
.filter-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: .75rem; align-items: end; }
.filter-grid label { margin-top: 0; }
.option-row { display: grid; grid-template-columns: auto minmax(0, 1fr) auto; gap: .6rem; align-items: center; margin: .65rem 0; }
.option-row input[type="radio"] { width: auto; }
.option-row label { margin: 0; font-weight: 500; }
.option-content { display: grid; gap: .55rem; min-width: 0; }
.question-prompt, .reference-answer { white-space: pre-wrap; overflow-wrap: anywhere; }
.question-text-lines { display: grid; min-width: 0; white-space: normal; }
.question-text-line { display: block; min-width: 0; overflow-wrap: anywhere; white-space: pre-wrap; word-break: break-word; }
.question-text-line-numbered {
    align-items: start;
    column-gap: .45rem;
    display: grid;
    grid-template-columns: max-content minmax(0, 1fr);
}
.question-text-number { white-space: nowrap; }
.question-text-body { min-width: 0; overflow-wrap: anywhere; white-space: pre-wrap; word-break: break-word; }
.question-text-line-empty { min-height: 1.5em; }
.question-image {
    display: block;
    height: auto;
    margin: .75rem 0;
    max-height: 70vh;
    max-width: 100%;
    object-fit: contain;
}
.question-image-preview { max-height: 220px; }
.option-image { max-height: 320px; }
.explanation-image { max-height: 70vh; width: auto; }
.existing-media { border-left: 3px solid var(--line); margin: .75rem 0; padding-left: .75rem; }
.existing-media .check-label { margin-top: .4rem; }
.pagination { display: flex; gap: .75rem; align-items: center; margin-top: 1rem; }
.badge { display: inline-block; border-radius: 99px; background: #e7edf5; font-size: .8rem; font-weight: 700; padding: .15rem .5rem; text-transform: uppercase; }
.mt-1 { margin-top: 1rem; }
.quiz-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 1rem; }
.quiz-card, .quiz-question, .picker-row { border: 1px solid var(--line); border-radius: .5rem; padding: 1rem; }
.quiz-card h2 { margin-top: 0; }
.quiz-question { margin: 1rem 0; min-width: 0; }
.quiz-question, .quiz-question > *, .student-quiz-summary { max-width: 100%; overflow-wrap: anywhere; }
.quiz-question fieldset { min-width: 0; }
.quiz-question-picker, .question-picker, .picker-row { min-width: 0; }
.quiz-question-picker { max-width: 100%; }
.question-picker { display: grid; gap: .75rem; }
.picker-row { display: grid; grid-template-columns: minmax(0, 1fr) minmax(150px, 240px) 90px; gap: .75rem; align-items: center; }
.picker-row > * { min-width: 0; }
.check-label, .option-choice { font-weight: 500; margin: .5rem 0; }
.check-label input, .option-choice input { width: auto; }
.picker-question {
    display: grid;
    grid-template-columns: auto auto auto minmax(0, 1fr);
    align-items: start;
    gap: .35rem;
    max-width: 100%;
}
.picker-question input { margin-top: .25rem; }
.picker-prompt, .picker-meta { min-width: 0; overflow-wrap: anywhere; word-break: break-word; }
.picker-prompt { white-space: pre-wrap; }
.picker-order { display: grid; gap: .25rem; justify-items: start; white-space: nowrap; }
.selected-question-row, .question-search-result {
    align-items: center;
    border: 1px solid var(--line);
    border-radius: .5rem;
    display: grid;
    gap: .75rem;
    grid-template-columns: minmax(0, 1fr) auto auto auto;
    min-width: 0;
    padding: .85rem;
}
.selected-question-main, .selected-question-prompt, .selected-question-meta { min-width: 0; overflow-wrap: anywhere; word-break: break-word; }
.selected-question-main.picker-question { display: block; }
.selected-question-badges { align-items: center; display: flex; flex-wrap: wrap; gap: .35rem; }
.selected-question-prompt { margin: .45rem 0; white-space: pre-wrap; }
.selected-question-meta { margin: 0; }
.points-input { width: 75px; }
.quiz-question-search { margin-top: 1rem; }
.question-search-status { min-height: 1.5rem; }
.question-search-results { display: grid; gap: .65rem; margin-top: .65rem; }
.question-search-result { grid-template-columns: minmax(0, 1fr) auto; }
.admin-quiz-search { margin: 1rem 0; max-width: 620px; }
.admin-quiz-search label { margin-top: 0; }
.admin-quiz-detail, .admin-quiz-questions, .admin-quiz-question, .admin-quiz-question-content {
    min-width: 0;
    max-width: 100%;
}
.admin-quiz-detail > .header-row > div { min-width: 0; max-width: 100%; }
.admin-quiz-detail h1, .admin-quiz-detail .confirmation-panel p {
    overflow-wrap: anywhere;
    word-break: break-word;
}
.admin-quiz-questions { padding-left: 1.5rem; }
.admin-quiz-question { margin: .75rem 0; }
.admin-quiz-question-content { overflow-wrap: anywhere; word-break: break-word; }
.admin-quiz-question-prompt { white-space: pre-wrap; overflow-wrap: anywhere; word-break: break-word; }
.option-choice { max-width: 100%; min-width: 0; overflow-wrap: anywhere; }
.option-choice-line {
    display: grid;
    grid-template-columns: auto auto minmax(0, 1fr);
    align-items: start;
    gap: .35rem;
    min-width: 0;
}
.option-choice-line input { flex: 0 0 auto; margin-top: .25rem; }
.option-choice-text { min-width: 0; overflow-wrap: anywhere; word-break: break-word; }
.practice-option-feedback { border: 1px solid var(--line); border-radius: .4rem; padding: .7rem; }
.practice-option-feedback.correct-option { border-color: #7fc5a2; background: #ecf8f2; }
.practice-option-feedback.selected-incorrect-option { border-color: #df9d9d; background: #fff0f0; }
.practice-progress { font-size: 1.05rem; }
.practice-flow-action { margin-top: 1rem; }
.answer-feedback { display: grid; gap: .85rem; margin-top: 1rem; }
.answer-feedback > * { margin-bottom: 0; margin-top: 0; }
.error-book-status { color: var(--success); font-weight: 650; }
.error-book-list-item { align-items: start; }
.error-book-prompt-summary {
    line-height: 1.5;
    margin-top: .4rem;
    max-height: 4.5em;
    overflow: hidden;
}
.pen-selection-guard-active, .pen-selection-guard-active * {
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    user-select: none;
}
.order-input { width: 75px; }
.reference-box { background: #eef5ff; border-left: 4px solid var(--brand); margin-top: .75rem; padding: 1rem; }
.count-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 180px)); gap: 1rem; }
.practice-filter-options {
    align-items: stretch;
    display: flex;
    flex-wrap: wrap;
    gap: .55rem;
}
.filter-choice {
    align-items: center;
    border: 1px solid var(--line);
    border-radius: .4rem;
    display: flex;
    flex: 1 1 180px;
    gap: .5rem;
    justify-content: center;
    margin: 0;
    min-width: 0;
    padding: .65rem .75rem;
}
.practice-filter-difficulties .filter-choice { flex-basis: 120px; }
.quick-difficulty-options .filter-choice { flex: 1 1 110px; }
.filter-choice input { flex: 0 0 auto; margin: 0; width: auto; }
.filter-choice-text { min-width: 0; overflow-wrap: anywhere; text-align: center; word-break: break-word; }
.filter-heading-row { align-items: center; display: flex; flex-wrap: wrap; gap: .75rem; justify-content: space-between; }
.filter-heading-row p { margin: .4rem 0; }
.compact-button { padding: .4rem .65rem; }
.quiz-list-heading, .quiz-search-controls, .student-quiz-row, .student-quiz-actions {
    align-items: center;
    display: flex;
    gap: .75rem;
}
.quiz-list-heading { justify-content: space-between; }
.quiz-search { margin: 1rem 0 1.25rem; }
.quiz-search label { margin-top: 0; }
.quiz-search-controls input { min-width: 0; }
.student-quiz-list { display: grid; gap: .65rem; }
.student-quiz-row { border-top: 1px solid var(--line); justify-content: space-between; padding: .9rem 0; }
.student-quiz-summary { min-width: 0; }
.student-quiz-summary h2 { font-size: 1.08rem; margin: 0; }
.student-quiz-summary p { margin: .25rem 0 0; }
.student-quiz-actions { flex: 0 0 auto; flex-wrap: wrap; justify-content: flex-end; }
.student-quiz-actions form { margin: 0; }
.result { font-weight: 750; }
.result-correct { color: var(--success); }
.result-incorrect { color: var(--danger); }
.concept-description, .concept-text { max-width: 100%; overflow-wrap: anywhere; white-space: pre-wrap; word-break: break-word; }
.concept-choice-grid { display: grid; gap: 1rem; grid-template-columns: repeat(auto-fit, minmax(min(240px, 100%), 1fr)); margin-top: 1rem; }
.concept-choice, .concept-card-preview { border: 1px solid var(--line); border-radius: .55rem; min-width: 0; padding: 1rem; }
.concept-choice h2 { font-size: 1.2rem; margin-top: 0; }
.concept-card-list { display: grid; gap: 1rem; }
.concept-preview-faces { display: grid; gap: .8rem; grid-template-columns: repeat(2, minmax(0, 1fr)); }
.concept-preview-faces section { background: var(--background); border-radius: .4rem; min-width: 0; padding: .8rem; }
.concept-preview-faces h3 { margin-top: 0; }
.flashcard-counter { font-size: 1.2rem; font-weight: 750; text-align: center; }
.concept-card-stage { margin: 1rem auto; max-width: 820px; min-width: 0; perspective: 1300px; }
.concept-flashcard {
    background: transparent;
    border: 0;
    color: var(--ink);
    display: block;
    min-height: 360px;
    padding: 0;
    text-align: left;
    width: 100%;
}
.concept-flashcard[hidden] { display: none; }
.concept-flashcard:hover { background: transparent; }
.concept-flashcard:focus-visible { border-radius: .7rem; outline: 3px solid rgba(34, 87, 166, .42); outline-offset: 4px; }
.concept-flashcard-inner {
    display: grid;
    min-height: 360px;
    position: relative;
    transform-style: preserve-3d;
    transition: transform .55s ease;
    width: 100%;
}
.concept-flashcard.is-flipped .concept-flashcard-inner { transform: rotateY(180deg); }
.concept-flashcard-face {
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    border: 2px solid #c9d6e7;
    border-radius: .7rem;
    box-shadow: 0 8px 24px rgba(19, 44, 82, .12);
    display: flex;
    flex-direction: column;
    grid-area: 1 / 1;
    justify-content: center;
    min-height: 360px;
    min-width: 0;
    padding: clamp(3.25rem, 8vw, 4.5rem) clamp(1.25rem, 4vw, 3rem);
    width: 100%;
}
.concept-flashcard-front { background: #ffffff; }
.concept-flashcard-back { background: #eef5ff; transform: rotateY(180deg); }
.concept-face-label { color: var(--muted); font-size: .85rem; font-weight: 750; left: 1rem; position: absolute; text-transform: uppercase; top: 1rem; }
.concept-flashcard .concept-text { display: block; font-size: clamp(1.1rem, 2.3vw, 1.45rem); text-align: center; width: 100%; }
.concept-flip-hint { bottom: 1rem; color: var(--muted); font-size: .8rem; left: 1rem; position: absolute; right: 1rem; text-align: center; }
.flashcard-navigation { display: flex; justify-content: space-between; gap: .75rem; margin-top: 1rem; }
.flashcard-navigation button:disabled { cursor: not-allowed; opacity: .5; }
.scratchpad { border: 1px solid var(--line); border-radius: .5rem; margin: 1rem 0; padding: .75rem; }
.scratchpad summary { cursor: pointer; font-weight: 750; }
.scratchpad-toolbar { display: flex; flex-wrap: wrap; gap: .4rem; margin-top: .65rem; }
.scratchpad-toolbar button { white-space: nowrap; }
.scratchpad-toolbar button[aria-pressed="true"] { box-shadow: 0 0 0 3px rgba(34, 87, 166, .25); }
.scratchpad-status { margin-bottom: .5rem; }
.scratchpad-canvas-frame { background: white; border: 1px solid #afbac9; border-radius: .4rem; overflow: hidden; }
.scratchpad canvas { display: block; height: 380px; width: 100%; }
.scratchpad-scroll-mode canvas { pointer-events: none; touch-action: pan-y; }
.scratchpad-ink-mode canvas { cursor: crosshair; pointer-events: auto; touch-action: none; }
hr { border: 0; border-top: 1px solid var(--line); margin: 1.5rem 0; }
@media (max-width: 800px) {
    .picker-row { grid-template-columns: 1fr; }
    .selected-question-row { grid-template-columns: minmax(0, 1fr) auto auto; }
    .selected-question-row > button { grid-column: 1 / -1; justify-self: start; }
}
@media (max-width: 640px) {
    main { padding-top: 1rem; }
    .actions { align-items: stretch; }
    .filter-grid { grid-template-columns: 1fr; }
    .count-grid { grid-template-columns: 1fr; }
    .card { padding: 1rem; }
    .scratchpad canvas { height: 330px; }
    .admin-nav { gap: .55rem; }
    .student-header-actions { align-items: center; }
    .confirmation-panel { left: 0; right: auto; }
    .signout-confirm { left: 0; right: auto; }
    .quiz-list-heading, .student-quiz-row { align-items: stretch; flex-direction: column; }
    .quiz-search-controls { align-items: stretch; flex-direction: column; }
    .student-quiz-actions { justify-content: flex-start; }
    .pagination { flex-wrap: wrap; }
    .concept-preview-faces { grid-template-columns: 1fr; }
    .concept-flashcard, .concept-flashcard-inner, .concept-flashcard-face { min-height: 300px; }
    .selected-question-row, .question-search-result { align-items: stretch; grid-template-columns: 1fr; }
}
@media (max-width: 480px) {
    .picker-question { grid-template-columns: auto auto minmax(0, 1fr); }
    .picker-question .badge { justify-self: start; }
    .picker-prompt { grid-column: 1 / -1; }
}
@media (prefers-reduced-motion: reduce) {
    .concept-flashcard-inner { transition-duration: .01ms; }
}

/* Customer acceptance: only the student catalogue/setup pages use these layouts. */
.student-page-heading { align-items: center; display: grid; gap: .75rem; grid-template-columns: minmax(0, 1fr) auto; margin-bottom: 1rem; }
.student-page-heading h1 { margin: 0; min-width: 0; overflow-wrap: anywhere; }
.student-page-heading > .button { white-space: nowrap; }
.student-practice-setup .practice-mode { display: grid; gap: .5rem; grid-template-columns: repeat(2, minmax(0, 1fr)); }
.student-practice-setup .practice-mode .option-choice { margin: 0; padding: .55rem .35rem; }
.student-practice-setup .practice-filter-options { display: grid; gap: .5rem; }
.student-practice-setup .practice-filter-topics { grid-template-columns: minmax(0, 1fr); }
.student-practice-setup .filter-choice { justify-content: flex-start; padding: .6rem .4rem; }
.student-practice-setup .filter-choice-text { text-align: left; }
.student-practice-setup .practice-filter-difficulties { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.student-practice-setup .practice-filter-difficulties .filter-choice { font-size: .875rem; gap: .25rem; padding-inline: .25rem; }
.student-practice-setup .practice-filter-sources, .student-practice-setup .count-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.student-practice-setup .quick-difficulty-options { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.student-practice-setup .count-grid > div { min-width: 0; }
.concept-choice { display: flex; flex-direction: column; }
.concept-choice h2 { overflow-wrap: anywhere; }
.concept-choice-actions, .error-book-actions { align-items: center; display: flex; gap: .75rem; justify-content: space-between; }
.concept-choice-actions { margin-top: auto; }
.concept-choice-actions > span { white-space: nowrap; }
.error-book-list-item { border: 1px solid var(--line); border-radius: .45rem; min-width: 0; overflow-wrap: anywhere; padding: 1rem; }
.error-book-detail-actions { align-items: center; display: grid; gap: .75rem; grid-template-columns: minmax(0, 1fr) auto; margin-top: 1rem; }
.error-book-detail-actions > div { min-width: 0; overflow-wrap: anywhere; }
.error-book-detail-actions button { min-height: 44px; white-space: nowrap; }
@media (max-width: 480px) {
    .error-book-detail-actions button { font-size: .875rem; padding-inline: .5rem; }
}
.error-book-detail { overflow-wrap: anywhere; }
.error-book-detail-actions p { margin: .3rem 0; }
.quiz-search-field { flex: 1; min-width: 0; position: relative; }
.quiz-title-suggestions { background: white; border: 1px solid var(--line); border-radius: .4rem; box-shadow: 0 4px 12px #0002; left: 0; list-style: none; margin: .2rem 0 0; max-height: 18rem; overflow-y: auto; padding: .25rem; position: absolute; right: 0; z-index: 5; }
.quiz-title-suggestions [role="option"] { cursor: pointer; min-height: 44px; overflow-wrap: anywhere; padding: .65rem; }
.quiz-title-suggestions [aria-selected="true"], .quiz-title-suggestions [role="option"]:hover { background: #eef5ff; }
.visually-hidden { clip-path: inset(50%); height: 1px; overflow: hidden; position: absolute; white-space: nowrap; width: 1px; }