/* ==========================================================================
   AS Knowledge – shared stylesheet
   One design system for every page (home, ACSL topics, practice tests,
   contact, privacy). Neutral background, one accent colour, system fonts,
   hairline borders instead of shadows.
   ========================================================================== */

:root {
    --bg: #f7f7f5;
    --surface: #ffffff;
    --text: #1f2933;
    --text-muted: #5f6b76;
    --border: #dfe3e8;
    --border-strong: #c5ccd3;

    --accent: #1f4e79;
    --accent-hover: #173b5c;
    --accent-soft: #eef3f8;

    --success: #256d3a;
    --success-bg: #eaf4ec;
    --error: #a8342b;
    --error-bg: #f9edeb;
    --note-bg: #f4f1e8;
    --note-border: #d9cfae;

    --code-bg: #f1f3f5;

    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
    --font-serif: Georgia, "Times New Roman", serif;

    --container: 1080px;
    --narrow: 780px;
    --radius: 4px;
}

/* --------------------------------------------------------------------------
   Base
   -------------------------------------------------------------------------- */

*,
*::before,
*::after {
    box-sizing: border-box;
}

html {
    -webkit-text-size-adjust: 100%;
}

body {
    margin: 0;
    font-family: var(--font-sans);
    font-size: 1rem;
    line-height: 1.65;
    color: var(--text);
    background: var(--bg);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

main {
    flex: 1 0 auto;
}

h1, h2, h3, h4 {
    color: var(--text);
    line-height: 1.25;
    margin: 0 0 0.6em;
    font-weight: 600;
}

h1 { font-size: 2rem; letter-spacing: -0.01em; }
h2 { font-size: 1.4rem; }
h3 { font-size: 1.15rem; }
h4 { font-size: 1rem; }

p { margin: 0 0 1rem; }

ul, ol {
    margin: 0 0 1rem;
    padding-left: 1.5rem;
}

li { margin-bottom: 0.35rem; }
li > ul, li > ol { margin-top: 0.35rem; margin-bottom: 0.35rem; }

a {
    color: var(--accent);
    text-decoration: underline;
    text-decoration-color: rgba(31, 78, 121, 0.35);
    text-underline-offset: 2px;
}

a:hover {
    color: var(--accent-hover);
    text-decoration-color: currentColor;
}

strong { font-weight: 600; }

hr {
    border: 0;
    border-top: 1px solid var(--border);
    margin: 2rem 0;
}

img, svg {
    max-width: 100%;
    height: auto;
}

/* Author display rules (e.g. display:flex) must not defeat the hidden attribute. */
[hidden] {
    display: none !important;
}

sup, sub {
    font-size: 0.72em;
    line-height: 0;
}

code, pre, kbd {
    font-family: var(--font-mono);
    font-size: 0.92em;
}

code {
    background: var(--code-bg);
    padding: 0.1em 0.35em;
    border-radius: 3px;
}

pre {
    background: var(--code-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 0.9rem 1rem;
    overflow-x: auto;
    line-height: 1.45;
    margin: 0.75rem 0 1rem;
}

pre code {
    background: none;
    padding: 0;
    font-size: inherit;
}

table {
    border-collapse: collapse;
    width: 100%;
    margin: 0.75rem 0 1rem;
    font-size: 0.95rem;
}

th, td {
    border: 1px solid var(--border);
    padding: 0.45rem 0.7rem;
    text-align: left;
    vertical-align: top;
}

th {
    background: var(--accent-soft);
    font-weight: 600;
}

.table-wrap { overflow-x: auto; }

.visually-hidden {
    position: absolute !important;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* --------------------------------------------------------------------------
   Layout helpers
   -------------------------------------------------------------------------- */

.container {
    width: 100%;
    max-width: var(--container);
    margin: 0 auto;
    padding: 0 1.25rem;
}

.container-narrow {
    max-width: var(--narrow);
}

.page {
    padding: 2rem 0 3.5rem;
}

.page-header {
    margin-bottom: 2rem;
    padding-bottom: 1.25rem;
    border-bottom: 1px solid var(--border);
}

.page-header h1 { margin-bottom: 0.35rem; }

.page-header .lead,
.lead {
    font-size: 1.1rem;
    color: var(--text-muted);
    margin-bottom: 0;
}

.eyebrow {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}

.back-link {
    display: inline-block;
    font-size: 0.92rem;
    margin-bottom: 0.75rem;
}

.muted { color: var(--text-muted); }

/* --------------------------------------------------------------------------
   Site header and footer
   -------------------------------------------------------------------------- */

.site-header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
}

.site-header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 0.5rem 1.5rem;
    min-height: 60px;
    padding-top: 0.6rem;
    padding-bottom: 0.6rem;
}

.site-brand {
    font-weight: 700;
    font-size: 1.1rem;
    letter-spacing: 0.01em;
    color: var(--text);
    text-decoration: none;
}

.site-brand:hover { color: var(--accent); }

.site-nav {
    display: flex;
    flex-wrap: wrap;
    gap: 0.25rem 0.25rem;
}

.site-nav a {
    display: inline-block;
    padding: 0.35rem 0.7rem;
    border-radius: var(--radius);
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.95rem;
}

.site-nav a:hover {
    color: var(--accent);
    background: var(--accent-soft);
}

.site-nav a[aria-current="page"] {
    color: var(--accent);
    font-weight: 600;
}

.site-footer {
    border-top: 1px solid var(--border);
    background: var(--surface);
    padding: 1.5rem 0;
    margin-top: auto;
    font-size: 0.9rem;
    color: var(--text-muted);
}

.site-footer-inner {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: 0.5rem 1.5rem;
}

.site-footer p { margin: 0; }

.site-footer nav {
    display: flex;
    flex-wrap: wrap;
    gap: 0.25rem 1rem;
}

.site-footer a { color: var(--text-muted); }
.site-footer a:hover { color: var(--accent); }

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

.btn {
    display: inline-block;
    font: inherit;
    font-size: 0.95rem;
    font-weight: 500;
    line-height: 1.2;
    padding: 0.55rem 1rem;
    border-radius: var(--radius);
    border: 1px solid var(--accent);
    background: var(--accent);
    color: #fff;
    cursor: pointer;
    text-decoration: none;
    transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

.btn:hover {
    background: var(--accent-hover);
    border-color: var(--accent-hover);
    color: #fff;
}

.btn:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

.btn-secondary {
    background: var(--surface);
    color: var(--accent);
}

.btn-secondary:hover {
    background: var(--accent-soft);
    color: var(--accent-hover);
}

.btn-ghost {
    background: transparent;
    border-color: var(--border-strong);
    color: var(--text-muted);
}

.btn-ghost:hover {
    background: var(--surface);
    border-color: var(--text-muted);
    color: var(--text);
}

.btn[disabled] {
    opacity: 0.55;
    cursor: default;
}

.btn-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
    margin: 1.25rem 0 0;
}

/* --------------------------------------------------------------------------
   Content sections (used on topic pages, hub pages, contact, privacy)
   -------------------------------------------------------------------------- */

.content-section {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem 1.75rem;
    margin-bottom: 1.5rem;
}

.content-section > h2 {
    padding-bottom: 0.6rem;
    margin-bottom: 1.1rem;
    border-bottom: 1px solid var(--border);
}

.content-section h3 {
    margin-top: 1.5rem;
}

.content-section h3:first-child,
.content-section > h2 + h3 {
    margin-top: 0;
}

.content-section > :last-child { margin-bottom: 0; }

/* Plain section (no box) for editorial pages such as the homepage */
.text-section {
    padding: 2rem 0;
    border-bottom: 1px solid var(--border);
}

.text-section:last-of-type { border-bottom: 0; }

.text-section h2 {
    margin-bottom: 1rem;
}

.text-section p:last-child { margin-bottom: 0; }

/* Generic boxed items (cards without shadows) */
.card,
.example-card,
.operator-card,
.law-card,
.system-card,
.gate-card,
.detail-item {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem 1.15rem;
    margin: 0 0 1rem;
}

.card > :last-child,
.example-card > :last-child,
.operator-card > :last-child,
.law-card > :last-child,
.system-card > :last-child,
.gate-card > :last-child,
.detail-item > :last-child {
    margin-bottom: 0;
}

.card h3, .card h4,
.example-card h3, .example-card h4,
.operator-card h4,
.law-card h4,
.system-card h3,
.gate-card h3,
.detail-item h3, .detail-item h4 {
    margin-top: 0;
    margin-bottom: 0.5rem;
}

.example-card .title,
.card .title {
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.card-grid,
.operator-grid,
.laws-grid,
.number-systems-grid,
.gate-container,
.contact-details {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
    gap: 1rem;
    margin: 0 0 1rem;
}

.card-grid > *,
.operator-grid > *,
.laws-grid > *,
.number-systems-grid > *,
.gate-container > *,
.contact-details > * {
    margin: 0;
}

/* Subtle highlighted boxes */
.key-points,
.tip-box,
.reference-box,
.note-box,
.precedence-list,
.conversion-steps,
.process-flow,
.code-structure,
.implementation-note,
.step-hint {
    background: var(--accent-soft);
    border-left: 3px solid var(--accent);
    border-radius: 0 var(--radius) var(--radius) 0;
    padding: 0.9rem 1.1rem;
    margin: 1rem 0;
}

.key-points > :last-child,
.tip-box > :last-child,
.reference-box > :last-child,
.note-box > :last-child,
.precedence-list > :last-child,
.conversion-steps > :last-child,
.process-flow > :last-child,
.code-structure > :last-child,
.implementation-note > :last-child,
.step-hint > :last-child {
    margin-bottom: 0;
}

.key-points h3,
.key-points h4,
.tip-box h4,
.note-box h4 {
    margin-top: 0;
    margin-bottom: 0.5rem;
    font-size: 1rem;
}

.step-hint {
    background: var(--note-bg);
    border-left-color: var(--note-border);
}

.process-flow p,
.code-structure {
    font-family: var(--font-mono);
    font-size: 0.95rem;
}

.note,
.problem-note,
.table-note,
.gate-note {
    color: var(--text-muted);
    font-size: 0.92rem;
    font-style: italic;
}

/* Maths / expressions */
.math-expression {
    font-family: var(--font-serif);
    font-size: 1.15rem;
    margin: 0.75rem 0 1rem;
    line-height: 1.6;
}

.problem-expression {
    background: var(--code-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 0.75rem 1rem;
    margin: 0.75rem 0 1rem;
}

.problem-expression code {
    background: none;
    padding: 0;
    font-size: 1.05rem;
    letter-spacing: 0.04em;
}

.problem-expression .math-expression { margin: 0; }

.step-result {
    font-family: var(--font-serif);
    font-size: 1.05rem;
    background: var(--code-bg);
    padding: 0.35rem 0.75rem;
    border-radius: 3px;
    margin: 0.4rem 0;
    display: inline-block;
}

.overline {
    text-decoration: overline;
    display: inline-block;
    padding: 0 1px;
}

.double-overline {
    text-decoration: overline;
    border-top: 1px solid currentColor;
    display: inline-block;
    padding: 0 2px;
    margin-top: 3px;
}

.law-equations,
.operator-notation {
    background: var(--code-bg);
    border-radius: 3px;
    padding: 0.5rem 0.8rem;
    margin-top: 0.5rem;
}

.law-equations p,
.operator-notation p {
    margin: 0.25rem 0;
    font-family: var(--font-serif);
    font-size: 1.05rem;
}

.law-card > p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* Truth tables and compact tables */
.truth-table,
.solution-table,
.conversion-table {
    width: auto;
    min-width: 200px;
}

.truth-table th,
.truth-table td,
.solution-table th,
.solution-table td,
.conversion-table th,
.conversion-table td {
    text-align: center;
    padding: 0.35rem 0.75rem;
    font-family: var(--font-mono);
    font-size: 0.92rem;
}

.truth-table th,
.solution-table th {
    font-family: var(--font-sans);
}

.instruction-table table,
.code-table table {
    width: 100%;
}

.code-table table {
    font-family: var(--font-mono);
    font-size: 0.95rem;
    max-width: 420px;
}

.code-table td {
    padding: 0.3rem 0.75rem;
}

.code-table td:first-child { color: var(--accent); }

.instruction-table td:first-child {
    font-family: var(--font-mono);
    white-space: nowrap;
}

/* Step-by-step blocks */
.step-by-step {
    margin-top: 0.75rem;
}

.step-by-step > p:first-child {
    font-weight: 600;
    margin-bottom: 0.4rem;
}

.step-by-step code {
    font-size: 0.95rem;
    letter-spacing: 0.03em;
}

.result,
.final-answer {
    font-weight: 600;
    margin-top: 0.75rem;
}

.binary-operation,
.truth-comparison {
    display: inline-block;
    background: var(--code-bg);
    border: 1px solid var(--border);
    border-radius: 3px;
    padding: 0.6rem 0.9rem;
    margin: 0.5rem 0;
    font-family: var(--font-mono);
}

.binary-operation code,
.truth-comparison code {
    display: block;
    background: none;
    padding: 0;
    margin: 0.15rem 0;
}

.operation-line {
    height: 1px;
    background: var(--text);
    margin: 0.4rem 0;
}

.conversion-calc {
    letter-spacing: 0.05em;
}

/* Diagrams (digital electronics) */
.gate-visual,
.circuit-visual,
.circuit-diagram,
.inverted-gate-example {
    text-align: center;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 0.75rem;
    margin: 0.75rem 0 1rem;
}

.gate-svg {
    width: 180px;
    height: 108px;
}

.circuit-svg {
    width: 100%;
    max-width: 640px;
    height: auto;
    display: block;
    margin: 0 auto;
}

.circuit-diagram svg {
    width: 320px;
    max-width: 100%;
    height: auto;
}

.gate-shape, .gate-circle, .gate-curve {
    fill: none;
    stroke: var(--text);
    stroke-width: 2;
}

.gate-line {
    stroke: var(--text);
    stroke-width: 2;
}

.gate-label {
    font-family: var(--font-mono);
    font-size: 9px;
    fill: var(--text);
    dominant-baseline: middle;
}

.gate-label-large {
    font-family: var(--font-mono);
    font-size: 16px;
    font-weight: 700;
    fill: var(--text);
    dominant-baseline: middle;
}

.gate-caption {
    margin: 0.5rem 0 0;
    font-family: var(--font-mono);
    font-size: 0.9rem;
}

.gate-example {
    font-style: italic;
    color: var(--text-muted);
    margin: 0.5rem 0;
}

.problem-circuit {
    display: block;
    max-width: 100%;
    width: auto;
    height: auto;
    margin: 0 auto;
}

.circuit-explanation {
    text-align: left;
}

/* --------------------------------------------------------------------------
   Practice problems (topic pages)
   -------------------------------------------------------------------------- */

.practice-problem {
    padding: 1.25rem 0;
    border-top: 1px solid var(--border);
}

.practice-problem:first-of-type {
    border-top: 0;
    padding-top: 0.5rem;
}

.practice-problem:last-child { padding-bottom: 0; }

.practice-problem h3 {
    margin-top: 0;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.6rem;
}

.level {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--accent);
    background: var(--accent-soft);
    border-radius: 3px;
    padding: 0.15rem 0.5rem;
}

.answer-row {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.6rem;
    margin: 1rem 0 0.75rem;
}

.answer-input,
input[type="text"].answer-input {
    font: inherit;
    font-size: 1rem;
    padding: 0.5rem 0.7rem;
    border: 1px solid var(--border-strong);
    border-radius: var(--radius);
    background: var(--surface);
    color: var(--text);
    min-width: 220px;
    flex: 0 1 260px;
}

.answer-input:focus {
    outline: 2px solid var(--accent);
    outline-offset: 1px;
    border-color: var(--accent);
}

.feedback {
    margin: 0.5rem 0;
    font-weight: 500;
    min-height: 1.2em;
}

.feedback.correct { color: var(--success); }
.feedback.incorrect { color: var(--error); }

.solution {
    background: var(--code-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem 1.15rem;
    margin-top: 0.75rem;
}

.solution[hidden] { display: none; }

.solution h4 {
    margin-top: 0;
    margin-bottom: 0.6rem;
}

.solution > :last-child { margin-bottom: 0; }

.solution pre {
    background: var(--surface);
}

/* --------------------------------------------------------------------------
   Topic hub (ACSL/acsl.html)
   -------------------------------------------------------------------------- */

.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
    gap: 0.75rem;
    margin: 0;
    padding: 0;
    list-style: none;
}

.topics-grid li { margin: 0; }

.topic-card {
    display: block;
    height: 100%;
    padding: 0.9rem 1rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-left: 3px solid var(--accent);
    border-radius: var(--radius);
    color: var(--text);
    text-decoration: none;
    font-weight: 500;
    transition: border-color 0.15s ease, background-color 0.15s ease;
}

.topic-card:hover {
    background: var(--accent-soft);
    border-color: var(--accent);
    color: var(--accent-hover);
}

.topic-card .topic-note {
    display: block;
    font-size: 0.85rem;
    font-weight: 400;
    color: var(--text-muted);
    margin-top: 0.15rem;
}

/* --------------------------------------------------------------------------
   Homepage
   -------------------------------------------------------------------------- */

.intro {
    padding: 3rem 0 2.5rem;
    border-bottom: 1px solid var(--border);
}

.intro h1 {
    font-size: 2.4rem;
    margin-bottom: 1rem;
}

.intro .lead {
    font-size: 1.25rem;
    color: var(--text);
    max-width: 44rem;
}

.two-col {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 2fr);
    gap: 1.5rem 3rem;
    align-items: start;
}

.two-col h2 { margin-bottom: 0; }

.pillars {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem 2rem;
    margin: 1.5rem 0 0;
    padding: 0;
    list-style: none;
}

.pillars li {
    margin: 0;
    padding-top: 0.75rem;
    border-top: 2px solid var(--text);
}

.pillars h3 {
    font-size: 1rem;
    margin-bottom: 0.35rem;
}

.pillars p {
    margin: 0;
    color: var(--text-muted);
    font-size: 0.95rem;
}

.impact-list {
    margin: 0;
}

.impact-list li { margin-bottom: 0.5rem; }

.link-list {
    list-style: none;
    padding: 0;
    margin: 1rem 0 0;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 0.75rem;
}

.link-list li { margin: 0; }

.link-list a {
    display: block;
    padding: 1rem 1.15rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--surface);
    text-decoration: none;
    color: var(--text);
}

.link-list a:hover {
    border-color: var(--accent);
    background: var(--accent-soft);
}

.link-list strong {
    display: block;
    color: var(--accent);
    margin-bottom: 0.2rem;
}

.link-list span {
    font-size: 0.92rem;
    color: var(--text-muted);
}

/* --------------------------------------------------------------------------
   Practice tests
   -------------------------------------------------------------------------- */

.contest-block h2 {
    margin-bottom: 0.25rem;
}

.contest-topics {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-bottom: 1rem;
}

.test-links {
    list-style: none;
    padding: 0;
    margin: 0;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 0.6rem;
}

.test-links li { margin: 0; }

.test-links a {
    display: block;
    padding: 0.7rem 0.9rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--surface);
    text-decoration: none;
    color: var(--text);
    font-size: 0.95rem;
}

.test-links a:hover {
    border-color: var(--accent);
    background: var(--accent-soft);
    color: var(--accent-hover);
}

.test-links a small {
    display: block;
    color: var(--text-muted);
    font-size: 0.82rem;
}

.test-links a.is-pending {
    color: var(--text-muted);
    border-style: dashed;
}

.test-problem-header .topic-link { white-space: nowrap; }

.solution-controls { margin: 0.75rem 0 0; }

.test-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem 1.5rem;
    color: var(--text-muted);
    font-size: 0.95rem;
    margin: 0.5rem 0 0;
}

.test-meta span strong { color: var(--text); }

.test-toolbar {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem 1.5rem;
    margin: 1.25rem 0;
    padding: 0.75rem 1rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
}

.timer {
    font-family: var(--font-mono);
    font-size: 1.05rem;
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
}

.timer .btn { padding: 0.3rem 0.7rem; font-size: 0.85rem; }

.test-problem {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.25rem 1.5rem;
    margin-bottom: 1.25rem;
}

.test-problem.is-correct { border-left: 3px solid var(--success); }
.test-problem.is-incorrect { border-left: 3px solid var(--error); }

.test-problem-header {
    display: flex;
    flex-wrap: wrap;
    align-items: baseline;
    justify-content: space-between;
    gap: 0.4rem 1rem;
    margin-bottom: 0.75rem;
}

.test-problem-header h2 {
    font-size: 1.1rem;
    margin: 0;
}

.test-problem-header a {
    font-size: 0.9rem;
}

.question > :last-child { margin-bottom: 0; }

.result-mark {
    font-weight: 600;
    font-size: 0.95rem;
}

.result-mark.correct { color: var(--success); }
.result-mark.incorrect { color: var(--error); }

.accepted-answer {
    font-size: 0.92rem;
    color: var(--text-muted);
    margin: 0.35rem 0 0;
}

.score-panel {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.25rem 1.5rem;
    margin: 1.5rem 0;
}

.score-panel[hidden] { display: none; }

.score-panel h2 {
    margin-bottom: 0.25rem;
}

.score-panel .score {
    font-size: 1.6rem;
    font-weight: 700;
}

.test-nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: 0.75rem;
    margin-top: 2rem;
    padding-top: 1.25rem;
    border-top: 1px solid var(--border);
}

.test-nav a { font-size: 0.95rem; }

.message-box {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem 1.75rem;
}

/* --------------------------------------------------------------------------
   Contact & privacy
   -------------------------------------------------------------------------- */

.email-link {
    font-size: 1.15rem;
    font-weight: 600;
    word-break: break-all;
}

.response-time {
    background: var(--success-bg);
    border-left: 3px solid var(--success);
    padding: 0.9rem 1.1rem;
    border-radius: 0 var(--radius) var(--radius) 0;
    margin: 1.25rem 0 0;
}

.response-time h4 {
    margin: 0 0 0.35rem;
    color: var(--success);
}

.response-time p { margin: 0; }

.legal h2 {
    font-size: 1.1rem;
    margin-top: 1.75rem;
}

.legal .effective {
    color: var(--text-muted);
    margin-bottom: 1.25rem;
}

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

@media (max-width: 720px) {
    h1 { font-size: 1.65rem; }
    .intro h1 { font-size: 1.9rem; }
    .intro .lead { font-size: 1.1rem; }

    .site-header-inner {
        flex-direction: column;
        align-items: flex-start;
    }

    .site-nav { margin-left: -0.7rem; }

    .content-section { padding: 1.15rem 1.15rem; }

    .two-col { grid-template-columns: 1fr; gap: 0.75rem; }

    .answer-input,
    input[type="text"].answer-input {
        flex: 1 1 100%;
        min-width: 0;
    }

    .test-problem { padding: 1rem 1.1rem; }
}

@media print {
    .site-header, .site-footer, .btn, .test-toolbar { display: none; }
    body { background: #fff; }
    .content-section, .test-problem { border: 0; padding: 0; }
}