/*
 * Controls Academy site styles, layered on Bootstrap 5.3.
 * Look: clean engineering-instrument feel. Ink navy text, "signal blue"
 * primary, a small amber accent (the setpoint trace in the brand mark and
 * hero), cool slate neutrals, IBM Plex Sans with Plex Mono for labels.
 */

:root {
    --ca-ink: #0f1b2d;
    --ca-text: #26334a;
    --ca-muted: #5b6880;
    --ca-line: #dfe5ee;
    --ca-line-strong: #c9d3e1;
    --ca-surface: #f4f7fb;
    --ca-surface-2: #eaf0f8;
    --ca-primary: #1d5bd8;
    --ca-primary-hover: #174bb4;
    --ca-primary-tint: #e8effc;
    --ca-amber: #e09b2d;
    --ca-success: #1f8a5b;

    --ca-font: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
    --ca-mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Consolas, monospace;

    --ca-radius: 0.75rem;
    --ca-radius-sm: 0.5rem;
    --ca-shadow: 0 1px 2px rgba(15, 27, 45, 0.05), 0 4px 16px rgba(15, 27, 45, 0.04);
    --ca-shadow-hover: 0 2px 4px rgba(15, 27, 45, 0.06), 0 12px 28px rgba(15, 27, 45, 0.08);

    /* Bootstrap hooks */
    --bs-body-font-family: var(--ca-font);
    --bs-body-color: var(--ca-text);
    --bs-body-bg: #ffffff;
    --bs-emphasis-color: var(--ca-ink);
    --bs-secondary-color: var(--ca-muted);
    --bs-border-color: var(--ca-line);
    --bs-primary: var(--ca-primary);
    --bs-primary-rgb: 29, 91, 216;
    --bs-link-color: var(--ca-primary);
    --bs-link-color-rgb: 29, 91, 216;
    --bs-link-hover-color: var(--ca-primary-hover);
    --bs-link-hover-color-rgb: 23, 75, 180;
    --bs-border-radius: var(--ca-radius-sm);
    --bs-border-radius-lg: var(--ca-radius);
    --bs-success-rgb: 31, 138, 91;
}

body {
    font-size: 1rem;
    line-height: 1.6;
    background: #ffffff;
    -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5, h6, .h1, .h2, .h3, .h4, .h5, .h6 {
    color: var(--ca-ink);
    font-weight: 600;
    letter-spacing: -0.015em;
    text-wrap: balance;
}

h1, .h1 { font-size: clamp(1.75rem, 1.3rem + 1.6vw, 2.35rem); }

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

a { text-underline-offset: 0.18em; }

:focus-visible {
    outline: 3px solid rgba(29, 91, 216, 0.35);
    outline-offset: 2px;
}

.skip-link {
    position: absolute;
    top: 0.5rem;
    left: 0.5rem;
    z-index: 1100;
    padding: 0.5rem 0.75rem;
    background: #fff;
    border-radius: var(--ca-radius-sm);
    box-shadow: var(--ca-shadow);
}

/* Small uppercase label above titles */
.eyebrow {
    display: inline-block;
    font-family: var(--ca-mono);
    font-size: 0.75rem;
    font-weight: 500;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--ca-primary);
    margin-bottom: 0.5rem;
}

.eyebrow a { color: inherit; text-decoration: none; }
.eyebrow a:hover { text-decoration: underline; }

/* ------------------------------------------------------------ buttons */

.btn {
    font-weight: 500;
    border-radius: var(--ca-radius-sm);
}

.btn-primary {
    --bs-btn-bg: var(--ca-primary);
    --bs-btn-border-color: var(--ca-primary);
    --bs-btn-hover-bg: var(--ca-primary-hover);
    --bs-btn-hover-border-color: var(--ca-primary-hover);
    --bs-btn-active-bg: var(--ca-primary-hover);
    --bs-btn-active-border-color: var(--ca-primary-hover);
    --bs-btn-disabled-bg: var(--ca-primary);
    --bs-btn-disabled-border-color: var(--ca-primary);
}

.btn-outline-primary {
    --bs-btn-color: var(--ca-primary);
    --bs-btn-border-color: var(--ca-line-strong);
    --bs-btn-hover-bg: var(--ca-primary-tint);
    --bs-btn-hover-color: var(--ca-primary-hover);
    --bs-btn-hover-border-color: var(--ca-primary);
    --bs-btn-active-bg: var(--ca-primary);
    --bs-btn-active-border-color: var(--ca-primary);
}

.btn-outline-secondary {
    --bs-btn-color: var(--ca-text);
    --bs-btn-border-color: var(--ca-line-strong);
    --bs-btn-hover-bg: var(--ca-surface);
    --bs-btn-hover-color: var(--ca-ink);
    --bs-btn-hover-border-color: var(--ca-line-strong);
    --bs-btn-active-bg: var(--ca-surface-2);
    --bs-btn-active-color: var(--ca-ink);
    --bs-btn-active-border-color: var(--ca-line-strong);
}

.btn-success {
    --bs-btn-bg: var(--ca-success);
    --bs-btn-border-color: var(--ca-success);
    --bs-btn-hover-bg: #19734b;
    --bs-btn-hover-border-color: #19734b;
}

.form-control,
.form-select {
    border-color: var(--ca-line-strong);
}

.form-control:focus,
.form-select:focus,
.form-check-input:focus {
    border-color: var(--ca-primary);
    box-shadow: 0 0 0 0.2rem rgba(29, 91, 216, 0.15);
}

.form-check-input:checked {
    background-color: var(--ca-primary);
    border-color: var(--ca-primary);
}

.form-label { font-weight: 500; color: var(--ca-ink); }

.form-range::-webkit-slider-thumb { background: var(--ca-primary); }
.form-range::-moz-range-thumb { background: var(--ca-primary); }

.badge { font-weight: 500; }

.alert { border-radius: var(--ca-radius-sm); }

/* --------------------------------------------------------- nav / footer */

.site-nav {
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: saturate(180%) blur(8px);
    border-bottom: 1px solid var(--ca-line);
    padding-block: 0.6rem;
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 0.55rem;
    font-weight: 700;
    color: var(--ca-ink);
    letter-spacing: -0.01em;
}

.brand:hover { color: var(--ca-ink); }

.brand-mark { width: 30px; height: 30px; flex: none; }
.brand-mark rect { fill: var(--ca-ink); }
.brand-mark path { fill: none; stroke-width: 2.25; stroke-linecap: round; stroke-linejoin: round; }
.brand-mark .brand-sp { stroke: var(--ca-amber); stroke-dasharray: 2.5 2.5; }
.brand-mark .brand-pv { stroke: #7fb0ff; }

.site-nav .nav-link {
    color: var(--ca-text);
    font-weight: 500;
    padding-inline: 0.75rem !important;
    border-radius: var(--ca-radius-sm);
}

.site-nav .nav-link:hover { color: var(--ca-ink); background: var(--ca-surface); }

.site-nav .nav-link.active {
    color: var(--ca-primary);
    background: var(--ca-primary-tint);
}

.nav-user {
    font-size: 0.85rem;
    color: var(--ca-muted);
    padding-inline: 0.75rem;
}

.site-nav .dropdown-menu {
    border-color: var(--ca-line);
    border-radius: var(--ca-radius-sm);
    box-shadow: var(--ca-shadow-hover);
}

@media (max-width: 991.98px) {
    .site-nav .navbar-collapse { padding-block: 0.5rem; }
    .site-nav .btn-primary { margin: 0.25rem 0.75rem; }
}

.site-footer {
    border-top: 1px solid var(--ca-line);
    background: var(--ca-surface);
    padding-block: 1.5rem;
    font-size: 0.875rem;
}

.flash-stack { margin-bottom: 1rem; }

/* ------------------------------------------------- page headers, cards */

.page-head {
    margin-bottom: 2rem;
}

.page-head .lead {
    font-size: 1.125rem;
    color: var(--ca-muted);
    max-width: 46rem;
    margin-bottom: 0;
}

.page-head-row {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: flex-end;
    gap: 1rem;
}

.card {
    --bs-card-border-color: var(--ca-line);
    --bs-card-border-radius: var(--ca-radius);
    --bs-card-inner-border-radius: calc(var(--ca-radius) - 1px);
    --bs-card-cap-bg: var(--ca-surface);
    box-shadow: var(--ca-shadow);
}

.card-hover {
    transition: box-shadow 0.15s ease, transform 0.15s ease, border-color 0.15s ease;
}

.card-hover:hover {
    box-shadow: var(--ca-shadow-hover);
    border-color: var(--ca-line-strong);
    transform: translateY(-2px);
}

.card-title a { color: inherit; text-decoration: none; }

.card-arrow {
    font-weight: 500;
    color: var(--ca-primary);
}

.meta-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem 1rem;
    font-size: 0.85rem;
    color: var(--ca-muted);
}

.tag {
    display: inline-flex;
    align-items: center;
    padding: 0.1rem 0.55rem;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 500;
    background: var(--ca-surface-2);
    color: var(--ca-text);
}

.tag-amber { background: #fdf1dc; color: #8a5a0b; }

.icon-tile {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2.5rem;
    height: 2.5rem;
    border-radius: var(--ca-radius-sm);
    background: var(--ca-primary-tint);
    color: var(--ca-primary);
    flex: none;
}

.icon-tile svg { width: 1.35rem; height: 1.35rem; }

.empty-state {
    padding: 2rem;
    border: 1px dashed var(--ca-line-strong);
    border-radius: var(--ca-radius);
    color: var(--ca-muted);
    text-align: center;
}

/* Tables inside cards (admin, tools) */
.table-card { overflow: hidden; }
.table-card .table { margin-bottom: 0; }

.table {
    --bs-table-border-color: var(--ca-line);
}

.table > thead th {
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    color: var(--ca-muted);
    background: var(--ca-surface);
    white-space: nowrap;
}

.table-card .table > :not(caption) > * > * { padding: 0.7rem 1rem; }

/* ----------------------------------------------------------------- home */

.hero {
    position: relative;
    background: var(--ca-surface);
    border-bottom: 1px solid var(--ca-line);
    overflow: hidden;
}

.hero::before {
    /* faint graph-paper grid */
    content: "";
    position: absolute;
    inset: 0;
    background-image:
        linear-gradient(var(--ca-line) 1px, transparent 1px),
        linear-gradient(90deg, var(--ca-line) 1px, transparent 1px);
    background-size: 32px 32px;
    opacity: 0.45;
    mask-image: linear-gradient(90deg, transparent 0%, #000 55%);
}

.hero .container { position: relative; }

.hero h1 {
    font-size: clamp(2rem, 1.4rem + 2.4vw, 3.1rem);
    font-weight: 700;
    letter-spacing: -0.025em;
    line-height: 1.12;
}

.hero .lead {
    font-size: 1.15rem;
    color: var(--ca-muted);
    max-width: 34rem;
}

.scope {
    background: #fff;
    border: 1px solid var(--ca-line);
    border-radius: var(--ca-radius);
    box-shadow: var(--ca-shadow-hover);
    padding: 1rem 1rem 0.75rem;
}

.scope-head {
    display: flex;
    justify-content: space-between;
    font-family: var(--ca-mono);
    font-size: 0.72rem;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    color: var(--ca-muted);
    margin-bottom: 0.5rem;
}

.scope svg { display: block; width: 100%; height: auto; }
.scope .grid line { stroke: var(--ca-line); stroke-width: 1; }
.scope .sp { fill: none; stroke: var(--ca-amber); stroke-width: 2; stroke-dasharray: 6 5; }
.scope .pv { fill: none; stroke: var(--ca-primary); stroke-width: 2.75; stroke-linecap: round; }
.scope .band { fill: var(--ca-primary-tint); }
.scope text { font-family: var(--ca-mono); font-size: 11px; fill: var(--ca-muted); }

.scope-legend {
    display: flex;
    gap: 1rem;
    font-size: 0.8rem;
    color: var(--ca-muted);
    margin-top: 0.4rem;
}

.scope-legend i {
    display: inline-block;
    width: 1rem;
    height: 0;
    margin-right: 0.35rem;
    vertical-align: middle;
    border-top: 2.5px solid var(--ca-primary);
}

.scope-legend i.sp-key { border-top: 2px dashed var(--ca-amber); }

@media (prefers-reduced-motion: no-preference) {
    .scope .pv {
        stroke-dasharray: 900;
        stroke-dashoffset: 900;
        animation: trace 1.6s 0.2s ease-out forwards;
    }
    @keyframes trace { to { stroke-dashoffset: 0; } }
}

.feature h3 { font-size: 1.05rem; margin-bottom: 0.25rem; }
.feature p { color: var(--ca-muted); margin-bottom: 0; font-size: 0.95rem; }

.section-title {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    gap: 1rem;
    margin-bottom: 1.25rem;
}

.section-title h2 { font-size: 1.35rem; margin-bottom: 0; }

/* ------------------------------------------------------- course outline */

.info-card {
    position: sticky;
    top: 5.5rem;
}

.info-list {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 0.5rem 1rem;
    margin-bottom: 1.25rem;
}

.info-list dt { font-weight: 500; color: var(--ca-muted); }
.info-list dd { margin: 0; text-align: right; color: var(--ca-ink); font-weight: 500; }

.progress {
    --bs-progress-bg: var(--ca-surface-2);
    --bs-progress-bar-bg: var(--ca-primary);
    --bs-progress-height: 0.5rem;
    --bs-progress-border-radius: 999px;
}

.module {
    border: 1px solid var(--ca-line);
    border-radius: var(--ca-radius);
    background: #fff;
    box-shadow: var(--ca-shadow);
    overflow: hidden;
}

.module + .module { margin-top: 1rem; }

.module-head {
    padding: 0.9rem 1.25rem;
    background: var(--ca-surface);
    border-bottom: 1px solid var(--ca-line);
}

.module-head .eyebrow { margin-bottom: 0.1rem; }
.module-head h3 { font-size: 1.05rem; margin: 0; }

.lesson-list { list-style: none; margin: 0; padding: 0; }

.lesson-list li + li { border-top: 1px solid var(--ca-line); }

.lesson-row {
    display: flex;
    align-items: center;
    gap: 0.9rem;
    padding: 0.8rem 1.25rem;
    color: var(--ca-text);
    text-decoration: none;
}

.lesson-row:hover { background: var(--ca-surface); color: var(--ca-ink); }

.lesson-num {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 1.9rem;
    height: 1.9rem;
    border-radius: 50%;
    border: 1.5px solid var(--ca-line-strong);
    font-family: var(--ca-mono);
    font-size: 0.8rem;
    color: var(--ca-muted);
    flex: none;
}

.lesson-row.is-done .lesson-num {
    background: var(--ca-success);
    border-color: var(--ca-success);
    color: #fff;
}

.lesson-row .lesson-title { flex: 1; min-width: 0; font-weight: 500; }
.lesson-row .lesson-state { font-size: 0.8rem; color: var(--ca-success); font-weight: 500; }

/* ----------------------------------------------------------- lesson page */

.reading {
    max-width: 920px;
    margin-inline: auto;
}

.lesson-content {
    font-size: 1.0625rem;
    line-height: 1.75;
    overflow-wrap: anywhere;
}

.lesson-content > :first-child { margin-top: 0; }

.lesson-content p,
.lesson-content ul,
.lesson-content ol { max-width: 70ch; }

.lesson-content h2,
.lesson-content h3 {
    margin-top: 2.25rem;
    margin-bottom: 0.75rem;
}

.lesson-content h2 { font-size: 1.45rem; }
.lesson-content h3 { font-size: 1.2rem; }

.lesson-content img {
    max-width: 100%;
    height: auto;
    border-radius: var(--ca-radius-sm);
}

.lesson-content pre {
    background: var(--ca-surface);
    border: 1px solid var(--ca-line);
    border-radius: var(--ca-radius-sm);
    padding: 0.85rem 1rem;
    overflow-x: auto;
    font-size: 0.9rem;
}

.lesson-content code { font-family: var(--ca-mono); }

.lesson-content table {
    width: 100%;
    margin: 1.25rem 0;
    border-collapse: separate;
    border-spacing: 0;
    border: 1px solid var(--ca-line);
    border-radius: var(--ca-radius-sm);
    overflow: hidden;
    font-size: 0.97rem;
}

.lesson-content th,
.lesson-content td {
    padding: 0.55rem 0.85rem;
    border-bottom: 1px solid var(--ca-line);
}

.lesson-content tr:last-child td { border-bottom: 0; }

.lesson-content th {
    background: var(--ca-surface);
    color: var(--ca-ink);
    font-weight: 600;
}

.lesson-content blockquote {
    border-left: 3px solid var(--ca-amber);
    background: #fffaf1;
    padding: 0.75rem 1rem;
    border-radius: 0 var(--ca-radius-sm) var(--ca-radius-sm) 0;
    color: var(--ca-text);
}

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

/* Wide equations scroll instead of breaking the page */
.lesson-content .katex-display {
    overflow-x: auto;
    overflow-y: hidden;
    padding-block: 0.25rem;
}

.lesson-video {
    border-radius: var(--ca-radius);
    overflow: hidden;
    box-shadow: var(--ca-shadow-hover);
}

.lesson-footer {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    padding-block: 1.5rem;
    margin-block: 2.5rem 2rem;
    border-top: 1px solid var(--ca-line);
    border-bottom: 1px solid var(--ca-line);
}

.complete-note {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 500;
    color: var(--ca-success);
}

.lesson-pager {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 3rem;
}

.pager-link {
    display: block;
    padding: 0.9rem 1.1rem;
    border: 1px solid var(--ca-line);
    border-radius: var(--ca-radius);
    text-decoration: none;
    color: var(--ca-ink);
    font-weight: 500;
    transition: border-color 0.15s ease, background 0.15s ease;
}

.pager-link:hover { border-color: var(--ca-primary); background: var(--ca-primary-tint); color: var(--ca-ink); }
.pager-link small { display: block; color: var(--ca-muted); font-weight: 400; font-size: 0.8rem; }
.pager-link.next { text-align: right; grid-column: 2; }

@media (max-width: 575.98px) {
    .lesson-pager { grid-template-columns: 1fr; }
    .pager-link.next { grid-column: 1; }
}

.feedback-panel {
    background: var(--ca-surface);
    border: 1px solid var(--ca-line);
    border-radius: var(--ca-radius);
    padding: 1.5rem;
}

.rating-scale {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.rating-scale .btn { min-width: 2.75rem; }

.btn-check:checked + .btn-outline-primary {
    background: var(--ca-primary);
    border-color: var(--ca-primary);
    color: #fff;
}

/* ------------------------------------------------------------------ auth */

.auth-wrap {
    display: flex;
    justify-content: center;
    padding-block: 1rem 3rem;
}

.auth-card {
    width: 100%;
    max-width: 26rem;
}

.auth-card .card-body { padding: 2rem; }

.auth-card .brand-mark { width: 40px; height: 40px; margin-bottom: 1rem; }

/* ----------------------------------------------------------------- admin */

.admin-form {
    max-width: 52rem;
}

.form-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    padding-top: 1rem;
    border-top: 1px solid var(--ca-line);
    margin-top: 0.5rem;
}

/* PID simulator ([[pid-simulator]] in lesson content, static/js/pid-simulator.js) */
.pid-sim {
    margin: 1.75rem 0;
    border: 1px solid var(--ca-line);
    border-radius: var(--ca-radius);
    box-shadow: var(--ca-shadow);
    background: #fff;
    font-size: 1rem;
    line-height: 1.5;
    overflow-wrap: normal;
}

.pid-sim-head {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    gap: 0.5rem 1rem;
    padding: 0.85rem 1rem;
    background: var(--ca-surface);
    border-bottom: 1px solid var(--ca-line);
    border-radius: var(--ca-radius) var(--ca-radius) 0 0;
}

.pid-sim-model { font-family: var(--ca-mono); font-size: 0.78rem !important; }

.pid-sim-plant {
    width: auto;
    max-width: 100%;
}

.pid-sim-body {
    display: grid;
    grid-template-columns: minmax(0, 17rem) minmax(0, 1fr);
    gap: 1.5rem;
    padding: 1rem;
}

@media (max-width: 767.98px) {
    .pid-sim-body {
        grid-template-columns: minmax(0, 1fr);
    }
}

.pid-sim-controls {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.pid-sim-presets {
    display: flex;
    flex-wrap: wrap;
    gap: 0.375rem;
}

.pid-sim-gains {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.pid-sim-num {
    width: 5.5rem;
    font-variant-numeric: tabular-nums;
}

.pid-sim-options .form-check-label .small {
    display: block;
}

.pid-sim-plots {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    min-width: 0;
}

.pid-sim-metrics {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 0.5rem;
    margin-bottom: 0.5rem;
}

@media (max-width: 991.98px) {
    .pid-sim-metrics {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}

.pid-sim-metric {
    padding: 0.45rem 0.65rem;
    border: 1px solid var(--ca-line);
    border-left: 3px solid var(--ca-line);
    border-radius: var(--ca-radius-sm);
}

.pid-sim-metric.is-good { border-left-color: #198754; }
.pid-sim-metric.is-warn { border-left-color: #ffc107; }
.pid-sim-metric.is-bad  { border-left-color: #dc3545; }

.pid-sim-metric-label {
    font-family: var(--ca-mono);
    font-size: 0.68rem;
    color: var(--ca-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.pid-sim-metric-value {
    font-weight: 600;
    color: var(--ca-ink);
    font-variant-numeric: tabular-nums;
}

.pid-sim-legend {
    display: flex;
    flex-wrap: wrap;
    gap: 0.25rem 1rem;
    color: var(--ca-text);
}

.pid-sim-legend i {
    display: inline-block;
    width: 1rem;
    height: 3px;
    margin-right: 0.35rem;
    vertical-align: middle;
}

.pid-sim-legend i.dashed {
    height: 0;
    border-top: 2px dashed;
}

.pid-sim-chart {
    display: block;
    width: 100%;
    touch-action: pan-y;
}

.pid-sim-chart-pv { height: 260px; }
.pid-sim-chart-u  { height: 160px; }

.pid-sim-readout {
    min-height: 1.5em;
    font-variant-numeric: tabular-nums;
}

/* Engineering Tools (templates/tools/) */
.tool-table {
    font-variant-numeric: tabular-nums;
}

.tool-table tr.tool-table-group td {
    border-top: 2px solid var(--ca-line-strong);
}

.tool-big {
    font-size: 1.25rem;
    font-variant-numeric: tabular-nums;
}

.tool-note {
    font-size: 0.875rem;
    color: var(--ca-muted);
}

/* Dashboard */
.stat-row {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1rem;
}

@media (max-width: 575.98px) {
    .stat-row { grid-template-columns: minmax(0, 1fr); }
}

.stat {
    padding: 1.1rem 1.25rem;
    border: 1px solid var(--ca-line);
    border-radius: var(--ca-radius);
    background: #fff;
    box-shadow: var(--ca-shadow);
}

.stat-label {
    font-family: var(--ca-mono);
    font-size: 0.72rem;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--ca-muted);
}

.stat-value {
    font-size: 2rem;
    font-weight: 600;
    color: var(--ca-ink);
    font-variant-numeric: tabular-nums;
    line-height: 1.2;
}

/* Admin: instructor signature */
.signature-preview {
    display: inline-block;
    padding: 0.75rem 1rem;
    border: 1px dashed var(--ca-line-strong);
    border-radius: var(--ca-radius-sm);
    background: #fff;
}

.signature-preview img { max-height: 80px; max-width: 100%; }