:root,
[data-reader-theme="light"] {
    --reader-bg: #f7f7f8;
    --reader-card: #ffffff;
    --reader-panel: #ffffff;
    --reader-border: #e5e7eb;
    --reader-text: #111827;
    --reader-ink: var(--reader-text);
    --reader-muted: #6b7280;
    --reader-accent: #2563eb;
    --reader-blue: var(--reader-accent);
    --reader-blue-soft: #eff6ff;
    --reader-statement-bg: #ffffff;
    --reader-subtle: #f8fafc;
    --reader-subtle-border: #e2e8f0;
    --reader-gold: #d99021;
    --reader-green: #166534;
    --reader-hint: #92400e;
    --reader-purple: #5b21b6;
    --reader-target: #be123c;
    --reader-hint-bg: #fffbeb;
    --reader-solution-bg: #f0fdf4;
    --reader-teacher-bg: #f5f3ff;
    --reader-shadow: 0 14px 32px rgba(15, 23, 42, 0.07);
    --reader-shadow-soft: 0 8px 24px rgba(15, 23, 42, 0.055);
}

[data-reader-theme="dark"] {
    color-scheme: dark;
    --reader-bg: #0f172a;
    --reader-card: #111827;
    --reader-panel: #111827;
    --reader-border: #334155;
    --reader-text: #e5e7eb;
    --reader-ink: var(--reader-text);
    --reader-muted: #94a3b8;
    --reader-accent: #60a5fa;
    --reader-blue: var(--reader-accent);
    --reader-blue-soft: #172554;
    --reader-statement-bg: #0b1220;
    --reader-subtle: #1e293b;
    --reader-subtle-border: #334155;
    --reader-gold: #fbbf24;
    --reader-green: #86efac;
    --reader-hint: #fbbf24;
    --reader-purple: #c4b5fd;
    --reader-target: #fb7185;
    --reader-hint-bg: #1f1a0b;
    --reader-solution-bg: #121b2a;
    --reader-teacher-bg: #1b1530;
    --reader-shadow: none;
    --reader-shadow-soft: none;
}

.reader-shell,
.reader-main,
.reader-sidebar,
.reader-card,
.reader-statement,
.reader-accordion-content,
.problem-card,
.problem-content,
.content-html {
    min-width: 0;
}

.min-w-0 {
    min-width: 0;
}

html[data-reader-theme] body {
    background: var(--reader-bg) !important;
    color: var(--reader-text) !important;
}

html[data-reader-theme] a {
    color: var(--reader-accent);
}

html[data-reader-theme] .site-nav {
    background: color-mix(in srgb, var(--reader-card) 91%, transparent);
    border-bottom-color: var(--reader-border);
}

html[data-reader-theme] .navbar-brand,
html[data-reader-theme] .nav-link {
    color: var(--reader-text);
}

html[data-reader-theme] .nav-link:hover,
html[data-reader-theme] .nav-link.active {
    color: var(--reader-accent);
}

html[data-reader-theme] .navbar-toggler {
    border-color: var(--reader-border);
}

html[data-reader-theme] .hero-panel,
html[data-reader-theme] .content-panel,
html[data-reader-theme] .surface-card {
    background: color-mix(in srgb, var(--reader-card) 94%, transparent);
    border-color: var(--reader-border);
    box-shadow: var(--reader-shadow-soft);
    color: var(--reader-text);
}

html[data-reader-theme] .hero-figure {
    background: linear-gradient(135deg, var(--reader-subtle), color-mix(in srgb, var(--reader-accent) 7%, var(--reader-card)));
    border-left-color: var(--reader-border);
}

html[data-reader-theme] .text-secondary,
html[data-reader-theme] .text-muted {
    color: var(--reader-muted) !important;
}

html[data-reader-theme] .btn-outline-secondary,
html[data-reader-theme] .btn-light,
html[data-reader-theme] .form-control,
html[data-reader-theme] .form-select {
    background-color: var(--reader-card);
    border-color: var(--reader-border);
    color: var(--reader-text);
}

html[data-reader-theme] .btn-outline-secondary:hover,
html[data-reader-theme] .btn-light:hover {
    background-color: var(--reader-subtle);
    border-color: color-mix(in srgb, var(--reader-accent) 35%, var(--reader-border));
    color: var(--reader-accent);
}

html[data-reader-theme] .badge.text-bg-light {
    background-color: var(--reader-subtle) !important;
    border-color: var(--reader-subtle-border) !important;
    color: var(--reader-muted) !important;
}

html[data-reader-theme] .content-html .card,
html[data-reader-theme] .module-theory .card,
html[data-reader-theme] .module-examples .card {
    background-color: var(--reader-card) !important;
    border: 1px solid var(--reader-border) !important;
    color: var(--reader-text) !important;
    box-shadow: var(--reader-shadow-soft) !important;
}

html[data-reader-theme] .content-html .card-body,
html[data-reader-theme] .module-theory .card-body,
html[data-reader-theme] .module-examples .card-body {
    color: var(--reader-text) !important;
}

html[data-reader-theme] .content-html .alert-light,
html[data-reader-theme] .module-theory .alert-light,
html[data-reader-theme] .module-examples .alert-light {
    background-color: var(--reader-subtle) !important;
    border-color: var(--reader-border) !important;
    color: var(--reader-text) !important;
}

html[data-reader-theme] .content-html h1,
html[data-reader-theme] .content-html h2,
html[data-reader-theme] .content-html h3,
html[data-reader-theme] .content-html h4,
html[data-reader-theme] .module-theory h1,
html[data-reader-theme] .module-theory h2,
html[data-reader-theme] .module-theory h3,
html[data-reader-theme] .module-theory h4,
html[data-reader-theme] .module-examples h1,
html[data-reader-theme] .module-examples h2,
html[data-reader-theme] .module-examples h3,
html[data-reader-theme] .module-examples h4 {
    color: var(--reader-text) !important;
}

html[data-reader-theme] .btn-primary,
html[data-reader-theme] .btn-outline-primary {
    background-color: var(--reader-card) !important;
    border-color: var(--reader-border) !important;
    color: var(--reader-text) !important;
    box-shadow: none !important;
}

html[data-reader-theme] .btn-primary:hover,
html[data-reader-theme] .btn-primary:focus-visible,
html[data-reader-theme] .btn-outline-primary:hover,
html[data-reader-theme] .btn-outline-primary:focus-visible {
    background-color: var(--reader-subtle) !important;
    border-color: color-mix(in srgb, var(--reader-accent) 34%, var(--reader-border)) !important;
    color: var(--reader-accent) !important;
}

.public-theme-toggle {
    border-radius: 999px;
    font-weight: 700;
    min-width: 72px;
}

.reader-tabs .btn,
.course-tabs .btn,
.chapter-tabs .btn {
    background: var(--reader-card, #ffffff) !important;
    border: 1px solid var(--reader-border, #d1d5db) !important;
    border-radius: 0.5rem;
    box-shadow: none !important;
    color: var(--reader-text, #111827) !important;
    font-weight: 500;
    padding: 0.55rem 0.95rem;
    transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

.reader-tabs .btn-sm,
.course-tabs .btn-sm,
.chapter-tabs .btn-sm {
    padding: 0.42rem 0.78rem;
}

[data-reader-theme] .reader-tabs.bg-white,
[data-reader-theme] .course-tabs.bg-white,
[data-reader-theme] .chapter-tabs.bg-white {
    background: color-mix(in srgb, var(--reader-card) 78%, transparent) !important;
    backdrop-filter: blur(10px);
}

.reader-tabs .btn:hover,
.course-tabs .btn:hover,
.chapter-tabs .btn:hover {
    background: var(--reader-subtle, #f8fafc) !important;
    border-color: var(--reader-accent, #2563eb) !important;
    color: var(--reader-accent, #1d4ed8) !important;
}

.reader-tabs .btn.active,
.course-tabs .btn.active,
.chapter-tabs .btn.active,
.reader-tabs .btn[aria-current="page"],
.course-tabs .btn[aria-current="page"],
.chapter-tabs .btn[aria-current="page"],
.reader-tabs .btn.btn-primary,
.course-tabs .btn.btn-primary,
.chapter-tabs .btn.btn-primary {
    background: var(--reader-blue-soft, #eff6ff) !important;
    border-color: var(--reader-accent, #2563eb) !important;
    color: var(--reader-accent, #1d4ed8) !important;
    font-weight: 600;
    box-shadow: 0 0 0 1px color-mix(in srgb, var(--reader-accent, #2563eb) 8%, transparent) !important;
}

[data-reader-theme="dark"] .reader-tabs .btn,
[data-reader-theme="dark"] .course-tabs .btn,
[data-reader-theme="dark"] .chapter-tabs .btn {
    background: #111827 !important;
    border-color: #334155 !important;
    color: #e5e7eb !important;
}

[data-reader-theme="dark"] .reader-tabs .btn:hover,
[data-reader-theme="dark"] .course-tabs .btn:hover,
[data-reader-theme="dark"] .chapter-tabs .btn:hover {
    background: #1e293b !important;
    border-color: #60a5fa !important;
    color: #bfdbfe !important;
}

[data-reader-theme="dark"] .reader-tabs .btn.active,
[data-reader-theme="dark"] .course-tabs .btn.active,
[data-reader-theme="dark"] .chapter-tabs .btn.active,
[data-reader-theme="dark"] .reader-tabs .btn[aria-current="page"],
[data-reader-theme="dark"] .course-tabs .btn[aria-current="page"],
[data-reader-theme="dark"] .chapter-tabs .btn[aria-current="page"],
[data-reader-theme="dark"] .reader-tabs .btn.btn-primary,
[data-reader-theme="dark"] .course-tabs .btn.btn-primary,
[data-reader-theme="dark"] .chapter-tabs .btn.btn-primary {
    background: #172554 !important;
    border-color: #60a5fa !important;
    color: #dbeafe !important;
    font-weight: 600;
}

body.reader-active {
    background: var(--reader-bg) !important;
    color: var(--reader-text);
}

body.reader-active .site-nav {
    background: color-mix(in srgb, var(--reader-card) 88%, transparent);
    border-bottom-color: var(--reader-border);
}

body.reader-active footer {
    color: var(--reader-muted);
}

.reader-toolbar {
    align-items: center;
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    justify-content: flex-end;
    margin-bottom: 14px;
}

.reader-toolbar-button {
    background: var(--reader-card);
    border: 1px solid var(--reader-border);
    border-radius: 999px;
    color: var(--reader-text);
    font-size: 0.85rem;
    font-weight: 700;
    line-height: 1;
    min-height: 34px;
    padding: 8px 13px;
}

.reader-toolbar-button:hover,
.reader-toolbar-button:focus-visible {
    background: var(--reader-subtle);
    border-color: color-mix(in srgb, var(--reader-accent) 35%, var(--reader-border));
    color: var(--reader-accent);
}

.reader-shell {
    display: grid;
    grid-template-columns: minmax(280px, 310px) minmax(0, 900px);
    gap: 32px;
    align-items: start;
    justify-content: center;
    color: var(--reader-text);
}

.reader-shell.is-sidebar-collapsed {
    grid-template-columns: minmax(0, 1000px);
}

.reader-shell.is-sidebar-collapsed .reader-sidebar {
    display: none;
}

.reader-shell.is-sidebar-collapsed .reader-main {
    max-width: 1000px;
}

.reader-main {
    width: 100%;
    max-width: 900px;
    color: var(--reader-text);
}

.reader-main .content-panel,
.reader-shell .content-panel {
    background: var(--reader-card);
    border-color: var(--reader-border);
    box-shadow: var(--reader-shadow-soft);
    color: var(--reader-text);
}

.reader-main .text-secondary,
.reader-shell .text-secondary,
.reader-main .small.text-secondary,
.reader-shell .small.text-secondary {
    color: var(--reader-muted) !important;
}

.reader-main .btn-outline-secondary,
.reader-shell .btn-outline-secondary,
.reader-main .btn-light,
.reader-shell .btn-light {
    background: var(--reader-card);
    border-color: var(--reader-border);
    color: var(--reader-text);
}

.reader-main .btn-outline-secondary:hover,
.reader-shell .btn-outline-secondary:hover,
.reader-main .btn-light:hover,
.reader-shell .btn-light:hover {
    background: var(--reader-subtle);
    border-color: color-mix(in srgb, var(--reader-accent) 30%, var(--reader-border));
    color: var(--reader-accent);
}

.reader-sidebar {
    position: sticky;
    top: 92px;
    align-self: start;
}

.reader-sidebar-card {
    background: var(--reader-card);
    border: 1px solid var(--reader-border);
    border-left: 3px solid var(--reader-accent);
    border-radius: 14px;
    box-shadow: var(--reader-shadow);
    padding: 14px;
    max-height: calc(100vh - 120px);
    overflow: auto;
}

.reader-sidebar-title {
    color: var(--reader-hint);
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.06em;
    margin-bottom: 10px;
    text-transform: uppercase;
}

.reader-nav-list {
    display: grid;
    gap: 6px;
}

.reader-nav-link {
    display: grid;
    grid-template-columns: 42px minmax(0, 1fr);
    gap: 10px;
    align-items: center;
    color: var(--reader-ink);
    text-decoration: none;
    border: 1px solid transparent;
    border-left: 3px solid transparent;
    border-radius: 10px;
    padding: 9px 10px;
}

.reader-nav-link:hover,
.reader-nav-link.is-active {
    background: var(--reader-blue-soft);
    border-color: color-mix(in srgb, var(--reader-accent) 28%, var(--reader-border));
    border-left-color: var(--reader-accent);
    box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--reader-accent) 8%, transparent);
}

.reader-nav-number {
    color: var(--reader-blue);
    font-weight: 800;
    font-variant-numeric: tabular-nums;
    position: relative;
}

.reader-nav-link.is-solved .reader-nav-number::after {
    background: var(--reader-green);
    border: 2px solid var(--reader-card);
    border-radius: 999px;
    content: "";
    height: 9px;
    position: absolute;
    right: -4px;
    top: 2px;
    width: 9px;
}

.reader-nav-link.reader-step-target,
.reader-nav-link.reader-step-target.is-active,
.reader-nav-link.reader-step-target:hover {
    background: color-mix(in srgb, var(--reader-target) 9%, var(--reader-card));
    border-color: color-mix(in srgb, var(--reader-target) 32%, var(--reader-border));
    border-left-color: var(--reader-target);
}

.reader-nav-link.reader-step-target .reader-nav-number {
    color: var(--reader-target);
}

.reader-nav-title {
    display: -webkit-box;
    line-height: 1.25;
    overflow: hidden;
    overflow-wrap: anywhere;
    -webkit-box-orient: vertical;
    -webkit-line-clamp: 2;
    white-space: normal;
}

.reader-nav-meta {
    color: var(--reader-muted);
    display: block;
    font-size: 0.72rem;
    margin-top: 2px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.reader-module-list ul,
.reader-module-list ol {
    list-style: none;
    margin-left: 0;
    padding-left: 0;
}

.reader-module-list li {
    margin-bottom: 0.45rem;
}

.reader-module-list li:last-child {
    margin-bottom: 0;
}

.reader-chip-nav {
    display: none;
    gap: 8px;
    overflow-x: auto;
    padding: 8px 2px 12px;
    scrollbar-width: thin;
}

.reader-chip {
    flex: 0 0 auto;
    border: 1px solid var(--reader-border);
    border-radius: 999px;
    background: var(--reader-card);
    color: var(--reader-ink);
    font-weight: 700;
    min-width: 44px;
    padding: 8px 12px;
    text-align: center;
    text-decoration: none;
}

.reader-chip:hover,
.reader-chip.is-active {
    background: var(--reader-blue);
    border-color: var(--reader-blue);
    color: #fff;
}

.reader-intro {
    background: var(--reader-panel);
    border-color: var(--reader-border);
    color: var(--reader-text);
}

.surface-card.reader-card,
.reader-card {
    background: var(--reader-card);
    border-color: var(--reader-border);
    border-radius: 14px;
    border-top: 3px solid rgba(31, 95, 159, 0.42);
    box-shadow: var(--reader-shadow-soft);
    scroll-margin-top: 96px;
}

.reader-card-header {
    align-items: flex-start;
    display: flex;
    gap: 14px;
    justify-content: space-between;
    margin-bottom: 14px;
}

.reader-title-block {
    flex: 1 1 auto;
    min-width: 0;
}

.reader-mobile-kicker {
    color: var(--reader-blue);
    display: none;
    font-size: 0.78rem;
    font-weight: 800;
    letter-spacing: 0.04em;
    margin-bottom: 4px;
    text-transform: uppercase;
}

.reader-number-badge {
    font-variant-numeric: tabular-nums;
}

.reader-problem-title {
    overflow-wrap: anywhere;
}

.reader-meta-actions {
    align-items: center;
    display: flex;
    flex: 0 0 auto;
    flex-wrap: wrap;
    gap: 5px;
    justify-content: flex-end;
    max-width: 46%;
}

.reader-icon-button {
    min-height: 30px;
    min-width: 32px;
}

.reader-tag-chip,
.reader-meta-actions .badge.text-bg-light {
    background: var(--reader-subtle) !important;
    border-color: var(--reader-subtle-border) !important;
    color: var(--reader-muted) !important;
    font-weight: 600;
}

.reader-difficulty {
    background: var(--reader-subtle) !important;
    border-color: var(--reader-subtle-border) !important;
    color: var(--reader-muted) !important;
    font-weight: 600;
}

.reader-statement {
    background: var(--reader-statement-bg);
    border: 1px solid var(--reader-border);
    border-left: 4px solid var(--reader-accent);
    border-radius: 12px;
    color: var(--reader-ink);
    font-size: 1.02rem;
    line-height: 1.72;
    overflow-wrap: anywhere;
    padding: 16px 18px;
}

.reader-accordion-content {
    background: var(--reader-card);
    border: 1px solid var(--reader-border);
    border-radius: 12px;
    line-height: 1.65;
    overflow-wrap: anywhere;
    padding: 14px 16px;
}

.reader-accordion-toggle {
    background: var(--reader-card);
    border-color: var(--reader-border) !important;
    color: var(--reader-ink);
    font-weight: 700;
    min-height: 44px;
    text-align: left;
}

.reader-accordion-toggle[aria-expanded="true"] {
    background: var(--reader-subtle);
    border-color: color-mix(in srgb, var(--reader-accent) 32%, var(--reader-border)) !important;
    box-shadow: inset 4px 0 0 var(--reader-accent);
}

.reader-accordion-toggle[data-reader-toggle="hint"],
.reader-icon-button[data-reader-toggle="hint"] {
    border-color: #f2d39b !important;
    color: var(--reader-hint);
}

.reader-accordion-toggle[data-reader-toggle="hint"][aria-expanded="true"],
[id$="-hint"].reader-accordion-content,
#problemHintBox.reader-accordion-content {
    background: var(--reader-hint-bg);
    border-color: color-mix(in srgb, var(--reader-hint) 32%, var(--reader-border));
}

.reader-accordion-toggle[data-reader-toggle="solution"] {
    border-color: #cbe8d3 !important;
    color: var(--reader-green);
}

.reader-accordion-toggle[data-reader-toggle="solution"][aria-expanded="true"],
[id$="-solution"].reader-accordion-content,
#problemSolutionBox.reader-accordion-content {
    background: var(--reader-solution-bg);
    border-color: color-mix(in srgb, var(--reader-green) 30%, var(--reader-border));
}

.reader-accordion-toggle[data-reader-toggle="teacher-note"] {
    border-color: #ddd0ff !important;
    color: var(--reader-purple);
}

.reader-accordion-toggle[data-reader-toggle="teacher-note"][aria-expanded="true"],
#problemTeacherNoteBox.reader-accordion-content {
    background: var(--reader-teacher-bg);
    border-color: color-mix(in srgb, var(--reader-purple) 30%, var(--reader-border));
}

.reader-card-footer {
    align-items: center;
    display: flex;
    gap: 12px;
    justify-content: space-between;
}

.reader-solution-button {
    color: var(--reader-green);
    font-weight: 700;
}

.reader-solution-button[aria-expanded="true"] {
    background: var(--reader-solution-bg);
    border-radius: 999px;
    color: var(--reader-green);
    padding: 4px 10px !important;
}

.reader-details {
    border-top: 1px solid rgba(217, 229, 238, 0.75);
    color: var(--reader-muted);
    display: none;
    font-size: 0.88rem;
    padding-top: 10px;
}

.reader-details summary {
    cursor: pointer;
    font-weight: 700;
}

.reader-details-body {
    display: grid;
    gap: 5px;
    padding-top: 8px;
}

.reader-step-header {
    align-items: center;
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 10px;
}

.reader-step-target {
    border-color: rgba(190, 18, 60, 0.36) !important;
    border-top-color: var(--reader-target) !important;
    box-shadow: 0 0 0 1px rgba(190, 18, 60, 0.08), var(--reader-shadow);
}

.reader-step-target-scope .problem-card {
    border-color: rgba(190, 18, 60, 0.32);
    border-top-color: var(--reader-target);
}

.reader-step-badge {
    border: 1px solid transparent;
    font-weight: 700;
}

.reader-step-badge.reader-step-warmup,
.reader-nav-link.reader-step-warmup .reader-nav-number {
    color: #166534;
}

.reader-step-badge.reader-step-warmup {
    background: color-mix(in srgb, #22c55e 12%, var(--reader-card));
    border-color: color-mix(in srgb, #22c55e 26%, var(--reader-border));
}

.reader-step-badge.reader-step-lemma,
.reader-nav-link.reader-step-lemma .reader-nav-number {
    color: #1f5f9f;
}

.reader-step-badge.reader-step-lemma {
    background: var(--reader-blue-soft);
    border-color: color-mix(in srgb, var(--reader-accent) 26%, var(--reader-border));
}

.reader-step-badge.reader-step-direct,
.reader-nav-link.reader-step-direct .reader-nav-number {
    color: #5b21b6;
}

.reader-step-badge.reader-step-direct {
    background: color-mix(in srgb, #8b5cf6 13%, var(--reader-card));
    border-color: color-mix(in srgb, #8b5cf6 28%, var(--reader-border));
}

.reader-step-badge.reader-step-mixed,
.reader-nav-link.reader-step-mixed .reader-nav-number {
    color: #92400e;
}

.reader-step-badge.reader-step-mixed {
    background: color-mix(in srgb, #f59e0b 13%, var(--reader-card));
    border-color: color-mix(in srgb, #f59e0b 28%, var(--reader-border));
}

.reader-step-badge.reader-step-target,
.reader-step-badge.reader-step-challenge,
.reader-nav-link.reader-step-target .reader-nav-number,
.reader-nav-link.reader-step-challenge .reader-nav-number {
    color: #be123c;
}

.reader-step-badge.reader-step-target,
.reader-step-badge.reader-step-challenge {
    background: color-mix(in srgb, var(--reader-target) 12%, var(--reader-card));
    border-color: color-mix(in srgb, var(--reader-target) 30%, var(--reader-border));
}

[data-reader-theme="light"] .reader-sidebar .reader-nav-link,
[data-reader-theme="light"] .reader-sidebar .reader-nav-link:hover,
[data-reader-theme="light"] .reader-sidebar .reader-nav-link.is-active,
[data-reader-theme="light"] .reader-sidebar .reader-nav-title,
[data-reader-theme="light"] .reader-sidebar .reader-nav-number,
[data-reader-theme="light"] .reader-sidebar .reader-nav-link.reader-step-warmup .reader-nav-number,
[data-reader-theme="light"] .reader-sidebar .reader-nav-link.reader-step-lemma .reader-nav-number,
[data-reader-theme="light"] .reader-sidebar .reader-nav-link.reader-step-direct .reader-nav-number,
[data-reader-theme="light"] .reader-sidebar .reader-nav-link.reader-step-mixed .reader-nav-number,
[data-reader-theme="light"] .reader-sidebar .reader-nav-link.reader-step-target .reader-nav-number,
[data-reader-theme="light"] .reader-sidebar .reader-nav-link.reader-step-challenge .reader-nav-number {
    color: #111827;
}

[data-reader-theme="dark"] .reader-sidebar .reader-nav-link,
[data-reader-theme="dark"] .reader-sidebar .reader-nav-link:hover,
[data-reader-theme="dark"] .reader-sidebar .reader-nav-link.is-active,
[data-reader-theme="dark"] .reader-sidebar .reader-nav-title,
[data-reader-theme="dark"] .reader-sidebar .reader-nav-number,
[data-reader-theme="dark"] .reader-sidebar .reader-nav-link.reader-step-warmup .reader-nav-number,
[data-reader-theme="dark"] .reader-sidebar .reader-nav-link.reader-step-lemma .reader-nav-number,
[data-reader-theme="dark"] .reader-sidebar .reader-nav-link.reader-step-direct .reader-nav-number,
[data-reader-theme="dark"] .reader-sidebar .reader-nav-link.reader-step-mixed .reader-nav-number,
[data-reader-theme="dark"] .reader-sidebar .reader-nav-link.reader-step-target .reader-nav-number,
[data-reader-theme="dark"] .reader-sidebar .reader-nav-link.reader-step-challenge .reader-nav-number {
    color: #dbe4ef;
}

[data-reader-theme="dark"] .reader-sidebar .reader-nav-meta {
    color: #cbd5e1;
}

[data-reader-theme="dark"] .reader-icon-button.btn-success,
[data-reader-theme="dark"] [data-action="toggle-solved"].btn-success,
[data-reader-theme="dark"] [data-problem-action="toggle-solved"].btn-success {
    background-color: #14532d !important;
    border-color: #166534 !important;
    color: #bbf7d0 !important;
}

[data-reader-theme="dark"] .reader-icon-button.btn-warning,
[data-reader-theme="dark"] [data-action="toggle-bookmark"].btn-warning,
[data-reader-theme="dark"] [data-problem-action="toggle-bookmark"].btn-warning {
    background-color: #713f12 !important;
    border-color: #92400e !important;
    color: #fde68a !important;
}

.reader-bottom-nav {
    align-items: center;
    display: flex;
    gap: 12px;
    justify-content: space-between;
}

.problem-media {
    margin: 18px 0;
    --problem-media-size: 100%;
}

.problem-media-frame {
    background: var(--reader-card);
    border: 1px solid var(--reader-border);
    border-radius: 12px;
    overflow-x: auto;
    padding: 10px;
}

.problem-media img {
    display: block;
    height: auto;
    margin-inline: auto;
    max-width: 100%;
}

.problem-media.is-resizable .problem-media-frame img {
    max-width: none;
    width: var(--problem-media-size, 100%);
}

.problem-media-resize {
    align-items: center;
    color: var(--reader-muted);
    display: flex;
    gap: 10px;
    justify-content: flex-end;
    margin-top: 8px;
    user-select: none;
    font-size: 0.82rem;
}

.problem-media-resize input[type="range"] {
    accent-color: var(--reader-accent);
    max-width: 170px;
    width: min(38vw, 170px);
}

.problem-media-resize [data-problem-media-size-value] {
    color: var(--reader-text);
    font-variant-numeric: tabular-nums;
    min-width: 42px;
    text-align: right;
}

.media-caption {
    color: var(--reader-muted);
    font-size: 0.88rem;
    margin-top: 8px;
    text-align: center;
}

mjx-container {
    max-width: 100%;
    overflow-x: auto;
    overflow-y: hidden;
}

mjx-container svg {
    color: var(--reader-text);
}

.reader-statement,
.reader-accordion-content,
.problem-content {
    overflow-wrap: anywhere;
}

@media (max-width: 1199.98px) {
    .reader-shell {
        display: block;
    }

    .reader-sidebar {
        display: none;
    }

    .reader-main {
        margin-inline: auto;
        max-width: 900px;
    }

    .reader-chip-nav {
        display: flex;
    }

    .reader-meta-actions {
        max-width: 58%;
    }

    .reader-sidebar-toggle {
        display: none;
    }
}

@media (max-width: 767.98px) {
    .reader-card {
        border-radius: 12px;
    }

    .reader-card-header {
        display: block;
        margin-bottom: 10px;
    }

    .reader-mobile-kicker {
        display: block;
    }

    .reader-number-badge,
    .reader-source-desktop,
    .reader-meta-desktop,
    .reader-open-link {
        display: none !important;
    }

    .reader-problem-title {
        font-size: 1rem;
        line-height: 1.35;
    }

    .reader-meta-actions {
        justify-content: flex-start;
        margin-top: 10px;
        max-width: 100%;
    }

    .reader-tag-chip {
        max-width: calc(100vw - 160px);
        overflow: hidden;
        text-overflow: ellipsis;
        white-space: nowrap;
    }

    .reader-difficulty {
        font-size: 0.72rem;
    }

    .reader-statement {
        font-size: 0.98rem;
        line-height: 1.65;
        padding: 14px;
    }

    .reader-accordion-content {
        padding: 13px;
    }

    .reader-card-footer {
        justify-content: flex-start;
    }

    .reader-details {
        display: block;
    }

    .reader-chip-nav {
        margin-inline: -4px;
        position: sticky;
        top: 65px;
        z-index: 8;
        background: color-mix(in srgb, var(--reader-bg) 92%, transparent);
        backdrop-filter: blur(10px);
    }

    .reader-bottom-nav {
        background: var(--reader-card);
        border: 1px solid var(--reader-border);
        border-radius: 999px;
        bottom: 12px;
        box-shadow: 0 8px 24px rgba(18, 58, 82, 0.14);
        padding: 8px 12px;
        position: sticky;
        z-index: 9;
    }

    .content-panel.reader-intro,
    .content-panel.reader-filter {
        padding: 1rem !important;
    }
}