/* Shared Arch Suite visual language, with enhanced RKP Masterclass components. */
:root {
    color-scheme: dark;
    --bg-main: #0b0b0c;
    --bg-surface: #111113;
    --bg-card: #161618;
    --bg-elevated: #1c1c1e;
    --bg-code: #0d0e11;
    --text-primary: #f5f5f7;
    --text-secondary: #a1a1a6;
    --text-tertiary: #6e6e73;
    --line: rgba(255, 255, 255, 0.07);
    --line-soft: rgba(255, 255, 255, 0.11);
    --line-strong: rgba(255, 255, 255, 0.17);
    --gold: #c5a059;
    --gold-bright: #e8c578;
    --gold-soft: rgba(197, 160, 89, 0.13);
    --blue: #8fb6ff;
    --green: #72d9a7;
    --red: #ff8e8e;
    --purple: #b7a4ff;
    --radius-xs: 8px;
    --radius-sm: 12px;
    --radius: 16px;
    --radius-lg: 22px;
    --shadow: 0 24px 70px rgba(0, 0, 0, 0.34);
    --content: 920px;
    --header: 58px;
    --ease: cubic-bezier(0.2, 0.75, 0.25, 1);
    --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
}

[hidden] { display: none !important; }
.login-wizard-brand::before { content: "RKP"; }

/* Responsive utility toggles */
.desktop-only { display: none; }
.mobile-only { display: inline-flex; }
@media (min-width: 1120px) {
    .desktop-only { display: block; }
    .mobile-only { display: none; }
}

/* Viewport and layout containment: completely eliminate horizontal scrollbar blowout */
html {
    overflow-x: hidden;
    width: 100%;
    max-width: 100vw;
    box-sizing: border-box;
    -webkit-text-size-adjust: 100%;
}
*, *::before, *::after {
    box-sizing: inherit;
}
body {
    overflow-x: hidden;
    width: 100%;
    max-width: 100vw;
    position: relative;
    margin: 0;
    padding: 0;
}
.layout {
    width: 100%;
    max-width: 1280px;
    min-width: 0;
    margin: 0 auto;
    padding: 0 16px 54px;
    overflow-x: clip;
    box-sizing: border-box;
}
main.course {
    min-width: 0;
    max-width: 100%;
    width: 100%;
    overflow-x: clip;
}
.rkp-module, .lesson, .section-heading, .rkp-lesson-body {
    min-width: 0;
    max-width: 100%;
    overflow-wrap: break-word;
    word-break: break-word;
}

/* Accessibility & navigation */
.rkp-skip-link {
    position: fixed;
    top: -100px;
    left: 12px;
    z-index: 200;
    padding: 10px 16px;
    border-radius: 10px;
    background: var(--gold-bright);
    color: #111;
    font-weight: 700;
    transition: top 0.2s ease;
}
.rkp-skip-link:focus { top: 8px; }

/* Sticky header polish */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 18px;
    min-height: 56px;
    background: rgba(11, 11, 12, 0.92);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}
.header-actions {
    display: flex;
    align-items: center;
    gap: 8px;
}
.header-actions .button {
    min-height: 38px;
    padding: 6px 14px;
    font-size: 0.82rem;
    border-radius: 8px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

/* Hero Section */
.hero {
    margin-bottom: 24px;
}
.hero h1 {
    font-size: clamp(2.2rem, 5.5vw, 4.2rem);
    line-height: 1.15;
    letter-spacing: -.03em;
    max-width: 16ch;
    margin: 12px 0 16px;
}
.hero-lede {
    font-size: clamp(0.96rem, 2vw, 1.12rem);
    line-height: 1.6;
    color: var(--text-secondary);
    max-width: 72ch;
}
.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin: 20px 0;
}
.hero-actions .button {
    min-height: 46px;
    padding: 10px 22px;
    font-size: 0.92rem;
    font-weight: 650;
    border-radius: 12px;
}
.hero-card {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 8px;
    margin: 24px 0 12px;
}
.hero-card div {
    padding: 14px 16px;
    border-radius: 12px;
    border: 1px solid rgba(255, 255, 255, 0.06);
    background: rgba(255, 255, 255, 0.02);
}
.hero-card span {
    font-size: 0.72rem;
    color: var(--text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.06em;
}
.hero-card strong {
    font-size: 0.92rem;
    color: var(--text-primary);
    margin-top: 4px;
}

/* Grids & Cards */
.rkp-orientation-grid, .rkp-download-grid {
    display: grid;
    gap: 14px;
    margin: 24px 0;
}
.rkp-orientation-grid h2 {
    margin: 10px 0 8px;
    font-size: 1.15rem;
    letter-spacing: -.025em;
    color: var(--text-primary);
}
.rkp-orientation-grid .info-card {
    padding: 18px 20px;
    border: 1px solid rgba(255, 255, 255, 0.07);
    border-radius: 14px;
    background: rgba(255, 255, 255, 0.02);
    transition: border-color 0.2s ease, transform 0.2s ease;
}
.rkp-orientation-grid .info-card:hover {
    border-color: rgba(197, 160, 89, 0.35);
    transform: translateY(-2px);
}
.rkp-orientation-grid .info-card p {
    font-size: .92rem;
    line-height: 1.55;
    color: var(--text-secondary);
    margin: 0;
}
.rkp-orientation-grid .step {
    display: inline-block;
    padding: 3px 10px;
    border-radius: 8px;
    background: rgba(197, 160, 89, 0.12);
    color: var(--gold-bright);
    font-size: 0.75rem;
    font-weight: 750;
    letter-spacing: 0.04em;
}

/* Download Grid */
.rkp-download-grid .info-card {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    padding: 22px;
    border: 1px solid rgba(197, 160, 89, 0.2);
    border-radius: 16px;
    background: radial-gradient(circle at 10% 10%, rgba(197, 160, 89, 0.05), transparent 70%), var(--bg-surface);
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.rkp-download-grid .info-card:hover {
    border-color: rgba(197, 160, 89, 0.45);
    box-shadow: 0 8px 28px -6px rgba(0, 0, 0, 0.45);
}
.rkp-download-grid h3 {
    margin: 12px 0 8px;
    font-size: 1.15rem;
    color: var(--text-primary);
}
.rkp-download-grid p {
    font-size: 0.88rem;
    line-height: 1.5;
    color: var(--text-secondary);
    margin: 0;
    flex-grow: 1;
}
.rkp-download-grid .button {
    margin-top: 18px;
    min-height: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 100%;
}
.rkp-progress-label { padding: 12px 0; margin: 0; color: var(--gold-bright); font-size: .75rem; }

/* Interactive research tool surfaces */
.interactive-tool-box {
    margin: 28px 0;
    padding: 24px;
    border: 1px solid rgba(197, 160, 89, 0.28);
    border-radius: 16px;
    background: radial-gradient(circle at 10% 10%, rgba(197, 160, 89, 0.06), transparent 70%), var(--bg-surface);
    box-shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
    max-width: 100%;
    overflow-x: clip;
}
.interactive-tool-box .tool-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 18px;
    border-bottom: 1px solid var(--line-soft);
    padding-bottom: 14px;
}
.interactive-tool-box .tool-header h3 {
    margin: 0;
    font-size: 1.15rem;
    color: var(--text-primary);
    letter-spacing: -.02em;
}
.interactive-tool-box .tool-header .tool-pill {
    padding: 4px 10px;
    border-radius: 999px;
    background: rgba(197, 160, 89, 0.15);
    color: var(--gold-bright);
    font-size: 0.72rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}
.interactive-tool-box p.tool-desc {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin: 0 0 16px;
    max-width: 74ch;
}
.interactive-tool-box .tool-controls {
    display: grid;
    gap: 12px;
    margin-bottom: 16px;
}
.interactive-tool-box select, .interactive-tool-box input, .interactive-tool-box textarea {
    width: 100%;
    max-width: 100%;
    min-height: 44px;
    padding: 10px 14px;
    border: 1px solid var(--line);
    border-radius: 10px;
    background: var(--bg-code);
    color: var(--text-primary);
    font-family: inherit;
    font-size: 0.9rem;
    box-sizing: border-box;
}
.interactive-tool-box select {
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
    background-color: var(--bg-code);
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='14' height='14' viewBox='0 0 24 24' fill='none' stroke='%23e8c578' stroke-width='2.2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 14px center;
    background-size: 14px 14px;
    padding-right: 42px;
    cursor: pointer;
}
.interactive-tool-box select option {
    background-color: #161618;
    color: #f5f5f7;
    padding: 8px 12px;
}
.interactive-tool-box select:focus, .interactive-tool-box input:focus, .interactive-tool-box textarea:focus {
    outline: none;
    border-color: var(--gold-bright);
    box-shadow: 0 0 0 2px rgba(197, 160, 89, 0.2);
}
.interactive-tool-box .tool-result {
    padding: 16px;
    border-radius: 12px;
    background: rgba(0, 0, 0, 0.35);
    border: 1px solid var(--line-soft);
    font-size: 0.88rem;
    line-height: 1.5;
    overflow-x: auto;
    word-break: break-word;
    overflow-wrap: anywhere;
}
.badge-vulnerable {
    display: inline-block;
    padding: 3px 8px;
    border-radius: 6px;
    background: rgba(239, 68, 68, 0.15);
    color: #f87171;
    font-size: 0.75rem;
    font-weight: 700;
    border: 1px solid rgba(239, 68, 68, 0.3);
}
.badge-patched {
    display: inline-block;
    padding: 3px 8px;
    border-radius: 6px;
    background: rgba(16, 185, 129, 0.15);
    color: #34d399;
    font-size: 0.75rem;
    font-weight: 700;
    border: 1px solid rgba(16, 185, 129, 0.3);
}
.badge-inconclusive {
    display: inline-block;
    padding: 3px 8px;
    border-radius: 6px;
    background: rgba(245, 158, 11, 0.15);
    color: #fbbf24;
    font-size: 0.75rem;
    font-weight: 700;
    border: 1px solid rgba(245, 158, 11, 0.3);
}

/* DICE Stack visualization */
.dice-stack {
    display: grid;
    gap: 8px;
    margin: 24px 0;
    max-width: 100%;
}
.dice-row {
    display: grid;
    grid-template-columns: 80px 1fr auto;
    align-items: center;
    gap: 14px;
    padding: 14px 18px;
    border: 1px solid var(--line);
    border-radius: 12px;
    background: var(--bg-surface);
}
.dice-row .dice-tag {
    font-size: 0.75rem;
    font-weight: 750;
    color: var(--gold-bright);
    letter-spacing: 0.04em;
}
.dice-row strong {
    color: var(--text-primary);
    font-size: 0.94rem;
}
.dice-row small {
    grid-column: 2;
    color: var(--text-tertiary);
    font-size: 0.8rem;
}
.dice-row .dice-status {
    font-size: 0.78rem;
    color: var(--text-secondary);
}

/* Reader tools (Search bar) */
.rkp-reader-tools {
    display: grid;
    grid-template-columns: 1fr auto;
    align-items: center;
    gap: 10px;
    margin: 32px 0 24px;
    padding: 18px;
    border: 1px solid var(--line-soft);
    border-radius: var(--radius);
    background: var(--bg-surface);
}
.rkp-reader-tools label {
    grid-column: 1 / -1;
    font-size: .8rem;
    color: var(--gold-bright);
    font-weight: 750;
    letter-spacing: 0.02em;
}
.rkp-reader-tools input {
    width: 100%;
    min-height: 46px;
    padding: 11px 14px;
    border: 1px solid var(--line-soft);
    border-radius: 10px;
    background: var(--bg-code);
    color: var(--text-primary);
    font-size: 0.92rem;
    box-sizing: border-box;
}
.rkp-reader-tools input::placeholder { color: #83838b; }
.rkp-reader-tools input:only-of-type { grid-column: 1; }
.rkp-reader-tools p {
    grid-column: 1 / -1;
    margin: 4px 0 0;
    color: var(--text-secondary);
    font-size: .78rem;
}

/* Lesson body typography */
.rkp-lesson-body {
    color: var(--text-secondary);
    max-width: 100%;
}
.rkp-lesson-body > h3 {
    margin: 32px 0 12px;
    color: var(--text-primary);
    font-size: 1.25rem;
    line-height: 1.35;
    letter-spacing: -.025em;
}
.rkp-lesson-body > h3:first-child { margin-top: 0; }
.rkp-lesson-body p {
    max-width: 78ch;
    margin: 0 0 16px;
    line-height: 1.65;
    font-size: 0.96rem;
}
.rkp-lesson-body strong { color: #e8e8ed; font-weight: 650; }
.rkp-lesson-body code {
    color: #e5d1a6;
    background: rgba(229, 209, 166, 0.08);
    padding: 2px 6px;
    border-radius: 5px;
    font-size: .87em;
    word-break: break-word;
}
.rkp-lesson-body pre code {
    color: #d9dde6;
    background: transparent;
    padding: 0;
    border-radius: 0;
    font-size: .82rem;
    word-break: normal;
}
.rkp-lesson-body li {
    padding-left: 4px;
    margin: 8px 0;
    line-height: 1.6;
}
.rkp-lesson-body ol, .rkp-lesson-body ul {
    padding-left: 22px;
}

/* Table styling with containment and scroll indicators */
.rkp-lesson-body .defense-table-wrap {
    margin: 24px 0;
    max-width: 100%;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    border: 1px solid var(--line);
    border-radius: 14px;
    background: var(--bg-surface);
    scrollbar-width: thin;
    box-shadow: inset -12px 0 16px -12px rgba(0, 0, 0, 0.4);
}
.rkp-lesson-body table {
    width: 100%;
    min-width: 580px;
    border-collapse: collapse;
    text-align: left;
    font-size: .88rem;
    line-height: 1.5;
    background: transparent;
}
.rkp-lesson-body th, .rkp-lesson-body td {
    padding: 14px 16px;
    vertical-align: top;
    border-bottom: 1px solid var(--line);
}
.rkp-lesson-body th {
    background: var(--bg-card);
    color: #e5d1a6;
    font-size: .74rem;
    font-weight: 750;
    letter-spacing: .04em;
    text-transform: uppercase;
}
.rkp-lesson-body td:first-child {
    color: #e2e2e8;
    font-weight: 650;
    width: 28%;
}
.rkp-lesson-body tr:last-child td { border-bottom: 0; }

/* Code blocks */
.code-block {
    margin: 18px 0;
    max-width: 100%;
    overflow: hidden;
    border: 1px solid var(--line);
    border-radius: 12px;
    background: var(--bg-code);
}
.code-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
    padding: 8px 14px;
    min-height: 42px;
    border-bottom: 1px solid var(--line);
    background: rgba(255, 255, 255, 0.025);
}
.code-header > span {
    font-size: .72rem;
    color: var(--text-secondary);
    letter-spacing: .02em;
    font-weight: 600;
    min-width: 0;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}
.copy-button {
    min-height: 32px;
    min-width: 44px;
    padding: 4px 12px;
    font-size: 0.75rem;
    font-weight: 650;
    border-radius: 6px;
    border: 1px solid rgba(197, 160, 89, 0.3);
    background: rgba(197, 160, 89, 0.08);
    color: var(--gold-bright);
    cursor: pointer;
    transition: all 0.15s ease;
}
.copy-button:hover {
    background: rgba(197, 160, 89, 0.2);
    border-color: var(--gold-bright);
}
.code-block pre {
    max-width: 100%;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    padding: 14px 16px;
    margin: 0;
    scrollbar-width: thin;
}

/* Flow diagram */
.rkp-flow {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 10px;
    padding: 18px;
    margin: 22px 0;
    border: 1px solid rgba(197, 160, 89, 0.22);
    border-radius: 14px;
    background: rgba(197, 160, 89, 0.04);
}
.rkp-flow span {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    color: #e5d1a6;
    font-size: .84rem;
    font-weight: 700;
}
.rkp-flow span:not(:last-child)::after {
    content: "→";
    color: var(--gold-bright);
    font-size: 1.1rem;
    margin-left: 2px;
}

/* Architecture Pipeline & Visual Diagrams */
.rkp-architecture-diagram {
    display: flex;
    flex-direction: column;
    gap: 0;
    margin: 28px 0;
    max-width: 100%;
}
.diagram-tier {
    padding: 20px 22px;
    border-radius: 14px;
    border: 1px solid var(--line);
    background: var(--bg-surface);
    transition: border-color 0.2s ease, transform 0.2s ease;
}
.diagram-tier:hover {
    border-color: rgba(197, 160, 89, 0.4);
    transform: translateY(-2px);
}
.diagram-tier.tier-hardware {
    border-color: rgba(197, 160, 89, 0.35);
    background: radial-gradient(circle at 10% 10%, rgba(197, 160, 89, 0.08), transparent 70%), var(--bg-surface);
}
.diagram-tier.tier-cloud {
    border-color: rgba(143, 182, 255, 0.3);
    background: radial-gradient(circle at 10% 10%, rgba(143, 182, 255, 0.06), transparent 70%), var(--bg-surface);
}
.diagram-tier.tier-app {
    border-color: rgba(114, 217, 167, 0.3);
    background: radial-gradient(circle at 10% 10%, rgba(114, 217, 167, 0.06), transparent 70%), var(--bg-surface);
}
.tier-badge {
    display: inline-block;
    padding: 3px 10px;
    border-radius: 999px;
    font-size: 0.72rem;
    font-weight: 750;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    background: rgba(197, 160, 89, 0.14);
    color: var(--gold-bright);
    margin-bottom: 8px;
}
.tier-cloud .tier-badge {
    background: rgba(143, 182, 255, 0.14);
    color: var(--blue);
}
.tier-app .tier-badge {
    background: rgba(114, 217, 167, 0.14);
    color: var(--green);
}
.tier-title {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 12px;
}
.tier-body {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 10px;
}
.tier-pill {
    padding: 6px 12px;
    border-radius: 8px;
    background: rgba(255, 255, 255, 0.035);
    border: 1px solid var(--line-soft);
    font-size: 0.84rem;
    color: var(--text-secondary);
    line-height: 1.4;
}
.tier-pill code {
    color: var(--gold-bright);
}
.tier-boundary {
    font-size: 0.8rem;
    color: var(--text-tertiary);
    font-style: italic;
    margin-top: 6px;
}
.diagram-connector {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 10px 0;
    position: relative;
}
.connector-label {
    padding: 4px 12px;
    border-radius: 999px;
    background: var(--bg-card);
    border: 1px solid var(--line-soft);
    font-size: 0.76rem;
    color: var(--text-secondary);
    font-weight: 600;
    margin-bottom: 4px;
}
.connector-arrow {
    font-size: 1.2rem;
    color: var(--gold-bright);
    line-height: 1;
}

/* Step-by-Step Flow Cards */
.rkp-stage-steps {
    display: grid;
    gap: 12px;
    margin: 24px 0;
    max-width: 100%;
}
.rkp-step-card {
    display: grid;
    grid-template-columns: 48px 1fr;
    gap: 16px;
    align-items: flex-start;
    padding: 18px 20px;
    border-radius: 14px;
    border: 1px solid var(--line);
    background: var(--bg-surface);
    transition: border-color 0.2s ease, transform 0.2s ease;
}
.rkp-step-card:hover {
    border-color: rgba(197, 160, 89, 0.4);
    transform: translateY(-2px);
}
.step-number {
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 12px;
    background: rgba(197, 160, 89, 0.12);
    border: 1px solid rgba(197, 160, 89, 0.28);
    color: var(--gold-bright);
    font-weight: 800;
    font-size: 1rem;
    letter-spacing: -0.02em;
    flex-shrink: 0;
}
.step-content strong {
    display: block;
    font-size: 0.98rem;
    color: var(--text-primary);
    margin-bottom: 6px;
}
.step-content p {
    margin: 0;
    font-size: 0.88rem;
    line-height: 1.55;
    color: var(--text-secondary);
}

/* ASN.1 Data Structure Inspector Diagram */
.rkp-asn1-diagram {
    display: grid;
    gap: 10px;
    margin: 24px 0;
    padding: 20px;
    border-radius: 16px;
    border: 1px solid rgba(197, 160, 89, 0.28);
    background: radial-gradient(circle at 10% 10%, rgba(197, 160, 89, 0.05), transparent 70%), var(--bg-surface);
    max-width: 100%;
}
.asn1-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--line-soft);
    margin-bottom: 6px;
}
.asn1-header strong {
    font-size: 1rem;
    color: var(--gold-bright);
}
.asn1-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 10px;
}
.asn1-block {
    padding: 12px 14px;
    border-radius: 10px;
    border: 1px solid var(--line);
    background: rgba(0, 0, 0, 0.3);
}
.asn1-tag {
    font-size: 0.72rem;
    font-weight: 700;
    color: var(--gold-bright);
    text-transform: uppercase;
    letter-spacing: 0.04em;
    margin-bottom: 4px;
}
.asn1-title {
    font-size: 0.88rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 4px;
}
.asn1-desc {
    font-size: 0.8rem;
    color: var(--text-secondary);
    line-height: 1.45;
}

/* Learner Track Visual Pipeline */
.rkp-learner-track {
    margin: 28px 0;
    padding: 22px 24px;
    border-radius: 16px;
    border: 1px solid rgba(197, 160, 89, 0.32);
    background: radial-gradient(circle at 10% 10%, rgba(197, 160, 89, 0.08), transparent 70%), var(--bg-surface);
}
.learner-track-header {
    margin-bottom: 18px;
}
.learner-track-header h2 {
    font-size: 1.22rem;
    color: var(--text-primary);
    margin: 0 0 6px;
    letter-spacing: -0.02em;
}
.learner-track-header p {
    margin: 0;
    font-size: 0.88rem;
    color: var(--text-secondary);
}
.learner-track-steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 14px;
}
.learner-step-card {
    padding: 16px 18px;
    border-radius: 12px;
    border: 1px solid var(--line);
    background: var(--bg-card);
    transition: border-color 0.2s ease, transform 0.2s ease;
}
.learner-step-card:hover {
    border-color: rgba(197, 160, 89, 0.4);
    transform: translateY(-2px);
}
.learner-step-card .step-badge {
    display: inline-block;
    padding: 3px 9px;
    border-radius: 6px;
    font-size: 0.72rem;
    font-weight: 750;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    background: rgba(197, 160, 89, 0.15);
    color: var(--gold-bright);
    margin-bottom: 10px;
}
.learner-step-card strong {
    display: block;
    font-size: 0.96rem;
    color: var(--text-primary);
    margin-bottom: 6px;
}
.learner-step-card p {
    margin: 0;
    font-size: 0.84rem;
    line-height: 1.5;
    color: var(--text-secondary);
}

/* Responsive adjustments for diagram cards */
@media (max-width: 600px) {
    .diagram-tier { padding: 16px; }
    .tier-body { flex-direction: column; }
    .tier-pill { width: 100%; }
    .rkp-step-card { grid-template-columns: 1fr; gap: 10px; }
    .step-number { width: 36px; height: 36px; font-size: 0.88rem; }
    .asn1-grid { grid-template-columns: 1fr; }
    .learner-track-steps { grid-template-columns: 1fr; }
}

/* Assignments */
.rkp-assignment-grid {
    display: grid;
    gap: 14px;
    margin: 28px 0 16px;
}
.rkp-assignment {
    padding: 18px 20px;
    border: 1px solid var(--line);
    border-radius: 14px;
    background: rgba(255, 255, 255, 0.018);
}
.rkp-assignment h3 {
    margin: 0 0 12px;
    color: var(--gold-bright);
    font-size: .84rem;
    font-weight: 750;
    letter-spacing: .03em;
    text-transform: uppercase;
}
.rkp-assignment ol { margin: 0; padding-left: 20px; }
.rkp-assignment li { margin: 8px 0; color: var(--text-secondary); font-size: .9rem; line-height: 1.5; }
.rkp-assignment p { color: var(--text-tertiary); margin: 12px 0 0; font-size: .78rem; }
.rkp-artifact-list { margin: 0; padding: 0; list-style: none; display: flex; flex-wrap: wrap; gap: 8px; }
.rkp-artifact-list code {
    color: #d2c9b7;
    background: rgba(255, 255, 255, 0.04);
    padding: 4px 8px;
    border-radius: 6px;
    font-size: .82rem;
}

/* AI Guidance Surface */
.rkp-guidance-surface {
    display: grid;
    gap: 14px;
    margin: 24px 0;
    max-width: 100%;
}

/* Master Accordions & Dropdown Menus (<details> / <summary>) */
.course details,
.rkp-review,
.lesson.sources details,
.rkp-accordion-card,
details.rkp-accordion-card {
    margin: 18px 0;
    border: 1px solid rgba(197, 160, 89, 0.24);
    border-radius: 14px;
    background: linear-gradient(180deg, rgba(197, 160, 89, 0.05) 0%, rgba(197, 160, 89, 0.015) 100%), var(--bg-surface);
    overflow: hidden;
    transition: border-color 0.22s ease, box-shadow 0.22s ease, background 0.22s ease;
    min-width: 0;
    max-width: 100%;
    box-sizing: border-box;
}
.course details:hover,
.rkp-review:hover,
.lesson.sources details:hover,
.rkp-accordion-card:hover {
    border-color: rgba(197, 160, 89, 0.48);
    box-shadow: 0 8px 28px -6px rgba(0, 0, 0, 0.55);
}
.course details summary,
.rkp-review summary,
.lesson.sources details summary,
.rkp-accordion-card summary {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 14px;
    min-height: 52px;
    padding: 14px 18px;
    font-size: 0.94rem;
    font-weight: 700;
    color: var(--gold-bright);
    cursor: pointer;
    user-select: none;
    list-style: none !important;
    list-style-type: none !important;
    background: transparent;
    transition: background 0.18s ease, color 0.18s ease;
    outline: none;
    box-sizing: border-box;
}
.course details summary > *,
.rkp-review summary > *,
.lesson.sources details summary > *,
.rkp-accordion-card summary > * {
    min-width: 0;
    line-height: 1.45;
}
.course details summary::-webkit-details-marker,
.rkp-review summary::-webkit-details-marker,
.lesson.sources details summary::-webkit-details-marker,
.rkp-accordion-card summary::-webkit-details-marker,
summary::marker {
    display: none !important;
    content: "" !important;
}
.course details summary:hover,
.rkp-review summary:hover,
.lesson.sources details summary:hover,
.rkp-accordion-card summary:hover {
    background: rgba(197, 160, 89, 0.07);
}
.course details summary:focus-visible,
.rkp-review summary:focus-visible,
.lesson.sources details summary:focus-visible,
.rkp-accordion-card summary:focus-visible {
    outline: 2px solid var(--gold-bright);
    outline-offset: -2px;
}
/* Modern circle-enclosed animated chevron arrow for details */
.course details summary::after,
.rkp-review summary::after,
.lesson.sources details summary::after,
.rkp-accordion-card summary::after {
    content: "";
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    min-width: 28px;
    border-radius: 50%;
    background-color: rgba(197, 160, 89, 0.12);
    border: 1px solid rgba(197, 160, 89, 0.28);
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%23e8c578' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: center;
    transform: rotate(0deg);
    transition: transform 0.28s cubic-bezier(0.16, 1, 0.3, 1), background-color 0.2s ease, border-color 0.2s ease;
    flex-shrink: 0;
    margin-left: 12px;
}
details[open] > summary::after {
    transform: rotate(180deg);
    background-color: rgba(197, 160, 89, 0.24);
    border-color: var(--gold-bright);
}
details[open] > summary {
    border-bottom: 1px solid rgba(197, 160, 89, 0.15);
    background: rgba(197, 160, 89, 0.035);
}
.rkp-accordion-content {
    padding: 16px 20px 20px;
    color: var(--text-secondary);
    font-size: 0.92rem;
    line-height: 1.65;
    box-sizing: border-box;
}
.rkp-accordion-content p {
    margin: 0 0 12px;
}
.rkp-accordion-content p:last-child {
    margin-bottom: 0;
}
.rkp-accordion-content ul {
    margin: 10px 0;
    padding-left: 20px;
}
.rkp-accordion-content li {
    margin: 6px 0;
    line-height: 1.55;
}
.rkp-accordion-content strong {
    color: var(--text-primary);
}

/* Checklist items inside review gate */
.rkp-review .checklist {
    padding: 12px 18px 20px;
    display: grid;
    gap: 8px;
    box-sizing: border-box;
}
.rkp-review .checklist label {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    min-height: 44px;
    padding: 11px 14px;
    border-radius: 10px;
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid rgba(255, 255, 255, 0.06);
    cursor: pointer;
    transition: background 0.15s ease, border-color 0.15s ease;
    box-sizing: border-box;
}
.rkp-review .checklist label:hover {
    background: rgba(197, 160, 89, 0.065);
    border-color: rgba(197, 160, 89, 0.25);
}
.rkp-review input[type="checkbox"] {
    width: 18px;
    height: 18px;
    min-width: 18px;
    margin-top: 2px;
    accent-color: var(--gold-bright);
    cursor: pointer;
}
.rkp-review .checklist label span {
    font-size: 0.88rem;
    line-height: 1.45;
    color: var(--text-secondary);
}
.rkp-module[data-reviewed="true"] .section-heading .eyebrow::after {
    content: " · Reviewed";
    color: var(--green);
    font-weight: 750;
}

/* Next module action button with animated arrow */
.rkp-next {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    width: 100%;
    min-height: 52px;
    padding: 14px 20px;
    margin: 24px 0 36px;
    border-radius: 14px;
    border: 1px solid rgba(197, 160, 89, 0.3);
    background: linear-gradient(90deg, rgba(197, 160, 89, 0.08) 0%, rgba(197, 160, 89, 0.02) 100%), var(--bg-surface);
    font-size: 0.92rem;
    font-weight: 650;
    color: var(--gold-bright);
    text-decoration: none;
    transition: all 0.22s cubic-bezier(0.16, 1, 0.3, 1);
    box-sizing: border-box;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.25);
}
.rkp-next:hover {
    background: linear-gradient(90deg, rgba(197, 160, 89, 0.16) 0%, rgba(197, 160, 89, 0.06) 100%), var(--bg-card);
    border-color: var(--gold-bright);
    transform: translateY(-2px);
    box-shadow: 0 6px 24px -2px rgba(197, 160, 89, 0.22);
}
.rkp-next:active {
    transform: scale(0.99);
}
.rkp-next-arrow {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 30px;
    height: 30px;
    min-width: 30px;
    flex-shrink: 0;
    border-radius: 50%;
    background: rgba(197, 160, 89, 0.15);
    border: 1px solid rgba(197, 160, 89, 0.3);
    color: var(--gold-bright);
    font-size: 1.15rem;
    line-height: 1;
    transition: transform 0.22s cubic-bezier(0.16, 1, 0.3, 1), background-color 0.2s ease, border-color 0.2s ease;
}
.rkp-next:hover .rkp-next-arrow {
    transform: translateX(5px);
    background: rgba(197, 160, 89, 0.3);
    border-color: var(--gold-bright);
}

/* Footer & Back to top button */
.course-footer {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 34px 0 22px;
    margin-top: 42px;
    border-top: 1px solid var(--line);
    box-sizing: border-box;
}
.course-footer a {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    min-height: 44px;
    padding: 10px 20px;
    border-radius: 999px;
    border: 1px solid rgba(197, 160, 89, 0.35);
    background: rgba(197, 160, 89, 0.1);
    color: var(--gold-bright);
    text-decoration: none;
    font-size: 0.86rem;
    font-weight: 650;
    transition: all 0.22s cubic-bezier(0.16, 1, 0.3, 1);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
    box-sizing: border-box;
}
.course-footer a:hover {
    background: rgba(197, 160, 89, 0.22);
    border-color: var(--gold-bright);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(197, 160, 89, 0.25);
}
.course-footer-arrow {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 22px;
    height: 22px;
    min-width: 22px;
    flex-shrink: 0;
    border-radius: 50%;
    background: rgba(197, 160, 89, 0.2);
    font-size: 0.95rem;
    line-height: 1;
    transition: transform 0.2s ease;
}
.course-footer a:hover .course-footer-arrow {
    transform: translateY(-2px);
}

/* References */
.rkp-reference-list {
    padding: 8px 20px 20px 36px;
    margin: 0;
    box-sizing: border-box;
}
.rkp-reference-list li {
    padding-left: 6px;
    margin: 16px 0;
}
.rkp-reference-list a {
    color: #e6d1a6;
    font-size: .94rem;
    font-weight: 650;
    text-decoration: underline;
    text-underline-offset: 3px;
}
.rkp-reference-list p {
    color: var(--text-secondary);
    margin: 6px 0 0;
    font-size: .88rem;
    line-height: 1.5;
}

/* Drawer backdrop with high z-index and smooth fade */
.drawer-backdrop {
    position: fixed;
    inset: 0;
    z-index: 999;
    background: rgba(0, 0, 0, 0.75);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}
.drawer-backdrop.open {
    opacity: 1;
    pointer-events: auto;
}

/* Mobile Drawer TOC */
.mobile-toc {
    position: fixed;
    inset: auto 0 0;
    z-index: 1000;
    max-height: min(84vh, 740px);
    padding: 12px 16px calc(24px + env(safe-area-inset-bottom));
    border-top: 1px solid rgba(197, 160, 89, 0.35);
    border-radius: 22px 22px 0 0;
    background: rgba(14, 14, 16, 0.98);
    box-shadow: 0 -24px 70px rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(28px) saturate(140%);
    -webkit-backdrop-filter: blur(28px) saturate(140%);
    transform: translateY(105%);
    transition: transform 0.28s cubic-bezier(0.16, 1, 0.3, 1);
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
    box-sizing: border-box;
}
.mobile-toc::before {
    content: "";
    display: block;
    width: 42px;
    height: 4px;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.25);
    margin: 2px auto 12px;
}
.mobile-toc.open { transform: translateY(0); }
.mobile-toc-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    margin-bottom: 12px;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--line-soft);
}
.mobile-toc-head strong {
    font-size: 1.05rem;
    color: var(--gold-bright);
}
.mobile-toc-head button {
    width: 44px;
    height: 44px;
    min-width: 44px;
    border-radius: 12px;
    border: 1px solid var(--line);
    background: var(--bg-elevated);
    color: var(--text-primary);
    font-size: 1.4rem;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: background 0.15s ease;
}
.mobile-toc-head button:hover {
    background: rgba(255, 255, 255, 0.08);
}
.mobile-toc nav {
    display: grid;
    gap: 4px;
}
.mobile-toc nav a {
    min-height: 48px;
    display: flex;
    align-items: center;
    padding: 10px 14px;
    border-radius: 10px;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    line-height: 1.4;
    transition: background 0.15s ease, color 0.15s ease;
}
.mobile-toc nav a:hover {
    background: rgba(197, 160, 89, 0.1);
    color: var(--gold-bright);
}

/* Responsive Media Queries */
@media (min-width: 700px) {
    .rkp-orientation-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
    .rkp-assignment-grid { grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr); }
    .interactive-tool-box .tool-controls { grid-template-columns: 1fr auto; }
}
@media (min-width: 900px) {
    .rkp-download-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
    .hero-card { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}
@media (min-width: 1120px) {
    .layout { grid-template-columns: 245px minmax(0, 960px); gap: 42px; padding: 0 24px 64px; }
    .toc { max-height: calc(100dvh - var(--header) - 44px); overflow-y: auto; scrollbar-width: thin; padding-right: 6px; }
    .toc nav a { padding-block: 6px; font-size: .78rem; line-height: 1.35; }
    .hero h1 { font-size: clamp(3.2rem, 5.2vw, 4.8rem); }
}
@media (max-width: 600px) {
    .layout { padding: 0 12px 48px; }
    .rkp-download-grid,
    .rkp-orientation-grid,
    .rkp-assignment-grid,
    .hero-card,
    .fact-grid {
        grid-template-columns: 1fr;
        min-width: 0;
        width: 100%;
    }
    .hero h1 {
        font-size: clamp(2rem, 8vw, 3rem);
        max-width: 100%;
        word-break: break-word;
    }
    .hero-actions .button {
        width: 100%;
        text-align: center;
    }
    .rkp-reader-tools {
        padding: 14px;
        grid-template-columns: 1fr;
        min-width: 0;
        width: 100%;
    }
    .rkp-reader-tools input {
        min-width: 0;
        width: 100%;
        font-size: 0.88rem;
    }
    .rkp-lesson-body table {
        min-width: 520px;
        font-size: 0.84rem;
    }
    .rkp-lesson-body th, .rkp-lesson-body td {
        padding: 11px 12px;
    }
    .rkp-lesson-body > h3 {
        font-size: 1.15rem;
    }
    .dice-row {
        grid-template-columns: 1fr;
        gap: 6px;
    }
    .dice-row small {
        grid-column: 1;
    }
    .interactive-tool-box {
        padding: 16px;
        min-width: 0;
        width: 100%;
    }
    .interactive-tool-box select,
    .interactive-tool-box input,
    .interactive-tool-box textarea {
        min-width: 0;
        width: 100%;
    }
    .course-footer {
        flex-direction: column;
        align-items: stretch;
        text-align: center;
        gap: 16px;
    }
    .course-footer a {
        justify-content: center;
        width: 100%;
    }
}
@media (max-width: 420px) {
    .site-header { padding: 8px 12px; }
    .course-brand span:last-child { display: inline; }
    .course-brand { max-width: 46vw; font-size: .78rem; }
    .header-actions .button { font-size: .75rem; padding: 6px 10px; }
    .hero-card { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    .drawer-backdrop, .mobile-toc, details summary::after, .rkp-next, .rkp-next-arrow, .course-footer a, .course-footer-arrow { transition: none !important; }
}
@media print {
    .site-header, .toc, .mobile-toc, .drawer-backdrop, .reading-progress, .rkp-reader-tools, .copy-button, .rkp-next, .rkp-skip-link { display: none !important; }
    body { background: white; color: #111; }
    body::before { display: none; }
    .layout, .course { display: block; width: 100%; padding: 0; }
    .rkp-lesson-body, .rkp-lesson-body strong, .rkp-lesson-body td:first-child, .rkp-assignment li, .rkp-reference-list p { color: #222; }
    .rkp-module { break-before: page; }
    .rkp-lesson-body table { min-width: 0; background: white; }
    .rkp-lesson-body th { color: #222; background: #eee; }
}


/* TEE3 2026 field case: readable compact trust-boundary diagram */
.tee3-field-case {
    margin: 2rem 0;
    padding: clamp(1rem, 2.4vw, 1.6rem);
    max-width: 100%;
    min-width: 0;
    overflow: clip;
    border: 1px solid rgba(197, 160, 89, .28);
    border-radius: 20px;
    background: linear-gradient(145deg, rgba(197,160,89,.085), transparent 47%), #141518;
}
.tee3-field-case__header { max-width: 76ch; }
.tee3-field-case__kicker {
    margin: 0 0 .6rem; color: var(--gold-bright); font-size: .73rem;
    font-weight: 750; letter-spacing: .10em;
}
.tee3-field-case__header h3 {
    margin: .2rem 0 .8rem; font-size: clamp(1.25rem, 2.8vw, 1.9rem);
    line-height: 1.22; letter-spacing: -.025em;
}
.tee3-field-case__header p, .tee3-field-case__footnote {
    line-height: 1.66; overflow-wrap: anywhere; color: var(--text-secondary);
}
.tee3-field-case__figure { margin: 1.5rem 0; min-width: 0; }
.tee3-field-case__flow {
    list-style: none; padding: 0; margin: 0;
    display: grid; gap: 1.05rem; grid-template-columns: repeat(4, minmax(0, 1fr));
}
.tee3-field-case__flow li {
    position: relative; isolation: isolate; min-width: 0;
    padding: 1rem .8rem; border: 1px solid var(--line-strong);
    border-radius: 14px; background: #1c1d22;
    display: flex; flex-direction: column; gap: .48rem;
    overflow-wrap: anywhere;
}
.tee3-field-case__flow li:not(:last-child)::after {
    content: "→"; position: absolute; z-index: 2; right: -.91rem;
    top: 50%; transform: translateY(-50%); color: var(--gold-bright);
    font-size: 1.1rem; background: #141518; width: .82rem;
    text-align: center; pointer-events: none;
}
.tee3-field-case__step {
    color: var(--gold-bright); font: 700 .68rem/1.4 var(--font-mono);
    letter-spacing: .03em;
}
.tee3-field-case__flow strong { font-size: clamp(.86rem, 1.7vw, 1rem); line-height: 1.4; }
.tee3-field-case__flow small { font-size: .77rem; line-height: 1.5; color: var(--text-secondary); }
.tee3-field-case figcaption {
    margin-top: 1rem; font-size: .8rem; line-height: 1.55;
    color: var(--text-tertiary);
}
.tee3-field-case__compare {
    display: grid; grid-template-columns: repeat(2,minmax(0,1fr));
    gap: .9rem; margin: 1.2rem 0;
}
.tee3-field-case__panel {
    border: 1px solid var(--line-strong); border-radius: 13px;
    background: rgba(255,255,255,.025); padding: 1rem; min-width: 0;
}
.tee3-field-case__panel--bad { border-top: 3px solid #ff9b8c; }
.tee3-field-case__panel--good { border-top: 3px solid #7adfb0; }
.tee3-field-case__panel h4 { margin: 0 0 .6rem; font-size: 1rem; }
.tee3-field-case__panel p { margin: .4rem 0; line-height: 1.6; overflow-wrap: anywhere; }
.tee3-field-case__panel code {
    white-space: normal; overflow-wrap: anywhere; font-size: .82rem;
}
.tee3-field-case .code-block { min-width: 0; max-width: 100%; }
.tee3-field-case pre { max-width: 100%; overflow-x: auto; }
@media (max-width: 760px) {
    .tee3-field-case__flow { grid-template-columns: repeat(2,minmax(0,1fr)); gap: 1rem; }
    .tee3-field-case__flow li:nth-child(2)::after { content: none; }
}
@media (max-width: 510px) {
    .tee3-field-case { border-radius: 14px; padding: .95rem; }
    .tee3-field-case__flow, .tee3-field-case__compare { grid-template-columns: minmax(0,1fr); }
    .tee3-field-case__flow { gap: 1.45rem; }
    .tee3-field-case__flow li { padding: .9rem 1rem; }
    .tee3-field-case__flow li:not(:last-child)::after,
    .tee3-field-case__flow li:nth-child(2)::after {
        content: "↓"; right: 50%; top: auto; bottom: -1.24rem;
        transform: translateX(50%); width: 1.5rem; height: 1.32rem;
    }
    .tee3-field-case__flow li strong { font-size: .98rem; }
}
@media print {
    .tee3-field-case { background: white; color: #111; border: 1px solid #888; }
    .tee3-field-case__panel, .tee3-field-case__flow li {
        background: white; color: #111; break-inside: avoid;
    }
    .tee3-field-case__header p, .tee3-field-case__flow small,
    .tee3-field-case__footnote { color: #222; }
}