/* ── CSS Custom Properties ─────────────────────────────────────── */

:root {
    --bg:           #fafafa;
    --surface:      #ffffff;
    --surface-alt:  #f5f5f5;
    --border:       #e5e7eb;
    --text:         #1a1a1a;
    --text-muted:   #6b7280;
    --text-dim:     #9ca3af;
    --primary:      #003366;
    --primary-hover:#002244;
    --nav-bg:       #ffffff;
    --nav-text:     #374151;
    --radius:       4px;
    --transition:   0.15s ease;
}

[data-theme="dark"] {
    --bg:           #111111;
    --surface:      #1a1a1a;
    --surface-alt:  #222222;
    --border:       #2e2e2e;
    --text:         #f0f0f0;
    --text-muted:   #888888;
    --text-dim:     #555555;
    --primary:      #4a90d9;
    --primary-hover:#60a5fa;
    --nav-bg:       #1a1a1a;
    --nav-text:     #d0d0d0;
}

/* ── Base ──────────────────────────────────────────────────────── */

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

html {
    transition: background-color var(--transition), color var(--transition);
}

body {
    background-color: var(--bg);
    color: var(--text);
    font-family: system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
    font-size: 15px;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    transition: background-color var(--transition), color var(--transition);
}

p {
    color: var(--text);
    font-size: 15px;
    margin: 0 0 12px;
}

a {
    color: var(--primary);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

/* ── Site Header ───────────────────────────────────────────────── */

.site-header {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
    background-color: var(--nav-bg);
    border-bottom: 1px solid var(--border);
    padding: 0 24px;
    height: 52px;
    position: sticky;
    top: 0;
    z-index: 100;
    transition: background-color var(--transition), border-color var(--transition);
}

.header-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-shrink: 0;
    text-decoration: none;
}

.img-logo {
    width: 28px;
    height: 28px;
}

.logo-text {
    font-size: 15px;
    font-weight: 600;
    color: var(--text);
    letter-spacing: -0.01em;
}

.site-nav {
    display: flex;
    justify-content: center;
}

.menu {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    align-items: center;
    gap: 2px;
}

.menu li {
    margin: 0;
}

.menu a {
    display: inline-block;
    text-decoration: none;
    color: var(--nav-text);
    padding: 5px 10px;
    font-size: 14px;
    font-weight: 500;
    border-radius: var(--radius);
    transition: color var(--transition), background-color var(--transition);
}

.menu a:hover {
    color: var(--text);
    background-color: var(--surface-alt);
}

.nav-sep {
    width: 1px;
    height: 16px;
    background-color: var(--border);
    margin: 0 6px;
    align-self: center;
    flex-shrink: 0;
}

/* ── Header Right Controls ─────────────────────────────────────── */

.header-right {
    justify-self: end;
    display: flex;
    align-items: center;
    gap: 8px;
}

/* ── Product Selector ──────────────────────────────────────────── */

.product-selector {
    display: flex;
    gap: 1px;
    background: var(--border);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    flex-shrink: 0;
}

.product-btn {
    padding: 5px 10px;
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.03em;
    background: var(--surface);
    color: var(--text-muted);
    border: none;
    cursor: pointer;
    transition: background var(--transition), color var(--transition);
    white-space: nowrap;
    line-height: 1;
}

.product-btn:hover {
    background: var(--surface-alt);
    color: var(--text);
}

.product-btn.active {
    background: var(--primary);
    color: #fff;
}

/* ── Dark Mode Toggle ──────────────────────────────────────────── */

.theme-toggle {
    width: 32px;
    height: 32px;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    background-color: transparent;
    color: var(--text-muted);
    font-size: 16px;
    line-height: 1;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color var(--transition), border-color var(--transition), color var(--transition);
}

.theme-toggle:hover {
    background-color: var(--surface-alt);
    color: var(--text);
    border-color: var(--text-muted);
}

/* ── Site Content & Footer ─────────────────────────────────────── */

.site-content {
    min-height: calc(100vh - 52px - 44px);
    padding: 24px 0;
}

.site-footer {
    text-align: center;
    padding: 12px;
    border-top: 1px solid var(--border);
}

.disclaimer {
    font-size: 13px;
    color: var(--text-dim);
    margin: 0;
}

/* ── Buttons ───────────────────────────────────────────────────── */

.button {
    display: inline-block;
    padding: 8px 18px;
    background-color: var(--primary);
    color: #fff;
    border: none;
    font-size: 14px;
    font-weight: 500;
    border-radius: var(--radius);
    cursor: pointer;
    transition: background-color var(--transition);
}

.button:hover {
    background-color: var(--primary-hover);
}

/* ── Lab Progress Bar ──────────────────────────────────────────── */

.lab-progress {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 8px 24px;
    position: sticky;
    top: 52px;
    z-index: 98;
    transition: background-color var(--transition), border-color var(--transition);
}

.lab-progress-inner {
    display: flex;
    align-items: center;
    gap: 14px;
    width: min(640px, 95vw);
    margin: 0 auto;
}

.lab-progress-steps {
    position: relative;
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.lab-progress-line {
    position: absolute;
    left: 0;
    right: 0;
    top: 50%;
    transform: translateY(-50%);
    height: 4px;
    background: var(--border);
    border-radius: 2px;
    overflow: hidden;
}

.lab-progress-line-fill {
    height: 100%;
    width: 0%;
    background: #16a34a;
    border-radius: 2px;
    transition: width 0.4s ease;
}

.lab-progress-pip {
    position: relative;
    z-index: 1;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--surface);
    border: 2px solid var(--border);
    flex-shrink: 0;
    transition: background var(--transition), border-color var(--transition);
}

.lab-progress-pip.complete {
    background: #16a34a;
    border-color: #16a34a;
}

.lab-progress-meta {
    font-size: 12px;
    color: var(--text-muted);
    white-space: nowrap;
    flex-shrink: 0;
    display: flex;
    gap: 4px;
    font-variant-numeric: tabular-nums;
}

.lab-progress-sep {
    color: var(--text-dim);
}

/* ── Challenge Page (original grid view) ───────────────────────── */

.challenge-page {
    width: min(640px, 95vw);
    margin: 0 auto;
    padding: 8px 0 24px;
}

.challenge-run-all-container {
    display: flex;
    justify-content: center;
    margin-bottom: 20px;
}

.challenge-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1px;
    background: var(--border);
    border: 1px solid var(--border);
}

.challenge-card {
    background: var(--surface);
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 10px;
    border: 1px solid var(--border);
    transition: background var(--transition), border-color var(--transition);
}

.challenge-card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.challenge-title {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 600;
    font-size: 15px;
    color: var(--text);
}

.challenge-icon {
    color: var(--text-dim);
    display: flex;
    align-items: center;
}

.challenge-section-label {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-dim);
}

.challenge-section-label::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--border);
}

.challenge-scenario {
    font-size: 13px;
    color: var(--text-muted);
    line-height: 1.5;
    margin: 0;
}

.challenge-desc {
    font-size: 13px;
    color: var(--text-muted);
    line-height: 1.5;
    margin: 0;
}

.challenge-card.locked {
    background: var(--surface-alt);
}

.challenge-card.locked > :not(.challenge-card-header) {
    display: none;
}

.challenge-card.passed {
    background: var(--surface-alt);
}

.challenge-desc code,
.challenge-scenario code {
    font-family: ui-monospace, 'SF Mono', 'Cascadia Code', monospace;
    font-size: 12px;
    background: var(--surface-alt);
    padding: 1px 4px;
    border-radius: 3px;
    border: 1px solid var(--border);
    color: var(--text);
}

.challenge-card-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 8px;
    margin-top: 2px;
}

.challenge-detail {
    font-size: 12px;
    color: var(--text-muted);
    font-family: ui-monospace, 'SF Mono', 'Cascadia Code', monospace;
    flex: 1;
    min-width: 0;
    word-break: break-word;
}

.challenge-run-btn {
    flex-shrink: 0;
    padding: 5px 14px;
    background-color: transparent;
    color: var(--primary);
    border: 1px solid var(--primary);
    border-radius: var(--radius);
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    transition: background-color var(--transition), color var(--transition);
}

.challenge-run-btn:hover {
    background-color: var(--primary);
    color: #fff;
}

.challenge-run-btn:disabled {
    opacity: 0.4;
    cursor: default;
}

/* Status indicator */

.challenge-status {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 24px;
    height: 24px;
    flex-shrink: 0;
    font-size: 14px;
    color: var(--text-dim);
}

.challenge-status[data-state="pass"] {
    color: #16a34a;
}

.challenge-status[data-state="fail"] {
    color: #dc2626;
}

.challenge-status[data-state="running"] {
    color: var(--primary);
}

@keyframes challenge-spin {
    to { transform: rotate(360deg); }
}

.challenge-spinner {
    display: inline-block;
    width: 14px;
    height: 14px;
    border: 2px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: challenge-spin 0.7s linear infinite;
}

/* ── Challenge Pts Badge ──── */

.challenge-header-right {
    display: flex;
    align-items: center;
    gap: 8px;
}

.challenge-pts {
    font-size: 12px;
    font-weight: 600;
    color: var(--text-muted);
    background: var(--surface-alt);
    padding: 4px 10px;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    white-space: nowrap;
    transition: color var(--transition), border-color var(--transition);
}

.challenge-pts.passed {
    color: #16a34a;
    border-color: #16a34a;
}

/* ── Challenge Hints ──── */

.challenge-hints {
    display: flex;
    flex-direction: column;
    gap: 1px;
    background: var(--border);
    border: 1px solid var(--border);
    margin-top: 8px;
}

.challenge-hint {
    background: var(--surface);
}

.challenge-hint-toggle {
    padding: 10px 14px;
    cursor: pointer;
    font-size: 12px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-dim);
    display: flex;
    align-items: center;
    gap: 8px;
    background: none;
    border: none;
    width: 100%;
    text-align: left;
    user-select: none;
    transition: color var(--transition), background var(--transition);
}

.challenge-hint-toggle:hover {
    color: var(--text-muted);
    background: var(--surface-alt);
}

.challenge-hint.open .challenge-hint-toggle {
    color: var(--text);
    border-bottom: 1px solid var(--border);
}

.hint-label { flex: 1; }

.hint-deduction-badge {
    font-size: 10px;
    font-weight: 700;
    color: #92400e;
    background: rgba(251, 191, 36, 0.15);
    padding: 1px 5px;
    border-radius: 3px;
    border: 1px solid rgba(251, 191, 36, 0.4);
    white-space: nowrap;
    flex-shrink: 0;
    transition: all var(--transition);
}

[data-theme="dark"] .hint-deduction-badge {
    color: #fbbf24;
    background: rgba(251, 191, 36, 0.08);
    border-color: rgba(251, 191, 36, 0.25);
}

.hint-deduction-badge.used {
    color: var(--text-dim);
    background: transparent;
    border-color: var(--border);
}

.hint-chevron {
    flex-shrink: 0;
    transition: transform 0.2s ease;
}

.challenge-hint.open .hint-chevron {
    transform: rotate(180deg);
}

.challenge-hint-confirm {
    padding: 9px 14px;
    font-size: 12px;
    color: var(--text-muted);
    background: var(--surface-alt);
    border-top: 1px solid var(--border);
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}

.challenge-hint-confirm span { flex: 1; min-width: 0; }

.hint-confirm-btn {
    flex-shrink: 0;
    padding: 3px 11px;
    font-size: 11px;
    font-weight: 600;
    border-radius: var(--radius);
    cursor: pointer;
    transition: background var(--transition), color var(--transition), border-color var(--transition);
}

.hint-confirm-btn.hint-cancel {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-muted);
}

.hint-confirm-btn.hint-cancel:hover {
    border-color: var(--text-muted);
    color: var(--text);
}

.hint-confirm-btn.hint-ok {
    background: transparent;
    border: 1px solid var(--primary);
    color: var(--primary);
}

.hint-confirm-btn.hint-ok:hover {
    background: var(--primary);
    color: #fff;
}

.challenge-hint-body {
    padding: 12px 14px;
    font-size: 13px;
    color: var(--text-muted);
    line-height: 1.55;
}

.challenge-hint-body p { margin: 0; }

.challenge-hint-body code {
    font-family: ui-monospace, 'SF Mono', 'Cascadia Code', monospace;
    font-size: 12px;
    background: var(--surface-alt);
    padding: 1px 4px;
    border-radius: 3px;
    border: 1px solid var(--border);
    color: var(--text);
}

.challenge-hint-body pre {
    margin: 8px 0 0;
    padding: 10px 12px;
    background: var(--surface-alt);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow-x: auto;
    font-family: ui-monospace, 'SF Mono', 'Cascadia Code', monospace;
    font-size: 12px;
    color: var(--text);
    line-height: 1.5;
}

.button-outline {
    background-color: transparent;
    color: var(--primary);
    border: 1px solid var(--primary);
}

.button-outline:hover {
    background-color: var(--primary);
    color: #fff;
}

.challenge-overview-actions {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-top: 20px;
}

.challenge-overview-status {
    display: none;
    flex-shrink: 0;
    align-items: center;
}

.challenge-overview-card.running {
    pointer-events: none;
}

.challenge-overview-card.running .challenge-overview-arrow,
.challenge-overview-card.running .challenge-overview-lock {
    display: none;
}

.challenge-overview-card.running .challenge-overview-status {
    display: flex;
    color: var(--primary);
}

.challenge-overview-card.failed .challenge-overview-arrow {
    display: none;
}

.challenge-overview-card.failed .challenge-overview-status {
    display: flex;
    color: #dc2626;
}

/* ── Challenge Individual Page ─────────────────────────────────── */

.challenge-single-page {
    width: min(640px, 95vw);
    margin: 0 auto;
    padding: 8px 0 24px;
}

.challenge-pager {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 16px;
}

.challenge-pager-btn {
    display: inline-flex;
    align-items: center;
    gap: 5px;
    padding: 5px 12px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 13px;
    font-weight: 500;
    text-decoration: none;
    color: var(--text-muted);
    background: transparent;
    transition: background var(--transition), color var(--transition), border-color var(--transition);
}

.challenge-pager-btn:hover {
    background: var(--surface-alt);
    color: var(--text);
    text-decoration: none;
    border-color: var(--text-muted);
}

.challenge-pager-btn.disabled {
    opacity: 0.3;
    pointer-events: none;
}

.challenge-pager-label {
    font-size: 12px;
    color: var(--text-dim);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-weight: 600;
}

.challenge-steps {
    font-size: 13px;
    color: var(--text-muted);
    line-height: 1.6;
    margin: 0;
}

.challenge-steps-placeholder {
    font-size: 13px;
    color: var(--text-dim);
    font-style: italic;
    margin: 0;
}

/* ── Challenge Overview Page ───────────────────────────────────── */

.challenge-overview-page {
    width: min(640px, 95vw);
    margin: 0 auto;
    padding: 8px 0 24px;
}

.challenge-overview-header {
    margin-bottom: 20px;
}

.challenge-overview-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--text);
    margin: 0 0 6px;
}

.challenge-overview-desc {
    font-size: 13px;
    color: var(--text-muted);
    margin: 0;
}

.challenge-overview-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1px;
    background: var(--border);
    border: 1px solid var(--border);
}

.challenge-overview-card {
    background: var(--surface);
    padding: 16px 20px;
    display: flex;
    align-items: center;
    gap: 14px;
    text-decoration: none;
    color: inherit;
    transition: background var(--transition);
}

.challenge-overview-card:hover {
    background: var(--surface-alt);
    text-decoration: none;
}

.challenge-overview-num {
    font-size: 11px;
    font-weight: 700;
    color: var(--text-dim);
    width: 20px;
    flex-shrink: 0;
    text-align: right;
}

.challenge-overview-icon {
    color: var(--text-dim);
    display: flex;
    align-items: center;
    flex-shrink: 0;
    transition: color var(--transition);
}

.challenge-overview-card:hover .challenge-overview-icon {
    color: var(--primary);
}

.challenge-overview-info {
    flex: 1;
    min-width: 0;
}

.challenge-overview-name {
    font-weight: 600;
    font-size: 14px;
    color: var(--text);
    margin-bottom: 2px;
}

.challenge-overview-scenario {
    font-size: 12px;
    color: var(--text-muted);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.challenge-overview-arrow {
    color: var(--text-dim);
    flex-shrink: 0;
    transition: color var(--transition), transform var(--transition);
}

.challenge-overview-card:hover .challenge-overview-arrow {
    color: var(--primary);
    transform: translateX(3px);
}

.challenge-overview-lock {
    display: none;
    color: var(--text-dim);
    flex-shrink: 0;
}

.challenge-overview-check {
    display: none;
    color: #16a34a;
    flex-shrink: 0;
}

.challenge-overview-card.locked {
    pointer-events: none;
    cursor: default;
}

.challenge-overview-card.locked .challenge-overview-arrow {
    display: none;
}

.challenge-overview-card.locked .challenge-overview-lock {
    display: flex;
    align-items: center;
}

.challenge-overview-card.completed {
    background: var(--surface-alt);
}

.challenge-overview-card.completed .challenge-overview-arrow {
    display: none;
}

.challenge-overview-card.completed .challenge-overview-check {
    display: flex;
    align-items: center;
}

.challenge-overview-card.completed .challenge-overview-name {
    color: var(--text-muted);
}

/* ── Home / Welcome Page ────────────────────────────────────────── */

.home-welcome {
    width: min(560px, 95vw);
    margin: 48px auto;
    text-align: center;
}

.home-welcome-logo {
    width: 48px;
    height: 48px;
    margin: 0 auto 20px;
    display: block;
}

.home-welcome-title {
    font-size: 24px;
    font-weight: 700;
    color: var(--text);
    margin: 0 0 10px;
    letter-spacing: -0.02em;
}

.home-welcome-subtitle {
    font-size: 15px;
    color: var(--text-muted);
    margin: 0 0 32px;
    line-height: 1.6;
}

.home-welcome-actions {
    display: flex;
    justify-content: center;
    gap: 12px;
    flex-wrap: wrap;
}

.home-welcome-start {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 9px 24px;
    background-color: var(--primary);
    color: #fff;
    border-radius: var(--radius);
    font-size: 14px;
    font-weight: 500;
    text-decoration: none;
    transition: background-color var(--transition);
}

.home-welcome-start:hover {
    background-color: var(--primary-hover);
    text-decoration: none;
    color: #fff;
}

/* ── Nav Toggle (hamburger) ────────────────────────────────────── */

.nav-toggle {
    display: none;
    width: 36px;
    height: 36px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: transparent;
    color: var(--text-muted);
    cursor: pointer;
    align-items: center;
    justify-content: center;
    transition: background-color var(--transition), color var(--transition), border-color var(--transition);
}

.nav-toggle:hover {
    background-color: var(--surface-alt);
    color: var(--text);
    border-color: var(--text-muted);
}

/* ── Mobile (≤768px) ───────────────────────────────────────────── */

@media (max-width: 768px) {

    .site-header {
        grid-template-columns: 1fr auto auto;
        gap: 8px;
    }

    .site-nav {
        display: none;
        position: fixed;
        top: 52px;
        left: 0;
        right: 0;
        background-color: var(--nav-bg);
        border-bottom: 1px solid var(--border);
        z-index: 99;
    }

    .site-header.nav-open .site-nav {
        display: block;
    }

    .menu {
        flex-direction: column;
        gap: 0;
        padding: 6px 0;
    }

    .menu a {
        display: block;
        padding: 11px 20px;
        border-radius: 0;
    }

    .nav-sep {
        width: auto;
        height: 1px;
        margin: 4px 16px;
    }

    .nav-toggle {
        display: flex;
    }

    .button {
        min-height: 44px;
        padding-top: 10px;
        padding-bottom: 10px;
    }

}