/* =====================================================================
   Class Page (Preparation Procedures) — modern redesign
   Used by /procedures/class-1.html … class-11.html
   ===================================================================== */

.class-page {
    --cp-accent: #2563eb;
    --cp-accent-dark: #1d4ed8;
    --cp-ink: #111827;
    --cp-ink-2: #374151;
    --cp-ink-3: #6b7280;
    --cp-line: #e5e7eb;
    --cp-line-2: #f1f3f5;
    --cp-bg: #ffffff;
    --cp-bg-soft: #f8fafc;
    --cp-bg-tint: #eef4ff;
    --cp-radius: 12px;
    --cp-radius-sm: 8px;
    --cp-shadow: 0 1px 2px rgba(15, 23, 42, 0.04);
    --cp-shadow-hover: 0 8px 24px rgba(15, 23, 42, 0.08);
    --cp-max: 1200px;

    color: var(--cp-ink);
    font-family: 'Inter', 'Roboto', Arial, sans-serif;
    line-height: 1.6;
    padding-top: 110px; /* clears site's fixed navigation */
}

/* ---------- HERO ---------- */
.cp-hero {
    max-width: var(--cp-max);
    margin: 0 auto;
    padding: 2rem 1.5rem 1.5rem;
}

.cp-back {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    color: var(--cp-ink-3);
    font-size: 0.875rem;
    text-decoration: none;
    margin-bottom: 1.25rem;
    transition: color 0.15s ease;
}
.cp-back:hover { color: var(--cp-accent); }
.cp-back svg { width: 16px; height: 16px; }

.cp-hero-inner {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 2rem;
    align-items: start;
}

.cp-eyebrow {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--cp-accent);
    background: var(--cp-bg-tint);
    padding: 0.25rem 0.625rem;
    border-radius: 999px;
    margin-bottom: 0.75rem;
}

.cp-title {
    font-size: clamp(1.75rem, 3vw, 2.25rem);
    font-weight: 700;
    color: var(--cp-ink);
    margin: 0 0 1rem;
    line-height: 1.15;
    letter-spacing: -0.01em;
}

.cp-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.25rem;
}
.cp-chip {
    display: inline-flex;
    align-items: baseline;
    gap: 0.5rem;
    padding: 0.5rem 0.875rem;
    background: var(--cp-bg-soft);
    border: 1px solid var(--cp-line);
    border-radius: 999px;
    font-size: 0.875rem;
    color: var(--cp-ink);
    white-space: nowrap;
}
.cp-chip-label {
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--cp-ink-3);
}

.cp-lede {
    font-size: 1rem;
    color: var(--cp-ink-2);
    margin: 0;
    max-width: 60ch;
}

.cp-hero-figure {
    margin: 0;
    width: 280px;
    flex-shrink: 0;
}
.cp-hero-figure img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: var(--cp-radius);
    border: 1px solid var(--cp-line);
    display: block;
}
.cp-hero-figure figcaption {
    font-size: 0.75rem;
    color: var(--cp-ink-3);
    margin-top: 0.5rem;
    line-height: 1.4;
    text-align: center;
    font-style: italic;
}

/* ---------- LAYOUT ---------- */
.cp-layout {
    max-width: var(--cp-max);
    margin: 1rem auto 4rem;
    padding: 0 1.5rem;
    display: grid;
    grid-template-columns: 220px minmax(0, 1fr);
    gap: 3rem;
    align-items: start;
}

.cp-sidebar {
    position: sticky;
    top: 120px;
    align-self: start;
}
.cp-sidebar-title {
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--cp-ink-3);
    margin: 0 0 0.75rem;
    padding-left: 0.875rem;
}
.cp-nav {
    display: flex;
    flex-direction: column;
    border-left: 2px solid var(--cp-line);
}
.cp-nav-link {
    display: block;
    padding: 0.5rem 0.875rem;
    margin-left: -2px;
    border-left: 2px solid transparent;
    color: var(--cp-ink-3);
    font-size: 0.9rem;
    text-decoration: none;
    transition: color 0.15s ease, border-color 0.15s ease;
}
.cp-nav-link:hover { color: var(--cp-ink); }
.cp-nav-link.is-active {
    color: var(--cp-accent);
    border-left-color: var(--cp-accent);
    font-weight: 600;
}

.cp-main { min-width: 0; }

/* ---------- SECTIONS ---------- */
.cp-section {
    margin-bottom: 3.5rem;
    scroll-margin-top: 120px;
}
.cp-section-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--cp-ink);
    margin: 0 0 1.25rem;
    letter-spacing: -0.01em;
}
.cp-section-lede {
    color: var(--cp-ink-2);
    margin: -0.5rem 0 1.5rem;
    max-width: 65ch;
}

/* ---------- CHALLENGES (expandable cards) ---------- */
.cp-challenge-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1rem;
}
.cp-challenge {
    background: var(--cp-bg);
    border: 1px solid var(--cp-line);
    border-radius: var(--cp-radius-sm);
    padding: 1rem 1.125rem;
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.cp-challenge[open] {
    border-color: var(--cp-accent);
    box-shadow: var(--cp-shadow);
}
.cp-challenge > summary {
    list-style: none;
    cursor: pointer;
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 0.25rem 0.75rem;
    align-items: start;
    outline: none;
}
.cp-challenge > summary::-webkit-details-marker { display: none; }
.cp-challenge-title {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--cp-ink);
}
.cp-challenge-summary {
    grid-column: 1 / -1;
    font-size: 0.875rem;
    color: var(--cp-ink-3);
    margin-top: 0.25rem;
}
.cp-chevron {
    width: 18px;
    height: 18px;
    color: var(--cp-ink-3);
    transition: transform 0.2s ease;
    flex-shrink: 0;
}
.cp-challenge[open] .cp-chevron { transform: rotate(180deg); }
.cp-challenge-detail {
    margin: 0.875rem 0 0;
    padding-top: 0.875rem;
    border-top: 1px solid var(--cp-line-2);
    font-size: 0.9rem;
    color: var(--cp-ink-2);
    line-height: 1.65;
}

/* ---------- MATERIALS (grouped accordion) ---------- */
.cp-materials {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}
.cp-material-group {
    border: 1px solid var(--cp-line);
    border-radius: var(--cp-radius-sm);
    background: var(--cp-bg);
    overflow: hidden;
}
.cp-material-group > summary {
    list-style: none;
    cursor: pointer;
    padding: 0.875rem 1.125rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--cp-ink);
    transition: background 0.15s ease;
}
.cp-material-group > summary:hover { background: var(--cp-bg-soft); }
.cp-material-group > summary::-webkit-details-marker { display: none; }
.cp-material-group-meta {
    display: flex;
    align-items: center;
    gap: 0.625rem;
    color: var(--cp-ink-3);
    font-size: 0.8rem;
    font-weight: 500;
}
.cp-count {
    background: var(--cp-bg-soft);
    border: 1px solid var(--cp-line);
    border-radius: 999px;
    padding: 0.1rem 0.55rem;
    font-size: 0.75rem;
    color: var(--cp-ink-2);
}
.cp-material-group[open] > summary {
    border-bottom: 1px solid var(--cp-line);
    background: var(--cp-bg-soft);
}
.cp-material-group[open] .cp-chevron { transform: rotate(180deg); }
.cp-material-list {
    list-style: none;
    margin: 0;
    padding: 0.75rem 1.125rem 1rem;
    columns: 2;
    column-gap: 1.5rem;
}
.cp-material-list li {
    padding: 0.25rem 0;
    break-inside: avoid;
    font-size: 0.875rem;
}
.cp-material-list a {
    color: var(--cp-ink-2);
    text-decoration: none;
    transition: color 0.15s ease;
}
.cp-material-list a:hover {
    color: var(--cp-accent);
    text-decoration: underline;
}
.cp-condition-note {
    display: block;
    font-size: 0.75rem;
    color: var(--cp-ink-3);
    font-style: italic;
    margin-top: 0.125rem;
}

/* ---------- PROCEDURE (numbered timeline) ---------- */
.cp-steps {
    list-style: none;
    counter-reset: cpstep;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 0;
    position: relative;
}
.cp-step {
    display: grid;
    grid-template-columns: 44px minmax(0, 1fr);
    gap: 1.25rem;
    padding: 0 0 1.5rem;
    position: relative;
}
.cp-step:not(:last-child)::before {
    content: '';
    position: absolute;
    left: 21px;
    top: 44px;
    bottom: 0;
    width: 2px;
    background: var(--cp-line);
}
.cp-step-num {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--cp-bg-tint);
    color: var(--cp-accent);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1rem;
    border: 2px solid var(--cp-bg);
    box-shadow: 0 0 0 2px var(--cp-line);
    position: relative;
    z-index: 1;
}
.cp-step-body { padding-top: 0.25rem; }
.cp-step-title {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--cp-ink);
    margin: 0 0 0.375rem;
}
.cp-step-lede {
    color: var(--cp-ink-2);
    margin: 0;
    font-size: 0.95rem;
}
.cp-step-detail {
    margin-top: 0.625rem;
}
.cp-step-detail > summary {
    list-style: none;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--cp-accent);
    padding: 0.25rem 0;
}
.cp-step-detail > summary::-webkit-details-marker { display: none; }
.cp-step-detail[open] > summary { margin-bottom: 0.5rem; }
.cp-step-detail[open] .cp-chevron { transform: rotate(180deg); }
.cp-step-detail-body {
    font-size: 0.9rem;
    color: var(--cp-ink-2);
    line-height: 1.65;
    padding: 0.75rem 1rem;
    background: var(--cp-bg-soft);
    border-left: 3px solid var(--cp-accent);
    border-radius: 0 var(--cp-radius-sm) var(--cp-radius-sm) 0;
}
.cp-step-detail-body p { margin: 0 0 0.5rem; }
.cp-step-detail-body p:last-child { margin-bottom: 0; }

.cp-safety {
    margin-top: 0.625rem;
    padding: 0.625rem 0.875rem;
    background: #fef3c7;
    border-left: 3px solid #d97706;
    border-radius: 0 var(--cp-radius-sm) var(--cp-radius-sm) 0;
    font-size: 0.85rem;
    color: #78350f;
}
.cp-safety strong { color: #78350f; }

/* ---------- ETCHANTS BY FAMILY ---------- */
.cp-etchants {
    margin-top: 1rem;
    padding: 1rem 1.125rem;
    background: var(--cp-bg-soft);
    border: 1px solid var(--cp-line);
    border-radius: var(--cp-radius-sm);
}
.cp-etchants-title {
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--cp-ink-3);
    margin: 0 0 0.75rem;
}
.cp-etchants-list {
    margin: 0;
    display: grid;
    gap: 0.5rem;
}
.cp-etchant-row {
    display: grid;
    grid-template-columns: 180px minmax(0, 1fr);
    gap: 0.875rem;
    padding: 0.5rem 0;
    border-top: 1px solid var(--cp-line-2);
}
.cp-etchant-row:first-child { border-top: none; padding-top: 0; }
.cp-etchant-row dt {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--cp-ink);
}
.cp-etchant-row dd {
    margin: 0;
    font-size: 0.875rem;
    color: var(--cp-ink-2);
    line-height: 1.55;
}
.cp-etchants-cta {
    margin: 1rem 0 0;
    padding-top: 0.875rem;
    border-top: 1px solid var(--cp-line);
    display: flex;
    flex-wrap: wrap;
    gap: 1.25rem;
}
.cp-etchants-link {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--cp-accent);
    text-decoration: none;
    transition: color 0.15s ease;
}
.cp-etchants-link:hover { color: var(--cp-accent-dark); text-decoration: underline; }

@media (max-width: 600px) {
    .cp-etchant-row { grid-template-columns: 1fr; gap: 0.125rem; }
    .cp-etchant-row dt { font-size: 0.8rem; }
}

/* ---------- QUALITY CHECKS ---------- */
.cp-checks {
    list-style: none;
    margin: 0;
    padding: 0;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 0.625rem;
}
.cp-checks li {
    display: flex;
    align-items: flex-start;
    gap: 0.625rem;
    padding: 0.75rem 0.875rem;
    background: var(--cp-bg-soft);
    border: 1px solid var(--cp-line);
    border-radius: var(--cp-radius-sm);
    font-size: 0.9rem;
    color: var(--cp-ink-2);
}
.cp-check-icon {
    flex-shrink: 0;
    width: 18px;
    height: 18px;
    color: #16a34a;
    margin-top: 1px;
}

/* ---------- MOBILE ---------- */
@media (max-width: 960px) {
    .class-page { padding-top: 90px; }

    .cp-hero-inner { grid-template-columns: 1fr; }
    .cp-hero-figure { width: 100%; max-width: 360px; }
    .cp-hero-figure img { height: auto; aspect-ratio: 4 / 3; }

    .cp-section { scroll-margin-top: 90px; }

    .cp-layout {
        grid-template-columns: 1fr;
        gap: 0;
    }
    .cp-sidebar {
        position: static;
        margin-bottom: 1.5rem;
        padding-bottom: 0.5rem;
        border-bottom: 1px solid var(--cp-line);
        overflow-x: auto;
    }
    .cp-sidebar-title { display: none; }
    .cp-nav {
        flex-direction: row;
        border-left: none;
        border-bottom: 2px solid var(--cp-line);
        gap: 0;
        padding-bottom: 0;
    }
    .cp-nav-link {
        margin-left: 0;
        margin-bottom: -2px;
        border-left: none;
        border-bottom: 2px solid transparent;
        padding: 0.625rem 0.875rem;
        white-space: nowrap;
    }
    .cp-nav-link.is-active {
        border-left-color: transparent;
        border-bottom-color: var(--cp-accent);
    }
}

@media (max-width: 600px) {
    .cp-hero { padding: 1.5rem 1rem 1rem; }
    .cp-layout { padding: 0 1rem; margin-bottom: 2.5rem; }
    .cp-title { font-size: 1.5rem; }
    .cp-section-title { font-size: 1.25rem; }
    .cp-material-list { columns: 1; }
    .cp-step { grid-template-columns: 36px minmax(0, 1fr); gap: 0.875rem; }
    .cp-step-num { width: 36px; height: 36px; font-size: 0.875rem; }
    .cp-step:not(:last-child)::before { left: 17px; top: 36px; }
}

/* ---------- PRINT ---------- */
@media print {
    .cp-sidebar, .cp-back { display: none; }
    .cp-layout { grid-template-columns: 1fr; }
    .cp-challenge, .cp-material-group, .cp-step-detail { open: true; }
    details > summary { list-style: none; }
    .cp-challenge[open], .cp-material-group[open] { box-shadow: none; }
    .cp-challenge-detail, .cp-material-list { display: block !important; }
}

/* ---------- REDUCED MOTION ---------- */
@media (prefers-reduced-motion: reduce) {
    .cp-chevron, .cp-challenge, .cp-material-group > summary,
    .cp-back, .cp-nav-link, .cp-material-list a {
        transition: none;
    }
}