/* ==========================================================================
   rtx-related.css — Self-contained Related Engineering Tools Design System
   Uses only --rtx-* custom properties; zero dependency on page CSS variables.
   ========================================================================== */

.rtx-section {
    --rtx-bg: #f6f8fb;
    --rtx-tint-blue: rgba(37, 99, 235, 0.06);
    --rtx-tint-green: rgba(5, 150, 105, 0.055);
    --rtx-card-bg: #ffffff;
    --rtx-border: #e5eaf2;
    --rtx-title-color: #0f172a;
    --rtx-text: #334155;
    --rtx-muted: #64748b;
    --rtx-shadow: 0 1px 2px rgba(15, 23, 42, 0.04),
                  0 6px 16px -4px rgba(15, 23, 42, 0.06);
    --rtx-shadow-hover: 0 4px 10px rgba(15, 23, 42, 0.06),
                        0 18px 34px -8px rgba(15, 23, 42, 0.12);
    --rtx-accent: #2563eb;
    --rtx-accent-2: #3b82f6;
    --rtx-accent-soft: rgba(37, 99, 235, 0.10);
    --rtx-font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --rtx-font-display: 'Montserrat', 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

    position: relative;
    display: block;
    width: 100%;
    margin: 0;
    padding: 72px 24px 80px;
    border: 0;
    border-top: 1px solid var(--rtx-border);
    background-color: var(--rtx-bg);
    background-image:
        radial-gradient(640px circle at 92% 8%, var(--rtx-tint-blue), transparent 65%),
        radial-gradient(640px circle at 8% 92%, var(--rtx-tint-green), transparent 65%);
    color: var(--rtx-text);
    font-family: var(--rtx-font-sans);
    line-height: 1.5;
    box-sizing: border-box;
    overflow-x: clip;
}

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

/* Defensive reset against global page styles (h2 borders, underlined links, p margins) */
.rtx-section h2,
.rtx-section h3,
.rtx-section p,
.rtx-section a {
    margin: 0;
    padding: 0;
    border: 0;
    background: transparent;
    box-shadow: none;
    text-decoration: none;
    text-transform: none;
    letter-spacing: normal;
}

.rtx-section h2::before,
.rtx-section h2::after,
.rtx-section h3::before,
.rtx-section h3::after {
    content: none;
    display: none;
}

.rtx-section .rtx-inner {
    width: 100%;
    max-width: 1180px;
    margin: 0 auto;
    padding: 0;
}

/* Centered Section Header */
.rtx-section .rtx-head {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    margin: 0 auto 44px;
    padding: 0;
}

.rtx-section .rtx-head-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    margin: 0 0 16px;
    padding: 0;
    border: 1px solid var(--rtx-border);
    border-radius: 12px;
    background: var(--rtx-accent-soft);
    color: var(--rtx-accent);
    flex-shrink: 0;
}

.rtx-section .rtx-head-icon svg {
    width: 22px;
    height: 22px;
    display: block;
    stroke: currentColor;
}

.rtx-section .rtx-title {
    margin: 0 0 12px;
    padding: 0;
    border: 0;
    font-family: var(--rtx-font-display);
    font-size: clamp(1.75rem, 3vw, 2.2rem);
    font-weight: 800;
    line-height: 1.2;
    letter-spacing: -0.025em;
    color: var(--rtx-title-color);
    text-align: center;
}

.rtx-section .rtx-sub {
    max-width: 640px;
    margin: 0 auto;
    padding: 0;
    border: 0;
    font-size: 1.02rem;
    font-weight: 400;
    line-height: 1.6;
    color: var(--rtx-muted);
    text-align: center;
}

/* Responsive Card Grid */
.rtx-section .rtx-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 26px;
    width: 100%;
    margin: 0;
    padding: 0;
}

/* Cards */
.rtx-section .rtx-card {
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    text-align: left;
    margin: 0;
    padding: 30px;
    background: var(--rtx-card-bg);
    border: 1px solid var(--rtx-border);
    border-radius: 18px;
    box-shadow: var(--rtx-shadow);
    color: var(--rtx-text);
    text-decoration: none;
    overflow: hidden;
    transition:
        transform 0.24s cubic-bezier(0.22, 1, 0.36, 1),
        box-shadow 0.24s cubic-bezier(0.22, 1, 0.36, 1),
        border-color 0.24s ease;
}

.rtx-section .rtx-card::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--rtx-accent), var(--rtx-accent-2));
    opacity: 0;
    transition: opacity 0.24s ease;
    pointer-events: none;
}

.rtx-section .rtx-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--rtx-shadow-hover);
    border-color: var(--rtx-accent);
    text-decoration: none;
}

.rtx-section .rtx-card:hover::before {
    opacity: 1;
}

.rtx-section .rtx-card:focus-visible,
.rtx-section a:focus-visible {
    outline: 2px solid var(--rtx-accent);
    outline-offset: 3px;
    border-color: var(--rtx-accent);
}

/* Card Internals */
.rtx-section .rtx-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 54px;
    height: 54px;
    margin: 0 0 20px;
    padding: 0;
    border: 0;
    border-radius: 14px;
    background: var(--rtx-accent-soft);
    color: var(--rtx-accent);
    flex-shrink: 0;
}

.rtx-section .rtx-icon svg {
    width: 26px;
    height: 26px;
    display: block;
    stroke: currentColor;
}

.rtx-section .rtx-card-title {
    margin: 0 0 10px;
    padding: 0;
    border: 0;
    font-family: var(--rtx-font-display);
    font-size: 1.2rem;
    font-weight: 700;
    line-height: 1.35;
    letter-spacing: -0.015em;
    color: var(--rtx-title-color);
}

.rtx-section .rtx-card-desc {
    flex-grow: 1;
    margin: 0 0 22px;
    padding: 0;
    border: 0;
    font-size: 0.94rem;
    font-weight: 400;
    line-height: 1.62;
    color: var(--rtx-muted);
}

.rtx-section .rtx-cta {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    margin: auto 0 0;
    padding: 0;
    border: 0;
    font-size: 0.92rem;
    font-weight: 700;
    line-height: 1.4;
    color: var(--rtx-accent);
    text-decoration: none;
}

.rtx-section .rtx-cta span,
.rtx-section .rtx-cta svg {
    display: inline-block;
    transition: transform 0.22s cubic-bezier(0.22, 1, 0.36, 1);
}

.rtx-section .rtx-card:hover .rtx-cta span,
.rtx-section .rtx-card:hover .rtx-cta svg {
    transform: translateX(4px);
}

/* Six Card Accent Families (Light Mode) */
.rtx-section .rtx-a-blue {
    --rtx-accent: #2563eb;
    --rtx-accent-2: #3b82f6;
    --rtx-accent-soft: rgba(37, 99, 235, 0.10);
}

.rtx-section .rtx-a-green {
    --rtx-accent: #059669;
    --rtx-accent-2: #10b981;
    --rtx-accent-soft: rgba(5, 150, 105, 0.10);
}

.rtx-section .rtx-a-amber {
    --rtx-accent: #d97706;
    --rtx-accent-2: #f59e0b;
    --rtx-accent-soft: rgba(217, 119, 6, 0.11);
}

.rtx-section .rtx-a-violet {
    --rtx-accent: #7c3aed;
    --rtx-accent-2: #8b5cf6;
    --rtx-accent-soft: rgba(124, 58, 237, 0.10);
}

.rtx-section .rtx-a-cyan {
    --rtx-accent: #0891b2;
    --rtx-accent-2: #06b6d4;
    --rtx-accent-soft: rgba(8, 145, 178, 0.10);
}

.rtx-section .rtx-a-rose {
    --rtx-accent: #e11d48;
    --rtx-accent-2: #f43f5e;
    --rtx-accent-soft: rgba(225, 29, 72, 0.10);
}

/* Dark Mode Overrides */
body.dark-mode .rtx-section {
    --rtx-bg: #0b1220;
    --rtx-tint-blue: rgba(96, 165, 250, 0.08);
    --rtx-tint-green: rgba(52, 211, 153, 0.06);
    --rtx-card-bg: #151f32;
    --rtx-border: #243247;
    --rtx-title-color: #f1f5f9;
    --rtx-text: #cbd5e1;
    --rtx-muted: #94a3b8;
    --rtx-accent: #60a5fa;
    --rtx-accent-2: #93c5fd;
    --rtx-accent-soft: rgba(96, 165, 250, 0.14);
    --rtx-shadow: 0 2px 6px rgba(2, 6, 23, 0.35),
                  0 10px 24px -6px rgba(2, 6, 23, 0.45);
    --rtx-shadow-hover: 0 6px 14px rgba(2, 6, 23, 0.5),
                        0 18px 36px -8px rgba(2, 6, 23, 0.65);
}

body.dark-mode .rtx-section .rtx-a-blue {
    --rtx-accent: #60a5fa;
    --rtx-accent-2: #93c5fd;
    --rtx-accent-soft: rgba(96, 165, 250, 0.15);
}

body.dark-mode .rtx-section .rtx-a-green {
    --rtx-accent: #34d399;
    --rtx-accent-2: #6ee7b7;
    --rtx-accent-soft: rgba(52, 211, 153, 0.15);
}

body.dark-mode .rtx-section .rtx-a-amber {
    --rtx-accent: #fbbf24;
    --rtx-accent-2: #fcd34d;
    --rtx-accent-soft: rgba(251, 191, 36, 0.15);
}

body.dark-mode .rtx-section .rtx-a-violet {
    --rtx-accent: #a78bfa;
    --rtx-accent-2: #c4b5fd;
    --rtx-accent-soft: rgba(167, 139, 250, 0.15);
}

body.dark-mode .rtx-section .rtx-a-cyan {
    --rtx-accent: #22d3ee;
    --rtx-accent-2: #67e8f9;
    --rtx-accent-soft: rgba(34, 211, 238, 0.15);
}

body.dark-mode .rtx-section .rtx-a-rose {
    --rtx-accent: #fb7185;
    --rtx-accent-2: #fda4af;
    --rtx-accent-soft: rgba(251, 113, 133, 0.15);
}

/* Responsive Breakpoints */
@media (max-width: 980px) {
    .rtx-section {
        padding: 56px 20px 64px;
    }

    .rtx-section .rtx-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}

@media (max-width: 640px) {
    .rtx-section {
        padding: 44px 16px 52px;
    }

    .rtx-section .rtx-head {
        margin-bottom: 32px;
    }

    .rtx-section .rtx-grid {
        grid-template-columns: 1fr;
        gap: 18px;
    }

    .rtx-section .rtx-card {
        padding: 24px;
    }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    .rtx-section .rtx-card,
    .rtx-section .rtx-card::before,
    .rtx-section .rtx-cta span,
    .rtx-section .rtx-cta svg {
        transition: none;
    }

    .rtx-section .rtx-card:hover,
    .rtx-section .rtx-card:hover .rtx-cta span,
    .rtx-section .rtx-card:hover .rtx-cta svg {
        transform: none;
    }
}