/* ===== Variables & Reset ===== */
:root {
    --primary: #4F7470;
    --primary-dark: #3d5a57;
    --primary-light: #6a9490;
    --accent: #FF8552;
    --accent-dark: #e6703f;
    --bg: #FAFAFA;
    --bg-dark: #4F7470;
    --text: #1a2a28;
    --text-light: #5a6e6c;
    --text-on-dark: #f0f5f4;
    --text-muted-dark: #b8ccc9;
    --white: #ffffff;
    --border: #e0e8e7;
    --radius: 8px;
    --radius-lg: 16px;
    --shadow: 0 1px 3px rgba(0,0,0,0.08);
    --shadow-lg: 0 8px 30px rgba(0,0,0,0.1);
}

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
    font-family: 'Space Grotesk', 'Inter', sans-serif;
    line-height: 1.2;
}

a {
    color: inherit;
    text-decoration: none;
}

img {
    max-width: 100%;
}

/* ===== Layout ===== */
.container {
    max-width: 1120px;
    margin: 0 auto;
    padding: 0 24px;
}

.section {
    padding: 100px 0;
}

.section-dark {
    background: var(--bg-dark);
    color: var(--text-on-dark);
}

.section-header {
    text-align: center;
    max-width: 680px;
    margin: 0 auto 60px;
}

.section-tag {
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--accent);
    margin-bottom: 12px;
}

.section-header h2 {
    font-size: 2.25rem;
    font-weight: 700;
}

.section-body {
    text-align: center;
    max-width: 720px;
    margin: -20px auto 50px;
    font-size: 1.1rem;
    line-height: 1.7;
    opacity: 0.9;
}

/* ===== Nav ===== */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: rgba(250, 250, 250, 0.92);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    transition: box-shadow 0.3s;
}

.nav.scrolled {
    box-shadow: var(--shadow);
}

.nav-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    font-family: 'Space Grotesk', sans-serif;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text);
}

.logo-foj {
    color: var(--primary);
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 32px;
}

.nav-links a {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-light);
    transition: color 0.2s;
}

.nav-links a:hover {
    color: var(--primary);
}

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.mobile-menu-btn span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--text);
    border-radius: 2px;
    transition: 0.3s;
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-family: 'Inter', sans-serif;
    font-weight: 600;
    font-size: 0.9rem;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
}

.btn-primary {
    background: var(--accent);
    color: var(--white);
    padding: 12px 28px;
}

.btn-primary:hover {
    background: var(--accent-dark);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(255, 133, 82, 0.3);
}

.btn-outline {
    background: transparent;
    color: var(--primary);
    border: 2px solid var(--primary);
    padding: 10px 26px;
}

.btn-outline:hover {
    background: var(--primary);
    color: var(--white);
}

.btn-nav {
    background: var(--accent);
    color: var(--white);
    padding: 8px 20px;
    border-radius: var(--radius);
}

.btn-nav:hover {
    background: var(--accent-dark);
}

.btn-lg {
    padding: 14px 32px;
    font-size: 1rem;
    border-radius: var(--radius);
}

.btn-full {
    width: 100%;
}

/* ===== Hero ===== */
.hero {
    position: relative;
    padding: 160px 0 120px;
    overflow: hidden;
}

.hero-content {
    max-width: 720px;
    position: relative;
    z-index: 2;
}

.hero-tag {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 16px;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 24px;
    line-height: 1.1;
}

.text-accent {
    color: var(--accent);
}

.hero-sub {
    font-size: 1.2rem;
    color: var(--text-light);
    line-height: 1.7;
    max-width: 600px;
    margin-bottom: 36px;
}

.hero-actions {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

.hero-bg-pattern {
    position: absolute;
    top: -50%;
    right: -20%;
    width: 800px;
    height: 800px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(79, 116, 112, 0.06) 0%, transparent 70%);
    z-index: 1;
}

/* ===== Mission Cards ===== */
.mission-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.mission-card {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 36px 28px;
    transition: box-shadow 0.3s, transform 0.3s;
}

.mission-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.mission-icon {
    width: 56px;
    height: 56px;
    border-radius: 12px;
    background: rgba(79, 116, 112, 0.08);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary);
    margin-bottom: 20px;
}

.mission-card h3 {
    font-size: 1.2rem;
    margin-bottom: 12px;
}

.mission-card p {
    color: var(--text-light);
    font-size: 0.95rem;
    line-height: 1.6;
}

/* ===== Solution Visual ===== */
.solution-visual {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0;
    max-width: 700px;
    margin: 0 auto;
}

.solution-layer {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-lg);
    padding: 24px 36px;
    text-align: center;
    width: 100%;
}

.layer-label {
    display: block;
    font-family: 'Space Grotesk', sans-serif;
    font-weight: 700;
    font-size: 1.1rem;
    margin-bottom: 4px;
}

.layer-desc {
    font-size: 0.9rem;
    opacity: 0.7;
}

.solution-connector {
    width: 2px;
    height: 32px;
    background: rgba(255, 255, 255, 0.3);
}

.solution-interactions {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
    padding: 8px 0;
}

.interaction-pill {
    background: var(--accent);
    color: var(--white);
    padding: 8px 18px;
    border-radius: 100px;
    font-size: 0.85rem;
    font-weight: 500;
}

/* ===== Principles ===== */
.principles-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 32px;
}

.principle-card {
    text-align: center;
    padding: 48px 32px;
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    background: var(--white);
    transition: box-shadow 0.3s, transform 0.3s;
}

.principle-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.principle-letter {
    font-family: 'Space Grotesk', sans-serif;
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--accent);
    line-height: 1;
    margin-bottom: 8px;
}

.principle-card h3 {
    font-size: 1.4rem;
    color: var(--primary);
    margin-bottom: 16px;
}

.principle-card p {
    color: var(--text-light);
    font-size: 0.95rem;
    line-height: 1.7;
}

/* ===== Domains ===== */
.domains-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.domain-card {
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: var(--radius-lg);
    padding: 36px 28px;
    transition: background 0.3s;
}

.domain-card:hover {
    background: rgba(255, 255, 255, 0.14);
}

.domain-card h4 {
    font-size: 1.2rem;
    margin-bottom: 12px;
    color: var(--accent);
}

.domain-card p {
    font-size: 0.95rem;
    line-height: 1.6;
    opacity: 0.85;
}

/* ===== Comparison Table ===== */
.comparison-table {
    max-width: 800px;
    margin: 0 auto;
    border-radius: var(--radius-lg);
    overflow: hidden;
    border: 1px solid var(--border);
    background: var(--white);
}

.comparison-row {
    display: grid;
    grid-template-columns: 180px 1fr 1fr;
    border-bottom: 1px solid var(--border);
}

.comparison-row:last-child {
    border-bottom: none;
}

.comparison-header {
    background: var(--primary);
    color: var(--white);
    font-weight: 600;
    font-size: 0.95rem;
}

.comparison-header div {
    padding: 16px 20px;
}

.comparison-row > div {
    padding: 14px 20px;
    font-size: 0.9rem;
}

.comparison-label {
    font-weight: 600;
    background: rgba(79, 116, 112, 0.04);
    color: var(--primary);
}

.comparison-row:not(.comparison-header) > div:last-child {
    color: var(--accent);
    font-weight: 500;
}

/* ===== CTA / Join ===== */
.section-cta {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: var(--white);
}

.cta-content {
    max-width: 480px;
    margin: 0 auto;
    text-align: center;
}

.cta-content h2 {
    font-size: 2.5rem;
    margin-bottom: 16px;
}

.cta-content > p {
    font-size: 1.1rem;
    opacity: 0.85;
    margin-bottom: 36px;
}

.join-form {
    text-align: left;
}

.form-group {
    margin-bottom: 16px;
}

.form-group label {
    display: block;
    font-size: 0.85rem;
    font-weight: 500;
    margin-bottom: 6px;
    opacity: 0.9;
}

.form-group input {
    width: 100%;
    padding: 14px 16px;
    border: 2px solid rgba(255, 255, 255, 0.25);
    border-radius: var(--radius);
    background: rgba(255, 255, 255, 0.1);
    color: var(--white);
    font-size: 1rem;
    font-family: 'Inter', sans-serif;
    transition: border-color 0.2s;
}

.form-group input::placeholder {
    color: rgba(255, 255, 255, 0.5);
}

.form-group input:focus {
    outline: none;
    border-color: var(--accent);
    background: rgba(255, 255, 255, 0.15);
}

.form-success {
    display: none;
    text-align: center;
    padding: 24px 0;
}

.form-success.show {
    display: block;
}

.form-success .success-icon {
    color: var(--accent);
    margin-bottom: 16px;
}

.form-success h3 {
    font-size: 1.5rem;
    margin-bottom: 8px;
}

.form-success p {
    opacity: 0.8;
}

/* ===== Footer ===== */
.footer {
    background: var(--text);
    color: var(--text-muted-dark);
    padding: 60px 0 0;
}

.footer-inner {
    display: flex;
    justify-content: space-between;
    gap: 40px;
    padding-bottom: 40px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-brand {
    max-width: 300px;
}

.footer-brand .logo {
    color: var(--white);
    margin-bottom: 12px;
    display: inline-block;
}

.footer-brand p {
    font-size: 0.9rem;
    line-height: 1.6;
}

.footer-links {
    display: flex;
    gap: 80px;
}

.footer-col h4 {
    color: var(--white);
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 16px;
}

.footer-col a {
    display: block;
    font-size: 0.9rem;
    margin-bottom: 10px;
    transition: color 0.2s;
}

.footer-col a:hover {
    color: var(--accent);
}

.footer-bottom {
    padding: 24px 0;
    text-align: center;
    font-size: 0.8rem;
}

/* ===== Mobile ===== */
@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: var(--bg);
        flex-direction: column;
        padding: 24px;
        gap: 20px;
        border-bottom: 1px solid var(--border);
        box-shadow: var(--shadow-lg);
    }

    .nav-links.open {
        display: flex;
    }

    .mobile-menu-btn {
        display: flex;
    }

    .mobile-menu-btn.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .mobile-menu-btn.active span:nth-child(2) {
        opacity: 0;
    }

    .mobile-menu-btn.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }

    .hero {
        padding: 120px 0 80px;
    }

    .hero h1 {
        font-size: 2.2rem;
    }

    .hero-sub {
        font-size: 1.05rem;
    }

    .section {
        padding: 64px 0;
    }

    .section-header {
        margin-bottom: 40px;
    }

    .section-header h2 {
        font-size: 1.75rem;
    }

    .mission-grid,
    .domains-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .principles-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 20px;
    }

    .comparison-row {
        grid-template-columns: 120px 1fr 1fr;
    }

    .comparison-row > div {
        padding: 10px 12px;
        font-size: 0.8rem;
    }

    .footer-inner {
        flex-direction: column;
    }

    .footer-links {
        gap: 40px;
    }

    .cta-content h2 {
        font-size: 2rem;
    }

    .solution-interactions {
        gap: 8px;
    }

    .interaction-pill {
        font-size: 0.75rem;
        padding: 6px 12px;
    }
}

@media (max-width: 480px) {
    .principles-grid {
        grid-template-columns: 1fr;
    }

    .hero h1 {
        font-size: 1.8rem;
    }

    .hero-actions {
        flex-direction: column;
    }

    .comparison-row {
        grid-template-columns: 1fr;
    }

    .comparison-header {
        display: none;
    }

    .comparison-label {
        border-bottom: none;
        padding-bottom: 0 !important;
        font-size: 0.75rem !important;
        text-transform: uppercase;
        letter-spacing: 0.05em;
    }

    .comparison-row {
        padding: 12px 0;
    }

    .comparison-row > div:nth-child(2),
    .comparison-row > div:nth-child(3) {
        padding-top: 4px;
    }

    .comparison-row > div:nth-child(2)::before {
        content: "Linux Foundation: ";
        font-weight: 600;
        color: var(--text-light);
    }

    .comparison-row > div:nth-child(3)::before {
        content: "FOJ Society: ";
        font-weight: 600;
    }
}