/* --- CSS Variables --- */
:root {
    --primary: #4361ee;
    --primary-dark: #3651d4;
    --primary-light: #eef0ff;
    --accent: #f59e0b;
    --accent-hover: #d97706;
    --dark: #0f172a;
    --text: #334155;
    --text-light: #64748b;
    --bg: #ffffff;
    --bg-alt: #f8fafc;
    --border: #e2e8f0;
    --success: #10b981;
    --radius: 16px;
    --shadow: 0 4px 24px rgba(0,0,0,0.06);
    --shadow-lg: 0 12px 48px rgba(0,0,0,0.1);
}

/* --- Reset & Base --- */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; overflow-x: hidden; }

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

img { max-width: 100%; display: block; }

/* --- Container --- */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* --- Header --- */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255,255,255,0.95);
    backdrop-filter: blur(12px);
    z-index: 1000;
    border-bottom: 1px solid var(--border);
    transition: box-shadow 0.3s;
}

.header.scrolled {
    box-shadow: 0 2px 20px rgba(0,0,0,0.08);
}

.header-inner {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0.8rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* --- Logo --- */
.logo {
    font-size: 1.6rem;
    font-weight: 800;
    color: var(--dark);
    text-decoration: none;
    letter-spacing: -0.5px;
}

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

/* --- Navigation --- */
.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
    list-style: none;
}

.nav-links a {
    color: var(--text);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: color 0.2s;
}

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

.nav-links a.nav-btn-sm {
    padding: 0.6rem 1.2rem;
    font-size: 0.9rem;
    color: #fff;
}

/* --- Buttons --- */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: 10px;
    font-weight: 700;
    font-size: 1rem;
    text-decoration: none;
    border: none;
    cursor: pointer;
    transition: all 0.2s;
    font-family: inherit;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: 0 6px 20px rgba(67,97,238,0.3);
}

.btn-accent {
    background: var(--accent);
    color: #fff;
}

.btn-accent:hover {
    background: var(--accent-hover);
    transform: translateY(-1px);
    box-shadow: 0 6px 20px rgba(245,158,11,0.3);
}

.btn-lg {
    padding: 1rem 2rem;
    font-size: 1.1rem;
    border-radius: 12px;
}

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

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

/* --- Mobile Menu Button --- */
.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--dark);
}

/* --- Back Link (Sub-pages) --- */
.back-link {
    color: var(--primary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 0.4rem;
    transition: opacity 0.2s;
}

.back-link:hover { opacity: 0.7; }

/* --- Section Helpers --- */
.section {
    padding: 5rem 1.5rem;
}

.section-alt { background: var(--bg-alt); }

.section-header {
    text-align: center;
    max-width: 700px;
    margin: 0 auto 3.5rem;
}

.section-tag {
    display: inline-block;
    background: var(--primary-light);
    color: var(--primary);
    padding: 0.3rem 1rem;
    border-radius: 50px;
    font-size: 0.82rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 1rem;
}

.section-header h2 {
    font-size: clamp(1.8rem, 3vw, 2.5rem);
    color: var(--dark);
    font-weight: 800;
    letter-spacing: -0.5px;
    margin-bottom: 1rem;
}

.section-header p {
    font-size: 1.05rem;
    color: var(--text-light);
}

/* --- Page Header (Sub-pages) --- */
.page-header {
    max-width: 1200px;
    margin: 0 auto;
    padding: 7rem 1.5rem 2rem;
    text-align: center;
}

.page-header h1 {
    font-size: 2.2rem;
    font-weight: 800;
    color: var(--dark);
    letter-spacing: -0.5px;
    margin-bottom: 0.5rem;
}

.page-header p {
    color: var(--text-light);
    font-size: 1rem;
    max-width: 600px;
    margin: 0 auto;
}

/* --- Footer --- */
.footer {
    background: var(--dark);
    color: rgba(255,255,255,0.5);
    padding: 3rem 1.5rem 2rem;
}

.footer-inner {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.footer-logo {
    font-size: 1.3rem;
    font-weight: 800;
    color: #fff;
    text-decoration: none;
}

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

.footer-links {
    display: flex;
    gap: 1.5rem;
    list-style: none;
}

.footer-links a {
    color: rgba(255,255,255,0.5);
    text-decoration: none;
    font-size: 0.85rem;
    transition: color 0.2s;
}

.footer-links a:hover { color: #fff; }

.footer-social {
    display: flex;
    gap: 1rem;
}

.footer-social a {
    color: rgba(255,255,255,0.5);
    text-decoration: none;
    font-size: 1.2rem;
    transition: color 0.2s;
}

.footer-social a:hover { color: #fff; }

.footer-social-link {
    width: 40px;
    height: 40px;
    border-radius: 10px;
    background: rgba(255,255,255,0.08);
    color: rgba(255,255,255,0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
    text-decoration: none;
}

.footer-social-link:hover {
    background: var(--primary);
    color: #fff;
}

.footer-copy {
    width: 100%;
    text-align: center;
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 1px solid rgba(255,255,255,0.08);
    font-size: 0.82rem;
}

/* --- Responsive --- */
@media (max-width: 768px) {
    .nav-links { display: none; }
    .nav-links.show {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: #fff;
        padding: 1.5rem;
        border-bottom: 1px solid var(--border);
        box-shadow: var(--shadow);
    }
    .mobile-menu-btn { display: block; }

    .page-header { padding: 6rem 1.5rem 1.5rem; }
    .page-header h1 { font-size: 1.6rem; }

    .footer-inner { flex-direction: column; text-align: center; }
    .footer-links { flex-direction: column; align-items: center; gap: 0.75rem; }
    .footer-social { justify-content: center; }
}