/* --------------------------------------------------
   Base
-------------------------------------------------- */

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
    background: #f5f7fa;
    margin: 0;
    padding: 0;
    color: #1a1a1a;
}

/* --------------------------------------------------
   Header (Final)
-------------------------------------------------- */

.site-header {
    background: #ffffff;
    border-bottom: 1px solid #e5e7eb;
    padding: 8px 20px;
}

.header-inner {
    max-width: 1100px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

/* Logo */
.logo img {
    height: 70px;   /* single source of truth */
    width: auto;
    display: block;
}

/* Navigation */
.main-nav {
    display: flex;
    align-items: center;
}

.main-nav a {
    margin-left: 25px;
    text-decoration: none;
    color: #1a1a1a;
    font-weight: 500;
    font-size: 15px;
    transition: opacity 0.2s ease;
}

.main-nav a:hover {
    opacity: 0.7;
}

/* --------------------------------------------------
   Layout
-------------------------------------------------- */

.container {
    max-width: 1100px;
    margin: 40px auto;
    background: #ffffff;
    padding: 40px;
    box-shadow: 0 8px 24px rgba(0,0,0,0.06);
    border-radius: 8px;
}

/* --------------------------------------------------
   Typography
-------------------------------------------------- */

h1 {
    font-size: 34px;
    line-height: 1.3;
    margin-bottom: 20px;
}

h2 {
    font-size: 26px;
    margin-top: 40px;
    margin-bottom: 15px;
    padding-bottom: 8px;
    border-bottom: 2px solid #eef2f7;
}

h3 {
    font-size: 20px;
    margin-top: 25px;
}

p {
    line-height: 1.7;
    margin-bottom: 16px;
}

/* Highlight key definition block */
.entity-definition {
    font-size: 18px;
    background: #f1f6ff;
    border-left: 4px solid #0073e6;
    padding: 15px 20px;
    margin-bottom: 25px;
}

/* --------------------------------------------------
   Links
-------------------------------------------------- */

a {
    color: #0073e6;
    text-decoration: none;
    font-weight: 500;
}

a:hover {
    text-decoration: underline;
}

/* --------------------------------------------------
   Lists
-------------------------------------------------- */

ul {
    padding-left: 20px;
    margin-bottom: 20px;
}

li {
    margin-bottom: 10px;
}

/* --------------------------------------------------
   Sections
-------------------------------------------------- */

hr {
    border: none;
    border-top: 1px solid #e5e7eb;
    margin: 40px 0;
}

/* --------------------------------------------------
   Footer (Clean + Real)
-------------------------------------------------- */

.site-footer {
    background: #0b1220;
    color: #e5e7eb;
    margin-top: 60px;
    padding: 60px 20px 30px;
}

.footer-container {
    max-width: 1100px;
    margin: 0 auto;
}

/* Layout */
.footer-columns {
    display: grid;
    grid-template-columns: 1.5fr 1fr 1fr 1fr;
    gap: 40px;
}

/* Brand column */
.footer-brand h3 {
    color: #ffffff;
    margin-bottom: 10px;
}

.footer-brand p {
    color: #9ca3af;
    font-size: 14px;
    line-height: 1.6;
}

/* Headings */
.footer-col h4 {
    color: #ffffff;
    margin-bottom: 12px;
    font-size: 15px;
}

/* Links */
.footer-col ul {
    list-style: none;
    padding: 0;
}

.footer-col li {
    margin-bottom: 8px;
}

.footer-col a {
    color: #cbd5f5;
    text-decoration: none;
    font-size: 14px;
}

.footer-col a:hover {
    color: #ffffff;
}

/* CTA */
.footer-cta {
    margin-top: 20px;
}

.footer-cta a {
    display: inline-block;
    background: #2563eb;
    color: #fff;
    padding: 10px 16px;
    border-radius: 6px;
    font-size: 14px;
    text-decoration: none;
}

.footer-cta a:hover {
    background: #1d4ed8;
}

/* Divider */
.footer-divider {
    border-top: 1px solid #1f2937;
    margin: 40px 0 20px;
}

/* Bottom */
.footer-bottom {
    text-align: center;
    font-size: 13px;
    color: #6b7280;
}

/* --------------------------------------------------
   Mobile
-------------------------------------------------- */

@media (max-width: 768px) {

    .container {
        padding: 25px;
        margin: 20px;
    }

    h1 {
        font-size: 28px;
    }

    h2 {
        font-size: 22px;
    }

    /* Header mobile adjustments */
    .site-header {
        padding: 10px 15px;
    }

    .header-inner {
        flex-direction: column;
        align-items: flex-start;
    }

    .main-nav {
        margin-top: 10px;
    }

    .main-nav a {
        margin-left: 0;
        margin-right: 15px;
    }

    .logo img {
        height: 45px;  /* consistent scaling */
    }
}