/* ==========================================================================
   CHAT X.509 — Apple-style Telecom Landing Page
   Clean • Minimal • Floating • Cross-platform
   ========================================================================== */

:root {
    --color-bg:       #f5f5f7;
    --color-text:     #1d1d1f;
    --color-text-sec: #6e6e73;
    --color-accent:   #0071e3;     /* Apple blue — used sparingly */
    --color-link:     #0071e3;
    --color-link-hov: #0066cc;
    --radius:         18px;
    --transition:     0.33s cubic-bezier(0.25, 0.1, 0.25, 1);
    --font-system:    -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --font-title:     SF Pro Display, -apple-system, BlinkMacSystemFont, sans-serif;
}

header {
    opacity: 0;
    transform: translateY(0px);
    animation: heroFade 0.9s 0.2s forwards;
}

@keyframes heroFade {
    to { opacity:1; transform:translateY(0); }
}

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

html {
    scroll-behavior: smooth;
}

body {
    background: var(--color-bg);
    color: var(--color-text);
    font-family: var(--font-system);
    line-height: 1.5;
    font-size: 17px;                    /* Apple's comfortable body size */
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ── Navigation ──────────────────────────────────────────────────────────── */
nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 44px;                       /* iOS-like nav height */
    background: rgba(245, 245, 247, 0.92);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid rgba(0,0,0,0.08);
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 24px;
    transition: background 0.4s ease;
}

nav.scrolled {
    background: rgba(245, 245, 247, 0.98);
}

nav a {
    color: var(--color-text);
    text-decoration: none;
    font-size: 14px;
    font-weight: 500;
}

nav .dropdown {
    position: relative;
}

.dropbtn {
    background: none;
    border: none;
    font-size: 14px;
    cursor: pointer;
    color: var(--color-text);
    padding: 8px 12px;
}

.dropdown-content {
    display: none;
    position: absolute;
    right: 0;
    top: 36px;
    background: white;
    min-width: 120px;
    box-shadow: 0 8px 32px rgba(0,0,0,0.15);
    border-radius: 10px;
    overflow: hidden;
    z-index: 1;
}

.dropdown-content a {
    display: block;
    padding: 10px 16px;
    color: var(--color-text);
    text-decoration: none;
}

.dropdown-content a:hover {
    background: #f0f0f0;
}

.dropdown:hover .dropdown-content {
    display: block;
}

/* ── Header / Hero ───────────────────────────────────────────────────────── */
header {
    padding: 120px 24px 80px;
    text-align: center;
}

header a img {
    width: 64px;
    height: 64px;
    margin-bottom: 24px;
}

header h1 {
    font-family: var(--font-title);
    font-size: clamp(56px, 10vw, 96px);
    font-weight: 600;
    letter-spacing: -0.02em;
    line-height: 0.95;
    margin-bottom: 16px;
}

/* ── Main Content ────────────────────────────────────────────────────────── */
main {
    max-width: 1024px;
    margin: 0 auto;
    padding: 0 24px;
}

main section {
    margin: 140px 0;
}

main h3 {
    font-family: var(--font-title);
    font-size: clamp(40px, 7vw, 64px);
    font-weight: 600;
    letter-spacing: -0.015em;
    line-height: 1.05;
    margin-bottom: 32px;
}

main p, main div {
    font-size: 19px;
    max-width: 720px;
    margin: 0 auto 28px;
    color: var(--color-text-sec);
}

main .se {
    color: var(--color-text);
    font-weight: 600;
}

/* Gallery ── floating cards style */
figure {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 24px;
    margin: 64px 0;
}

figure img {
    width: 100%;
    height: auto;
    border-radius: var(--radius);
    box-shadow: 0 20px 60px rgba(0,0,0,0.12);
    transition: transform 0.5s cubic-bezier(0.165, 0.84, 0.44, 1),
                box-shadow 0.5s ease;
}

figure img:hover {
    transform: translateY(-12px);
    box-shadow: 0 40px 100px rgba(0,0,0,0.18);
}

/* ── Aside (sidebar-like info) ───────────────────────────────────────────── */
aside {
    max-width: 860px;
    margin: 80px auto;
    padding: 0 24px;
}

aside h3 {
    font-size: 32px;
    margin-bottom: 24px;
}

aside ul {
    list-style: none;
}

aside ul li a {
    display: block;
    padding: 2px 0;
    color: var(--color-link);
    text-decoration: none;
    font-size: 19px;
    transition: color var(--transition);
}

aside ul li a:hover {
    color: var(--color-link-hov);
}

/* ── Code snippet ────────────────────────────────────────────────────────── */
figure code {
    display: block;
    background: #1d1d1f;
    color: #f5f5f7;
    padding: 20px 24px;
    border-radius: var(--radius);
    font-family: SF Mono, Menlo, monospace;
    font-size: 15px;
    overflow-x: auto;
    margin: 32px 0;
}

/* ── Footer ──────────────────────────────────────────────────────────────── */
footer {
    text-align: center;
    padding: 80px 24px 120px;
    color: var(--color-text-sec);
    font-size: 15px;
}

.heart {
    color: #ff3b30;
}

/* ── Responsive adjustments ──────────────────────────────────────────────── */
@media (max-width: 768px) {
    header { padding-top: 100px; }
    main section { margin: 100px 0; }
    main h3 { font-size: 48px; }
    figure { gap: 16px; }
}

@media (max-width: 480px) {
    nav { padding: 0 16px; }
    header h1 { font-size: 56px; }
    main h3 { font-size: 40px; }
}