/* ===========================
   AS428 Networks — Design System
   =========================== */

/* --- Design Tokens: Light Theme --- */
:root {
    /* Primary palette */
    --primary: #0072e5;
    --primary-light: #4da3ff;
    --primary-dark: #004fa3;
    --accent: #00d4ff;

    /* Surface & background */
    --bg-body: #f0f2f5;
    --bg-surface: #ffffff;
    --bg-surface-alt: #f7f8fa;
    --bg-glass: rgba(255, 255, 255, 0.65);
    --bg-glass-border: rgba(255, 255, 255, 0.35);

    /* Text */
    --text-primary: #111827;
    --text-secondary: #4b5563;
    --text-muted: #9ca3af;
    --text-on-dark: #f0f4f8;

    /* Hero (same both themes) */
    --hero-from: #0a1628;
    --hero-to: #112240;
    --hero-dot: rgba(255, 255, 255, 0.06);
    --hero-glow: rgba(0, 212, 255, 0.15);

    /* Shadows & effects */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.12);
    --shadow-glow: 0 0 0 transparent;

    /* Borders & radii */
    --radius-sm: 8px;
    --radius-md: 14px;
    --radius-lg: 20px;
    --radius-pill: 100px;
    --border-subtle: 1px solid rgba(0, 0, 0, 0.06);

    /* Spacing */
    --section-pad: 100px;
    --container-max: 1140px;

    /* Transitions */
    --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
    --duration-fast: 0.2s;
    --duration-normal: 0.35s;

    /* Typography */
    --font-display: 'Space Grotesk', sans-serif;
    --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

    /* Footer */
    --footer-bg: #0a1628;
    --footer-text: rgba(240, 244, 248, 0.7);

    /* Selection */
    --selection-bg: rgba(0, 114, 229, 0.2);
    --selection-text: inherit;
}

/* --- Design Tokens: Dark Theme --- */
[data-theme="dark"] {
    --primary: #4da3ff;
    --primary-light: #80c0ff;
    --primary-dark: #0060d0;
    --accent: #00e5ff;

    --bg-body: #0b1120;
    --bg-surface: #131b2e;
    --bg-surface-alt: #0f1729;
    --bg-glass: rgba(19, 27, 46, 0.7);
    --bg-glass-border: rgba(77, 163, 255, 0.1);

    --text-primary: #e8edf5;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --text-on-dark: #f0f4f8;

    --hero-dot: rgba(255, 255, 255, 0.04);
    --hero-glow: rgba(0, 229, 255, 0.12);

    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.35);
    --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.45);
    --shadow-glow: 0 0 20px rgba(77, 163, 255, 0.08);

    --border-subtle: 1px solid rgba(255, 255, 255, 0.06);

    --footer-bg: #070d1a;
    --footer-text: rgba(240, 244, 248, 0.5);

    --selection-bg: rgba(77, 163, 255, 0.25);
}

/* --- Reset & Base --- */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-body);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transition: background-color var(--duration-normal) var(--ease-out),
                color var(--duration-normal) var(--ease-out);
}

::selection {
    background: var(--selection-bg);
    color: var(--selection-text);
}

.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 24px;
}

/* --- Header & Navigation --- */
header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: var(--bg-glass);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: var(--border-subtle);
    transition: background var(--duration-normal) var(--ease-out);
}

.navbar {
    padding: 0.85rem 0;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand a {
    font-family: var(--font-display);
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--primary);
    text-decoration: none;
    letter-spacing: -0.02em;
    transition: color var(--duration-fast) var(--ease-out);
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 16px;
}

/* Pill-style language switcher */
.language-switcher {
    display: flex;
    align-items: center;
    background: var(--bg-surface-alt);
    border-radius: var(--radius-pill);
    padding: 3px;
    border: var(--border-subtle);
    transition: background var(--duration-fast) var(--ease-out);
}

.language-switcher span {
    display: none; /* hide the pipe separator */
}

.language-switcher a {
    color: var(--text-muted);
    text-decoration: none;
    padding: 5px 14px;
    border-radius: var(--radius-pill);
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    transition: all var(--duration-fast) var(--ease-out);
}

.language-switcher a:hover {
    color: var(--text-primary);
}

.language-switcher a.active {
    color: var(--bg-surface);
    background: var(--primary);
}

/* Theme toggle */
.theme-toggle {
    background: var(--bg-surface-alt);
    border: var(--border-subtle);
    border-radius: var(--radius-pill);
    cursor: pointer;
    font-size: 1.05rem;
    padding: 6px 10px;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background var(--duration-fast) var(--ease-out),
                transform var(--duration-fast) var(--ease-out);
}

.theme-toggle:hover {
    background: var(--primary);
    color: #fff;
    transform: scale(1.08);
}

.theme-toggle:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

/* --- Hero Section --- */
.hero {
    position: relative;
    overflow: hidden;
    background: linear-gradient(160deg, var(--hero-from) 0%, var(--hero-to) 100%);
    color: var(--text-on-dark);
    padding: 130px 24px 120px;
    text-align: center;
}

/* Dot-grid texture overlay */
.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background-image: radial-gradient(var(--hero-dot) 1px, transparent 1px);
    background-size: 24px 24px;
    pointer-events: none;
}

/* Radial cyan glow orb */
.hero::after {
    content: '';
    position: absolute;
    width: 600px;
    height: 600px;
    border-radius: 50%;
    background: radial-gradient(circle, var(--hero-glow) 0%, transparent 70%);
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    pointer-events: none;
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 720px;
    margin: 0 auto;
}

.hero-content h1 {
    font-family: var(--font-display);
    font-size: clamp(2.2rem, 5vw, 3.5rem);
    font-weight: 700;
    letter-spacing: -0.03em;
    line-height: 1.15;
    margin-bottom: 1.2rem;
}

.hero-content .tagline {
    font-size: clamp(1.05rem, 2.5vw, 1.35rem);
    opacity: 0.85;
    line-height: 1.6;
    max-width: 560px;
    margin: 0 auto;
}

/* --- Services Section --- */
.services {
    padding: var(--section-pad) 24px;
    background-color: var(--bg-body);
}

.services h2,
.why-us h2,
.contact h2 {
    font-family: var(--font-display);
    font-size: clamp(1.8rem, 4vw, 2.5rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    color: var(--text-primary);
    text-align: center;
    margin-bottom: 3.5rem;
}

.services-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
    max-width: 1200px;
    margin: 0 auto;
}

.service-card {
    background: var(--bg-glass);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: var(--border-subtle);
    border-radius: var(--radius-md);
    padding: 36px 28px;
    text-align: left;
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: transform var(--duration-normal) var(--ease-out),
                box-shadow var(--duration-normal) var(--ease-out),
                background var(--duration-normal) var(--ease-out);
}

/* Gradient accent top border on hover */
.service-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    opacity: 0;
    transition: opacity var(--duration-normal) var(--ease-out);
}

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

.service-card:hover::before {
    opacity: 1;
}

.service-icon {
    width: 52px;
    height: 52px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.6rem;
    background: var(--bg-surface-alt);
    border: var(--border-subtle);
    border-radius: var(--radius-sm);
    margin-bottom: 1.2rem;
    transition: transform var(--duration-normal) var(--ease-out);
}

.service-card:hover .service-icon {
    transform: translateY(-2px);
}

.service-card h3 {
    font-family: var(--font-display);
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.6rem;
    letter-spacing: -0.01em;
}

.service-card p {
    color: var(--text-secondary);
    font-size: 0.925rem;
    line-height: 1.65;
}

/* --- Why Us Section --- */
.why-us {
    padding: var(--section-pad) 24px;
    background-color: var(--bg-surface-alt);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 32px;
    max-width: 960px;
    margin: 0 auto;
}

.feature {
    text-align: center;
    padding: 36px 28px;
    border-radius: var(--radius-md);
    border: var(--border-subtle);
    background: var(--bg-glass);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--duration-normal) var(--ease-out),
                transform var(--duration-normal) var(--ease-out);
}

.feature:hover {
    box-shadow: var(--shadow-md), var(--shadow-glow);
    transform: translateY(-2px);
}

.feature h3 {
    font-family: var(--font-display);
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--primary);
    letter-spacing: -0.01em;
}

.feature p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.65;
}

/* --- Contact Section --- */
.contact {
    position: relative;
    overflow: hidden;
    padding: var(--section-pad) 24px;
    background: linear-gradient(160deg, var(--hero-from) 0%, var(--hero-to) 100%);
    color: var(--text-on-dark);
    text-align: center;
}

/* Dot-grid texture (matches hero) */
.contact::before {
    content: '';
    position: absolute;
    inset: 0;
    background-image: radial-gradient(var(--hero-dot) 1px, transparent 1px);
    background-size: 24px 24px;
    pointer-events: none;
}

.contact .container {
    position: relative;
    z-index: 1;
}

.contact h2 {
    color: var(--text-on-dark);
    margin-bottom: 1rem;
}

.contact > .container > p {
    font-size: clamp(1rem, 2vw, 1.15rem);
    opacity: 0.8;
    margin-bottom: 2.5rem;
    max-width: 520px;
    margin-left: auto;
    margin-right: auto;
}

.contact-info {
    display: flex;
    justify-content: center;
    gap: 32px;
    flex-wrap: wrap;
    margin-top: 1rem;
}

.contact-item {
    background: rgba(255, 255, 255, 0.06);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    padding: 28px 32px;
    font-size: 0.95rem;
    text-align: left;
    line-height: 1.7;
    transition: background var(--duration-fast) var(--ease-out);
}

.contact-item:hover {
    background: rgba(255, 255, 255, 0.1);
}

.contact-item strong {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--accent);
    font-weight: 600;
    font-size: 0.85rem;
    letter-spacing: 0.04em;
    text-transform: uppercase;
}

/* --- Footer --- */
footer {
    background-color: var(--footer-bg);
    color: var(--footer-text);
    padding: 28px 24px;
    text-align: center;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

footer p {
    font-size: 0.85rem;
}

/* --- Scroll Animations --- */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(28px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.js .animate-on-scroll {
    opacity: 0;
    transform: translateY(28px);
}

.animate-on-scroll.is-visible {
    animation: fadeInUp 0.7s var(--ease-out) forwards;
}

/* Stagger delays */
.stagger-1.is-visible { animation-delay: 0s; }
.stagger-2.is-visible { animation-delay: 0.08s; }
.stagger-3.is-visible { animation-delay: 0.16s; }
.stagger-4.is-visible { animation-delay: 0.24s; }
.stagger-5.is-visible { animation-delay: 0.32s; }
.stagger-6.is-visible { animation-delay: 0.40s; }
.stagger-7.is-visible { animation-delay: 0.48s; }

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }

    .js .animate-on-scroll {
        opacity: 1;
        transform: none;
    }

    html {
        scroll-behavior: auto;
    }
}

/* --- Focus Visible --- */
a:focus-visible,
button:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

/* --- Button Active State --- */
.theme-toggle:active {
    transform: scale(0.95);
}

/* --- Responsive: Tablet (1024px) --- */
@media (max-width: 1024px) {
    :root {
        --section-pad: 80px;
    }

    .services-grid {
        grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    }
}

/* --- Responsive: Small Tablet / Large Phone (768px) --- */
@media (max-width: 768px) {
    :root {
        --section-pad: 64px;
    }

    .hero {
        padding: 90px 20px 80px;
    }

    .services-grid,
    .features-grid {
        grid-template-columns: 1fr;
        gap: 18px;
    }

    .contact-info {
        flex-direction: column;
        gap: 18px;
    }

    .contact-item {
        padding: 22px 24px;
    }
}

/* --- Responsive: Phone (480px) --- */
@media (max-width: 480px) {
    :root {
        --section-pad: 48px;
    }

    .navbar {
        padding: 0.65rem 0;
    }

    .nav-brand a {
        font-size: 1.15rem;
    }

    .language-switcher a {
        padding: 4px 10px;
        font-size: 0.75rem;
    }

    .hero {
        padding: 64px 16px 56px;
    }

    .service-card {
        padding: 28px 22px;
    }

    .feature {
        padding: 28px 22px;
    }
}