/* ============================================
   4 Core Build — Style System
   ============================================ */

/* --- Custom Properties --- */
:root {
    --bg-primary: #0a0a0f;
    --bg-secondary: #10101a;
    --bg-card: #141422;
    --bg-card-hover: #1a1a2e;
    --bg-elevated: #1c1c30;

    --text-primary: #e8e8f0;
    --text-secondary: #a0a0b8;
    --text-muted: #6a6a82;

    --accent: #00b4d8;
    --accent-hover: #00d4f8;
    --accent-dark: #0077b6;
    --accent-glow: rgba(0, 180, 216, 0.15);
    --accent-glow-strong: rgba(0, 180, 216, 0.3);

    --gradient-accent: linear-gradient(135deg, #00b4d8, #0077b6);
    --gradient-hero: linear-gradient(180deg, #0a0a0f 0%, #0d1117 50%, #0a0a0f 100%);
    --gradient-card-border: linear-gradient(135deg, rgba(0, 180, 216, 0.3), rgba(0, 119, 182, 0.1), transparent);

    --border: rgba(255, 255, 255, 0.06);
    --border-accent: rgba(0, 180, 216, 0.2);

    --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', 'SF Mono', Consolas, monospace;

    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 28px;

    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 24px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 48px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 40px rgba(0, 180, 216, 0.1);

    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color var(--transition);
}

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

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

/* --- Utility --- */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

.text--accent {
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* --- Scroll Animations --- */
.fade-up {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.7s cubic-bezier(0.4, 0, 0.2, 1),
                transform 0.7s cubic-bezier(0.4, 0, 0.2, 1);
}

.fade-up.visible {
    opacity: 1;
    transform: translateY(0);
}

/* --- Buttons --- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-family: var(--font);
    font-weight: 600;
    font-size: 0.95rem;
    padding: 12px 28px;
    border-radius: var(--radius-md);
    border: none;
    cursor: pointer;
    transition: all var(--transition);
    position: relative;
    overflow: hidden;
    white-space: nowrap;
}

.btn__icon {
    width: 18px;
    height: 18px;
    flex-shrink: 0;
}

.btn--primary {
    background: var(--gradient-accent);
    color: #fff;
    box-shadow: 0 4px 20px rgba(0, 180, 216, 0.25);
}

.btn--primary:hover {
    box-shadow: 0 6px 30px rgba(0, 180, 216, 0.4);
    transform: translateY(-2px);
    color: #fff;
}

.btn--accent {
    background: linear-gradient(135deg, #0096c7, #00b4d8);
    color: #fff;
    box-shadow: 0 4px 20px rgba(0, 150, 199, 0.25);
}

.btn--accent:hover {
    box-shadow: 0 6px 30px rgba(0, 150, 199, 0.4);
    transform: translateY(-2px);
    color: #fff;
}

.btn--outline {
    background: transparent;
    color: var(--accent);
    border: 1.5px solid var(--border-accent);
}

.btn--outline:hover {
    background: var(--accent-glow);
    border-color: var(--accent);
    transform: translateY(-2px);
    color: var(--accent-hover);
}

.btn--small {
    font-size: 0.85rem;
    padding: 8px 20px;
    border-radius: var(--radius-sm);
}

.btn--large {
    font-size: 1.05rem;
    padding: 16px 36px;
    border-radius: var(--radius-lg);
    width: 100%;
}

/* --- Navigation --- */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 20px 0;
    transition: all var(--transition);
}

.nav.scrolled {
    background: rgba(10, 10, 15, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    padding: 12px 0;
}

.nav__container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav__logo {
    font-size: 1.2rem;
    font-weight: 800;
    color: var(--text-primary);
    letter-spacing: -0.5px;
    display: flex;
    align-items: center;
    gap: 6px;
}

.nav__logo-icon {
    color: var(--accent);
    font-size: 1.4rem;
}

.nav__logo:hover {
    color: var(--text-primary);
}

.nav__menu {
    display: flex;
    align-items: center;
    gap: 8px;
    list-style: none;
}

.nav__link {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    transition: all var(--transition);
}

.nav__link:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.05);
}

.nav__link--cta {
    background: var(--gradient-accent);
    color: #fff;
    font-weight: 600;
    margin-left: 8px;
}

.nav__link--cta:hover {
    color: #fff;
    box-shadow: 0 4px 16px rgba(0, 180, 216, 0.3);
}

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

.nav__toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: all var(--transition);
}

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

.nav__toggle.active span:nth-child(2) {
    opacity: 0;
}

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

/* --- Hero --- */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    background: var(--gradient-hero);
    padding: 120px 24px 80px;
}

.hero__bg {
    position: absolute;
    inset: 0;
    overflow: hidden;
}

.hero__grid {
    position: absolute;
    inset: 0;
    background-image:
        linear-gradient(rgba(0, 180, 216, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(0, 180, 216, 0.03) 1px, transparent 1px);
    background-size: 60px 60px;
    mask-image: radial-gradient(ellipse 70% 60% at 50% 50%, black 30%, transparent 70%);
    -webkit-mask-image: radial-gradient(ellipse 70% 60% at 50% 50%, black 30%, transparent 70%);
}

.hero__glow {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.4;
}

.hero__glow--1 {
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(0, 180, 216, 0.2), transparent 70%);
    top: -10%;
    right: -10%;
    animation: float 8s ease-in-out infinite;
}

.hero__glow--2 {
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(0, 119, 182, 0.15), transparent 70%);
    bottom: 10%;
    left: -5%;
    animation: float 10s ease-in-out infinite reverse;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0); }
    50% { transform: translate(30px, -20px); }
}

.hero__content {
    text-align: center;
    max-width: 800px;
    position: relative;
    z-index: 2;
}

.hero__badge {
    display: inline-block;
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 2px;
    text-transform: uppercase;
    color: var(--accent);
    background: var(--accent-glow);
    border: 1px solid var(--border-accent);
    padding: 8px 20px;
    border-radius: 100px;
    margin-bottom: 32px;
}

.hero__title {
    font-size: clamp(2.8rem, 7vw, 5.5rem);
    font-weight: 900;
    line-height: 1.05;
    letter-spacing: -2px;
    margin-bottom: 24px;
}

.hero__title--accent {
    display: block;
}

.hero__tagline {
    font-size: clamp(1rem, 2vw, 1.2rem);
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 40px;
    line-height: 1.8;
}

.hero__actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

.hero__scroll-indicator {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    color: var(--text-muted);
    font-size: 0.75rem;
    letter-spacing: 2px;
    text-transform: uppercase;
}

.hero__scroll-line {
    width: 1px;
    height: 40px;
    background: linear-gradient(to bottom, var(--accent), transparent);
    animation: scroll-pulse 2s ease-in-out infinite;
}

@keyframes scroll-pulse {
    0%, 100% { opacity: 0.3; transform: scaleY(0.6); }
    50% { opacity: 1; transform: scaleY(1); }
}

/* --- Sections --- */
.section {
    padding: 120px 0;
    position: relative;
}

.section__header {
    text-align: center;
    margin-bottom: 64px;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.section__label {
    display: inline-block;
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 3px;
    text-transform: uppercase;
    color: var(--accent);
    margin-bottom: 16px;
    position: relative;
}

.section__label::before,
.section__label::after {
    content: '';
    position: absolute;
    top: 50%;
    width: 30px;
    height: 1px;
    background: var(--accent);
    opacity: 0.4;
}

.section__label::before {
    right: calc(100% + 12px);
}

.section__label::after {
    left: calc(100% + 12px);
}

.section__title {
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 800;
    line-height: 1.15;
    letter-spacing: -1px;
    margin-bottom: 20px;
}

.section__subtitle {
    font-size: 1.05rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

/* --- PC Services Section --- */
.section--pc {
    background: var(--bg-primary);
}

.pc-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
    margin-bottom: 48px;
}

.pc-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 36px;
    transition: all var(--transition);
    position: relative;
    overflow: hidden;
}

.pc-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--gradient-accent);
    opacity: 0;
    transition: opacity var(--transition);
}

.pc-card:hover {
    border-color: var(--border-accent);
    transform: translateY(-4px);
    box-shadow: var(--shadow-glow);
    background: var(--bg-card-hover);
}

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

.pc-card--wide {
    grid-column: 1 / -1;
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 24px;
    align-items: start;
}

.pc-card__icon {
    width: 48px;
    height: 48px;
    color: var(--accent);
    margin-bottom: 20px;
}

.pc-card--wide .pc-card__icon {
    margin-bottom: 0;
}

.pc-card h3 {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 12px;
}

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

.pc-card--wide p {
    grid-column: 2;
}

.pc-pledge {
    background: var(--accent-glow);
    border: 1px solid var(--border-accent);
    border-radius: var(--radius-lg);
    padding: 32px;
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.pc-pledge__icon {
    font-size: 2rem;
    margin-bottom: 12px;
}

.pc-pledge p {
    color: var(--text-secondary);
    font-size: 1.05rem;
    line-height: 1.8;
}

.pc-pledge strong {
    color: var(--accent);
}

/* --- AI Services Section --- */
.section--ai {
    background: var(--bg-secondary);
}

.section__bg-glow {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 800px;
    height: 800px;
    background: radial-gradient(circle, rgba(0, 180, 216, 0.04), transparent 60%);
    pointer-events: none;
}

.ai-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
    gap: 24px;
}

.ai-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 32px;
    transition: all var(--transition);
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.ai-card::after {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: var(--radius-lg);
    padding: 1px;
    background: var(--gradient-card-border);
    -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
    mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
    -webkit-mask-composite: xor;
    mask-composite: exclude;
    opacity: 0;
    transition: opacity var(--transition);
}

.ai-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-glow);
    background: var(--bg-card-hover);
}

.ai-card:hover::after {
    opacity: 1;
}

.ai-card__top {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 20px;
}

.ai-card__price {
    font-size: 1.6rem;
    font-weight: 800;
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.ai-card__price span {
    font-size: 0.85rem;
    font-weight: 500;
}

.ai-card__icon {
    width: 36px;
    height: 36px;
    color: var(--text-muted);
    opacity: 0.5;
}

.ai-card h3 {
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 12px;
}

.ai-card p {
    color: var(--text-secondary);
    font-size: 0.93rem;
    line-height: 1.7;
    margin-bottom: 24px;
    flex: 1;
}

.ai-card .btn {
    align-self: flex-start;
}

/* --- How It Works --- */
.section--steps {
    background: var(--bg-primary);
}

.steps {
    max-width: 700px;
    margin: 0 auto;
    position: relative;
}

.steps::before {
    content: '';
    position: absolute;
    left: 35px;
    top: 40px;
    bottom: 40px;
    width: 2px;
    background: linear-gradient(to bottom, var(--accent), var(--border));
}

.step {
    display: flex;
    gap: 32px;
    padding: 40px 0;
    position: relative;
}

.step__number {
    flex-shrink: 0;
    width: 70px;
    height: 70px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-card);
    border: 2px solid var(--accent);
    border-radius: 50%;
    font-size: 1.3rem;
    font-weight: 800;
    color: var(--accent);
    position: relative;
    z-index: 2;
}

.step__content h3 {
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: 8px;
}

.step__content p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.7;
}

/* --- Why Us Section --- */
.section--why {
    background: var(--bg-secondary);
}

.values-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
}

.value {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 36px;
    transition: all var(--transition);
}

.value:hover {
    border-color: var(--border-accent);
    transform: translateY(-4px);
    box-shadow: var(--shadow-glow);
}

.value__icon {
    width: 44px;
    height: 44px;
    color: var(--accent);
    margin-bottom: 20px;
}

.value h3 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 10px;
}

.value p {
    color: var(--text-secondary);
    font-size: 0.93rem;
    line-height: 1.7;
}

/* --- Book Section --- */
.section--book {
    background: var(--bg-primary);
    padding: 100px 0;
}

.book {
    background: var(--bg-card);
    border: 1px solid var(--border-accent);
    border-radius: var(--radius-xl);
    padding: 64px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.book::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 50% 0%, rgba(0, 180, 216, 0.06), transparent 40%);
    pointer-events: none;
}

.book__content {
    position: relative;
    margin-bottom: 48px;
}

.book__title {
    font-size: clamp(1.8rem, 4vw, 2.8rem);
    font-weight: 800;
    letter-spacing: -1px;
    margin-bottom: 16px;
}

.book__text {
    font-size: 1.05rem;
    color: var(--text-secondary);
    max-width: 550px;
    margin: 0 auto;
    line-height: 1.8;
}

.book__buttons {
    position: relative;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 16px;
    max-width: 800px;
    margin: 0 auto;
}

/* --- Footer --- */
.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border);
    padding: 64px 0 32px;
}

.footer__grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 48px;
    margin-bottom: 48px;
}

.footer__logo {
    font-size: 1.3rem;
    font-weight: 800;
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 6px;
}

.footer__brand p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    max-width: 300px;
}

.footer__contact h4,
.footer__social h4 {
    font-size: 0.85rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 2px;
    color: var(--text-muted);
    margin-bottom: 16px;
}

.footer__contact p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 8px;
}

.footer__contact a {
    color: var(--text-secondary);
}

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

.footer__social-links {
    display: flex;
    gap: 12px;
}

.footer__social-links a {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-sm);
    background: var(--bg-card);
    border: 1px solid var(--border);
    color: var(--text-secondary);
    transition: all var(--transition);
}

.footer__social-links a svg {
    width: 18px;
    height: 18px;
}

.footer__social-links a:hover {
    color: var(--accent);
    border-color: var(--border-accent);
    background: var(--accent-glow);
    transform: translateY(-2px);
}

.footer__bottom {
    border-top: 1px solid var(--border);
    padding-top: 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
}

.footer__bottom p {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.footer__legal {
    display: flex;
    gap: 24px;
}

.footer__legal a {
    color: var(--text-muted);
    font-size: 0.85rem;
}

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

/* ============================================
   Responsive Design
   ============================================ */

@media (max-width: 1024px) {
    .ai-grid {
        grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    }
}

@media (max-width: 768px) {
    .nav__toggle {
        display: flex;
    }

    .nav__menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 280px;
        height: 100vh;
        background: var(--bg-secondary);
        border-left: 1px solid var(--border);
        flex-direction: column;
        padding: 80px 24px 24px;
        gap: 4px;
        transition: right var(--transition);
        box-shadow: var(--shadow-lg);
    }

    .nav__menu.active {
        right: 0;
    }

    .nav__link {
        width: 100%;
        padding: 12px 16px;
        font-size: 1rem;
    }

    .nav__link--cta {
        margin-left: 0;
        margin-top: 8px;
        text-align: center;
    }

    .section {
        padding: 80px 0;
    }

    .section__header {
        margin-bottom: 48px;
    }

    .pc-grid,
    .ai-grid,
    .values-grid {
        grid-template-columns: 1fr;
    }

    .pc-card--wide {
        grid-template-columns: 1fr;
    }

    .pc-card--wide p {
        grid-column: 1;
    }

    .book {
        padding: 40px 24px;
    }

    .book__buttons {
        grid-template-columns: 1fr;
    }

    .footer__grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .footer__bottom {
        flex-direction: column;
        text-align: center;
    }

    .steps::before {
        left: 25px;
    }

    .step__number {
        width: 50px;
        height: 50px;
        font-size: 1rem;
    }

    .step {
        gap: 20px;
    }

    .hero {
        padding: 100px 24px 60px;
    }

    .hero__scroll-indicator {
        display: none;
    }

    .section__label::before,
    .section__label::after {
        display: none;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 16px;
    }

    .hero__title {
        letter-spacing: -1px;
    }

    .hero__actions {
        flex-direction: column;
        align-items: center;
    }

    .hero__actions .btn {
        width: 100%;
    }

    .pc-card,
    .ai-card,
    .value {
        padding: 24px;
    }

    .book__title {
        font-size: 1.6rem;
    }

    .footer__legal {
        flex-direction: column;
        gap: 12px;
        align-items: center;
    }
}

/* --- Selection --- */
::selection {
    background: rgba(0, 180, 216, 0.3);
    color: #fff;
}

/* --- Scrollbar --- */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
    background: var(--bg-elevated);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-dark);
}