/* ==========================================================================
   Ashutosh Kumar Portfolio — Anthropic Learn Design System Replica
   ========================================================================== */

/* --- CSS Custom Properties (Anthropic Design Tokens) --- */
:root {
    /* Anthropic Core Colors */
    --color-ivory: #faf9f5;
    --color-ivory-dark: #f0efe8;
    --color-parchment: #e8e6de;
    --color-sand: #d4d1c7;
    --color-stone: #b0aea5;
    --color-charcoal: #393832;
    --color-night: #1d1d1b;
    --color-black: #141413;

    /* Section Background Colors */
    --color-oat: #e8e0d0;
    --color-cactus: #d2dcc8;
    --color-heather: #d8d0e0;
    --color-sky: #c8d8e8;

    /* Accent */
    --color-accent: #c4704b;
    --color-accent-hover: #b0603d;

    /* Typography — matched to Anthropic's font stack */
    /* Copernicus ≈ Source Serif 4 (display headings) */
    --font-display-serif: 'Source Serif 4', 'Georgia', serif;
    /* TiemposText ≈ Newsreader (body serif) */
    --font-serif: 'Newsreader', 'Georgia', 'Times New Roman', serif;
    /* StyreneA / AnthropicSans ≈ DM Sans */
    --font-sans: 'DM Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;

    /* Spacing */
    --page-max-width: 1280px;
    --page-padding: 24px;
    --section-padding: 80px;
    --section-padding-sm: 48px;

    /* Borders & Radius */
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 28px;

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.25, 0.1, 0.25, 1);
    --transition-base: 250ms cubic-bezier(0.25, 0.1, 0.25, 1);
    --transition-smooth: 400ms cubic-bezier(0.25, 0.1, 0.25, 1);
    --transition-slow: 600ms cubic-bezier(0.16, 1, 0.3, 1);
}

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

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    background-color: var(--color-ivory);
    color: var(--color-charcoal);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

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

ul {
    list-style: none;
}

img {
    max-width: 100%;
    height: auto;
}

button {
    border: none;
    background: none;
    cursor: pointer;
    font-family: inherit;
    color: inherit;
}

/* --- Utility Classes --- */
.page-wrapper {
    max-width: var(--page-max-width);
    margin: 0 auto;
    padding-left: var(--page-padding);
    padding-right: var(--page-padding);
}

.serif {
    font-family: var(--font-serif);
}

/* --- Header --- */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background-color: rgba(250, 249, 245, 0.85);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.06);
    transition: background-color var(--transition-base), box-shadow var(--transition-base);
}

.site-header.scrolled {
    background-color: rgba(250, 249, 245, 0.95);
    box-shadow: 0 1px 12px rgba(0, 0, 0, 0.06);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo-link {
    display: flex;
    align-items: center;
    gap: 12px;
    transition: opacity var(--transition-fast);
}

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

.logo-text {
    font-family: var(--font-display-serif);
    font-size: 22px;
    font-weight: 600;
    color: var(--color-ivory);
    letter-spacing: -0.3px;
    line-height: 1;
    background: var(--color-black);
    width: 42px;
    height: 42px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 10px;
}

.logo-full {
    font-family: var(--font-sans);
    font-size: 16px;
    font-weight: 500;
    color: var(--color-black);
    letter-spacing: -0.2px;
}

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

.nav-list {
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-item {
    position: relative;
}

.nav-text {
    font-size: 14px;
    font-weight: 400;
    color: var(--color-charcoal);
    padding: 8px 14px;
    border-radius: var(--radius-sm);
    transition: color var(--transition-fast), background-color var(--transition-fast);
    display: flex;
    align-items: center;
    gap: 4px;
}

.nav-text:hover {
    color: var(--color-black);
    background-color: rgba(0, 0, 0, 0.04);
}

.header-cta-wrapper {
    display: flex;
    align-items: center;
    gap: 8px;
}

.header-cta-button {
    font-size: 14px;
    font-weight: 500;
    color: var(--color-ivory);
    background-color: var(--color-black);
    padding: 8px 20px;
    border-radius: 999px;
    transition: background-color var(--transition-fast), transform var(--transition-fast);
}

.header-cta-button:hover {
    background-color: var(--color-charcoal);
    transform: translateY(-1px);
}

.mobile-menu-btn {
    display: none;
    padding: 4px;
    color: var(--color-charcoal);
}

/* Mobile Menu */
.mobile-menu {
    display: none;
    background-color: var(--color-ivory);
    border-top: 1px solid rgba(0, 0, 0, 0.06);
    padding: 16px var(--page-padding) 24px;
}

.mobile-menu.open {
    display: block;
    animation: slideDown 0.3s ease-out;
}

@keyframes slideDown {
    from { opacity: 0; transform: translateY(-8px); }
    to { opacity: 1; transform: translateY(0); }
}

.mobile-nav-list {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.mobile-nav-link {
    display: block;
    padding: 12px 16px;
    font-size: 16px;
    color: var(--color-charcoal);
    border-radius: var(--radius-sm);
    transition: background-color var(--transition-fast);
}

.mobile-nav-link:hover {
    background-color: rgba(0, 0, 0, 0.04);
}

.mobile-nav-link.cta {
    margin-top: 12px;
    text-align: center;
    background-color: var(--color-black);
    color: var(--color-ivory);
    border-radius: 999px;
    font-weight: 500;
}

/* --- Hero Section --- */
.hero-section {
    padding-top: calc(64px + var(--section-padding));
    padding-bottom: var(--section-padding);
    background-color: var(--color-ivory);
}

.hero-text-wrapper {
    max-width: 780px;
}

.hero-title {
    font-family: var(--font-display-serif);
    font-size: clamp(48px, 7vw, 80px);
    font-weight: 300;
    line-height: 1.05;
    letter-spacing: -2px;
    color: var(--color-black);
    margin-bottom: 24px;
    opacity: 0;
    animation: fadeInUp 0.8s var(--transition-slow) forwards;
    animation-delay: 0.1s;
}

.hero-summary {
    font-family: var(--font-serif);
    font-size: clamp(17px, 2.2vw, 21px);
    font-weight: 400;
    line-height: 1.55;
    letter-spacing: -0.1px;
    color: var(--color-charcoal);
    margin-bottom: 32px;
    opacity: 0;
    animation: fadeInUp 0.8s var(--transition-slow) forwards;
    animation-delay: 0.25s;
}

.hero-badges {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    opacity: 0;
    animation: fadeInUp 0.8s var(--transition-slow) forwards;
    animation-delay: 0.4s;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
    font-weight: 400;
    color: var(--color-stone);
    padding: 6px 14px;
    border: 1px solid var(--color-parchment);
    border-radius: 999px;
    transition: border-color var(--transition-fast), color var(--transition-fast);
}

.hero-badge:hover {
    border-color: var(--color-stone);
    color: var(--color-charcoal);
}

.hero-badge svg {
    flex-shrink: 0;
    opacity: 0.6;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(24px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* --- Featured Banner Section (Anthropic PackageBanner) --- */
.featured-section {
    padding-bottom: var(--section-padding-sm);
    background-color: var(--color-ivory);
}

.package-banner {
    border-radius: var(--radius-xl);
    overflow: hidden;
}

.bg-oat {
    background-color: var(--color-oat);
}

.banner-announcement {
    padding: 48px 48px 32px;
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 32px;
}

.banner-text-wrapper {
    flex: 1;
    max-width: 640px;
}

.banner-title {
    font-family: var(--font-display-serif);
    font-size: clamp(26px, 3.5vw, 34px);
    font-weight: 400;
    line-height: 1.2;
    letter-spacing: -0.5px;
    color: var(--color-black);
    margin-bottom: 12px;
}

.banner-description {
    font-family: var(--font-serif);
    font-size: 16px;
    line-height: 1.6;
    letter-spacing: -0.1px;
    color: var(--color-charcoal);
}

.banner-metadata {
    flex-shrink: 0;
    padding-top: 4px;
}

.btn-secondary {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
    font-weight: 500;
    color: var(--color-black);
    padding: 10px 24px;
    border: 1.5px solid var(--color-charcoal);
    border-radius: 999px;
    transition: background-color var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast);
    white-space: nowrap;
}

.btn-secondary:hover {
    background-color: var(--color-black);
    border-color: var(--color-black);
    color: var(--color-ivory);
    transform: translateY(-1px);
}

.banner-packages {
    padding: 0 48px 48px;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
}

.package-link {
    display: block;
    cursor: default;
}

.package-card {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    padding: 24px;
    background-color: rgba(255, 255, 255, 0.5);
    border-radius: var(--radius-lg);
    border: 1px solid rgba(0, 0, 0, 0.06);
    transition: background-color var(--transition-base), transform var(--transition-base), box-shadow var(--transition-base);
    height: 100%;
}

.package-card:hover {
    background-color: rgba(255, 255, 255, 0.85);
    transform: translateY(-3px);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.06);
}

.package-text {
    flex: 1;
}

.package-label {
    font-size: 13px;
    font-weight: 500;
    color: var(--color-stone);
    margin-bottom: 8px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.package-summary {
    font-size: 18px;
    font-weight: 500;
    color: var(--color-black);
    line-height: 1.3;
    margin-bottom: 8px;
}

.package-detail {
    font-size: 14px;
    color: var(--color-charcoal);
    line-height: 1.5;
    opacity: 0.8;
}

.package-arrow {
    flex-shrink: 0;
    margin-left: 12px;
    color: var(--color-stone);
    transition: color var(--transition-fast), transform var(--transition-fast);
}

.package-card:hover .package-arrow {
    color: var(--color-black);
    transform: translateX(4px);
}

/* --- Section Cards (Anthropic EducationSections) --- */
.section-cards-wrapper {
    display: flex;
    flex-direction: column;
    gap: 16px;
    padding-bottom: var(--section-padding);
}

.section-card {
    border-radius: var(--radius-xl);
    overflow: hidden;
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.section-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.06);
}

.bg-cactus {
    background-color: var(--color-cactus);
}

.bg-heather {
    background-color: var(--color-heather);
}

.bg-sky {
    background-color: var(--color-sky);
}

.section-card-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 48px;
    gap: 40px;
}

.section-content-cta {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.section-content-wrapper {
    max-width: 520px;
}

.section-card-title {
    font-family: var(--font-display-serif);
    font-size: clamp(24px, 3.5vw, 30px);
    font-weight: 400;
    color: var(--color-black);
    margin-bottom: 12px;
    line-height: 1.2;
    letter-spacing: -0.3px;
}

.section-card-body {
    font-family: var(--font-serif);
    font-size: 16px;
    line-height: 1.6;
    letter-spacing: -0.1px;
    color: var(--color-charcoal);
}

.section-card-meta {
    font-size: 13px;
    color: var(--color-stone);
    margin-top: 8px;
    font-weight: 500;
}

.section-illustration {
    flex-shrink: 0;
    width: 160px;
    height: 160px;
    color: var(--color-charcoal);
    opacity: 0.6;
    transition: opacity var(--transition-base), transform var(--transition-base);
}

.section-card:hover .section-illustration {
    opacity: 0.8;
    transform: scale(1.05);
}

/* --- Projects Section --- */
.projects-section {
    padding: var(--section-padding) 0;
    background-color: var(--color-ivory);
}

.projects-wrapper {
    max-width: 100%;
}

.projects-header {
    margin-bottom: 48px;
}

.projects-title {
    font-family: var(--font-display-serif);
    font-size: clamp(22px, 3vw, 28px);
    font-weight: 400;
    color: var(--color-black);
    margin-bottom: 8px;
    letter-spacing: -0.3px;
}

.projects-subtitle {
    font-family: var(--font-serif);
    font-size: 16px;
    color: var(--color-charcoal);
    line-height: 1.55;
    letter-spacing: -0.1px;
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
    gap: 16px;
}

.project-card {
    background-color: var(--color-ivory-dark);
    border: 1px solid rgba(0, 0, 0, 0.05);
    border-radius: var(--radius-lg);
    padding: 28px 24px;
    transition: background-color var(--transition-base), transform var(--transition-base), box-shadow var(--transition-base);
    cursor: default;
}

.project-card:hover {
    background-color: #fff;
    transform: translateY(-4px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.08);
}

.project-icon {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--color-parchment);
    border-radius: var(--radius-md);
    margin-bottom: 20px;
    color: var(--color-charcoal);
    transition: background-color var(--transition-base), color var(--transition-base);
}

.project-card:hover .project-icon {
    background-color: var(--color-black);
    color: var(--color-ivory);
}

.project-name {
    font-size: 17px;
    font-weight: 600;
    color: var(--color-black);
    margin-bottom: 8px;
    line-height: 1.3;
}

.project-desc {
    font-size: 14px;
    color: var(--color-charcoal);
    line-height: 1.55;
    opacity: 0.8;
}

/* --- Newsletter / Contact Section --- */
.newsletter-section {
    padding: var(--section-padding-sm) 0 var(--section-padding);
    background-color: var(--color-ivory);
}

.newsletter-wrapper {
    border-top: 1px solid var(--color-parchment);
    padding-top: var(--section-padding-sm);
}

.newsletter-content {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 48px;
}

.newsletter-text {
    flex: 1;
    max-width: 480px;
}

.newsletter-title {
    font-size: 22px;
    font-weight: 600;
    color: var(--color-black);
    margin-bottom: 12px;
}

.newsletter-body {
    font-family: var(--font-serif);
    font-size: 16px;
    line-height: 1.6;
    letter-spacing: -0.1px;
    color: var(--color-charcoal);
}

.newsletter-form-container {
    flex: 1;
    max-width: 460px;
}

.newsletter-form {
    width: 100%;
}

.input-wrapper {
    display: flex;
    align-items: center;
    border: 1.5px solid var(--color-sand);
    border-radius: 999px;
    padding: 4px;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
    background-color: #fff;
}

.input-wrapper:focus-within {
    border-color: var(--color-black);
    box-shadow: 0 0 0 3px rgba(20, 20, 19, 0.08);
}

.email-input {
    flex: 1;
    border: none;
    outline: none;
    padding: 10px 16px;
    font-family: var(--font-sans);
    font-size: 15px;
    color: var(--color-black);
    background: transparent;
    border-radius: 999px;
}

.email-input::placeholder {
    color: var(--color-stone);
}

.submit-button {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--color-black);
    color: var(--color-ivory);
    border-radius: 50%;
    flex-shrink: 0;
    transition: background-color var(--transition-fast), transform var(--transition-fast);
}

.submit-button:hover {
    background-color: var(--color-charcoal);
    transform: scale(1.05);
}

.newsletter-disclaimer {
    font-size: 13px;
    color: var(--color-stone);
    margin-top: 12px;
    line-height: 1.5;
    padding-left: 16px;
}

/* --- Footer (Anthropic SiteFooter) --- */
.site-footer {
    background-color: var(--color-black);
    color: var(--color-stone);
    padding: 64px 0 40px;
}

.footer-inner {
    display: flex;
    flex-direction: column;
    gap: 48px;
}

.footer-logo-wrapper {
    margin-bottom: 8px;
}

.footer-logo {
    font-family: var(--font-display-serif);
    font-size: 26px;
    font-weight: 600;
    color: var(--color-ivory);
    letter-spacing: -0.3px;
    background: rgba(250, 249, 245, 0.1);
    width: 48px;
    height: 48px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 12px;
    transition: background-color var(--transition-fast);
}

.footer-logo:hover {
    background: rgba(250, 249, 245, 0.15);
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 40px;
}

.footer-column {
    display: flex;
    flex-direction: column;
    gap: 32px;
}

.footer-list-section {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.footer-heading {
    font-size: 13px;
    font-weight: 600;
    color: var(--color-ivory);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 4px;
}

.footer-list {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.footer-link {
    font-size: 14px;
    color: var(--color-stone);
    transition: color var(--transition-fast);
    padding: 2px 0;
    display: inline-block;
}

a.footer-link:hover {
    color: var(--color-ivory);
}

.footer-bottom {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: 32px;
    border-top: 1px solid rgba(250, 249, 245, 0.08);
}

.footer-copyright {
    font-size: 13px;
    color: var(--color-stone);
}

.footer-social {
    display: flex;
    align-items: center;
    gap: 16px;
}

.footer-social a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    transition: background-color var(--transition-fast), transform var(--transition-fast);
}

.footer-social a:hover {
    background-color: rgba(250, 249, 245, 0.08);
    transform: translateY(-2px);
}

.footer-social svg {
    width: 20px;
    height: 20px;
}

/* --- Scroll Animations (IntersectionObserver) --- */
.animate-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.7s var(--transition-slow), transform 0.7s var(--transition-slow);
}

.animate-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Staggered entry for children */
.stagger-children .animate-in:nth-child(1) { transition-delay: 0.05s; }
.stagger-children .animate-in:nth-child(2) { transition-delay: 0.1s; }
.stagger-children .animate-in:nth-child(3) { transition-delay: 0.15s; }
.stagger-children .animate-in:nth-child(4) { transition-delay: 0.2s; }
.stagger-children .animate-in:nth-child(5) { transition-delay: 0.25s; }

/* --- Responsive Design --- */

/* Tablet */
@media (max-width: 1024px) {
    :root {
        --page-padding: 20px;
        --section-padding: 60px;
        --section-padding-sm: 40px;
    }

    .banner-packages {
        grid-template-columns: 1fr;
    }

    .section-card-inner {
        padding: 36px;
    }

    .footer-links {
        grid-template-columns: repeat(2, 1fr);
    }

    .newsletter-content {
        flex-direction: column;
    }

    .newsletter-text,
    .newsletter-form-container {
        max-width: 100%;
    }
}

/* Mobile */
@media (max-width: 768px) {
    :root {
        --section-padding: 48px;
        --section-padding-sm: 32px;
    }

    /* Header */
    .main-nav {
        display: none;
    }

    .mobile-menu-btn {
        display: block;
    }

    .logo-full {
        display: none;
    }

    /* Hero */
    .hero-section {
        padding-top: calc(64px + 40px);
    }

    .hero-badges {
        flex-direction: column;
        gap: 8px;
    }

    .hero-badge {
        width: fit-content;
    }

    /* Banner */
    .banner-announcement {
        flex-direction: column;
        padding: 32px 24px 24px;
        gap: 20px;
    }

    .banner-packages {
        padding: 0 24px 32px;
        grid-template-columns: 1fr;
    }

    .package-card {
        padding: 20px;
    }

    /* Section Cards */
    .section-card-inner {
        flex-direction: column;
        padding: 32px 24px;
        gap: 24px;
    }

    .section-illustration {
        width: 120px;
        height: 120px;
        order: -1;
    }

    /* Projects */
    .projects-grid {
        grid-template-columns: 1fr;
    }

    /* Footer */
    .footer-links {
        grid-template-columns: repeat(2, 1fr);
        gap: 32px;
    }

    .footer-bottom {
        flex-direction: column;
        gap: 16px;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .footer-links {
        grid-template-columns: 1fr;
    }

    .hero-title {
        font-size: 42px;
    }
}