/* -------------------------------------------------------------------------- */
/* Kayi Flashcards — Official Website Stylesheet                              */
/* Pure Minimalist, Apple-inspired aesthetics with pastel mint green palette   */
/* -------------------------------------------------------------------------- */

:root {
    --color-bg-base: #F6FBF8;
    --color-mint-light: #C1F6DA;
    --color-mint-soft: #D9F9E7;
    --color-mint-card: #EAFBF2;
    --color-blush-soft: #FDECEF;
    
    --color-primary: #059669;
    --color-primary-dark: #047857;
    --color-primary-light: #10B981;
    --color-heading: #064E3B;
    --color-heading-dark: #0F172A;
    --color-text: #334155;
    --color-text-muted: #64748B;
    
    --card-bg: rgba(255, 255, 255, 0.82);
    --card-bg-solid: #FFFFFF;
    --card-border: rgba(255, 255, 255, 0.9);
    --card-border-subtle: rgba(16, 185, 129, 0.12);
    
    --shadow-sm: 0 4px 12px rgba(6, 78, 59, 0.04);
    --shadow-md: 0 12px 28px -6px rgba(6, 78, 59, 0.08);
    --shadow-lg: 0 24px 48px -12px rgba(6, 78, 59, 0.12);
    --shadow-glow: 0 16px 32px rgba(16, 185, 129, 0.2);

    --radius-sm: 12px;
    --radius-md: 18px;
    --radius-lg: 24px;
    --radius-xl: 32px;
    --radius-pill: 9999px;
    
    --container-max: 1140px;
    --transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

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

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Inter", "Segoe UI", Roboto, sans-serif;
    background-color: var(--color-bg-base);
    background-image: 
        radial-gradient(at 0% 0%, rgba(193, 246, 218, 0.75) 0px, transparent 55%),
        radial-gradient(at 100% 10%, rgba(209, 250, 229, 0.6) 0px, transparent 50%),
        radial-gradient(at 50% 50%, rgba(240, 253, 244, 0.5) 0px, transparent 60%),
        radial-gradient(at 100% 90%, rgba(253, 236, 239, 0.65) 0px, transparent 50%),
        radial-gradient(at 0% 100%, rgba(217, 249, 231, 0.5) 0px, transparent 60%);
    background-attachment: fixed;
    color: var(--color-text);
    line-height: 1.6;
    overflow-x: hidden;
}

/* Typography */
h1, h2, h3, h4 {
    color: var(--color-heading-dark);
    font-weight: 700;
    line-height: 1.25;
    letter-spacing: -0.025em;
}

p {
    font-size: 1.05rem;
    color: var(--color-text-muted);
    line-height: 1.7;
}

a {
    color: inherit;
    text-decoration: none;
}

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

.section {
    padding: 96px 0;
    position: relative;
}

.section-header {
    text-align: center;
    max-width: 680px;
    margin: 0 auto 56px;
}

.tag-pill {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 6px 14px;
    border-radius: var(--radius-pill);
    background: rgba(16, 185, 129, 0.12);
    color: var(--color-heading);
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 0.02em;
    margin-bottom: 16px;
    border: 1px solid rgba(16, 185, 129, 0.18);
}

.tag-pill svg {
    width: 14px;
    height: 14px;
}

.section-title {
    font-size: 2.5rem;
    margin-bottom: 16px;
    color: var(--color-heading-dark);
}

.section-subtitle {
    font-size: 1.15rem;
    color: var(--color-text-muted);
}

/* Navigation Bar */
.navbar {
    position: sticky;
    top: 0;
    width: 100%;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    transition: var(--transition);
}

.nav-container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 14px 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.brand {
    display: flex;
    align-items: center;
    gap: 12px;
}

.brand-icon {
    width: 38px;
    height: 38px;
    border-radius: 10px;
    box-shadow: 0 4px 10px rgba(6, 78, 59, 0.12);
    display: block;
}

.brand-name {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-heading);
    letter-spacing: -0.02em;
}

.brand-badge {
    font-size: 0.72rem;
    font-weight: 600;
    padding: 2px 8px;
    border-radius: var(--radius-pill);
    background: var(--color-mint-soft);
    color: var(--color-heading);
    margin-left: 2px;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 28px;
    list-style: none;
}

.nav-link {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--color-text);
    transition: var(--transition);
}

.nav-link:hover {
    color: var(--color-primary);
}

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

.btn-nav-download {
    padding: 8px 18px;
    border-radius: var(--radius-pill);
    background: var(--color-heading-dark);
    color: #FFFFFF;
    font-size: 0.88rem;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.btn-nav-download:hover {
    background: var(--color-primary);
    transform: translateY(-1px);
    box-shadow: var(--shadow-glow);
}

.menu-toggle {
    display: none;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 6px;
    color: var(--color-heading-dark);
}

/* Hero Section */
.hero {
    padding: 70px 0 90px;
    text-align: center;
    position: relative;
}

.hero-inner {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.hero-title {
    font-size: 4rem;
    font-weight: 800;
    letter-spacing: -0.035em;
    color: var(--color-heading-dark);
    margin-bottom: 20px;
    max-width: 820px;
    line-height: 1.12;
}

.hero-title span.highlight {
    background: linear-gradient(135deg, #065F46 0%, #059669 60%, #10B981 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-desc {
    font-size: 1.25rem;
    max-width: 660px;
    margin: 0 auto 36px;
    color: var(--color-text-muted);
}

.hero-cta-group {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 16px;
    margin-bottom: 24px;
}

/* App Store Button */
.btn-appstore {
    background: #000000;
    color: #FFFFFF;
    padding: 12px 28px;
    border-radius: var(--radius-pill);
    display: inline-flex;
    align-items: center;
    gap: 14px;
    font-weight: 600;
    transition: var(--transition);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.15);
    border: 1px solid rgba(255, 255, 255, 0.15);
}

.btn-appstore:hover {
    background: #1F2937;
    transform: translateY(-2px);
    box-shadow: 0 16px 32px rgba(0, 0, 0, 0.22);
}

.btn-appstore svg {
    width: 26px;
    height: 26px;
    fill: currentColor;
}

.btn-appstore-text {
    text-align: left;
    display: flex;
    flex-direction: column;
}

.btn-appstore-text .subtext {
    font-size: 0.68rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    opacity: 0.85;
}

.btn-appstore-text .maintext {
    font-size: 1.12rem;
    font-weight: 700;
    line-height: 1.2;
}

.btn-secondary {
    background: var(--card-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    color: var(--color-heading);
    padding: 14px 26px;
    border-radius: var(--radius-pill);
    font-size: 0.98rem;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    border: 1px solid var(--card-border-subtle);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.btn-secondary:hover {
    background: #FFFFFF;
    color: var(--color-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.hero-meta {
    display: flex;
    align-items: center;
    gap: 20px;
    font-size: 0.85rem;
    color: var(--color-text-muted);
}

.hero-meta-item {
    display: flex;
    align-items: center;
    gap: 6px;
}

.hero-meta-item svg {
    color: var(--color-primary);
    width: 16px;
    height: 16px;
}

/* Hero Key Highlights Strip */
.hero-highlights {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    max-width: 1040px;
    width: 100%;
    margin: 44px auto 8px;
    z-index: 4;
}

.hero-highlight-card {
    background: rgba(255, 255, 255, 0.78);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid rgba(255, 255, 255, 0.95);
    border-radius: var(--radius-md);
    padding: 16px;
    text-align: left;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    display: flex;
    align-items: flex-start;
    gap: 12px;
}

.hero-highlight-card:hover {
    transform: translateY(-3px);
    background: rgba(255, 255, 255, 0.95);
    box-shadow: var(--shadow-md);
    border-color: rgba(16, 185, 129, 0.25);
}

.hero-highlight-icon {
    width: 36px;
    height: 36px;
    border-radius: 10px;
    background: var(--color-mint-soft);
    color: var(--color-primary-dark);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.hero-highlight-icon svg {
    width: 18px;
    height: 18px;
}

.hero-highlight-title {
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--color-heading-dark);
    margin-bottom: 2px;
    line-height: 1.3;
}

.hero-highlight-desc {
    font-size: 0.78rem;
    color: var(--color-text-muted);
    line-height: 1.4;
}

/* Hero Showcase Visual */
.hero-visual {
    margin-top: 56px;
    position: relative;
    width: 100%;
    max-width: 900px;
    display: flex;
    justify-content: center;
}

.phone-mockup-wrapper {
    position: relative;
    z-index: 2;
}

.phone-frame {
    width: 320px;
    border-radius: 44px;
    padding: 10px;
    background: linear-gradient(145deg, #2D3748 0%, #1A202C 100%);
    box-shadow: 
        0 30px 70px -15px rgba(6, 78, 59, 0.25),
        0 15px 30px rgba(0, 0, 0, 0.12),
        inset 0 1px 2px rgba(255, 255, 255, 0.3);
    border: 1px solid rgba(255, 255, 255, 0.15);
    transition: transform 0.4s ease;
}

.phone-frame:hover {
    transform: translateY(-6px);
}

.phone-screen {
    border-radius: 36px;
    overflow: hidden;
    background: #FFFFFF;
    display: block;
}

.phone-screen img {
    width: 100%;
    height: auto;
    display: block;
    object-fit: cover;
}

/* Floating Feature Badges */
.floating-chip {
    position: absolute;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    padding: 12px 18px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
    border: 1px solid rgba(255, 255, 255, 0.9);
    display: flex;
    align-items: center;
    gap: 12px;
    z-index: 3;
    animation: float 6s ease-in-out infinite;
}

.chip-left {
    left: 40px;
    top: 25%;
    animation-delay: 0s;
}

.chip-right {
    right: 40px;
    top: 55%;
    animation-delay: 3s;
}

.chip-icon {
    width: 36px;
    height: 36px;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-mint-soft);
    color: var(--color-primary);
    flex-shrink: 0;
}

.chip-content {
    text-align: left;
}

.chip-title {
    font-size: 0.92rem;
    font-weight: 700;
    color: var(--color-heading-dark);
}

.chip-subtitle {
    font-size: 0.78rem;
    color: var(--color-text-muted);
}

@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-10px);
    }
}

/* Core Features Section */
.features-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
}

.feature-card {
    background: var(--card-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-radius: var(--radius-xl);
    padding: 44px;
    border: 1px solid var(--card-border);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    position: relative;
    overflow: hidden;
}

.feature-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(16, 185, 129, 0.25);
    background: rgba(255, 255, 255, 0.92);
}

.feature-icon-box {
    width: 58px;
    height: 58px;
    border-radius: var(--radius-md);
    background: linear-gradient(135deg, var(--color-mint-card) 0%, var(--color-mint-soft) 100%);
    color: var(--color-primary-dark);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 24px;
    box-shadow: inset 0 2px 4px rgba(255, 255, 255, 0.8), 0 4px 10px rgba(6, 78, 59, 0.05);
}

.feature-icon-box svg {
    width: 28px;
    height: 28px;
}

.feature-title {
    font-size: 1.5rem;
    margin-bottom: 12px;
    color: var(--color-heading-dark);
}

.feature-desc {
    font-size: 1rem;
    color: var(--color-text-muted);
    line-height: 1.65;
    margin-bottom: 24px;
}

.feature-badge-list {
    margin-top: auto;
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.feature-badge-item {
    font-size: 0.8rem;
    font-weight: 500;
    padding: 4px 12px;
    border-radius: var(--radius-pill);
    background: rgba(243, 244, 246, 0.9);
    color: #475569;
    border: 1px solid rgba(0, 0, 0, 0.04);
}

/* Gallery Showcase Section */
.gallery-section {
    padding: 80px 0;
}

.gallery-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.gallery-item {
    background: var(--card-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-radius: var(--radius-lg);
    padding: 16px;
    border: 1px solid var(--card-border);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    text-align: center;
}

.gallery-item:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.gallery-img-wrapper {
    border-radius: var(--radius-md);
    overflow: hidden;
    background: #0F172A;
    margin-bottom: 16px;
    aspect-ratio: 9 / 19.5;
    box-shadow: 0 10px 24px rgba(0, 0, 0, 0.08);
}

.gallery-img-wrapper img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    transition: transform 0.4s ease;
}

.gallery-item:hover .gallery-img-wrapper img {
    transform: scale(1.03);
}

.gallery-caption {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--color-heading-dark);
    margin-bottom: 6px;
}

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

/* Local-First & Privacy Spotlight */
.privacy-spotlight {
    background: linear-gradient(135deg, #064E3B 0%, #065F46 60%, #047857 100%);
    border-radius: var(--radius-xl);
    padding: 64px 48px;
    color: #FFFFFF;
    position: relative;
    overflow: hidden;
    box-shadow: 0 24px 48px -12px rgba(6, 78, 59, 0.3);
    margin-top: 20px;
}

.privacy-spotlight::before {
    content: '';
    position: absolute;
    width: 300px;
    height: 300px;
    border-radius: 50%;
    background: rgba(16, 185, 129, 0.25);
    filter: blur(60px);
    top: -50px;
    right: -50px;
}

.privacy-spotlight-inner {
    position: relative;
    z-index: 2;
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 48px;
    align-items: center;
}

.privacy-content h2 {
    color: #FFFFFF;
    font-size: 2.2rem;
    margin-bottom: 16px;
}

.privacy-content p {
    color: #D1FAE5;
    font-size: 1.1rem;
    line-height: 1.7;
    margin-bottom: 24px;
}

.privacy-pillars {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 18px;
}

.pillar-item {
    background: rgba(255, 255, 255, 0.08);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    padding: 20px;
    border-radius: var(--radius-md);
    border: 1px solid rgba(255, 255, 255, 0.12);
}

.pillar-title {
    font-size: 1.05rem;
    font-weight: 700;
    color: #FFFFFF;
    margin-bottom: 6px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.pillar-title svg {
    color: #6EE7B7;
    width: 18px;
    height: 18px;
}

.pillar-desc {
    font-size: 0.88rem;
    color: #A7F3D0;
    line-height: 1.5;
}

/* Call to Action (CTA) Section */
.cta-section {
    padding: 96px 0;
    text-align: center;
}

.cta-box {
    background: var(--card-bg);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    border-radius: var(--radius-xl);
    padding: 64px 32px;
    border: 1px solid var(--card-border);
    box-shadow: var(--shadow-lg);
    max-width: 840px;
    margin: 0 auto;
}

.cta-icon {
    width: 72px;
    height: 72px;
    border-radius: 18px;
    margin-bottom: 20px;
    box-shadow: 0 10px 24px rgba(6, 78, 59, 0.15);
}

.cta-title {
    font-size: 2.5rem;
    margin-bottom: 14px;
}

.cta-desc {
    font-size: 1.15rem;
    max-width: 580px;
    margin: 0 auto 32px;
}

.cta-compat {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    margin-top: 18px;
}

/* Footer */
.footer {
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-top: 1px solid rgba(0, 0, 0, 0.06);
    padding: 48px 0 32px;
}

.footer-inner {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 24px;
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: 10px;
}

.footer-brand img {
    width: 28px;
    height: 28px;
    border-radius: 6px;
}

.footer-links {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 24px;
    list-style: none;
}

.footer-link {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    transition: var(--transition);
}

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

.footer-legal-badge {
    font-size: 0.82rem;
    padding: 4px 12px;
    border-radius: var(--radius-pill);
    background: #E5E7EB;
    color: #374151;
    font-weight: 500;
}

.footer-copy {
    font-size: 0.85rem;
    color: #94A3B8;
}

/* Responsive Media Queries */
@media (max-width: 1024px) {
    .hero-title {
        font-size: 3.2rem;
    }
    .hero-highlights {
        grid-template-columns: repeat(2, 1fr);
        gap: 12px;
    }
    .gallery-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 24px;
    }
    .privacy-spotlight-inner {
        grid-template-columns: 1fr;
        gap: 36px;
    }
    .floating-chip {
        display: none;
    }
}

@media (max-width: 768px) {
    .hero-highlights {
        grid-template-columns: 1fr;
        margin: 32px auto 0;
    }
    .section {
        padding: 64px 0;
    }
    .hero {
        padding: 40px 0 60px;
    }
    .hero-title {
        font-size: 2.5rem;
    }
    .hero-desc {
        font-size: 1.05rem;
    }
    .features-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    .feature-card {
        padding: 30px 24px;
    }
    .gallery-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 16px;
    }
    .privacy-spotlight {
        padding: 40px 24px;
    }
    .privacy-pillars {
        grid-template-columns: 1fr;
    }
    .phone-frame {
        width: 270px;
    }
    
    /* Mobile Navigation */
    .menu-toggle {
        display: block;
    }
    .nav-menu {
        position: fixed;
        top: 67px;
        left: 0;
        width: 100%;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        flex-direction: column;
        padding: 24px;
        gap: 18px;
        border-bottom: 1px solid rgba(0, 0, 0, 0.08);
        box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
        transform: translateY(-150%);
        transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
        z-index: 999;
    }
    .nav-menu.active {
        transform: translateY(0);
    }
    .btn-nav-download {
        display: none;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2.15rem;
    }
    .gallery-grid {
        grid-template-columns: 1fr;
        max-width: 280px;
        margin: 0 auto;
    }
    .cta-box {
        padding: 40px 20px;
    }
    .btn-appstore {
        width: 100%;
        justify-content: center;
    }
    .btn-secondary {
        width: 100%;
        justify-content: center;
    }
}