/* ==============================================
   Swiss Modern Design System for B-Flap
   Color: Monochrome + Single Accent
   Motion: IntersectionObserver Fade-ins
   ============================================== */

/* ============== CSS Reset ============== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* ============== Design Tokens ============== */
:root {
    /* Colors - Monochrome Base */
    --color-bg: #FAFAFA;
    --color-fg: #050505;
    --color-border: #E5E5E5;
    --color-accent: #0066FF;

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

    /* Type Scale */
    --text-xs: 0.75rem;      /* 12px */
    --text-sm: 0.875rem;     /* 14px */
    --text-base: 1rem;       /* 16px */
    --text-lg: 1.125rem;     /* 18px */
    --text-xl: 1.5rem;       /* 24px */
    --text-2xl: 2rem;        /* 32px */
    --text-3xl: 2.5rem;      /* 40px */
    --text-4xl: 3rem;        /* 48px */
    --text-5xl: 4rem;        /* 64px */
    --text-6xl: 5rem;        /* 80px */

    /* Spacing Scale */
    --space-1: 0.25rem;      /* 4px */
    --space-2: 0.5rem;       /* 8px */
    --space-3: 0.75rem;      /* 12px */
    --space-4: 1rem;         /* 16px */
    --space-6: 1.5rem;       /* 24px */
    --space-8: 2rem;         /* 32px */
    --space-12: 3rem;        /* 48px */
    --space-16: 4rem;        /* 64px */
    --space-24: 6rem;        /* 96px */
    --space-32: 8rem;        /* 128px */

    /* Line Heights */
    --leading-none: 1;
    --leading-tight: 1.25;
    --leading-snug: 1.375;
    --leading-normal: 1.5;
    --leading-relaxed: 1.625;
    --leading-loose: 2;

    /* Font Weights */
    --weight-regular: 400;
    --weight-medium: 500;
    --weight-semibold: 600;
    --weight-bold: 700;

    /* Border Radius */
    --radius-sm: 0.125rem;
    --radius-md: 0.25rem;
    --radius-lg: 0.5rem;

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* ============== Base Styles ============== */
html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    font-size: var(--text-base);
    line-height: var(--leading-normal);
    color: var(--color-fg);
    background-color: var(--color-bg);
    font-weight: var(--weight-regular);
}

/* ============== Typography ============== */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-display);
    font-weight: var(--weight-semibold);
    line-height: var(--leading-tight);
    letter-spacing: -0.02em;
}

h1 {
    font-size: var(--text-5xl);
    font-weight: var(--weight-semibold);
}

h2 {
    font-size: var(--text-4xl);
}

h3 {
    font-size: var(--text-3xl);
}

h4 {
    font-size: var(--text-2xl);
}

p {
    line-height: var(--leading-relaxed);
}

/* ============== Container System ============== */
.container {
    max-width: 1280px;
    margin-left: auto;
    margin-right: auto;
    padding-left: var(--space-6);
    padding-right: var(--space-6);
}

/* ============== Navigation ============== */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background-color: rgba(250, 250, 250, 0.8);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
}

.nav-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 var(--space-6);
}

.nav-logo {
    font-size: var(--text-lg);
    font-weight: var(--weight-semibold);
    color: var(--color-fg);
    text-decoration: none;
    letter-spacing: -0.01em;
}

.nav-links {
    display: flex;
    gap: var(--space-8);
    align-items: center;
}

.nav-link {
    font-size: var(--text-sm);
    font-weight: var(--weight-medium);
    color: var(--color-fg);
    text-decoration: none;
    transition: opacity var(--transition-fast);
    letter-spacing: -0.01em;
}

.nav-link:hover {
    opacity: 0.6;
}

.nav-cta {
    padding: var(--space-2) var(--space-4);
    background-color: var(--color-accent);
    color: var(--color-bg);
    border: none;
    border-radius: var(--radius-md);
    font-size: var(--text-sm);
    font-weight: var(--weight-medium);
    cursor: pointer;
    transition: opacity var(--transition-fast);
    letter-spacing: -0.01em;
}

.nav-cta:hover {
    opacity: 0.9;
}

/* ============== Hero Section ============== */
.hero {
    padding-top: calc(64px + var(--space-32));
    padding-bottom: var(--space-32);
    min-height: 90vh;
    display: flex;
    align-items: center;
}

.hero-content {
    max-width: 960px;
}

.hero-badge {
    display: inline-block;
    padding: var(--space-1) var(--space-3);
    background-color: var(--color-fg);
    color: var(--color-bg);
    font-size: var(--text-xs);
    font-weight: var(--weight-medium);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: var(--space-8);
}

.hero-title {
    font-size: clamp(2.5rem, 8vw, 6rem);
    font-weight: var(--weight-semibold);
    line-height: var(--leading-none);
    margin-bottom: var(--space-6);
    letter-spacing: -0.03em;
}

.hero-subtitle {
    font-size: var(--text-xl);
    line-height: var(--leading-relaxed);
    color: var(--color-fg);
    opacity: 0.7;
    margin-bottom: var(--space-12);
    max-width: 720px;
}

.hero-cta {
    display: flex;
    gap: var(--space-4);
}

.btn-primary {
    padding: var(--space-4) var(--space-8);
    background-color: var(--color-accent);
    color: var(--color-bg);
    border: none;
    font-size: var(--text-base);
    font-weight: var(--weight-medium);
    cursor: pointer;
    transition: opacity var(--transition-fast);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    letter-spacing: -0.01em;
}

.btn-primary:hover {
    opacity: 0.9;
}

.btn-secondary {
    padding: var(--space-4) var(--space-8);
    background-color: transparent;
    color: var(--color-fg);
    border: 1px solid var(--color-border);
    font-size: var(--text-base);
    font-weight: var(--weight-medium);
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    letter-spacing: -0.01em;
}

.btn-secondary:hover {
    border-color: var(--color-fg);
}

/* ============== Section Styles ============== */
.section {
    padding: var(--space-32) 0;
}

.section-header {
    margin-bottom: var(--space-16);
}

.section-label {
    font-size: var(--text-xs);
    font-weight: var(--weight-medium);
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--color-fg);
    opacity: 0.5;
    margin-bottom: var(--space-4);
}

.section-title {
    font-size: var(--text-4xl);
    font-weight: var(--weight-semibold);
    line-height: var(--leading-tight);
    margin-bottom: var(--space-6);
    letter-spacing: -0.02em;
}

.section-description {
    font-size: var(--text-lg);
    line-height: var(--leading-relaxed);
    color: var(--color-fg);
    opacity: 0.7;
    max-width: 720px;
}

/* ============== Grid System ============== */
.grid {
    display: grid;
    gap: var(--space-8);
}

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

.grid-3 {
    grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
    grid-template-columns: repeat(4, 1fr);
}

@media (max-width: 1024px) {
    .grid-3,
    .grid-4 {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 640px) {
    .grid-2,
    .grid-3,
    .grid-4 {
        grid-template-columns: 1fr;
    }
}

/* ============== Card Component ============== */
.card {
    padding: var(--space-8);
    border: 1px solid var(--color-border);
    background-color: var(--color-bg);
    transition: all var(--transition-base);
}

.card:hover {
    border-color: var(--color-fg);
}

.card-title {
    font-size: var(--text-xl);
    font-weight: var(--weight-semibold);
    margin-bottom: var(--space-4);
    letter-spacing: -0.01em;
}

.card-description {
    font-size: var(--text-base);
    line-height: var(--leading-relaxed);
    color: var(--color-fg);
    opacity: 0.7;
}

/* ============== Stats Component ============== */
.stats {
    display: flex;
    gap: var(--space-16);
    padding: var(--space-16) 0;
}

.stat {
    flex: 1;
}

.stat-value {
    font-size: var(--text-5xl);
    font-weight: var(--weight-semibold);
    line-height: var(--leading-none);
    margin-bottom: var(--space-2);
    letter-spacing: -0.03em;
}

.stat-label {
    font-size: var(--text-sm);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-fg);
    opacity: 0.5;
}

/* ============== Features Section ============== */
.feature-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-16);
    padding: var(--space-16) 0;
}

.feature-item {
    padding: var(--space-8) 0;
}

.feature-number {
    font-size: var(--text-sm);
    font-weight: var(--weight-medium);
    color: var(--color-fg);
    opacity: 0.4;
    margin-bottom: var(--space-4);
    letter-spacing: 0.1em;
}

.feature-title {
    font-size: var(--text-2xl);
    font-weight: var(--weight-semibold);
    margin-bottom: var(--space-4);
    letter-spacing: -0.02em;
}

.feature-description {
    font-size: var(--text-base);
    line-height: var(--leading-relaxed);
    color: var(--color-fg);
    opacity: 0.7;
}

/* ============== Accent Elements ============== */
.accent {
    color: var(--color-accent);
}

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

.divider {
    height: 1px;
    background-color: var(--color-border);
    margin: var(--space-16) 0;
}

/* ============== Form Styles ============== */
.form-group {
    margin-bottom: var(--space-6);
}

.form-label {
    display: block;
    font-size: var(--text-sm);
    font-weight: var(--weight-medium);
    margin-bottom: var(--space-2);
    letter-spacing: -0.01em;
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: var(--space-3) var(--space-4);
    border: 1px solid var(--color-border);
    background-color: var(--color-bg);
    font-size: var(--text-base);
    font-family: var(--font-sans);
    color: var(--color-fg);
    transition: border-color var(--transition-fast);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--color-accent);
}

.form-textarea {
    resize: vertical;
    min-height: 120px;
}

/* ============== Footer ============== */
.footer {
    padding: var(--space-24) 0 var(--space-8);
    border-top: 1px solid var(--color-border);
    margin-top: var(--space-32);
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: var(--space-12);
    margin-bottom: var(--space-12);
}

.footer-brand {
    max-width: 320px;
}

.footer-title {
    font-size: var(--text-lg);
    font-weight: var(--weight-semibold);
    margin-bottom: var(--space-4);
    letter-spacing: -0.01em;
}

.footer-description {
    font-size: var(--text-sm);
    line-height: var(--leading-relaxed);
    color: var(--color-fg);
    opacity: 0.7;
}

.footer-links {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

.footer-link {
    font-size: var(--text-sm);
    color: var(--color-fg);
    text-decoration: none;
    transition: opacity var(--transition-fast);
}

.footer-link:hover {
    opacity: 0.6;
}

.footer-bottom {
    padding-top: var(--space-8);
    border-top: 1px solid var(--color-border);
    text-align: center;
}

.footer-copyright {
    font-size: var(--text-sm);
    color: var(--color-fg);
    opacity: 0.5;
}

/* ============== Animation Classes ============== */
.fade-in {
    opacity: 0;
    transform: translateY(24px);
    transition: opacity 0.6s cubic-bezier(0.4, 0, 0.2, 1),
                transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

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

.fade-in-delay-1 {
    transition-delay: 0.1s;
}

.fade-in-delay-2 {
    transition-delay: 0.2s;
}

.fade-in-delay-3 {
    transition-delay: 0.3s;
}

.fade-in-delay-4 {
    transition-delay: 0.4s;
}

/* ============== Responsive Typography ============== */
@media (max-width: 1024px) {
    :root {
        --text-5xl: 3rem;
        --text-4xl: 2.5rem;
        --text-3xl: 2rem;
    }
}

@media (max-width: 640px) {
    :root {
        --text-5xl: 2.5rem;
        --text-4xl: 2rem;
        --text-3xl: 1.75rem;
        --space-32: 4rem;
        --space-24: 3rem;
    }

    .nav-links {
        display: none;
    }

    .hero-cta {
        flex-direction: column;
    }

    .stats {
        flex-direction: column;
        gap: var(--space-8);
    }

    .footer-content {
        grid-template-columns: 1fr;
    }
}

/* ============== Utility Classes ============== */
.text-center {
    text-align: center;
}

.mt-0 { margin-top: 0; }
.mt-4 { margin-top: var(--space-4); }
.mt-8 { margin-top: var(--space-8); }
.mt-16 { margin-top: var(--space-16); }
.mt-24 { margin-top: var(--space-24); }

.mb-0 { margin-bottom: 0; }
.mb-4 { margin-bottom: var(--space-4); }
.mb-8 { margin-bottom: var(--space-8); }
.mb-16 { margin-bottom: var(--space-16); }
.mb-24 { margin-bottom: var(--space-24); }

.opacity-50 { opacity: 0.5; }
.opacity-70 { opacity: 0.7; }

/* ============== Image Modal ============== */
.image-modal {
    display: none;
    position: fixed;
    z-index: 9999;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgba(0, 0, 0, 0.9);
    align-items: center;
    justify-content: center;
}

.image-modal-content {
    max-width: 90%;
    max-height: 90vh;
    object-fit: contain;
    animation: zoomIn 0.3s;
}

.image-modal-close {
    position: absolute;
    top: 20px;
    right: 40px;
    color: #f1f1f1;
    font-size: 40px;
    font-weight: bold;
    cursor: pointer;
    transition: 0.3s;
}

.image-modal-close:hover,
.image-modal-close:focus {
    color: #bbb;
}

@keyframes zoomIn {
    from {
        transform: scale(0.8);
        opacity: 0;
    }
    to {
        transform: scale(1);
        opacity: 1;
    }
}