/* ==========================================================================
   toki suli — Promotional Website
   Minimalist black and white design
   ========================================================================== */

/* --------------------------------------------------------------------------
   CSS Variables
   -------------------------------------------------------------------------- */
:root {
    /* Colours - predominantly black and white */
    --color-black: #000000;
    --color-white: #ffffff;
    --color-gray-900: #111111;
    --color-gray-800: #1a1a1a;
    --color-gray-700: #333333;
    --color-gray-600: #4a4a4a;
    --color-gray-500: #666666;
    --color-gray-400: #888888;
    --color-gray-300: #b3b3b3;
    --color-gray-200: #d4d4d4;
    --color-gray-100: #f0f0f0;
    --color-gray-50: #f8f8f8;
    
    /* Typography */
    /* Adobe Fonts: Replace 'Inter' with your Adobe font, e.g.:
       - "source-sans-3", sans-serif (Source Sans 3)
       - "acumin-pro", sans-serif (Acumin Pro)
       - "neue-haas-grotesk-display", sans-serif (Neue Haas Grotesk)
    */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Segoe UI', Roboto, sans-serif;
    
    --font-size-xs: 0.75rem;    /* 12px */
    --font-size-sm: 0.875rem;   /* 14px */
    --font-size-base: 1rem;     /* 16px */
    --font-size-lg: 1.125rem;   /* 18px */
    --font-size-xl: 1.25rem;    /* 20px */
    --font-size-2xl: 1.5rem;    /* 24px */
    --font-size-3xl: 2rem;      /* 32px */
    --font-size-4xl: 2.5rem;    /* 40px */
    --font-size-5xl: 3.5rem;    /* 56px */
    
    --font-weight-light: 300;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    
    --line-height-tight: 1.2;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.75;
    
    /* Spacing */
    --space-1: 0.25rem;   /* 4px */
    --space-2: 0.5rem;    /* 8px */
    --space-3: 0.75rem;   /* 12px */
    --space-4: 1rem;      /* 16px */
    --space-5: 1.5rem;    /* 24px */
    --space-6: 2rem;      /* 32px */
    --space-8: 3rem;      /* 48px */
    --space-10: 4rem;     /* 64px */
    --space-12: 5rem;     /* 80px */
    --space-16: 8rem;     /* 128px */
    
    /* Container */
    --container-max: 1200px;
    --container-narrow: 800px;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-normal);
    line-height: var(--line-height-normal);
    color: var(--color-black);
    background-color: var(--color-white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

a:hover {
    opacity: 0.7;
}

ul {
    list-style: none;
}

/* --------------------------------------------------------------------------
   Container
   -------------------------------------------------------------------------- */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--space-5);
}

/* --------------------------------------------------------------------------
   Header & Navigation
   -------------------------------------------------------------------------- */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background-color: var(--color-white);
    border-bottom: 1px solid var(--color-gray-200);
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: var(--space-4) var(--space-5);
}

.nav-logo {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    letter-spacing: -0.02em;
}

.nav-links {
    display: flex;
    gap: var(--space-6);
}

.nav-links a {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    text-transform: lowercase;
}

/* --------------------------------------------------------------------------
   Hero Section
   -------------------------------------------------------------------------- */
.hero {
    padding: var(--space-16) 0 var(--space-12);
    margin-top: 60px; /* Account for fixed header */
    background-color: var(--color-white);
}

.hero-content {
    max-width: var(--container-narrow);
    margin: 0 auto;
    text-align: center;
}

.hero-logo {
    margin-bottom: var(--space-8);
}

.hero-logo img {
    margin: 0 auto;
    width: 50%;
    height: auto;
}

.logo-placeholder {
    width: 200px;
    height: 200px;
    margin: 0 auto;
    background-color: var(--color-gray-100);
    border: 2px dashed var(--color-gray-300);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-sm);
    color: var(--color-gray-500);
    border-radius: 24px;
}

.hero h1 {
    font-size: var(--font-size-5xl);
    font-weight: var(--font-weight-bold);
    line-height: var(--line-height-tight);
    letter-spacing: -0.03em;
    margin-bottom: var(--space-5);
}

.hero h1 .highlight {
    color: var(--color-gray-500);
}

.hero-tagline {
    font-size: var(--font-size-xl);
    color: var(--color-gray-600);
    max-width: 600px;
    margin: 0 auto var(--space-8);
    line-height: var(--line-height-relaxed);
}

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

/* --------------------------------------------------------------------------
   Buttons
   -------------------------------------------------------------------------- */
.btn {
    display: inline-block;
    padding: var(--space-3) var(--space-6);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    border-radius: 8px;
    transition: all var(--transition-fast);
    cursor: pointer;
    border: none;
}

.btn-primary {
    background-color: var(--color-black);
    color: var(--color-white);
}

.btn-primary:hover {
    background-color: var(--color-gray-800);
    opacity: 1;
}

.btn-secondary {
    background-color: var(--color-white);
    color: var(--color-black);
    border: 1px solid var(--color-black);
}

.btn-secondary:hover {
    background-color: var(--color-gray-100);
    opacity: 1;
}

/* --------------------------------------------------------------------------
   Sections
   -------------------------------------------------------------------------- */
.section {
    padding: var(--space-12) 0;
}

.section-header {
    text-align: center;
    margin-bottom: var(--space-10);
}

.section-header h2 {
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-bold);
    letter-spacing: -0.02em;
    margin-bottom: var(--space-2);
}

.section-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-gray-500);
}

/* --------------------------------------------------------------------------
   App Section
   -------------------------------------------------------------------------- */
.section-app {
    background-color: var(--color-gray-50);
}

.app-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-10);
    align-items: center;
}

.app-description h3 {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--space-4);
}

.app-description > p {
    font-size: var(--font-size-lg);
    color: var(--color-gray-600);
    line-height: var(--line-height-relaxed);
    margin-bottom: var(--space-6);
}

.language-list {
    margin-bottom: var(--space-6);
}

.language-list h4 {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-gray-500);
    margin-bottom: var(--space-3);
}

.language-list ul {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.language-list li {
    font-size: var(--font-size-base);
    color: var(--color-gray-700);
}

.language-list li strong {
    color: var(--color-black);
}

.app-store-badge {
    height: 48px;
    width: auto;
}

/* Screenshot placeholder */
.screenshot-placeholder {
    width: 100%;
    max-width: 300px;
    aspect-ratio: 9 / 19.5;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-sm);
    color: var(--color-gray-500);
    border-radius: 32px;
}

/* --------------------------------------------------------------------------
   Features Section
   -------------------------------------------------------------------------- */
.section-features {
    background-color: var(--color-white);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-6);
    margin-bottom: var(--space-10);
}

.feature {
    text-align: center;
    padding: var(--space-6);
}

.feature-icon {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--space-4);
}

.feature h3 {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--space-2);
}

.feature p {
    font-size: var(--font-size-sm);
    color: var(--color-gray-600);
}

.features-list {
    max-width: var(--container-narrow);
    margin: 0 auto;
    padding: var(--space-6);
    background-color: var(--color-gray-50);
    border-radius: 12px;
}

.features-list ul {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-3);
}

.features-list li {
    font-size: var(--font-size-base);
    color: var(--color-gray-700);
    padding-left: var(--space-5);
    position: relative;
}

.features-list li::before {
    content: '·';
    position: absolute;
    left: var(--space-2);
    font-weight: bold;
}

.features-list li strong {
    color: var(--color-black);
}

/* --------------------------------------------------------------------------
   Book Section
   -------------------------------------------------------------------------- */
.section-book {
    background-color: var(--color-black);
    color: var(--color-white);
}

.section-book .section-header h2 {
    color: var(--color-white);
}

.section-book .section-subtitle {
    color: var(--color-gray-400);
}

.book-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: var(--space-10);
    align-items: start;
}

.cover-placeholder {
    width: 100%;
    max-width: 300px;
    aspect-ratio: 1 / 1.5;
    margin: 0 auto;
    background-color: var(--color-gray-800);
    border: 2px dashed var(--color-gray-600);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-sm);
    color: var(--color-gray-500);
    border-radius: 4px;
}

.book-description h3 {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--space-2);
}

.book-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-gray-400);
    margin-bottom: var(--space-5);
}

.book-description > p {
    font-size: var(--font-size-base);
    color: var(--color-gray-300);
    line-height: var(--line-height-relaxed);
    margin-bottom: var(--space-4);
}

.book-features {
    margin: var(--space-6) 0;
    padding: var(--space-5);
    background-color: var(--color-gray-900);
    border-radius: 8px;
}

.book-features h4 {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-gray-400);
    margin-bottom: var(--space-3);
}

.book-features ul {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.book-features li {
    font-size: var(--font-size-sm);
    color: var(--color-gray-300);
    padding-left: var(--space-4);
    position: relative;
}

.book-features li::before {
    content: '·';
    position: absolute;
    left: 0;
    color: var(--color-gray-500);
}

.book-quote {
    font-size: var(--font-size-lg);
    font-style: italic;
    color: var(--color-gray-400);
    margin: var(--space-6) 0;
}

.book-cta {
    margin: var(--space-6) 0 var(--space-4);
}

.section-book .btn-primary {
    background-color: var(--color-white);
    color: var(--color-black);
}

.section-book .btn-primary:hover {
    background-color: var(--color-gray-200);
}

.book-formats {
    font-size: var(--font-size-sm);
    color: var(--color-gray-500);
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */
.footer {
    background-color: var(--color-white);
    border-top: 1px solid var(--color-gray-200);
    padding: var(--space-10) 0 var(--space-6);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--space-8);
}

.footer-logo {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    letter-spacing: -0.02em;
}

.footer-tagline {
    font-size: var(--font-size-sm);
    color: var(--color-gray-500);
    margin-top: var(--space-1);
}

.footer-links {
    display: flex;
    gap: var(--space-6);
}

.footer-links a {
    font-size: var(--font-size-sm);
    color: var(--color-gray-600);
}

.footer-bottom {
    text-align: center;
    padding-top: var(--space-6);
    border-top: 1px solid var(--color-gray-100);
}

.footer-bottom p {
    font-size: var(--font-size-sm);
    color: var(--color-gray-500);
}

/* --------------------------------------------------------------------------
   Responsive
   -------------------------------------------------------------------------- */
@media (max-width: 1024px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .hero {
        padding: var(--space-12) 0 var(--space-10);
    }
    
    .hero h1 {
        font-size: var(--font-size-4xl);
    }
    
    .hero-tagline {
        font-size: var(--font-size-lg);
    }
    
    .section-header h2 {
        font-size: var(--font-size-3xl);
    }
    
    .app-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .app-screenshot {
        order: -1;
    }
    
    .screenshot-placeholder {
        max-width: 200px;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
        gap: var(--space-4);
    }
    
    .feature {
        padding: var(--space-4);
    }
    
    .features-list ul {
        grid-template-columns: 1fr;
    }
    
    .book-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .cover-placeholder {
        max-width: 200px;
    }
    
    .book-features {
        text-align: left;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
        gap: var(--space-6);
    }
    
    .nav-links {
        gap: var(--space-4);
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: var(--font-size-3xl);
    }
    
    .hero-cta {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        text-align: center;
    }
    
    .logo-placeholder {
        width: 150px;
        height: 150px;
    }
}