/* =============================================================================
   PROSILIENT — Stylesheet
   Dark theme, typography-forward, minimal
   ============================================================================= */

/* -----------------------------------------------------------------------------
   CSS Variables
   ----------------------------------------------------------------------------- */
:root {
    --color-bg-primary: #0a0a0a;
    --color-bg-secondary: #141414;
    --color-bg-tertiary: #1a1a1a;
    --color-text-primary: #f5f5f5;
    --color-text-secondary: #a0a0a0;
    --color-text-muted: #666666;
    --color-accent: #3b82f6;
    --color-accent-hover: #60a5fa;
    --color-accent-alt: #10b981;
    --color-border: #2a2a2a;
    --color-border-light: #333333;

    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;

    --max-width: 1200px;
    --max-width-narrow: 800px;

    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
}

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

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

body {
    font-family: var(--font-family);
    background-color: var(--color-bg-primary);
    color: var(--color-text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

ul {
    list-style: none;
}

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

/* -----------------------------------------------------------------------------
   Layout
   ----------------------------------------------------------------------------- */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

section {
    padding: var(--spacing-xl) 0;
}

/* -----------------------------------------------------------------------------
   Navigation
   ----------------------------------------------------------------------------- */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: rgba(10, 10, 10, 0.9);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
}

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

.nav-logo {
    font-size: 0.875rem;
    font-weight: 700;
    letter-spacing: 0.2em;
    color: var(--color-text-primary);
}

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

.nav-links {
    display: flex;
    gap: var(--spacing-md);
}

.nav-links a {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    transition: color var(--transition-fast);
}

.nav-links a:hover {
    color: var(--color-text-primary);
}

/* -----------------------------------------------------------------------------
   Hero Section
   ----------------------------------------------------------------------------- */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding-top: var(--spacing-xl);
}

.hero-title {
    font-size: clamp(2rem, 8vw, 4.5rem);
    font-weight: 900;
    letter-spacing: 0.3em;
    margin-bottom: var(--spacing-md);
    background: linear-gradient(180deg, var(--color-text-primary) 0%, var(--color-text-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-tagline {
    font-size: clamp(1.125rem, 3vw, 1.5rem);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
    font-weight: 400;
}

.hero-narrative {
    max-width: 600px;
    margin: 0 auto;
}

.hero-narrative p {
    font-size: 1.125rem;
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-sm);
    line-height: 1.8;
}

.hero-narrative p:last-child {
    color: var(--color-text-secondary);
    font-weight: 500;
}

/* -----------------------------------------------------------------------------
   Section Headers
   ----------------------------------------------------------------------------- */
.section-header {
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.section-header h2 {
    font-size: 0.875rem;
    font-weight: 700;
    letter-spacing: 0.3em;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-sm);
}

.section-header p {
    font-size: 1.125rem;
    color: var(--color-text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* -----------------------------------------------------------------------------
   Propositions Section
   ----------------------------------------------------------------------------- */
.propositions {
    background-color: var(--color-bg-secondary);
}

.propositions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
    gap: var(--spacing-md);
}

.proposition {
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: var(--spacing-md);
    transition: border-color var(--transition-normal);
}

.proposition:hover {
    border-color: var(--color-border-light);
}

.proposition h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-sm);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.proposition .position {
    font-size: 0.9375rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: var(--spacing-sm);
}

.proposition .sources {
    display: none;
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--color-border);
    margin-top: var(--spacing-sm);
}

.proposition[data-expanded="true"] .sources {
    display: block;
    animation: fadeIn 0.3s ease;
}

.proposition .sources h4 {
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.1em;
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-xs);
    text-transform: uppercase;
}

.proposition .sources ul {
    padding-left: var(--spacing-sm);
}

.proposition .sources li {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-xs);
    position: relative;
    padding-left: var(--spacing-sm);
}

.proposition .sources li::before {
    content: "—";
    position: absolute;
    left: 0;
    color: var(--color-text-muted);
}

.proposition .sources a {
    color: var(--color-accent);
}

.expand-toggle {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 0.8125rem;
    color: var(--color-text-muted);
    padding: var(--spacing-xs) 0;
    transition: color var(--transition-fast);
}

.expand-toggle:hover {
    color: var(--color-accent);
}

.expand-icon {
    transition: transform var(--transition-normal);
}

.proposition[data-expanded="true"] .expand-icon {
    transform: rotate(90deg);
}

.proposition[data-expanded="true"] .expand-text::after {
    content: " (hide)";
}

/* -----------------------------------------------------------------------------
   Tools Section
   ----------------------------------------------------------------------------- */
.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-md);
}

.tool-card {
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: var(--spacing-md);
    display: flex;
    flex-direction: column;
    transition: border-color var(--transition-normal), transform var(--transition-normal);
}

.tool-card:hover {
    border-color: var(--color-accent);
    transform: translateY(-4px);
}

.tool-header {
    margin-bottom: var(--spacing-sm);
}

.tool-header h3 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-xs);
}

.tool-tagline {
    font-size: 0.875rem;
    color: var(--color-accent-alt);
    font-weight: 500;
}

.tool-description {
    font-size: 0.9375rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: var(--spacing-sm);
}

.tool-highlight {
    font-size: 0.9375rem;
    color: var(--color-text-primary);
    font-style: italic;
    margin-bottom: var(--spacing-sm);
}

.tool-features {
    margin-bottom: var(--spacing-md);
    flex-grow: 1;
}

.tool-features li {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    padding: var(--spacing-xs) 0;
    padding-left: var(--spacing-sm);
    position: relative;
}

.tool-features li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--color-accent-alt);
    font-size: 0.75rem;
}

.tool-cta {
    display: inline-flex;
    align-items: center;
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--color-accent);
    transition: gap var(--transition-fast);
}

.tool-cta:hover {
    gap: var(--spacing-xs);
}

/* -----------------------------------------------------------------------------
   About Section
   ----------------------------------------------------------------------------- */
.about {
    background-color: var(--color-bg-secondary);
}

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

.about-content p {
    font-size: 1.125rem;
    color: var(--color-text-secondary);
    line-height: 1.8;
    margin-bottom: var(--spacing-md);
}

.about-coda {
    color: var(--color-text-muted) !important;
    font-style: italic;
    margin-top: var(--spacing-lg);
}

/* -----------------------------------------------------------------------------
   Footer
   ----------------------------------------------------------------------------- */
.footer {
    border-top: 1px solid var(--color-border);
    padding: var(--spacing-lg) 0;
    text-align: center;
}

.footer-brand {
    font-size: 0.875rem;
    font-weight: 700;
    letter-spacing: 0.3em;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-md);
}

.footer-nav {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.footer-nav a {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
}

.footer-contact {
    margin-bottom: var(--spacing-md);
}

.footer-contact a {
    font-size: 0.9375rem;
    color: var(--color-text-secondary);
}

.footer-legal {
    margin-bottom: var(--spacing-sm);
}

.footer-legal a {
    font-size: 0.8125rem;
    color: var(--color-text-muted);
}

.footer-legal .separator {
    color: var(--color-text-muted);
    margin: 0 var(--spacing-xs);
}

.footer-copyright {
    font-size: 0.8125rem;
    color: var(--color-text-muted);
}

/* -----------------------------------------------------------------------------
   Animations
   ----------------------------------------------------------------------------- */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(-8px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* -----------------------------------------------------------------------------
   Responsive
   ----------------------------------------------------------------------------- */
@media (max-width: 768px) {
    :root {
        --spacing-lg: 3rem;
        --spacing-xl: 4rem;
    }

    .nav-links {
        gap: var(--spacing-sm);
    }

    .hero-title {
        letter-spacing: 0.15em;
    }

    .propositions-grid,
    .tools-grid {
        grid-template-columns: 1fr;
    }

    .footer-nav {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
}

@media (max-width: 480px) {
    .nav-container {
        flex-direction: column;
        gap: var(--spacing-sm);
    }

    .hero-title {
        letter-spacing: 0.1em;
    }
}

/* -----------------------------------------------------------------------------
   Accessibility
   ----------------------------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus states */
a:focus-visible,
button:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

/* Screen reader only */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}