/* Modern CSS with NSF-proposal inspired design */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&display=swap');

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary: #64748b;
    --accent: #0ea5e9;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --dark: #0f172a;
    --light: #f8fafc;
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1e293b;
    --gray-900: #0f172a;
    --white: #ffffff;
    --gradient-primary: linear-gradient(135deg, #2563eb, #0ea5e9);
    --gradient-secondary: linear-gradient(135deg, #8b5cf6, #ec4899);
    --gradient-success: linear-gradient(135deg, #10b981, #06b6d4);
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    --radius: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    line-height: 1.6;
    color: var(--gray-800);
    background: var(--white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4 {
    line-height: 1.2;
    font-weight: 700;
    color: var(--gray-900);
}

h1 { font-size: 3rem; margin-bottom: 1.5rem; }
h2 { font-size: 2.5rem; margin-bottom: 1.5rem; }
h3 { font-size: 1.5rem; margin-bottom: 1rem; }
h4 { font-size: 1.125rem; margin-bottom: 0.75rem; }

p { 
    margin-bottom: 1rem; 
    color: var(--gray-600);
    line-height: 1.7;
}

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

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

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* Header */
header {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--gray-200);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    transition: var(--transition);
}

header.scrolled {
    box-shadow: var(--shadow-md);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
}

.nav-brand a {
    font-size: 1.5rem;
    font-weight: 800;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-menu a {
    color: var(--gray-700);
    font-weight: 500;
    position: relative;
    transition: var(--transition);
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-primary);
    transition: var(--transition);
}

.nav-menu a:hover::after,
.nav-menu a.active::after {
    width: 100%;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--primary);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--gray-700);
    transition: var(--transition);
    border-radius: 2px;
}

/* Main Content */
main {
    margin-top: 80px;
}

/* Hero Section */
.hero {
    background: var(--gradient-primary);
    color: var(--white);
    padding: 6rem 0;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: -50%;
    width: 200%;
    height: 100%;
    background: linear-gradient(45deg, transparent 30%, rgba(255,255,255,0.1) 50%, transparent 70%);
    animation: shine 3s infinite;
}

@keyframes shine {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(100%); }
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    color: var(--white);
    text-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.tagline {
    font-size: 1.25rem;
    opacity: 0.95;
    margin-bottom: 2.5rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

/* Lead Text */
.lead {
    font-size: 1.125rem;
    color: var(--gray-600);
    max-width: 800px;
    margin: 0 auto 2rem;
    line-height: 1.8;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.875rem 2rem;
    border-radius: var(--radius-lg);
    font-weight: 600;
    font-size: 0.875rem;
    letter-spacing: 0.025em;
    transition: var(--transition);
    border: 2px solid transparent;
    cursor: pointer;
    text-transform: uppercase;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255,255,255,0.5);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.btn:hover::before {
    width: 300px;
    height: 300px;
}

.btn-primary {
    background: var(--white);
    color: var(--primary);
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: transparent;
    color: var(--white);
    border-color: rgba(255,255,255,0.3);
}

.btn-secondary:hover {
    background: rgba(255,255,255,0.1);
    border-color: var(--white);
    transform: translateY(-2px);
}

.btn-outline {
    background: transparent;
    color: var(--primary);
    border: 2px solid var(--primary);
}

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

.btn-link {
    color: var(--primary);
    font-weight: 600;
    padding: 0;
    border: none;
    background: none;
    text-transform: none;
}

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

/* Sections */
section {
    padding: 5rem 0;
    position: relative;
}

.page-header {
    background: var(--gradient-primary);
    color: var(--white);
    padding: 4rem 0 3rem;
    text-align: center;
}

.page-header h1 {
    color: var(--white);
    font-weight: 800;
    text-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.page-header .lead {
    color: rgba(255,255,255,0.9);
    max-width: 600px;
}

section h2 {
    text-align: center;
    font-weight: 800;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 3rem;
}

.intro {
    text-align: center;
    padding: 3rem 0;
}

/* Features Grid */
.features {
    background: var(--gray-50);
}

.grid {
    display: grid;
    gap: 2rem;
    margin: 2rem 0;
}

.grid-2 { grid-template-columns: repeat(auto-fit, minmax(350px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }

.feature {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 1px solid var(--gray-200);
    text-align: center;
}

.feature:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary);
}

.feature h3 {
    color: var(--primary);
    margin-bottom: 1rem;
}

/* Cards */
.card {
    background: var(--white);
    border-radius: var(--radius-xl);
    padding: 2rem;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    border: 1px solid var(--gray-200);
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gradient-primary);
    transform: scaleX(0);
    transition: var(--transition);
}

.card:hover::before {
    transform: scaleX(1);
}

.card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-xl);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.card-header h3 {
    font-weight: 700;
}

.card-actions {
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--gray-200);
    display: flex;
    gap: 1rem;
    align-items: center;
}

/* Tags */
.tag {
    display: inline-block;
    padding: 0.375rem 0.875rem;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    transition: var(--transition);
}

.tag-data { 
    background: linear-gradient(135deg, #3b82f6, #06b6d4);
    color: var(--white);
}

.tag-benchmark { 
    background: linear-gradient(135deg, #ec4899, #f97316);
    color: var(--white);
}

.tag-method { 
    background: linear-gradient(135deg, #10b981, #84cc16);
    color: var(--white);
}

.tag-review { 
    background: linear-gradient(135deg, #f59e0b, #fbbf24);
    color: var(--white);
}

.tag-draft { 
    background: linear-gradient(135deg, #6b7280, #9ca3af);
    color: var(--white);
}

/* Callout Box */
.callout {
    text-align: center;
    padding: 2rem 0;
}

.callout-box {
    background: var(--gradient-primary);
    color: var(--white);
    padding: 3rem;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    position: relative;
    overflow: hidden;
}

.callout-box::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: pulse 3s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.1); }
}

.callout-box h2 {
    color: var(--white);
    background: none;
    -webkit-text-fill-color: var(--white);
    margin-bottom: 1rem;
}

.callout-box p {
    color: rgba(255,255,255,0.9);
    margin-bottom: 2rem;
}

/* Content Sections */
.content {
    max-width: 900px;
    margin: 0 auto;
}

.content h2 {
    text-align: left;
    margin-top: 3rem;
}

.content h3 {
    color: var(--gray-800);
    margin-top: 2rem;
}

.content ul {
    margin: 1rem 0 2rem 1.5rem;
}

.content ul li {
    margin-bottom: 0.75rem;
    color: var(--gray-600);
}

/* Data Tiers */
.tier-card {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    border: 2px solid var(--gray-200);
    transition: var(--transition);
}

.tier-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.tier-card h3 {
    color: var(--primary);
}

/* Tables */
table {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0;
    margin: 2rem 0;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow);
}

th {
    background: var(--gradient-primary);
    color: var(--white);
    padding: 1rem;
    text-align: left;
    font-weight: 600;
}

td {
    padding: 1rem;
    border-bottom: 1px solid var(--gray-200);
    color: var(--gray-700);
}

tr:hover td {
    background: var(--gray-50);
}

/* Code Blocks */
pre {
    background: var(--gray-900);
    color: var(--gray-100);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    overflow-x: auto;
    margin: 1.5rem 0;
    font-family: 'Courier New', monospace;
    box-shadow: var(--shadow-lg);
}

code {
    background: var(--gray-100);
    color: var(--primary);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.875rem;
}

pre code {
    background: none;
    color: inherit;
    padding: 0;
}

.bibtex {
    background: linear-gradient(135deg, var(--gray-50), var(--gray-100));
    border-left: 4px solid var(--primary);
}

/* Working Groups */
.working-group {
    background: var(--white);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    border: 1px solid var(--gray-200);
    transition: var(--transition);
}

.working-group:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--primary);
}

.working-group h4 {
    color: var(--primary);
}

/* Ladder Steps */
.ladder {
    margin: 2rem 0;
}

.ladder-step {
    padding: 2rem;
    margin-bottom: 1.5rem;
    background: var(--white);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--primary);
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.ladder-step:hover {
    transform: translateX(8px);
    box-shadow: var(--shadow-lg);
}

.ladder-step h3 {
    color: var(--primary);
    margin-bottom: 0.5rem;
}

/* Publications */
.publication {
    padding: 2rem 0;
    border-bottom: 1px solid var(--gray-200);
}

.publication:hover {
    background: var(--gray-50);
}

.authors {
    color: var(--gray-500);
    font-style: italic;
}

.venue {
    color: var(--gray-600);
    margin: 0.5rem 0;
}

.doi a {
    color: var(--primary);
    font-weight: 500;
}

/* Community Cards */
.community-channel {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--radius-xl);
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    border: 1px solid var(--gray-200);
}

.community-channel:hover {
    transform: translateY(-6px) rotate(-1deg);
    box-shadow: var(--shadow-xl);
}

/* Events */
.event {
    background: linear-gradient(135deg, var(--gray-50), var(--white));
    padding: 2rem;
    margin-bottom: 1.5rem;
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--accent);
    box-shadow: var(--shadow);
}

/* Maintainer Cards */
.maintainers-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
}

.maintainer-card {
    background: var(--white);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    transition: var(--transition);
    border-top: 3px solid var(--primary);
}

.maintainer-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

/* Inquiry Cards */
.inquiry-types {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
}

.inquiry-card {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--radius-lg);
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.inquiry-card:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-xl);
}

/* Footer */
footer {
    background: var(--gray-900);
    color: var(--gray-300);
    padding: 3rem 0 1rem;
    margin-top: 5rem;
}

footer p {
    color: var(--gray-400);
    text-align: center;
    margin: 0;
}

footer a {
    color: var(--gray-300);
}

footer a:hover {
    color: var(--white);
}

/* Mobile Responsive */
@media (max-width: 768px) {
    h1 { font-size: 2rem; }
    h2 { font-size: 1.75rem; }
    
    .hero h1 { font-size: 2.5rem; }
    
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--white);
        flex-direction: column;
        padding: 1rem;
        box-shadow: var(--shadow-xl);
        border-radius: 0 0 var(--radius-lg) var(--radius-lg);
    }
    
    .nav-menu.active {
        display: flex;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .nav-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }
    
    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }
    
    .hero-actions {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        width: 100%;
        max-width: 300px;
    }
    
    .grid-2, .grid-3 {
        grid-template-columns: 1fr;
    }
    
    table {
        font-size: 0.875rem;
    }
    
    th, td {
        padding: 0.75rem 0.5rem;
    }
}

/* Loading Animation */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.card, .feature, .tier-card, .community-channel {
    animation: fadeIn 0.6s ease-out;
}

/* Smooth Scrolling */
@media (prefers-reduced-motion: no-preference) {
    html { scroll-behavior: smooth; }
}

/* Focus Styles */
*:focus {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

/* Print Styles */
@media print {
    header, footer, .nav-toggle, .hero-actions {
        display: none;
    }
    
    main {
        margin-top: 0;
    }
    
    .card, .feature {
        break-inside: avoid;
    }
}