:root {
    --white: #ffffff;
    --black: #1a1a1a;
    --text-gray: #2d2d2d;
    --light-gray: #e5e5e5;
    --medium-gray: #999999;
    --dark-gray: #666666;
    --border-gray: #d1d1d1;
}

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

body {
    font-family: 'Fraunces', serif;
    font-optical-sizing: auto;
    background: var(--white);
    color: var(--text-gray);
    line-height: 1.7;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Navigation */
nav {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid #f0f0f0;
    z-index: 1000;
    padding: 20px 0;
}

nav .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 28px;
    font-weight: 700;
    color: #1a1a1a;
    letter-spacing: -0.5px;
    cursor: pointer;
}

.nav-links {
    display: flex;
    gap: 40px;
    list-style: none;
}

.nav-links a {
    text-decoration: none;
    color: #666;
    font-size: 15px;
    font-weight: 500;
    transition: color 0.3s ease;
    cursor: pointer;
}

.nav-links a:hover {
    color: #1a1a1a;
}


/* Animated background */
.bg-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    opacity: 0.02;
    background: 
        radial-gradient(circle at 20% 50%, var(--light-gray) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, var(--light-gray) 0%, transparent 50%),
        radial-gradient(circle at 40% 80%, var(--light-gray) 0%, transparent 50%);
    animation: float 20s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    33% { transform: translate(30px, -30px) scale(1.1); }
    66% { transform: translate(-20px, 20px) scale(0.9); }
}

/* Header */
header {
    position: relative;
    padding: 3rem 2rem;
    text-align: center;
    border-bottom: 1px solid var(--border-gray);
    background: linear-gradient(180deg, var(--light-gray) 0%, transparent 100%);
    animation: slideDown 1s ease-out;
}

@keyframes slideDown {
    from { opacity: 0; transform: translateY(-30px); }
    to { opacity: 1; transform: translateY(0); }
}

.logo {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.9rem;
    font-weight: 600;
    letter-spacing: 3px;
    color: var(--black);
    text-transform: uppercase;
    margin-bottom: 1rem;
    opacity: 0;
    animation: fadeIn 1s ease-out 0.3s forwards;
}

@keyframes fadeIn {
    to { opacity: 1; }
}

/* Hero Section */
.hero {
    position: relative;
    padding: 5rem 2rem 3rem;
    max-width: 900px;
    margin: 0 auto;
    text-align: center;
}

h1 {
    font-size: clamp(2.5rem, 7vw, 5rem);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 2rem;
    color: var(--black);
    animation: slideUp 1s ease-out 0.5s backwards;
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(40px); }
    to { opacity: 1; transform: translateY(0); }
}

.subtitle {
    font-size: clamp(1.2rem, 3vw, 1.8rem);
    font-weight: 300;
    font-style: italic;
    color: var(--dark-gray);
    margin-bottom: 2.5rem;
    animation: slideUp 1s ease-out 0.7s backwards;
}

.meta {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.85rem;
    color: var(--medium-gray);
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
    animation: slideUp 1s ease-out 0.9s backwards;
}

.meta-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.meta-item::before {
    content: '◆';
    color: var(--dark-gray);
    font-size: 0.6rem;
}

/* Article Content */
article {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
    padding: 3rem 2rem 5rem;
}

.section {
    margin-bottom: 4rem;
    opacity: 0;
    animation: fadeInUp 1s ease-out forwards;
    animation-timeline: view();
    animation-range: entry 0% cover 30%;
}

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(30px); }
    to { opacity: 1; transform: translateY(0); }
}

h2 {
    font-size: clamp(1.8rem, 4vw, 2.5rem);
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--black);
    position: relative;
    padding-left: 2rem;
}

h2::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 4px;
    height: 80%;
    background: var(--dark-gray);
    border-radius: 2px;
}

h3 {
    font-size: clamp(1.3rem, 3vw, 1.7rem);
    font-weight: 600;
    margin: 2.5rem 0 1rem;
    color: var(--black);
}

p {
    font-size: 1.1rem;
    font-weight: 300;
    margin-bottom: 1.5rem;
    color: var(--text-gray);
}

/* Callout Box */
.callout {
    background: var(--light-gray);
    border-left: 4px solid var(--dark-gray);
    padding: 2rem;
    margin: 3rem 0;
    border-radius: 0 8px 8px 0;
    font-style: italic;
    font-size: 1.2rem;
    position: relative;
    overflow: hidden;
}

.callout::before {
    content: '"';
    position: absolute;
    top: -1rem;
    left: 1rem;
    font-size: 8rem;
    color: var(--border-gray);
    opacity: 0.3;
    font-family: Georgia, serif;
}

/* Stats Box */
.stats-box {
    background: var(--white);
    border: 2px solid var(--border-gray);
    padding: 2rem;
    margin: 3rem 0;
    border-radius: 8px;
}

.stat-item {
    margin-bottom: 1.5rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid var(--light-gray);
}

.stat-item:last-child {
    margin-bottom: 0;
    padding-bottom: 0;
    border-bottom: none;
}

.stat-label {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.85rem;
    color: var(--medium-gray);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 0.5rem;
}

.stat-value {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--black);
}

/* Lists */
ul {
    list-style: none;
    margin: 2rem 0;
}

ul li {
    /* position: relative; */
    padding-left: 2rem;
    margin-bottom: 1rem;
    font-size: 1.05rem;
    color: var(--text-gray);
}

ul li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--dark-gray);
    font-weight: 600;
}

/* Highlight Box */
.highlight-box {
    background: var(--light-gray);
    border: 1px solid var(--border-gray);
    padding: 2rem;
    margin: 3rem 0;
    border-radius: 8px;
}

.highlight-box h3 {
    color: var(--black);
    margin-top: 0;
}

/* Principles Grid */
.principles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin: 3rem 0;
}

.principle-card {
    background: var(--white);
    border: 1px solid var(--border-gray);
    padding: 2rem;
    border-radius: 12px;
    transition: all 0.3s ease;
}

.principle-card:hover {
    transform: translateY(-5px);
    border-color: var(--dark-gray);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.1);
}

.principle-number {
    font-family: 'IBM Plex Mono', monospace;
    color: var(--dark-gray);
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.principle-card h4 {
    font-size: 1.4rem;
    margin-bottom: 1rem;
    color: var(--black);
}

.principle-card p {
    font-size: 1rem;
    color: var(--text-gray);
}

/* Challenge Cards */
.challenge-grid {
    display: grid;
    gap: 2rem;
    margin: 3rem 0;
}

.challenge-card {
    background: var(--white);
    border: 1px solid var(--border-gray);
    padding: 2rem;
    border-radius: 12px;
    transition: all 0.3s ease;
}

.challenge-card:hover {
    transform: translateY(-5px);
    border-color: var(--dark-gray);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.1);
}

.challenge-number {
    font-family: 'IBM Plex Mono', monospace;
    color: var(--dark-gray);
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.challenge-card h3 {
    font-size: 1.5rem;
    margin: 0 0 1rem 0;
    color: var(--black);
}

.challenge-problem {
    font-weight: 600;
    color: var(--black);
    margin-bottom: 1rem;
}

.solution-label {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.85rem;
    color: var(--medium-gray);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin: 1.5rem 0 1rem 0;
}

/* Feature Grid */
.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin: 3rem 0;
}

.feature-item {
    padding: 1.5rem;
    border: 1px solid var(--border-gray);
    border-radius: 8px;
    transition: all 0.3s ease;
}

.feature-item:hover {
    border-color: var(--dark-gray);
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
}

.feature-number {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 2rem;
    font-weight: 600;
    color: var(--dark-gray);
    margin-bottom: 1rem;
}

.feature-item h4 {
    font-size: 1.2rem;
    margin-bottom: 0.75rem;
    color: var(--black);
}

.feature-item p {
    font-size: 1rem;
    color: var(--text-gray);
}

/* Table */
.sensor-table {
    width: 100%;
    margin: 2rem 0;
    border-collapse: separate;
    border-spacing: 0;
    overflow: hidden;
    border-radius: 8px;
    background: var(--white);
    border: 1px solid var(--border-gray);
}

.sensor-table th {
    background: var(--light-gray);
    padding: 1.5rem 1rem;
    text-align: left;
    font-weight: 600;
    color: var(--black);
    font-size: 0.95rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.sensor-table td {
    padding: 1.5rem 1rem;
    border-top: 1px solid var(--border-gray);
    color: var(--text-gray);
}

.sensor-table tr:hover {
    background: var(--light-gray);
}

/* Checklist */
.checklist {
    background: var(--light-gray);
    padding: 2rem;
    margin: 3rem 0;
    border-radius: 8px;
}

.checklist li {
    padding-left: 2.5rem;
    margin-bottom: 1.5rem;
}

.checklist li::before {
    content: '✓';
    left: 0.5rem;
    font-weight: 600;
    font-size: 1.2rem;
}

/* Footer CTA */
.cta-section {
    margin-top: 6rem;
    padding: 4rem 2rem;
    text-align: center;
    background: var(--light-gray);
    border-radius: 16px;
    border: 1px solid var(--border-gray);
}

.cta-section h2 {
    padding-left: 0;
    margin-bottom: 1rem;
}

.cta-section h2::before {
    display: none;
}

.cta-section p {
    font-size: 1.2rem;
    max-width: 600px;
    margin: 0 auto 2rem;
}

.tagline {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.9rem;
    color: var(--medium-gray);
    margin-top: 2rem;
    letter-spacing: 2px;
}

/* Footer */
footer {
    position: relative;
    padding: 3rem 2rem;
    text-align: center;
    border-top: 1px solid var(--border-gray);
    margin-top: 5rem;
}

footer p {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.85rem;
    color: var(--medium-gray);
}

/* Responsive */
@media (max-width: 768px) {
    .hero {
        padding: 3rem 1.5rem 2rem;
    }

    .principles-grid {
        grid-template-columns: 1fr;
    }

    h2 {
        padding-left: 1.5rem;
    }

    .meta {
        gap: 1rem;
    }

    .feature-grid {
        grid-template-columns: 1fr;
    }
}

/* Scroll indicator */
.scroll-indicator {
    position: fixed;
    top: 0;
    left: 0;
    height: 4px;
    background: var(--dark-gray);
    width: 0%;
    z-index: 1000;
    transition: width 0.1s ease;
}

strong {
    font-weight: 600;
    color: var(--black);
}