/* CSS Variables for Color Scheme */
:root {
    /* Dark Background Colors */
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-tertiary: #3a3a3a;
    --bg-card: #252525;
    
    /* Accent Colors */
    --accent-olive: #6b7c32;      /* Military olive green */
    --accent-olive-light: #8a9d4a;
    --accent-orange: #cc7a3a;     /* Matte orange */
    --accent-orange-light: #e6944d;
    
    /* Text Colors */
    --text-primary: #ffffff;
    --text-secondary: #b0b0b0;
    --text-muted: #808080;
    
    /* Border Colors */
    --border-primary: #404040;
    --border-secondary: #555555;
    
    /* Status Colors */
    --success: #4caf50;
    --warning: #ff9800;
    --error: #f44336;
    
    /* Fonts */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-xxl: 4rem;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    
    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 16px rgba(0, 0, 0, 0.5);
}

/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

body {
    font-family: var(--font-primary);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(26, 26, 26, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-primary);
    z-index: 1000;
    transition: all 0.3s ease;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.nav-logo {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-olive);
}

.logo-subtitle {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-top: -4px;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-lg);
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--accent-orange);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-orange);
    transition: width 0.3s ease;
}

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

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    transition: all 0.3s ease;
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding: var(--spacing-xxl) 0;
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 30% 70%, rgba(107, 124, 50, 0.1) 0%, transparent 50%),
                radial-gradient(circle at 70% 30%, rgba(204, 122, 58, 0.1) 0%, transparent 50%);
    pointer-events: none;
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xxl);
    align-items: center;
    position: relative;
    z-index: 2;
}

.hero-title {
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: var(--spacing-md);
}

.title-main {
    display: block;
    background: linear-gradient(135deg, var(--accent-olive) 0%, var(--accent-orange) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.title-sub {
    display: block;
    font-size: 0.6em;
    color: var(--text-secondary);
    font-weight: 400;
    margin-top: var(--spacing-sm);
}

.hero-description {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    line-height: 1.7;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.btn {
    padding: var(--spacing-md) var(--spacing-xl);
    border: none;
    border-radius: var(--radius-lg);
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent-olive) 0%, var(--accent-olive-light) 100%);
    color: white;
    box-shadow: var(--shadow-md);
}

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

.btn-secondary {
    background: transparent;
    color: var(--accent-orange);
    border: 2px solid var(--accent-orange);
}

.btn-secondary:hover {
    background: var(--accent-orange);
    color: white;
}

.btn-export {
    background: linear-gradient(135deg, var(--accent-olive), var(--accent-orange));
    color: white;
    margin-left: 10px;
    position: relative;
    overflow: hidden;
}

.btn-export:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(107, 124, 50, 0.3);
}

.btn-export:active {
    transform: translateY(0);
}

.btn-export::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
    transition: left 0.5s;
}

.btn-export:hover::before {
    left: 100%;
}

.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.circuit-animation {
    width: 400px;
    height: 300px;
    position: relative;
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    border: 2px solid var(--border-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.esp32-board {
    width: 120px;
    height: 80px;
    background: linear-gradient(135deg, var(--accent-olive) 0%, var(--accent-olive-light) 100%);
    border-radius: var(--radius-md);
    position: relative;
    z-index: 2;
}

.esp32-board::before {
    content: 'ESP32';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: white;
    font-weight: 600;
    font-size: 0.9rem;
}

/* Section Titles */
.section-title {
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 700;
    text-align: center;
    margin-bottom: var(--spacing-xxl);
    background: linear-gradient(135deg, var(--accent-olive) 0%, var(--accent-orange) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Overview Section */
.overview {
    padding: var(--spacing-xxl) 0;
    background: var(--bg-secondary);
}

.overview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-xl);
}

.protocol-card {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    border: 2px solid var(--border-primary);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.protocol-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--accent-olive) 0%, var(--accent-orange) 100%);
}

.protocol-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent-olive);
}

.card-icon {
    width: 60px;
    height: 60px;
    margin-bottom: var(--spacing-md);
    color: var(--accent-olive);
}

.card-icon svg {
    width: 100%;
    height: 100%;
}

.protocol-card h3 {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    color: var(--accent-orange);
}

.protocol-card p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    font-size: 1.1rem;
}

.protocol-card ul {
    list-style: none;
}

.protocol-card li {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
    position: relative;
    padding-left: var(--spacing-md);
}

.protocol-card li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--accent-olive);
    font-weight: bold;
}

/* Connections Section */
.connections {
    padding: var(--spacing-xxl) 0;
    background: var(--bg-primary);
}

.connection-visual {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xxl);
    align-items: center;
}

.esp32-diagram {
    position: relative;
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    border: 2px solid var(--border-primary);
}

.esp32-image {
    width: 100%;
    height: auto;
    border-radius: var(--radius-md);
    filter: brightness(0.9) contrast(1.1);
}

.pin-labels {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    pointer-events: none;
}

.pin-label {
    position: absolute;
    background: var(--bg-primary);
    color: var(--text-primary);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 600;
    border: 2px solid;
}

.uart-pin {
    border-color: var(--accent-orange);
    color: var(--accent-orange);
}

.i2c-pin {
    border-color: var(--accent-olive);
    color: var(--accent-olive);
}

.sensors-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-md);
}

.sensor-item {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    text-align: center;
    border: 2px solid var(--border-primary);
    transition: all 0.3s ease;
}

.sensor-item:hover {
    border-color: var(--accent-olive);
    transform: translateY(-3px);
}

.sensor-item img {
    width: 80px;
    height: 80px;
    object-fit: cover;
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-sm);
}

.sensor-item span {
    display: block;
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-weight: 500;
}

/* Protocol Sections */
.uart-section,
.i2c-section {
    padding: var(--spacing-xxl) 0;
}

.uart-section {
    background: var(--bg-secondary);
}

.i2c-section {
    background: var(--bg-primary);
}

.protocol-explanation {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xxl);
    margin-bottom: var(--spacing-xxl);
    align-items: center;
}

.explanation-text h3 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    color: var(--accent-orange);
}

.explanation-text p {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
    line-height: 1.7;
}

.features-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.feature {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--accent-olive);
}

.feature-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.feature strong {
    color: var(--accent-orange);
}

/* UART Visualization */
.uart-visualization {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    border: 2px solid var(--border-primary);
}

.signal-diagram {
    position: relative;
}

.signal-line {
    display: flex;
    height: 60px;
    border: 2px solid var(--border-secondary);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.bit {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    font-weight: 600;
    border-right: 1px solid var(--border-secondary);
    position: relative;
}

.start-bit,
.stop-bit {
    background: var(--accent-orange);
    color: white;
}

.data-bit {
    background: var(--accent-olive);
    color: white;
}

.data-bit:nth-child(even) {
    background: var(--accent-olive-light);
}

.signal-labels {
    text-align: center;
    margin-top: var(--spacing-sm);
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* I2C Visualization */
.i2c-visualization {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    border: 2px solid var(--border-primary);
}

.bus-diagram {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.bus-line {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.line-label {
    width: 100px;
    font-weight: 600;
    color: var(--accent-olive);
}

.signal-wave,
.clock-signal {
    flex: 1;
    height: 40px;
    background: var(--bg-secondary);
    border-radius: var(--radius-sm);
    position: relative;
    overflow: hidden;
}

.signal-wave::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--accent-orange);
    transform: translateY(-50%);
}

.clock-signal::before {
    content: '';
    position: absolute;
    top: 20%;
    left: 0;
    right: 0;
    height: 60%;
    background: repeating-linear-gradient(
        90deg,
        var(--accent-olive) 0px,
        var(--accent-olive) 20px,
        transparent 20px,
        transparent 40px
    );
}

/* Detail Cards */
.uart-details,
.i2c-details {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: var(--spacing-xl);
}

.detail-card {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    border: 2px solid var(--border-primary);
}

.detail-card h4 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    color: var(--accent-orange);
}

/* Connection Diagram */
.connection-diagram {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-md);
}

.device {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    text-align: center;
    border: 2px solid var(--border-secondary);
    min-width: 120px;
}

.device span {
    display: block;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.pins {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.pin {
    padding: var(--spacing-xs);
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 600;
}

.pin.tx {
    background: var(--accent-orange);
    color: white;
}

.pin.rx {
    background: var(--accent-olive);
    color: white;
}

.pin.gnd {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
}

.wires {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
    flex: 1;
}

.wire {
    height: 3px;
    border-radius: 2px;
}

.tx-wire {
    background: var(--accent-orange);
}

.rx-wire {
    background: var(--accent-olive);
}

.gnd-wire {
    background: var(--text-muted);
}

/* Configuration Options */
.config-options {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-md);
}

.config-item {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.config-item label {
    font-weight: 600;
    color: var(--text-primary);
}

.config-select {
    padding: var(--spacing-sm);
    border: 2px solid var(--border-primary);
    border-radius: var(--radius-md);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 1rem;
}

.config-select:focus {
    outline: none;
    border-color: var(--accent-olive);
}

/* Bus Topology */
.bus-topology {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    align-items: center;
}

.master-device {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    text-align: center;
    border: 2px solid var(--accent-olive);
    min-width: 150px;
}

.master-device span {
    display: block;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--accent-olive);
}

.device-pins {
    display: flex;
    gap: var(--spacing-sm);
    justify-content: center;
}

.pin.sda {
    background: var(--accent-orange);
    color: white;
}

.pin.scl {
    background: var(--accent-olive);
    color: white;
}

.bus-lines {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    width: 100%;
    position: relative;
}

.bus-line {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-sm);
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    border: 2px solid var(--border-secondary);
}

.pullup-resistor {
    background: var(--accent-orange);
    color: white;
    padding: var(--spacing-xs);
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 600;
}

.slave-devices {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
    justify-content: center;
}

.slave-device {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    text-align: center;
    border: 2px solid var(--border-secondary);
    min-width: 100px;
}

.slave-device span {
    display: block;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.address {
    background: var(--accent-olive);
    color: white;
    padding: var(--spacing-xs);
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 600;
}

/* Communication Flow */
.communication-flow {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.flow-step {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--accent-olive);
}

.step-number {
    width: 30px;
    height: 30px;
    background: var(--accent-orange);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    flex-shrink: 0;
}

.step-content strong {
    color: var(--accent-orange);
    display: block;
    margin-bottom: var(--spacing-xs);
}

.step-content p {
    color: var(--text-secondary);
    margin: 0;
}

/* Comparison Section */
.comparison {
    padding: var(--spacing-xxl) 0;
    background: var(--bg-secondary);
}

.comparison-table {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    overflow: hidden;
    border: 2px solid var(--border-primary);
}

.table-header {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    background: var(--bg-tertiary);
}

.header-cell {
    padding: var(--spacing-lg);
    font-weight: 700;
    text-align: center;
    border-right: 1px solid var(--border-primary);
}

.uart-header {
    color: var(--accent-orange);
}

.i2c-header {
    color: var(--accent-olive);
}

.table-row {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    border-bottom: 1px solid var(--border-primary);
}

.table-row:last-child {
    border-bottom: none;
}

.cell {
    padding: var(--spacing-md) var(--spacing-lg);
    border-right: 1px solid var(--border-primary);
    display: flex;
    align-items: center;
}

.property {
    font-weight: 600;
    color: var(--text-primary);
    background: var(--bg-secondary);
}

.uart-cell {
    color: var(--text-secondary);
    background: rgba(204, 122, 58, 0.05);
}

.i2c-cell {
    color: var(--text-secondary);
    background: rgba(107, 124, 50, 0.05);
}

/* Examples Section */
.examples {
    padding: var(--spacing-xxl) 0;
    background: var(--bg-primary);
}

.examples-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-xl);
}

.example-card {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    overflow: hidden;
    border: 2px solid var(--border-primary);
    transition: all 0.3s ease;
}

.example-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.uart-example {
    border-top: 4px solid var(--accent-orange);
}

.i2c-example {
    border-top: 4px solid var(--accent-olive);
}

.example-header {
    padding: var(--spacing-lg);
    background: var(--bg-secondary);
}

.example-header h4 {
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.example-header p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.code-block {
    background: var(--bg-primary);
    padding: var(--spacing-lg);
    font-family: 'Fira Code', 'Monaco', 'Consolas', monospace;
    font-size: 0.9rem;
    line-height: 1.5;
    overflow-x: auto;
}

.code-block pre {
    margin: 0;
    color: var(--text-primary);
}

/* Syntax highlighting */
.keyword {
    color: #ff7b72;
}

.string {
    color: #a5d6ff;
}

.comment {
    color: #8b949e;
    font-style: italic;
}

.number {
    color: #79c0ff;
}

.function {
    color: #d2a8ff;
}

.variable {
    color: #ffa657;
}

/* Footer */
.footer {
    background: var(--bg-tertiary);
    padding: var(--spacing-xxl) 0 var(--spacing-lg);
    border-top: 1px solid var(--border-primary);
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
}

.footer-section h4 {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    color: var(--accent-orange);
}

.footer-section p,
.footer-section li {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
    line-height: 1.6;
}

.footer-section ul {
    list-style: none;
}

.footer-section a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-section a:hover {
    color: var(--accent-orange);
}

.footer-bottom {
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--border-primary);
    text-align: center;
    color: var(--text-muted);
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        height: calc(100vh - 70px);
        background: var(--bg-primary);
        flex-direction: column;
        justify-content: flex-start;
        align-items: center;
        padding-top: var(--spacing-xxl);
        transition: left 0.3s ease;
    }

    .nav-menu.active {
        left: 0;
    }

    .hamburger {
        display: flex;
    }

    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
        gap: var(--spacing-xl);
    }

    .hero-visual {
        order: -1;
    }

    .circuit-animation {
        width: 300px;
        height: 200px;
    }

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

    .connection-visual {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }

    .protocol-explanation {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }

    .uart-details,
    .i2c-details {
        grid-template-columns: 1fr;
    }

    .table-header,
    .table-row {
        grid-template-columns: 1fr;
    }

    .cell {
        border-right: none;
        border-bottom: 1px solid var(--border-primary);
    }

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

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

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }

    .nav-container {
        padding: 0 var(--spacing-sm);
    }

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

    .hero-content {
        padding: 0 var(--spacing-sm);
    }

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .btn {
        width: 100%;
        justify-content: center;
    }

    .circuit-animation {
        width: 250px;
        height: 150px;
    }

    .esp32-board {
        width: 80px;
        height: 50px;
    }

    .esp32-board::before {
        font-size: 0.7rem;
    }
}

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

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

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

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
}

/* Animation classes */
.fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}

.slide-in-left {
    animation: slideInLeft 0.6s ease-out;
}

.slide-in-right {
    animation: slideInRight 0.6s ease-out;
}

.pulse-animation {
    animation: pulse 2s infinite;
}

/* Scroll animations */
.animate-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease-out;
}

.animate-on-scroll.animated {
    opacity: 1;
    transform: translateY(0);
}

/* Loading states */
.loading {
    position: relative;
    overflow: hidden;
}

.loading::after {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.1), transparent);
    animation: shimmer 1.5s infinite;
}

@keyframes shimmer {
    0% {
        left: -100%;
    }
    100% {
        left: 100%;
    }
}

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

.text-left {
    text-align: left;
}

.text-right {
    text-align: right;
}

.mb-0 {
    margin-bottom: 0;
}

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

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

.mb-lg {
    margin-bottom: var(--spacing-lg);
}

.mt-0 {
    margin-top: 0;
}

.mt-sm {
    margin-top: var(--spacing-sm);
}

.mt-md {
    margin-top: var(--spacing-md);
}

.mt-lg {
    margin-top: var(--spacing-lg);
}

.hidden {
    display: none;
}

.visible {
    display: block;
}

/* Filter buttons - keeping existing functionality */
.filter-section {
    text-align: center;
    margin-bottom: var(--spacing-xxl);
}

.filter-section h2 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    color: var(--accent-orange);
}

.filter-buttons {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.filter-btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    border: 2px solid var(--border-primary);
    background: var(--bg-card);
    color: var(--text-secondary);
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 500;
}

.filter-btn:hover,
.filter-btn.active {
    background: var(--accent-olive);
    color: white;
    border-color: var(--accent-olive);
    transform: translateY(-2px);
}

/* Projects grid - improved design */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(380px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-xl);
}

.project-card {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    overflow: hidden;
    border: 2px solid var(--border-primary);
    transition: all 0.3s ease;
    position: relative;
    display: flex;
    flex-direction: column;
    height: 100%;
}

.project-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent-olive);
}

.project-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--accent-olive) 0%, var(--accent-orange) 100%);
}

.project-image {
    position: relative;
    padding: var(--spacing-lg);
    background: var(--bg-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 80px;
}

.project-favicon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-md);
    flex-shrink: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-primary);
    border: 2px solid var(--border-primary);
}

.external-indicator {
    position: absolute;
    top: var(--spacing-sm);
    right: var(--spacing-sm);
    width: 20px;
    height: 20px;
    color: var(--accent-olive);
    opacity: 0.7;
}

.project-content {
    padding: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    flex-grow: 1;
}

.project-header {
    margin-bottom: var(--spacing-md);
}

.project-title {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--text-primary);
    margin: 0 0 var(--spacing-xs) 0;
    line-height: 1.3;
}

.project-category {
    display: inline-block;
    background: var(--accent-olive);
    color: white;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 600;
}

.project-description {
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: var(--spacing-md);
    flex-grow: 1;
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-lg);
}

.tag {
    background: var(--bg-secondary);
    color: var(--text-secondary);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 500;
    border: 1px solid var(--border-primary);
}

.project-actions {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: auto;
}

.project-btn {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.project-btn svg {
    width: 16px;
    height: 16px;
}

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

.btn-primary:hover {
    background: var(--accent-orange-light);
    transform: translateY(-2px);
}

.btn-secondary {
    background: transparent;
    color: var(--text-secondary);
    border-color: var(--border-primary);
}

.btn-secondary:hover {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border-color: var(--accent-olive);
}

/* Legacy card styles for compatibility */
.card-header {
    padding: var(--spacing-lg);
    background: var(--bg-secondary);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.card-favicon {
    width: 32px;
    height: 32px;
    border-radius: var(--radius-sm);
    flex-shrink: 0;
}

.card-title {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
}

.card-content {
    padding: var(--spacing-lg);
}

.card-category {
    display: inline-block;
    background: var(--accent-olive);
    color: white;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

.card-description {
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: var(--spacing-lg);
}

.card-link {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    color: var(--accent-orange);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.3s ease;
}

.card-link:hover {
    color: var(--accent-orange-light);
}

/* Keep existing main content structure */
main {
    padding-top: 70px;
    min-height: calc(100vh - 70px);
}