:root {
    --bg-main: #0b0f15;
    --bg-grid: #121922;
    --card-bg: #141b25;
    --card-border: #2a3441;
    --accent: #00e59b;
    --accent-hover: #00c786;
    --text-primary: #ffffff;
    --text-secondary: #8b949e;
    --font-sans: 'Inter', -apple-system, sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
}

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

body {
    background-color: var(--bg-main);
    color: var(--text-primary);
    font-family: var(--font-sans);
    line-height: 1.6;
    min-height: 100vh;
    position: relative;
    overflow-x: hidden;
}

/* Subtle Grid Background */
.grid-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
    background-image: 
        linear-gradient(var(--bg-grid) 1px, transparent 1px),
        linear-gradient(90deg, var(--bg-grid) 1px, transparent 1px);
    background-size: 40px 40px;
    background-position: center top;
}

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

/* Header */
header {
    border-bottom: 1px solid var(--card-border);
    background-color: rgba(11, 15, 21, 0.8);
    backdrop-filter: blur(8px);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-family: var(--font-mono);
    font-weight: 800;
    font-size: 1.1rem;
    letter-spacing: 1px;
}

.logo-img {
    width: 32px;
    height: 32px;
    border-radius: 6px;
    object-fit: contain;
}

nav {
    display: flex;
    align-items: center;
    gap: 20px;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: color 0.2s;
}

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

.install-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    border: 1px solid var(--card-border);
    padding: 6px 14px;
    border-radius: 4px;
    color: var(--accent);
    text-decoration: none;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    transition: all 0.2s;
}

.install-btn:hover {
    background-color: rgba(0, 229, 155, 0.1);
    border-color: var(--accent);
}

/* Hero Section */
.hero {
    padding: 100px 0 80px 0;
}

.hero-title {
    font-family: var(--font-mono);
    font-size: 4rem;
    font-weight: 700;
    margin-bottom: 16px;
    letter-spacing: -1px;
}

.cursor {
    color: var(--accent);
    animation: blink 1s step-end infinite;
}

@keyframes blink {
    50% { opacity: 0; }
}

.hero-subtitle {
    color: var(--text-secondary);
    font-family: var(--font-mono);
    font-size: 1.1rem;
    margin-bottom: 40px;
    border-left: 2px solid var(--accent);
    padding-left: 16px;
}

.hero-actions {
    display: flex;
    gap: 16px;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 24px;
    font-family: var(--font-mono);
    font-weight: 700;
    font-size: 0.9rem;
    text-decoration: none;
    border-radius: 4px;
    transition: all 0.2s;
    letter-spacing: 0.5px;
}

.btn-primary {
    background-color: var(--accent);
    color: var(--bg-main);
    border: 1px solid var(--accent);
}

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

.btn-secondary {
    background-color: transparent;
    color: var(--text-primary);
    border: 1px solid var(--card-border);
}

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

/* Features Section */
.features-section {
    padding: 40px 0 100px 0;
}

.section-title {
    font-family: var(--font-mono);
    font-size: 1.2rem;
    color: var(--text-primary);
    margin-bottom: 24px;
}

.features-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

.feature-card {
    background-color: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 8px;
    padding: 32px;
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.feature-header {
    margin-bottom: 8px;
}

.feature-title {
    font-family: var(--font-mono);
    color: var(--accent);
    font-size: 1rem;
    margin-bottom: 8px;
}

.feature-desc {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Mockup Windows */
.mockup-window {
    background-color: var(--bg-main);
    border: 1px solid var(--card-border);
    border-radius: 6px;
    overflow: hidden;
    margin-bottom: 16px;
}

.small-window {
    margin-bottom: 0;
}

.mockup-window:last-child {
    margin-bottom: 0;
}

.mockup-title {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    color: var(--text-secondary);
    text-align: center;
    padding: 8px 0;
    border-bottom: 1px solid var(--card-border);
    position: relative;
    background-color: rgba(255, 255, 255, 0.02);
}

.mockup-dots {
    position: absolute;
    left: 12px;
    top: 10px;
    display: flex;
    gap: 6px;
}

.mockup-dots span {
    width: 8px;
    height: 8px;
    border-radius: 50%;
}
.mockup-dots span:nth-child(1) { background-color: #ff5f56; }
.mockup-dots span:nth-child(2) { background-color: #ffbd2e; }
.mockup-dots span:nth-child(3) { background-color: #27c93f; }

.mockup-content {
    padding: 24px;
    min-height: 120px;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* Math Rendering Mock */
.editor-preview {
    font-size: 2rem;
    font-family: 'Times New Roman', serif;
}

.math-preview {
    display: flex;
    align-items: center;
    gap: 8px;
}

.math-integral {
    font-size: 3.5rem;
    font-weight: lighter;
    margin-right: -4px;
}

.math-bounds {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    height: 3.5rem;
    font-size: 1rem;
    margin-right: 8px;
}

.bound-upper { margin-top: -4px; }
.bound-lower { margin-bottom: -4px; }

.code-preview {
    min-height: 60px;
    background-color: rgba(0, 0, 0, 0.3);
}

.code-preview code {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* Browser Mockup */
.browser-preview {
    align-items: flex-start;
    padding: 20px;
}

.fake-input-group {
    width: 100%;
    position: relative;
}

.fake-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

.fake-textarea {
    width: 100%;
    border: 1px solid var(--card-border);
    background-color: var(--bg-main);
    border-radius: 4px;
    padding: 12px;
    font-size: 0.9rem;
    color: var(--text-primary);
    min-height: 100px;
}

.highlight-math {
    background-color: rgba(0, 229, 155, 0.15);
    color: var(--accent);
    padding: 2px 4px;
    border-radius: 3px;
    font-family: var(--font-mono);
    font-size: 0.85rem;
}

.fake-tooltip {
    position: absolute;
    bottom: 12px;
    right: 12px;
    background-color: var(--accent);
    color: var(--bg-main);
    font-family: var(--font-mono);
    font-size: 0.7rem;
    padding: 4px 8px;
    border-radius: 4px;
    font-weight: 700;
}

/* Footer */
footer {
    border-top: 1px solid var(--card-border);
    padding: 40px 0;
    margin-top: 40px;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.footer-links {
    display: flex;
    gap: 24px;
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.2s;
}

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

/* User Manual Section */
.manual-section {
    padding: 60px 0 40px 0;
}

.manual-container {
    background-color: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    padding: 32px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
}

.manual-tabs {
    display: flex;
    gap: 12px;
    margin-bottom: 32px;
    border-bottom: 1px solid var(--card-border);
    padding-bottom: 16px;
    overflow-x: auto;
}

.manual-tab {
    background: transparent;
    border: 1px solid transparent;
    color: var(--text-secondary);
    padding: 10px 20px;
    border-radius: 6px;
    cursor: pointer;
    font-family: var(--font-mono);
    font-weight: 700;
    font-size: 0.9rem;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    transition: all 0.25s ease;
    white-space: nowrap;
}

.manual-tab:hover {
    color: var(--text-primary);
    background-color: rgba(255, 255, 255, 0.02);
}

.manual-tab.active {
    color: var(--accent);
    background-color: rgba(0, 229, 155, 0.05);
    border-color: rgba(0, 229, 155, 0.2);
}

.tab-icon {
    transition: transform 0.25s ease;
}

.manual-tab:hover .tab-icon,
.manual-tab.active .tab-icon {
    transform: scale(1.1);
}

.manual-content {
    position: relative;
}

.manual-panel {
    display: none;
    animation: fadeIn 0.4s ease forwards;
}

.manual-panel.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.manual-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.manual-card {
    background-color: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--card-border);
    border-radius: 8px;
    padding: 24px;
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

.manual-card:hover {
    transform: translateY(-4px);
    border-color: var(--accent);
    box-shadow: 0 8px 24px rgba(0, 229, 155, 0.05);
}

.manual-card.wide-card {
    grid-column: 1 / -1;
    background: linear-gradient(135deg, rgba(255,255,255,0.02) 0%, rgba(255,255,255,0.01) 100%);
}

.card-icon-wrap {
    font-size: 1.5rem;
    margin-bottom: 16px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    background-color: rgba(0, 229, 155, 0.05);
    border: 1px solid rgba(0, 229, 155, 0.15);
    border-radius: 8px;
    color: var(--accent);
}

.manual-card h4 {
    font-family: var(--font-mono);
    color: var(--text-primary);
    font-size: 1rem;
    margin-bottom: 12px;
}

.card-text {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
}

/* Keyboard styling */
kbd {
    background-color: #1e293b;
    border: 1px solid #334155;
    border-bottom: 3px solid #334155;
    border-radius: 5px;
    color: var(--accent);
    font-family: var(--font-mono);
    font-size: 0.8rem;
    padding: 2px 6px;
    margin: 0 2px;
    display: inline-block;
    box-shadow: 0 2px 0 rgba(0,0,0,0.3);
    font-weight: 700;
}

/* Inline code styling */
.manual-card code {
    background-color: rgba(0, 0, 0, 0.3);
    color: var(--text-primary);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: var(--font-mono);
    font-size: 0.85rem;
}

@media (max-width: 900px) {
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .hero-title {
        font-size: 3rem;
    }
    
    .manual-tabs {
        padding-bottom: 8px;
    }
    
    .manual-card.wide-card {
        grid-column: span 1;
    }
}