:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --secondary-color: #64748b;
    --accent-color: #0ea5e9;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    color: var(--text-primary);
    background-color: var(--bg-secondary);
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }
}

/* Navigation */
.navbar {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 1.5rem 0;
    box-shadow: var(--shadow-md);
}

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

.nav-brand h1 {
    font-size: 1.75rem;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.nav-brand .tagline {
    font-size: 0.875rem;
    opacity: 0.9;
    margin-top: 0.25rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 1.5rem;
    flex-wrap: nowrap;
    align-items: center;
}

.nav-link {
    white-space: nowrap;
}

.nav-link {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: opacity 0.2s;
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
}

.nav-link:hover {
    background: rgba(255, 255, 255, 0.1);
}

/* Navbar Dropdown */
.nav-dropdown {
    position: relative;
    display: inline-block;
}

.dropdown-trigger {
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.dropdown-trigger i {
    font-size: 0.8rem;
    transition: transform 0.2s;
}

.nav-dropdown.active .dropdown-trigger i {
    transform: rotate(180deg);
}

.dropdown-content {
    display: none;
    position: absolute;
    right: 0;
    top: 100%;
    background-color: white;
    min-width: 180px;
    box-shadow: var(--shadow-lg);
    border-radius: 0.5rem;
    z-index: 1000;
    margin-top: 0.5rem;
    overflow: hidden;
    border: 1px solid var(--border-color);
}

.nav-dropdown.active .dropdown-content {
    display: block;
}

.dropdown-item {
    color: var(--text-primary);
    padding: 0.75rem 1rem;
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 0.875rem;
    font-weight: 500;
    transition: background 0.2s;
}

.dropdown-item:hover {
    background-color: var(--bg-secondary);
    color: var(--primary-color);
}

.dropdown-divider {
    height: 1px;
    background-color: var(--border-color);
    margin: 0;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 4rem 0;
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
    letter-spacing: -1px;
}

.hero-subtitle {
    font-size: 1.5rem;
    font-weight: 400;
    opacity: 0.95;
    margin-bottom: 1.5rem;
}

.hero-logo {
    max-width: 350px;
    width: 100%;
    height: auto;
}

.hero-illustration {
    max-width: 350px;
    width: 100%;
    height: auto;
}

.hero-description {
    font-size: 1.125rem;
    line-height: 1.8;
    opacity: 0.9;
    margin-bottom: 2rem;
}

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

.network-preview {
    width: 100%;
    height: 400px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 1rem;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.875rem 2rem;
    border-radius: 0.5rem;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.2s;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

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

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

.btn-secondary {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.3);
}

/* Features Section */
.features {
    padding: 4rem 0;
    background: var(--bg-primary);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.feature-card {
    background: var(--bg-primary);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
    transition: transform 0.2s, box-shadow 0.2s;
}

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

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.feature-card p {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* Info Section */
.info-section {
    padding: 4rem 0;
    background: var(--bg-secondary);
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.info-block {
    background: var(--bg-primary);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-sm);
}

.info-block h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.info-block p {
    color: var(--text-secondary);
    line-height: 1.7;
}

.info-block a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
}

.info-block a:hover {
    text-decoration: underline;
}

/* Content Section */
.content-section {
    background: var(--bg-primary);
    padding: 3rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
    margin: 3rem 0;
}

/* Ensure buttons in content-section are visible */
.content-section .btn-primary {
    background: var(--primary-color);
    color: white;
}

.content-section .btn-primary:hover {
    background: var(--primary-dark);
}

.content-section .btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.content-section .btn-secondary:hover {
    background: var(--border-color);
}

.content-section h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 2rem;
    color: var(--text-primary);
}

.about-section {
    margin-bottom: 2.5rem;
}

.about-section h2 {
    font-size: 1.75rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.about-section p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 1rem;
}

.publication {
    background: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: 0.5rem;
    margin-bottom: 1rem;
}

/* Footer */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 3rem 0;
    margin-top: 4rem;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 2rem;
}

.footer-info {
    flex: 1;
    min-width: 300px;
    text-align: left;
}

.footer-links {
    display: flex;
    gap: 2rem;
    font-size: 0.875rem;
}

.footer-section-title {
    opacity: 0.6;
    margin-right: 0.5rem;
    text-transform: uppercase;
    font-weight: 600;
}

@media (max-width: 768px) {
    .footer {
        text-align: center;
    }

    .footer-content {
        flex-direction: column;
        gap: 1.5rem;
    }

    .footer-info {
        min-width: 100%;
        text-align: center;
    }

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

/* Registration Page Specifics */
.register-card {
    max-width: 800px;
    margin: 2rem auto;
}

.auth-form-horizontal {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.form-group.horiz {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.form-group.horiz .form-control {
    flex: 0 0 60%;
    /* Input takes 60% */
}

.form-group.horiz label {
    flex: 1;
    margin-bottom: 0;
    font-weight: 500;
    color: var(--text-secondary);
    text-align: left;
}

.form-control {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.checkbox-group {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.checkbox-group input {
    width: 1.25rem;
    height: 1.25rem;
    cursor: pointer;
}

/* Nav Toggle (Hamburger) */
.nav-toggle {
    display: none;
    background: transparent;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
}

/* Mobile Responsiveness */
@media (max-width: 768px) {
    .container {
        padding: 0 1rem;
    }

    /* Navbar Mobile */
    .nav-toggle {
        display: block;
    }

    .nav-menu {
        display: none;
        width: 100%;
        flex-direction: column;
        gap: 0;
        margin-top: 1rem;
        background: rgba(255, 255, 255, 0.1);
        border-radius: 0.5rem;
        padding: 0.5rem;
    }

    .nav-menu.active {
        display: flex;
    }

    .nav-menu li {
        width: 100%;
    }

    .nav-link {
        display: block;
        padding: 0.75rem 1rem;
        width: 100%;
        border-radius: 0.25rem;
    }

    .nav-link:hover {
        background: rgba(255, 255, 255, 0.2);
    }

    /* Mobile Dropdowns */
    .nav-dropdown .dropdown-content {
        position: static;
        display: none;
        width: 100%;
        background: rgba(0, 0, 0, 0.1);
        box-shadow: none;
        border: none;
        margin-top: 0;
        padding-left: 1rem;
    }

    .nav-dropdown:hover .dropdown-content,
    .nav-dropdown.active .dropdown-content {
        display: block;
    }

    .dropdown-item {
        color: white;
        padding: 0.75rem 1rem;
    }

    .dropdown-item:hover {
        background: rgba(255, 255, 255, 0.1);
        color: white;
    }

    .dropdown-divider {
        background-color: rgba(255, 255, 255, 0.2);
    }

    .navbar .container {
        flex-wrap: wrap;
    }

    /* General Layout Adjustments */
    .hero {
        padding: 3rem 0;
    }

    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 2.5rem;
    }

    .hero-text img {
        max-width: 100% !important;
        height: auto;
    }

    .hero-image img {
        max-width: 100% !important;
        height: auto;
    }

    .hero-title {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1.25rem;
    }

    .hero-actions {
        justify-content: center;
    }

    .nav-brand h1 {
        font-size: 1.5rem;
    }

    .section-title {
        font-size: 2rem;
        margin-bottom: 2rem;
    }

    /* Form Adjustments */
    .form-group.horiz {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }

    .form-group.horiz .form-control {
        flex: 1 1 auto;
        width: 100%;
    }

    .form-group.horiz label {
        order: -1;
    }

    .auth-card {
        padding: 1.5rem;
    }
}