:root {
    /* Light mode colors */
    --bg-primary: #f5f7fa;
    --bg-secondary: white;
    --bg-tertiary: #f9fafb;
    --text-primary: #374151;
    --text-secondary: #6b7280;
    --text-muted: #9ca3af;
    --border-color: #e5e7eb;
    --border-hover: #d1d5db;
    --accent-primary: #4f46e5;
    --accent-secondary: #7c3aed;
    --success-bg: #d1fae5;
    --success-text: #065f46;
    --success-border: #a7f3d0;
    --error-bg: #fee2e2;
    --error-text: #991b1b;
    --error-border: #fca5a5;
    --shadow-sm: 0 2px 10px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 15px rgba(0,0,0,0.05);
    --shadow-lg: 0 20px 50px rgba(0,0,0,0.3);
    --claude-bg: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 100%);
    --claude-border: #38bdf8;
    --claude-text: #0369a1;
    --claude-text-secondary: #0c4a6e;
}

[data-theme="dark"] {
    /* Dark mode colors */
    --bg-primary: #1f2937;
    --bg-secondary: #374151;
    --bg-tertiary: #4b5563;
    --text-primary: #f9fafb;
    --text-secondary: #d1d5db;
    --text-muted: #9ca3af;
    --border-color: #4b5563;
    --border-hover: #6b7280;
    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --success-bg: #064e3b;
    --success-text: #a7f3d0;
    --success-border: #065f46;
    --error-bg: #7f1d1d;
    --error-text: #fca5a5;
    --error-border: #991b1b;
    --shadow-sm: 0 2px 10px rgba(0,0,0,0.3);
    --shadow-md: 0 4px 15px rgba(0,0,0,0.2);
    --shadow-lg: 0 20px 50px rgba(0,0,0,0.5);
    --claude-bg: linear-gradient(135deg, #1e3a8a 0%, #1e40af 100%);
    --claude-border: #3b82f6;
    --claude-text: #93c5fd;
    --claude-text-secondary: #dbeafe;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    min-height: 100vh;
    color: var(--text-primary);
    transition: background-color 0.3s ease, color 0.3s ease;
}

.header {
    position: fixed;
    top: 0;
    right: 0;
    left: 0;
    z-index: 100;
    padding: 20px;
    display: flex;
    justify-content: flex-end;
    gap: 15px;
}

.theme-toggle {
    background: rgba(255,255,255,0.2);
    border: 2px solid rgba(255,255,255,0.3);
    color: white;
    padding: 10px 16px;
    border-radius: 10px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
}

.theme-toggle:hover {
    background: rgba(255,255,255,0.3);
    transform: translateY(-2px);
}

.btn {
    padding: 6px 12px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 500;
    text-decoration: none;
    display: inline-block;
    transition: all 0.3s ease;
    font-size: 13px;
}

.btn-secondary {
    background: rgba(255,255,255,0.2);
    color: white;
}

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 80px 20px 40px;
}

.hero {
    text-align: center;
    color: white;
    margin-bottom: 60px;
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 20px;
    text-shadow: 0 4px 20px rgba(0,0,0,0.3);
    font-weight: 800;
}

.hero p {
    font-size: 1.3rem;
    opacity: 0.95;
    margin-bottom: 30px;
    text-shadow: 0 2px 10px rgba(0,0,0,0.2);
}

.hero-badge {
    display: inline-block;
    background: rgba(255,255,255,0.15);
    color: white;
    padding: 8px 20px;
    border-radius: 25px;
    font-size: 14px;
    font-weight: 600;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255,255,255,0.2);
    margin-bottom: 40px;
}

.main-content {
    display: grid;
    grid-template-columns: 1fr;
    gap: 40px;
    max-width: 800px;
    margin: 0 auto;
}

.claude-info {
    background: var(--claude-bg);
    border: 2px solid var(--claude-border);
    border-radius: 20px;
    padding: 30px;
    text-align: center;
    box-shadow: var(--shadow-lg);
}

.claude-info h3 {
    color: var(--claude-text);
    margin-bottom: 15px;
    font-size: 1.4rem;
    font-weight: 700;
}

.claude-info p {
    color: var(--claude-text-secondary);
    font-size: 16px;
    line-height: 1.6;
}

.signup-card {
    background: var(--bg-secondary);
    border-radius: 20px;
    padding: 40px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
}

.signup-header {
    text-align: center;
    margin-bottom: 30px;
}

.signup-header h2 {
    color: var(--text-primary);
    margin-bottom: 10px;
    font-size: 1.8rem;
    font-weight: 700;
}

.signup-header p {
    color: var(--text-secondary);
    font-size: 14px;
}

.signup-summary {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 25px;
}

.summary-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}

.summary-item:last-child {
    margin-bottom: 0;
}

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

.summary-value {
    color: var(--text-secondary);
    font-size: 14px;
}

.form-group {
    margin-bottom: 20px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--text-primary);
}

input {
    width: 100%;
    padding: 14px 16px;
    border: 2px solid var(--border-color);
    border-radius: 12px;
    font-size: 14px;
    background: var(--bg-secondary);
    color: var(--text-primary);
    transition: all 0.3s ease;
}

input:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
    transform: translateY(-1px);
}

input.valid {
    border-color: var(--success-text);
}

input.invalid {
    border-color: var(--error-text);
}

.form-status {
    position: absolute;
    right: 16px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 18px;
}

.form-group {
    position: relative;
}

.btn-primary {
    width: 100%;
    padding: 15px;
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    color: white;
    border: none;
    border-radius: 12px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(79, 70, 229, 0.4);
}

.btn-primary:disabled {
    background: var(--text-muted);
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.alert {
    padding: 15px;
    border-radius: 12px;
    margin-bottom: 20px;
    display: none;
    text-align: center;
}

.alert-success {
    background: var(--success-bg);
    color: var(--success-text);
    border: 1px solid var(--success-border);
}

.alert-error {
    background: var(--error-bg);
    color: var(--error-text);
    border: 1px solid var(--error-border);
}


.features {
    color: white;
    margin-top: 60px;
    text-align: center;
}

.features h2 {
    font-size: 2.5rem;
    margin-bottom: 20px;
    font-weight: 700;
}

.features-subtitle {
    font-size: 1.1rem;
    opacity: 0.9;
    margin-bottom: 40px;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
    margin-top: 30px;
}

.feature {
    padding: 30px 25px;
    background: rgba(255,255,255,0.12);
    border-radius: 16px;
    backdrop-filter: blur(15px);
    border: 1px solid rgba(255,255,255,0.2);
    transition: all 0.3s ease;
}

.feature:hover {
    transform: translateY(-5px);
    background: rgba(255,255,255,0.18);
    box-shadow: 0 15px 35px rgba(0,0,0,0.2);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 15px;
    display: block;
}

.feature h3 {
    margin-bottom: 12px;
    font-size: 1.2rem;
    font-weight: 600;
}

.feature p {
    opacity: 0.95;
    line-height: 1.5;
    font-size: 14px;
}

.stats-section {
    background: rgba(255,255,255,0.1);
    border-radius: 20px;
    padding: 40px;
    margin: 50px 0;
    backdrop-filter: blur(15px);
    border: 1px solid rgba(255,255,255,0.2);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 30px;
    text-align: center;
}

.stat-item {
    color: white;
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 8px;
    display: block;
}

.stat-label {
    font-size: 14px;
    opacity: 0.9;
    font-weight: 500;
}

/* Loading state */
.loading {
    position: relative;
}

.loading::after {
    content: '';
    position: absolute;
    right: 16px;
    top: 50%;
    transform: translateY(-50%);
    width: 16px;
    height: 16px;
    border: 2px solid var(--border-color);
    border-radius: 50%;
    border-top-color: var(--accent-primary);
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to { transform: translateY(-50%) rotate(360deg); }
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 60px 15px 30px;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .hero p {
        font-size: 1.1rem;
    }

    .signup-card {
        padding: 30px 25px;
    }

    .feature-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .features h2 {
        font-size: 2rem;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 20px;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 2rem;
    }

    .signup-card {
        padding: 25px 20px;
    }

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