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

:root {
    --primary: #000;
    --primary-light: #333;
    --bg: #fff;
    --bg-alt: #f8f9fa;
    --text: #1a1a1a;
    --text-muted: #666;
    --border: #e0e0e0;
    --radius: 8px;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

html {
    scroll-behavior: smooth;
}

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

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Hero */
.hero {
    padding: 100px 0 80px;
    text-align: center;
    background: linear-gradient(180deg, var(--bg-alt) 0%, var(--bg) 100%);
}

.logo img {
    width: 80px;
    height: 80px;
    margin-bottom: 32px;
}

.hero h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 16px;
    letter-spacing: -0.02em;
}

.subtitle {
    font-size: 1.25rem;
    color: var(--text-muted);
    margin-bottom: 40px;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

.cta-button {
    display: inline-block;
    background: var(--primary);
    color: white;
    padding: 14px 32px;
    border-radius: var(--radius);
    text-decoration: none;
    font-weight: 600;
    font-size: 1rem;
    transition: background 0.2s, transform 0.2s;
}

.cta-button:hover {
    background: var(--primary-light);
    transform: translateY(-2px);
}

/* How It Works */
.how-it-works {
    padding: 80px 0;
}

h2 {
    font-size: 2rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 48px;
    letter-spacing: -0.01em;
}

.steps {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 40px;
}

.step {
    text-align: center;
}

.step-number {
    width: 48px;
    height: 48px;
    border: 2px solid var(--primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    font-weight: 700;
    margin: 0 auto 20px;
}

.step h3 {
    font-size: 1.125rem;
    margin-bottom: 8px;
}

.step p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* Features */
.features {
    padding: 80px 0;
    background: var(--bg-alt);
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
}

.feature {
    background: var(--bg);
    padding: 32px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.feature-icon {
    width: 48px;
    height: 48px;
    margin-bottom: 16px;
}

.feature-icon svg {
    width: 100%;
    height: 100%;
    stroke: var(--primary);
}

.feature h3 {
    font-size: 1.125rem;
    margin-bottom: 8px;
}

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

/* Create Mailbox */
.create-mailbox {
    padding: 100px 0;
    text-align: center;
}

.section-subtitle {
    color: var(--text-muted);
    margin-bottom: 40px;
    font-size: 1.1rem;
}

#mailbox-form {
    max-width: 500px;
    margin: 0 auto;
}

.input-group {
    display: flex;
    background: var(--bg);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    transition: border-color 0.2s;
}

.input-group:focus-within {
    border-color: var(--primary);
}

.input-group input {
    flex: 1;
    border: none;
    padding: 16px 20px;
    font-size: 1.125rem;
    outline: none;
    font-family: ui-monospace, 'SF Mono', Menlo, monospace;
}

.input-group input::placeholder {
    color: #aaa;
}

.domain {
    background: var(--bg-alt);
    padding: 16px 20px;
    font-size: 1.125rem;
    color: var(--text-muted);
    font-family: ui-monospace, 'SF Mono', Menlo, monospace;
    border-left: 2px solid var(--border);
}

.submit-button {
    display: block;
    width: 100%;
    margin-top: 16px;
    background: var(--primary);
    color: white;
    border: none;
    padding: 16px 32px;
    border-radius: var(--radius);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s, transform 0.2s;
}

.submit-button:hover {
    background: var(--primary-light);
    transform: translateY(-2px);
}

.submit-button:disabled {
    background: var(--text-muted);
    cursor: not-allowed;
    transform: none;
}

.form-message {
    margin-top: 20px;
    padding: 16px;
    border-radius: var(--radius);
    display: none;
}

.form-message.success {
    display: block;
    background: #e8f5e9;
    color: #2e7d32;
}

.form-message.error {
    display: block;
    background: #ffebee;
    color: #c62828;
}

/* Footer */
footer {
    padding: 48px 0;
    border-top: 1px solid var(--border);
}

.footer-content {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
}

.footer-logo img {
    width: 32px;
    height: 32px;
    opacity: 0.6;
}

footer p {
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 768px) {
    .hero {
        padding: 60px 0;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .subtitle {
        font-size: 1.1rem;
    }

    .steps {
        grid-template-columns: 1fr;
        gap: 32px;
    }

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

    .input-group {
        flex-direction: column;
    }

    .domain {
        border-left: none;
        border-top: 2px solid var(--border);
        text-align: center;
    }
}