:root {
    --bg-primary: #0f1117;
    --bg-secondary: #1a1d2e;
    --bg-card: #1e2235;
    --text-primary: #e8eaed;
    --text-secondary: #9aa0b0;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --accent-glow: rgba(59, 130, 246, 0.15);
    --success: #10b981;
    --border: #2a2f45;
    --radius: 12px;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Inter, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ── Nav ── */
nav {
    padding: 20px 0;
    border-bottom: 1px solid var(--border);
}

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

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
    letter-spacing: -0.02em;
}

.logo span { color: var(--accent); }

.nav-tag {
    font-size: 0.75rem;
    color: var(--accent);
    background: var(--accent-glow);
    padding: 4px 12px;
    border-radius: 20px;
    font-weight: 500;
}

/* ── Hero ── */
.hero {
    padding: 80px 0 60px;
    text-align: center;
}

.hero h1 {
    font-size: clamp(2.2rem, 5vw, 3.5rem);
    font-weight: 800;
    line-height: 1.15;
    letter-spacing: -0.03em;
    margin-bottom: 20px;
}

.hero h1 .highlight { color: var(--accent); }

.hero .subtitle {
    font-size: 1.2rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 40px;
    line-height: 1.6;
}

/* ── Signup form ── */
.signup-form {
    display: flex;
    gap: 12px;
    max-width: 480px;
    margin: 0 auto;
    justify-content: center;
}

.signup-form input[type="email"] {
    flex: 1;
    padding: 14px 20px;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 1rem;
    outline: none;
    transition: border-color 0.2s;
}

.signup-form input[type="email"]:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.signup-form input[type="email"]::placeholder {
    color: var(--text-secondary);
}

.btn-primary {
    padding: 14px 28px;
    border-radius: var(--radius);
    border: none;
    background: var(--accent);
    color: #fff;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s, transform 0.1s;
    white-space: nowrap;
}

.btn-primary:hover { background: var(--accent-hover); }
.btn-primary:active { transform: scale(0.98); }
.btn-primary:disabled { opacity: 0.6; cursor: not-allowed; }

.signup-message {
    margin-top: 14px;
    font-size: 0.9rem;
    min-height: 1.4em;
}

.signup-message.success { color: var(--success); }
.signup-message.error { color: #ef4444; }
.signup-message.duplicate { color: var(--accent); }

.signup-note {
    margin-top: 10px;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* ── Sample briefing ── */
.preview {
    padding: 60px 0;
}

.preview h2 {
    text-align: center;
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 12px;
    letter-spacing: -0.02em;
}

.preview .preview-sub {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 40px;
    font-size: 0.95rem;
}

.preview-frame {
    max-width: 680px;
    margin: 0 auto;
    border-radius: var(--radius);
    overflow: hidden;
    border: 1px solid var(--border);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
}

.preview-frame img {
    width: 100%;
    display: block;
}

/* ── Features ── */
.features {
    padding: 60px 0;
}

.features h2 {
    text-align: center;
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 40px;
    letter-spacing: -0.02em;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 24px;
}

.feature-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
}

.feature-icon {
    font-size: 1.8rem;
    margin-bottom: 14px;
}

.feature-card h3 {
    font-size: 1.05rem;
    font-weight: 600;
    margin-bottom: 8px;
}

.feature-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

/* ── How it works ── */
.how-it-works {
    padding: 60px 0;
}

.how-it-works h2 {
    text-align: center;
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 40px;
    letter-spacing: -0.02em;
}

.steps {
    display: flex;
    gap: 32px;
    justify-content: center;
    flex-wrap: wrap;
}

.step {
    text-align: center;
    max-width: 260px;
}

.step-number {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--accent-glow);
    color: var(--accent);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 16px;
    border: 1px solid rgba(59, 130, 246, 0.3);
}

.step h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 8px;
}

.step p {
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

/* ── Bottom CTA ── */
.bottom-cta {
    padding: 60px 0;
    text-align: center;
}

.bottom-cta h2 {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: 12px;
    letter-spacing: -0.02em;
}

.bottom-cta p {
    color: var(--text-secondary);
    margin-bottom: 32px;
    font-size: 1rem;
}

/* ── Footer ── */
footer {
    padding: 32px 0;
    border-top: 1px solid var(--border);
    text-align: center;
}

footer p {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

footer a {
    color: var(--text-secondary);
    text-decoration: none;
}

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

/* ── Responsive ── */
@media (max-width: 600px) {
    .hero { padding: 50px 0 40px; }

    .signup-form {
        flex-direction: column;
    }

    .signup-form input[type="email"],
    .btn-primary {
        width: 100%;
    }

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