/* ===== CSS RESET + BASE ===== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    /* Brand tokens — replace with designer values */
    --color-bg: #FFFFFF;
    --color-text: #1A1A1A;
    --color-text-secondary: #666666;
    --color-accent: #4A6CF7;    /* primary brand color */
    --color-accent-hover: #3B5DE7;
    --color-input-border: #DDDDDD;
    --color-input-bg: #FFFFFF;
    --color-error: #DC3545;
    --color-success: #28A745;
    --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-heading: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

/* Dark mode */
@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #111111;
        --color-text: #F0F0F0;
        --color-text-secondary: #AAAAAA;
        --color-input-border: #444444;
        --color-input-bg: #222222;
    }
}

html {
    font-size: 16px; /* prevents iOS Safari auto-zoom on input focus */
}

body {
    font-family: var(--font-body);
    background-color: var(--color-bg);
    color: var(--color-text);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 2rem 1rem;
}

/* ===== HERO SECTION ===== */
.hero {
    text-align: center;
    max-width: 600px;
    width: 100%;
}

.logo {
    width: 120px;
    height: auto;
    margin-bottom: 1.5rem;
}

/* Optional partner logo (Harvard page) */
.partner-logo {
    width: 160px;
    height: auto;
    margin-bottom: 0.5rem;
    opacity: 0.8;
}

h1 {
    font-family: var(--font-heading);
    font-size: 1.75rem;
    font-weight: 600;
    line-height: 1.3;
    margin-bottom: 0.75rem;
}

.subtitle {
    font-size: 1.1rem;
    color: var(--color-text-secondary);
    margin-bottom: 2rem;
    line-height: 1.5;
}

/* ===== FORM ===== */
.capture-form {
    margin-bottom: 1rem;
}

.form-row {
    display: flex;
    gap: 0.5rem;
    justify-content: center;
    flex-wrap: wrap;
}

.form-row input[type="email"] {
    flex: 1;
    min-width: 220px;
    max-width: 320px;
    padding: 0.75rem 1rem;
    font-size: 1rem;
    border: 1px solid var(--color-input-border);
    border-radius: 8px;
    background: var(--color-input-bg);
    color: var(--color-text);
    outline: none;
    transition: border-color 0.2s;
}

.form-row input[type="email"]:focus {
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(74, 108, 247, 0.15);
}

.form-row button[type="submit"] {
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    color: #FFFFFF;
    background: var(--color-accent);
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: background 0.2s;
    white-space: nowrap;
}

.form-row button[type="submit"]:hover {
    background: var(--color-accent-hover);
}

.form-row button[type="submit"]:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

/* Focus styles (accessibility — never remove outline without replacement) */
.form-row input:focus-visible,
.form-row button:focus-visible,
a:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

/* ===== HONEYPOT (must be invisible to humans, visible to bots) ===== */
.honeypot {
    position: absolute;
    left: -9999px;
    opacity: 0;
    height: 0;
    overflow: hidden;
}

/* ===== MESSAGES ===== */
.message {
    font-size: 1rem;
    padding: 1rem;
    margin-top: 1rem;
    border-radius: 8px;
    animation: fadeIn 0.3s ease-in;
}

.message:not(.message-error) {
    color: var(--color-success);
}

.message-error {
    color: var(--color-error);
}

.retry-btn {
    display: inline-block;
    margin-top: 0.5rem;
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
    background: transparent;
    border: 1px solid var(--color-error);
    border-radius: 6px;
    color: var(--color-error);
    cursor: pointer;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-4px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ===== SUBSCRIBER COUNT ===== */
.subscriber-count {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    margin-top: 1rem;
    font-weight: 500;
}

/* ===== PRIVACY TEXT ===== */
.privacy-text {
    font-size: 0.8rem;
    color: var(--color-text-secondary);
    margin-top: 1.25rem;
    line-height: 1.5;
    max-width: 400px;
    margin-left: auto;
    margin-right: auto;
}

/* ===== FOOTER ===== */
.site-footer {
    margin-top: 3rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--color-input-border);
    width: 100%;
    max-width: 600px;
    text-align: center;
}

.site-footer p {
    font-size: 0.75rem;
    color: var(--color-text-secondary);
    line-height: 1.6;
}

/* ===== SCREEN READER ONLY ===== */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

/* ===== RESPONSIVE ===== */
/* Mobile: ≤640px — stacked form */
@media (max-width: 640px) {
    h1 { font-size: 1.5rem; }
    .form-row {
        flex-direction: column;
        align-items: center;
    }
    .form-row input[type="email"] {
        max-width: 100%;
        width: 100%;
    }
    .form-row button[type="submit"] {
        width: 100%;
    }
}

/* Tablet: 641–1024px */
@media (min-width: 641px) and (max-width: 1024px) {
    .hero { max-width: 60%; }
}

/* Desktop: 1025px+ — already good at max-width: 600px */