/* --- Main Content Container --- */
.container {
    width: 100%;
    max-width: 550px;
    text-align: center;
}

.intro-text {
    margin-bottom: 2rem;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.intro-text h1 {
    font-family: var(--heading-font-family);
    font-weight: 700;
    font-size: 2.5rem;
    line-height: 1.1;
    margin-bottom: 1rem;
    letter-spacing: -0.5px;
}

.intro-text h2 {
    font-family: var(--heading-font-family);
    font-weight: 700;
    font-size: 1.75rem;
    line-height: 1.4;
    margin-bottom: 1.5rem;
}

.intro-text p {
    font-size: 1.125rem;
    line-height: 1.6;
    max-width: 50ch;
    margin-left: auto;
    margin-right: auto;
}

.intro-text .tagline {
    font-size: 1.25rem;
    font-weight: 700;
}

.intro-text .highlight-paragraph {
        margin-top: 1rem;
}

/* --- The Main Content Card --- */
.card {
    background-color: var(--card-background);
    width: 100%;
    padding: 2rem;
    border: var(--border-width) solid var(--text-color);
    box-shadow: var(--shadow-offset) var(--shadow-offset) 0 var(--text-color);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    text-align: center;
}

.card p {
    font-size: 1.0625rem;
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

.card .sign-off {
    margin-top: 1.5rem;
    margin-bottom: 0;
}

/* --- Highlighting for text --- */
.highlight {
    background-color: var(--highlight-color);
    padding: 0.1em 0.4em;
    border-radius: 4px;
}

/* --- Signup Form --- */
.signup-form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.signup-form textarea,
.signup-form input[type="email"] {
    width: 100%;
    padding: 1rem;
    font-size: 1rem;
    font-family: var(--body-font-family);
    border: var(--border-width) solid var(--text-color);
    background-color: var(--card-background);
    caret-color: var(--text-color);
    resize: vertical;
}

.email-group {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.signup-form button {
    padding: 1rem;
    font-size: 1rem;
    font-weight: 700;
    font-family: var(--body-font-family);
    background-color: var(--background-color);
    color: var(--text-color);
    border: var(--border-width) solid var(--text-color);
    cursor: pointer;
    transition: background-color 0.2s ease;
}

.signup-form button:hover {
    background-color: var(--hover-background-color);
}

/* --- Error Message --- */
.error-message {
    color: var(--error-color);
    font-weight: 700;
    margin-top: 0.5rem;
    display: none; /* Hidden by default */
}

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

/* --- Media Queries for Responsiveness --- */
@media (min-width: 768px) {
    .intro-text h1 {
        font-size: 3rem;
        white-space: nowrap;
    }

    .email-group {
        flex-direction: row;
    }

    .signup-form button {
        width: auto;
        min-width: 150px; 
    }
    
    .card {
        padding: 3rem;
    }
}