* { box-sizing: border-box; }

body {
    font-family: system-ui, -apple-system, sans-serif;
    max-width: 36rem;
    margin: 4rem auto;
    padding: 0 1.5rem;
    line-height: 1.5;
    color: #1a1a1a;
}

h1 {
    font-size: 1.5rem;
    font-weight: 600;
    margin: 0 0 0.5rem;
}

p {
    margin: 0 0 1.5rem;
    color: #444;
}

h2 {
    font-size: 1.125rem;
    font-weight: 600;
    margin: 2rem 0 0.75rem;
}

h2:first-of-type {
    margin-top: 1.5rem;
}

h3 {
    font-size: 0.9375rem;
    font-weight: 600;
    margin: 1.25rem 0 0.5rem;
    color: #444;
}

ul {
    margin: 0;
    padding: 0;
    list-style: none;
}

li + li {
    margin-top: 0.5rem;
}

a {
    color: #2563eb;
    text-decoration: none;
}

a:hover {
    color: #1d4ed8;
    text-decoration: underline;
}

form {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

label {
    font-weight: 500;
    font-size: 0.875rem;
}

input {
    width: 100%;
    padding: 0.625rem 0.75rem;
    font-size: 1rem;
    border: 1px solid #ccc;
    border-radius: 6px;
}

input:focus {
    outline: 2px solid #2563eb;
    outline-offset: 1px;
    border-color: #2563eb;
}

button {
    padding: 0.625rem 1rem;
    font-size: 1rem;
    font-weight: 500;
    color: #fff;
    background: #2563eb;
    border: none;
    border-radius: 6px;
    cursor: pointer;
}

button:hover {
    background: #1d4ed8;
}

button:disabled {
    background: #94a3b8;
    cursor: not-allowed;
}

#error {
    display: none;
    margin-top: 1rem;
    padding: 0.75rem;
    font-size: 0.875rem;
    color: #991b1b;
    background: #fef2f2;
    border: 1px solid #fecaca;
    border-radius: 6px;
}

#error.visible {
    display: block;
}