*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", sans-serif;
    background: #f0f2f5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}
header {
    background: #1c2b4a;
    padding: 0.9rem 1.5rem;
}
header a {
    color: #fff;
    text-decoration: none;
    font-size: 1rem;
    font-weight: 600;
    letter-spacing: 0.04em;
}
main {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem 1rem;
}
.card {
    background: #fff;
    border-radius: 14px;
    box-shadow: 0 2px 20px rgba(0,0,0,0.08);
    padding: 2.5rem 2rem;
    width: 100%;
    max-width: 400px;
    text-align: center;
}
.card img {
    max-width: 100%;
    height: auto;
    margin-bottom: 1.8rem;
}
.card .pc { display: block; }
.card .sp { display: none; }
@media (max-width: 600px) {
    .card .pc { display: none; }
    .card .sp { display: block; }
}
.form-group { margin-bottom: 1rem; text-align: left; }
.form-group label {
    display: block;
    font-size: 0.82rem;
    font-weight: 600;
    color: #555;
    margin-bottom: 0.35rem;
    letter-spacing: 0.02em;
}
.form-group input {
    width: 100%;
    padding: 0.65rem 0.9rem;
    border: 1px solid #dce1e9;
    border-radius: 8px;
    font-size: 0.95rem;
    color: #222;
    outline: none;
    transition: border-color 0.15s, box-shadow 0.15s;
}
.form-group input:focus {
    border-color: #4071e8;
    box-shadow: 0 0 0 3px rgba(64,113,232,0.12);
}
.btn-submit {
    display: block;
    width: 100%;
    margin-top: 1.5rem;
    padding: 0.75rem;
    background: #4071e8;
    color: #fff;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 700;
    cursor: pointer;
    letter-spacing: 0.03em;
    transition: background 0.15s, transform 0.1s;
}
.btn-submit:hover { background: #2f5dd4; }
.btn-submit:active { transform: scale(0.98); }
.message {
    background: #f5f7fb;
    border-left: 4px solid #4071e8;
    border-radius: 6px;
    padding: 1rem 1.1rem;
    font-size: 0.95rem;
    color: #333;
    line-height: 1.65;
    text-align: left;
}
footer {
    text-align: center;
    padding: 1.2rem;
    font-size: 0.78rem;
    color: #aaa;
}