:root {
    color-scheme: light dark;
    font-family: "Pretendard", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    line-height: 1.5;
    background-color: #f4f6fb;
}

body {
    margin: 0;
    background: linear-gradient(180deg, #f4f6fb 0%, #ffffff 60%);
    color: #1f2937;
}

.container {
    max-width: 480px;
    margin: 0 auto;
    padding: 32px 20px 48px;
}

h1 {
    font-size: 1.8rem;
    margin-bottom: 8px;
    text-align: center;
}

.description {
    text-align: center;
    color: #6b7280;
    margin-bottom: 24px;
}

.sms-form {
    display: flex;
    flex-direction: column;
    gap: 16px;
    background: #ffffff;
    padding: 24px;
    border-radius: 16px;
    box-shadow: 0 18px 45px rgba(15, 23, 42, 0.08);
}

label {
    font-weight: 600;
    font-size: 0.95rem;
}

input,
select,
textarea {
    border: 1px solid #d1d5db;
    border-radius: 10px;
    padding: 12px;
    font-size: 1rem;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
    background: rgba(255, 255, 255, 0.9);
}

input:focus,
select:focus,
textarea:focus {
    outline: none;
    border-color: #6366f1;
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.15);
}

textarea {
    resize: vertical;
    min-height: 120px;
}

.submit-button {
    border: none;
    border-radius: 12px;
    padding: 14px;
    font-size: 1.05rem;
    font-weight: 700;
    color: #ffffff;
    background: linear-gradient(135deg, #6366f1, #8b5cf6);
    cursor: pointer;
    transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.submit-button:hover {
    transform: translateY(-1px);
    box-shadow: 0 12px 24px rgba(99, 102, 241, 0.2);
}

.alert {
    margin-bottom: 16px;
    padding: 14px 16px;
    border-radius: 12px;
    font-weight: 500;
}

.alert ul {
    margin: 0;
    padding-left: 18px;
}

.alert-success {
    background: #ecfdf5;
    color: #047857;
    border: 1px solid #6ee7b7;
}

.alert-error {
    background: #fef2f2;
    color: #b91c1c;
    border: 1px solid #fecaca;
}

.notes {
    margin-top: 32px;
    background: rgba(255, 255, 255, 0.9);
    border-radius: 16px;
    padding: 20px 24px;
    box-shadow: 0 12px 24px rgba(15, 23, 42, 0.06);
}

.notes h2 {
    margin-top: 0;
}

.result-heading {
    font-weight: 600;
    margin-bottom: 8px;
}

.result-list {
    margin: 0;
    padding-left: 18px;
    color: #374151;
}

.result-list li + li {
    margin-top: 4px;
}

.message-info {
    background: rgba(99, 102, 241, 0.08);
    border-radius: 12px;
    padding: 16px;
    font-size: 0.95rem;
    color: #3730a3;
}

.message-info.is-lms {
    background: rgba(16, 185, 129, 0.08);
    color: #047857;
}

.message-info p {
    margin: 0 0 6px;
}

.message-info .notice {
    color: #4b5563;
    font-size: 0.85rem;
    margin-bottom: 0;
}

.message-info .warning {
    margin-top: 6px;
    color: #b91c1c;
    font-weight: 600;
}

.subject-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.subject-group[hidden] {
    display: none;
}

.subject-info {
    display: flex;
    flex-direction: column;
    gap: 4px;
    font-size: 0.9rem;
}

.subject-info .warning {
    font-weight: 600;
}

.subject-help {
    margin: 0;
    font-size: 0.85rem;
    color: #6b7280;
}

@media (max-width: 600px) {
    .sms-form {
        padding: 20px 16px;
    }

    h1 {
        font-size: 1.6rem;
    }

    .submit-button {
        width: 100%;
    }
}