* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, sans-serif;
}

body {
    background-color: #f2f3f6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

section {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 50px 20px;
}

#main_content {
    width: 100%;
    max-width: 440px;
}

#join_box {
    background: #ffffff;
    border-radius: 20px;
    padding: 40px 32px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.04);
}

#join_box h2 {
    text-align: center;
    font-size: 22px;
    font-weight: 700;
    color: #111827;
    margin-bottom: 28px;
}

.form-group {
    margin-bottom: 18px;
}

.form-group label {
    display: block;
    font-size: 13px;
    font-weight: 600;
    color: #374151;
    margin-bottom: 6px;
}

.input-with-btn {
    display: flex;
    gap: 8px;
}

.input-with-btn input {
    flex: 1;
}

.btn-check {
    padding: 0 14px;
    background-color: #4b5563;
    color: #ffffff;
    border: none;
    border-radius: 10px;
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    white-space: nowrap;
    transition: background-color 0.2s;
}

.btn-check:hover {
    background-color: #1f2937;
}

.form-group input[type="text"],
.form-group input[type="password"],
.form-group input[type="email"],
.form-group input[type="tel"] {
    width: 100%;
    padding: 13px 16px;
    border: 1px solid #d1d5db;
    border-radius: 10px;
    font-size: 14px;
    color: #1f2937;
    outline: none;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.form-group input:focus {
    border-color: #f95e07;
    box-shadow: 0 0 0 3px rgba(249, 94, 7, 0.12);
}

.button-group {
    display: flex;
    gap: 10px;
    margin-top: 28px;
}

.btn-submit {
    flex: 2;
    padding: 14px;
    background-color: #f95e07;
    color: #ffffff;
    border: none;
    border-radius: 10px;
    font-size: 15px;
    font-weight: 700;
    cursor: pointer;
    transition: background-color 0.2s;
}

.btn-submit:hover {
    background-color: #e05000;
}

.btn-reset {
    flex: 1;
    padding: 14px;
    background-color: #e5e7eb;
    color: #374151;
    border: none;
    border-radius: 10px;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

.btn-reset:hover {
    background-color: #d1d5db;
}
.label-optional {
    font-size: 12px;
    font-weight: 400;
    color: #9ca3af;
    margin-left: 2px;
}