/* 基础布局 */
.main-container {
    margin-top: 80px;
}

.justify-center {
    justify-content: center;
}

/* column base */
.col {
    padding-left: 12px;
    padding-right: 12px;
    box-sizing: border-box;
    flex: 0 0 100%;
    max-width: 100%;
}

/* responsive columns */
@media (min-width: 768px) {
    .col-md-8 {
        flex: 0 0 66.666666%;
        max-width: 66.666666%;
    }

    .col-md-4 {
        flex: 0 0 33.333333%;
        max-width: 33.333333%;
    }
}

/* spacing utilities */
.mt-3 {
    margin-top: 1rem;
}

.mb-3 {
    margin-bottom: 1rem;
}

.mt-12 {
    margin-top: 12px;
}

.mt-8 {
    margin-top: 8px;
}

.card {
    background: #fff;
    border: 1px solid #ddd;
    border-radius: 8px;
    padding: 16px;
}

.card-body {
    padding: 12px;
}

.text-center {
    text-align: center;
}

.text-primary {
    color: #007bff;
}

.text-muted {
    color: #666;
}

.small {
    font-size: 14px;
}

.mt-3 {
    margin-top: 16px;
}

/* tabs */
.tabs {
    list-style: none;
    display: flex;
    padding: 0;
    margin: 0 0 16px 0;
}

.tab-item {
    padding: 10px 20px;
    cursor: pointer;
    border: 1px solid #ddd;
    background: #f9f9f9;
    margin-right: 4px;
    border-radius: 6px;
}

.tab-item.active {
    background: #fff;
    font-weight: bold;
}

/* tab content */
.tab-content {
    border: 1px solid #ddd;
    border-radius: 6px;
    padding: 16px;
    background: #fff;
}

.tab-pane {
    display: none;
}

.tab-pane.active {
    display: block;
}

/* form */
.form-group {
    margin-bottom: 12px;
}

label {
    display: block;
    margin-bottom: 6px;
    font-weight: bold;
}

input {
    width: 100%;
    padding: 8px;
    border: 1px solid #ccc;
    border-radius: 6px;
}

/* button */
.btn {
    display: inline-block;
    padding: 8px 16px;
    background: #007bff;
    color: #fff;
    border: none;
    border-radius: 6px;
    cursor: pointer;
}

.btn:hover {
    background: #0056b3;
}

@media (max-width: 767.98px) {
    .main-container {
        margin-top: 60px;
    }
}