body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.main-content {
    flex: 1;
    padding-top: 20px;
    padding-bottom: 20px;
}

.footer {
    background-color: #f8f9fa;
    padding: 20px 0;
    margin-top: auto;
}

.card {
    margin-bottom: 20px;
    
}

.container {
    max-width: 900px;
}

@media (max-width: 768px) {
    .navbar-nav {
        text-align: center;
    }
}

.navbar-custom {
    background-color: #2c3e50;
}

.navbar-custom .navbar-brand,
.navbar-custom .nav-link {
    color: #ecf0f1 !important;
}

.navbar-custom .nav-link:hover,
.navbar-custom .navbar-brand:hover {
    color: #ffd54f !important;
}

.navbar-custom .navbar-toggler {
    border-color: rgba(255,255,255,0.5);
}

.navbar-custom .nav-user-center {
    color: #ffd54f !important;
    font-weight: bold;
    background-color: rgba(255,213,79,0.15);
    border-radius: 15px;
    padding-left: 15px !important;
    padding-right: 15px !important;
    margin-right: 5px;
}

.navbar-custom .nav-user-center:hover {
    color: #2c3e50 !important;
    background-color: #ffd54f !important;
}

.alert-custom {
    border: 2px solid;
    border-radius: 5px;
    padding: 15px;
}

.card-header-custom {
    padding: 15px;
}

.btn-custom {
    border-radius: 4px;
}

.attachment-card {
    height: 315px;
    overflow: hidden;
}

.custom-file {
    position: relative;
    display: inline-block;
    width: 100%;
}

.custom-file-input {
    position: relative;
    z-index: 2;
    width: 100%;
    height: calc(1.5em + .75rem + 2px);
    margin: 0;
    opacity: 0;
}

.custom-file-label {
    position: absolute;
    top: 0;
    right: 0;
    left: 0;
    z-index: 1;
    height: calc(1.5em + .75rem + 2px);
    padding: .375rem .75rem;
    font-weight: 400;
    line-height: 1.5;
    color: #fff;
    background-color: #0dcaf0;
    border: 1px solid #0dcaf0;
    border-radius: .25rem;
    display: flex;
    align-items: center;
}

.custom-file-label::after {
    content: "选择文件";
}

.submit-attachment-page .form-group label[for="id_file"] {
    display: inline-block;
    padding: 8px 16px;
    background: linear-gradient(135deg, #0dcaf0 0%, #0891b2 100%);
    color: white;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 2px 8px rgba(13, 202, 240, 0.3);
}

.submit-attachment-page .form-group label[for="id_file"]:hover {
    background: linear-gradient(135deg, #0891b2 0%, #0e7490 100%);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(13, 202, 240, 0.4);
}