/* --- 统一样式变量 --- */
:root {
    --primary: #4361ee;
    --secondary: #3f37c9;
    --success: #4cc9f0;
    --danger: #f72585;
    --warning: #f8961e;
    --info: #4895ef;
    --light: #f8f9fa;
    --dark: #212529;
    --background: #f0f2f5;
    --card-bg: #ffffff;
    --text-color: #333333;
    --text-muted: #6c757d;
    --border-color: #dee2e6;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
    --nav-bg: #1e2a4a;
    --footer-text: #888888;
    --input-bg: #2c2c2c;
    --link-color: #3391ff;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: var(--text-color);
    line-height: 1.6;
    padding: 0;
    margin: 0;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* --- 通用组件样式 --- */
.main-container {
    max-width: 1200px;
    margin: 40px auto;
    padding: 20px;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.card {
    background: var(--card-bg);
    border-radius: 12px;
    box-shadow: var(--shadow);
    padding: 2rem;
    margin-bottom: 2rem;
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    text-align: center;
}

.btn-primary {
    background: var(--primary);
    color: white;
}

.btn-primary:hover {
    background: var(--secondary);
    transform: translateY(-2px);
}

.btn-success {
    background: var(--success);
    color: white;
}

.btn-danger {
    background: var(--danger);
    color: white;
}

.btn-warning {
    background: var(--warning);
    color: white;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-color);
}

.form-control {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: var(--transition);
    background: white;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.1);
}

.alert {
    padding: 12px 16px;
    border-radius: 8px;
    margin-bottom: 1rem;
    border: 1px solid transparent;
}

.alert-success {
    background: rgba(76, 201, 240, 0.1);
    border-color: var(--success);
    color: var(--success);
}

.alert-danger {
    background: rgba(247, 37, 133, 0.1);
    border-color: var(--danger);
    color: var(--danger);
}

.alert-warning {
    background: rgba(248, 150, 30, 0.1);
    border-color: var(--warning);
    color: var(--warning);
}

/* --- 响应式设计 --- */
@media (max-width: 768px) {
    .main-container {
        margin: 20px auto;
        padding: 15px;
    }

    .card {
        padding: 1.5rem;
    }

    .btn {
        width: 100%;
        margin-bottom: 10px;
    }
}

/* --- 动画效果 --- */
@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes spin {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

.fade-in-down {
    animation: fadeInDown 1s ease-out;
}

.fade-in-up {
    animation: fadeInUp 1s ease-out 0.3s both;
}

/* --- 加载动画 --- */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255,255,255,.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 1s ease-in-out infinite;
}

/* --- 工具类 --- */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }
.mt-1 { margin-top: 0.25rem; }
.mt-2 { margin-top: 0.5rem; }
.mt-3 { margin-top: 1rem; }
.mb-1 { margin-bottom: 0.25rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-3 { margin-bottom: 1rem; }
.p-1 { padding: 0.25rem; }
.p-2 { padding: 0.5rem; }
.p-3 { padding: 1rem; }
.d-none { display: none; }
.d-block { display: block; }
.d-flex { display: flex; }
.justify-content-between { justify-content: space-between; }
.align-items-center { align-items: center; }