/* 极简样式 */
* { box-sizing: border-box; }
body { margin: 0; font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans', 'Microsoft YaHei', sans-serif; background: #f5f7fb; color: #222; }
.header { display: flex; justify-content: space-between; align-items: center; padding: 12px 16px; background: #0b1c2e; color: #fff; }
.container { max-width: 1080px; margin: 0 auto; padding: 16px; }
.card { background: #fff; padding: 16px; border-radius: 8px; box-shadow: 0 8px 24px rgba(0,0,0,0.08); }
.form { display: grid; gap: 12px; max-width: 420px; }
.form.inline { display: flex; gap: 8px; }
.form input[type=text], .form input[type=password] { width: 100%; padding: 10px; border: 1px solid #d6d9e0; border-radius: 8px; background: #fff; }
.form input[type=text]:focus, .form input[type=password]:focus { outline: none; border-color: #4c8bf5; box-shadow: 0 0 0 3px rgba(76,139,245,0.15); }
.form button { padding: 10px 14px; border: none; border-radius: 8px; background: #4c8bf5; color: #fff; cursor: pointer; transition: background .2s ease; }
.form button:hover { background: #3d79e0; }
.alert { padding: 10px 12px; background: #ffe6e6; border: 1px solid #f5c2c7; color: #b02a37; border-radius: 8px; margin-bottom: 12px; }
.table-wrap { overflow: auto; background: #fff; padding: 12px; border-radius: 8px; box-shadow: 0 8px 24px rgba(0,0,0,0.08); }
table { width: 100%; border-collapse: collapse; }
th, td { text-align: left; padding: 10px; border-bottom: 1px solid #eef0f5; }
th { background: #f8fafc; font-weight: 600; }

/* 登录页：全屏居中 */
.page-centered { min-height: 100vh; display: flex; align-items: center; justify-content: center; background: linear-gradient(145deg, #edf2ff 0%, #f5f7fb 60%); padding: 24px; }
.auth-card { width: 100%; max-width: 420px; background: #fff; border-radius: 12px; box-shadow: 0 16px 48px rgba(0,0,0,0.12); padding: 24px; }
.auth-card h1 { margin: 0 0 12px; font-size: 20px; }
.brand { display: flex; align-items: center; gap: 8px; font-weight: 600; color: #0b1c2e; margin-bottom: 16px; }

/* 后台：左右两列布局 */
.layout { display: grid; grid-template-columns: 240px 1fr; min-height: calc(100vh - 52px); }
.sidebar { background: #0f1f35; color: #cfe0ff; padding: 16px 12px; }
.sidebar .nav-group { display: grid; gap: 8px; }
.nav-item { display: block; padding: 10px 12px; border-radius: 8px; color: #cfe0ff; text-decoration: none; transition: background .2s ease, color .2s ease; }
.nav-item:hover { background: #102949; }
.nav-item.active { background: #16365e; color: #fff; }
.content { padding: 16px; }
.content h2 { margin-top: 0; }