/* ===== 基础变量与重置 ===== */
:root {
    /* 主色调 - 科技蓝 */
    --primary: #1a73e8;
    --primary-dark: #1557b0;
    --primary-light: #e8f0fe;

    /* 中性色 */
    --gray-50: #f8f9fa;
    --gray-100: #f1f3f5;
    --gray-200: #e9ecef;
    --gray-300: #dee2e6;
    --gray-400: #ced4da;
    --gray-500: #adb5bd;
    --gray-600: #868e96;
    --gray-700: #495057;
    --gray-800: #343a40;
    --gray-900: #212529;

    /* 功能色 */
    --success: #2ecc71;
    --warning: #f39c12;
    --danger: #e74c3c;
    --info: #3498db;

    /* 布局 */
    --sidebar-width: 220px;
    --header-height: 60px;
    --border-radius: 8px;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.12);
    --transition: all 0.2s ease;
}

/* 重置 */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC',
                 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    color: var(--gray-800);
    background: var(--gray-50);
    line-height: 1.6;
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--primary-dark);
}

img {
    max-width: 100%;
}

/* 通用排版 */
h1, h2, h3, h4, h5, h6 {
    color: var(--gray-900);
    font-weight: 600;
    line-height: 1.3;
}

h1 { font-size: 1.75rem; }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.1rem; }

/* 消息提示 - GitHub 风格顶部居中 toast */
.flashes {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 10000;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding-top: 12px;
    pointer-events: none;
}

.flash-message {
    padding: 10px 24px;
    border-radius: 6px;
    font-size: 0.9rem;
    font-weight: 500;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    pointer-events: auto;
    cursor: pointer;
    animation: slideDown 0.3s ease;
    text-align: center;
    max-width: 480px;
    width: max-content;
}

@keyframes slideDown {
    from { transform: translateY(-100%); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

.flash-message.success {
    background: #1a7f37;
    color: #fff;
    border: none;
}

.flash-message.error {
    background: #cf222e;
    color: #fff;
    border: none;
}

.flash-message.info {
    background: #0969da;
    color: #fff;
    border: none;
}