/* CSS变量定义 */
:root {
    --primary: #4CAF50;
    --primary-light: #81C784;
    --primary-dark: #388E3C;
    --secondary: #FF9800;
    --accent: #2196F3;
    --bg: #f8fdf9;
    --surface: #ffffff;
    --surface-light: #f1f8e9;
    --text: #2E3A30;
    --text-dim: #6D7C72;
    --border: #E0E0E0;
    --radius: 16px;
    --shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Noto Sans SC', sans-serif;
}

body {
    background: var(--bg);
    color: var(--text);
    height: 100vh;
    overflow: hidden;
    position: relative;
}

/* 封面页样式 */
.cover-page {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #f8fdf9 0%, #e8f5e9 100%);
    z-index: 2000;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    transition: all 0.8s ease;
    padding: 20px;
    text-align: center;
}

.cover-page.hidden {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

.cover-content {
    max-width: 800px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 30px;
    position: relative;
    z-index: 10;
}

.cover-logo {
    width: 120px;
    height: 120px;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow);
    margin-bottom: 3px;
}

.cover-logo i {
    font-size: 50px;
    color: white;
}

.cover-title {
    font-size: 3.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 10px;
    line-height: 1.2;
}

.cover-subtitle {
    font-size: 1.5rem;
    color: var(--text-dim);
    margin-bottom: 40px;
    max-width: 600px;
    line-height: 1.5;
}

.cover-features {
    display: flex;
    gap: 30px;
    margin-bottom: 8px;
    flex-wrap: wrap;
    justify-content: center;
}

.feature {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    max-width: 190px;
    padding: 24px 16px;
    background: var(--surface);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
    transition: var(--transition);
}

.feature-icon {
    width: 70px;
    height: 70px;
    background: var(--surface-light);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 8px;
}

.feature-icon i {
    font-size: 30px;
    color: var(--primary);
}

.feature-title {
    font-weight: 600;
    color: var(--primary-dark);
    font-size: 1.1rem;
}

.feature-desc {
    color: var(--text-dim);
    font-size: 0.9rem;
    text-align: center;
    line-height: 1.3;
}

.cover-enter-btn {
    padding: 18px 50px;
    font-size: 1.2rem;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    border: none;
    border-radius: 50px;
    color: white;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    font-weight: 600;
    box-shadow: 0 8px 20px rgba(76, 175, 80, 0.3);
    display: flex;
    align-items: center;
    gap: 10px;
}

.cover-enter-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 12px 25px rgba(76, 175, 80, 0.4);
}

.cover-enter-btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.cover-enter-btn:hover::before {
    width: 300px;
    height: 300px;
}