* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html, body {
    height: 100%;
    width: 100%;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
    background: radial-gradient(circle at top right, #eff6ff 0%, #f8fafc 100%);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 2rem 1rem 4rem;
    color: #1e293b;
    position: relative;
}

/* ========== 主容器 ========== */
#mainbody {
    text-align: center;
    width: 100%;
    max-width: 460px;
}

@media (min-width: 768px) {
    #mainbody {
        max-width: 500px;
    }
}

/* ========== Logo 区域 ========== */
.logo-box {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 64px;
    height: 64px;
    background-color: #fff;
    border-radius: 1rem;
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    margin-bottom: 1rem;
}

.logo-box img {
    border-radius: 1rem;
}

@media (min-width: 768px) {
    .logo-box {
        width: 72px;
        height: 72px;
        margin-bottom: 1.25rem;
    }
}

.logo-box i {
    color: #fff;
    font-size: 2rem;
}

@media (min-width: 768px) {
    .logo-box i {
        font-size: 2.5rem;
    }
}

/* ========== 标题 ========== */
#mainbody h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: #1e293b;
    letter-spacing: -0.025em;
    margin-bottom: 0.5rem;
}

@media (min-width: 768px) {
    #mainbody h1 {
        font-size: 1.875rem;
    }
}

/* ========== 副标题 ========== */
.subtitle {
    color: #64748b;
    font-size: 0.9375rem;
    font-weight: 500;
    margin-bottom: 2rem;
    line-height: 1.6;
}

@media (min-width: 768px) {
    .subtitle {
        font-size: 1rem;
        margin-bottom: 2.5rem;
    }
}

/* ========== 卡片 ========== */
.home-card {
    background-color: #fff;
    border-radius: 1.5rem;
    box-shadow: 0 20px 25px -5px rgba(148, 163, 184, 0.2), 0 10px 10px -5px rgba(148, 163, 184, 0.1);
    border: 1px solid #f1f5f9;
    padding: 2rem 1.5rem;
    margin-bottom: 2rem;
}

@media (min-width: 768px) {
    .home-card {
        padding: 2.5rem 2rem;
    }
}

/* ========== 功能网格 ========== */
.feature-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin: 0 0 1.5rem;
}

.feature-title {
    grid-column: 1 / -1;
    text-align: center;
    color: #1e293b;
    font-size: 1rem;
    font-weight: 600;
    margin: 0 0 0.25rem;
    letter-spacing: 0.05em;
}

.feature-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding: 1rem 0.5rem;
    background: #f8fafc;
    border-radius: 0.75rem;
    color: #475569;
    font-size: 0.875rem;
    transition: background 0.15s;
}

.feature-item:hover {
    background: #eff6ff;
}

.feature-item i {
    color: #2563eb;
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.feature-item span {
    font-weight: 500;
}

/* ========== 进入按钮 ========== */
.btn-enter {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    width: 100%;
    background-color: #2563eb;
    color: #fff;
    font-weight: 700;
    font-size: 1rem;
    text-decoration: none;
    border: none;
    padding: 0.875rem 0;
    border-radius: 0.75rem;
    box-shadow: 0 10px 15px -3px rgba(37, 99, 235, 0.25);
    cursor: pointer;
    transition: background-color 0.15s, transform 0.1s;
}

.btn-enter:hover,
.btn-enter:focus {
    background-color: #1d4ed8;
    color: #fff;
    text-decoration: none;
}

.btn-enter:active {
    transform: scale(0.98);
}

/* ========== 版本信息 ========== */
.footer {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 0;
    text-align: center;
    color: #94a3b8;
    font-size: 0.8125rem;
    padding: 0.75rem 1rem;
    background: linear-gradient(to top, rgba(248, 250, 252, 0.95), rgba(248, 250, 252, 0));
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
}

.footer p {
    font-size: 0.8125rem;
    margin-bottom: 0.25rem;
}

.footer a {
    color: #64748b;
    text-decoration: none;
}

.footer a:hover {
    color: #2563eb;
}