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

body {
    font-family: 'Inter', sans-serif;
    background: #ffffff;
    color: #1f2328;
    line-height: 1.5;
    transition: background 0.2s, color 0.2s;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ========== 导航栏 ========== */
nav {
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.95);
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid #e1e4e8;
    padding: 16px 0;
    z-index: 100;
    transition: background 0.2s, border-color 0.2s;
}

.nav-flex {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1.5rem;
    font-weight: 700;
    color: #00b8b8;
}

.logo-icon {
    width: 32px;
    height: 32px;
    object-fit: contain;
}

.nav-links {
    display: flex;
    gap: 24px;
    align-items: center;
    flex-wrap: wrap;
}

.nav-links a {
    color: #57606a;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

.nav-links a:hover {
    color: #00b8b8;
}

.dark-mode-btn {
    background: none;
    border: 1px solid #d0d7de;
    border-radius: 30px;
    font-size: 1.2rem;
    cursor: pointer;
    padding: 6px 12px;
    transition: all 0.2s;
}

.dark-mode-btn:hover {
    background: #f0f0f0;
}

.lang-switch-btn {
    background: none;
    border: 1px solid #d0d7de;
    border-radius: 30px;
    font-size: 0.8rem;
    cursor: pointer;
    padding: 6px 12px;
    transition: all 0.2s;
}

body.dark-mode .lang-switch-btn {
    border-color: #3d444d;
    color: #e6edf3;
}

/* ========== Hero 区域 ========== */
.hero {
    padding: 80px 0;
    background: #f6f8fa;
    transition: background 0.2s;
}

.hero-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 48px;
}

.hero-text {
    flex: 1;
}

.badge {
    display: inline-block;
    background: rgba(0, 184, 184, 0.1);
    color: #00b8b8;
    padding: 6px 14px;
    border-radius: 30px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 24px;
}

h1 {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 24px;
    line-height: 1.2;
    color: #1f2328;
}

.hero-text p {
    font-size: 1.2rem;
    color: #57606a;
    margin-bottom: 32px;
}

.btn-group {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    border-radius: 40px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.2s;
}

.btn-primary {
    background: #00b8b8;
    color: white;
}

.btn-primary:hover {
    background: #009999;
    transform: translateY(-2px);
}

.btn-secondary {
    background: #f0f0f0;
    color: #1f2328;
    border: 1px solid #d0d7de;
}

.btn-secondary:hover {
    background: #e0e0e0;
}

/* 右侧吉祥物 */
.hero-right {
    text-align: center;
}

.corvus-circle {
    width: 180px;
    height: 180px;
    background: #ffffff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 16px;
    border: 3px solid #00b8b8;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
    overflow: hidden;
}

.corvus-circle img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.corvus-name {
    font-size: 1.2rem;
    font-weight: 600;
    color: #00b8b8;
}

.corvus-desc {
    font-size: 0.9rem;
    color: #57606a;
}

/* ========== 通用 ========== */
.section-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 40px;
    border-left: 4px solid #00b8b8;
    padding-left: 20px;
}

.grid-2, .grid-3 {
    display: grid;
    gap: 28px;
}

.grid-2 {
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.grid-3 {
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.card {
    background: #ffffff;
    border: 1px solid #e1e4e8;
    border-radius: 20px;
    padding: 28px;
    transition: all 0.2s;
}

.card:hover {
    border-color: #00b8b8;
    transform: translateY(-4px);
}

.card i {
    font-size: 2.2rem;
    color: #00b8b8;
    margin-bottom: 16px;
}

.card h3 {
    margin-bottom: 12px;
    font-size: 1.2rem;
    font-weight: 600;
}

.card p {
    color: #57606a;
    font-size: 0.9rem;
    line-height: 1.6;
}

/* 交替背景 */
.alt-bg {
    background: #f6f8fa;
    padding: 60px 0;
}

/* ========== QnA ========== */
.qna-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.qna-item {
    background: #ffffff;
    border: 1px solid #e1e4e8;
    border-radius: 16px;
    overflow: hidden;
}

.qna-q {
    background: #f6f8fa;
    padding: 18px 24px;
    font-weight: 600;
    color: #1f2328;
    cursor: pointer;
    position: relative;
}

.qna-q::after {
    content: '▼';
    position: absolute;
    right: 24px;
    font-size: 0.8rem;
    transition: transform 0.2s;
    color: #57606a;
}

.qna-item.active .qna-q::after {
    transform: rotate(180deg);
}

.qna-a {
    padding: 0 24px;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease, padding 0.3s ease;
    color: #57606a;
    border-top: none;
}

.qna-item.active .qna-a {
    padding: 20px 24px;
    max-height: 300px;
    border-top: 1px solid #e1e4e8;
}

/* ========== 页脚 ========== */
footer {
    text-align: center;
    padding: 48px 0;
    border-top: 1px solid #e1e4e8;
    margin-top: 48px;
}

.footer-note {
    color: #8b949e;
    font-size: 0.8rem;
    margin-top: 8px;
}

/* ========== 深色模式 ========== */
body.dark-mode {
    background: #0d1117;
    color: #e6edf3;
}

body.dark-mode nav {
    background: rgba(13, 17, 23, 0.95);
    border-bottom-color: #21262d;
}

body.dark-mode .nav-links a {
    color: #e6edf3;
}

body.dark-mode .nav-links a:hover {
    color: #00ffff;
}

body.dark-mode .dark-mode-btn {
    border-color: #3d444d;
    color: #e6edf3;
}

body.dark-mode .dark-mode-btn:hover {
    background: #21262d;
}

body.dark-mode .hero {
    background: #161b22;
}

body.dark-mode h1 {
    color: #e6edf3;
}

body.dark-mode .hero-text p {
    color: #8b949e;
}

body.dark-mode .badge {
    background: rgba(0, 255, 255, 0.1);
}

body.dark-mode .btn-secondary {
    background: #21262d;
    color: #e6edf3;
    border-color: #3d444d;
}

body.dark-mode .btn-secondary:hover {
    background: #30363d;
}

body.dark-mode .corvus-circle {
    background: #0d1117;
    border-color: #00ffff;
    box-shadow: 0 0 20px rgba(0, 255, 255, 0.2);
}

body.dark-mode .corvus-name {
    color: #00ffff;
}

body.dark-mode .corvus-desc {
    color: #8b949e;
}

body.dark-mode .card {
    background: #161b22;
    border-color: #30363d;
}

body.dark-mode .card p {
    color: #8b949e;
}

body.dark-mode .alt-bg {
    background: #161b22;
}

body.dark-mode .qna-item {
    background: #161b22;
    border-color: #30363d;
}

body.dark-mode .qna-q {
    background: #21262d;
    color: #e6edf3;
}

body.dark-mode .qna-q::after {
    color: #8b949e;
}

body.dark-mode .qna-a {
    color: #8b949e;
}

body.dark-mode .qna-item.active .qna-a {
    border-top-color: #30363d;
}

body.dark-mode footer {
    border-top-color: #21262d;
}

body.dark-mode .footer-note {
    color: #8b949e;
}

/* ========== 响应式 ========== */
@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }
    .hero-content {
        flex-direction: column;
        text-align: center;
    }
    .btn-group {
        justify-content: center;
    }
    .section-title {
        font-size: 1.5rem;
    }
    .corvus-circle {
        width: 140px;
        height: 140px;
    }
}