:root {
    --primary-color: #0a84ff; /* 稍微提亮以在暗色背景更清晰 */
    --primary-hover: #409cff;
    --text-color: #f5f5f7; /* 浅色文字 */
    --text-secondary: #a1a1a6; /* 浅灰色次要文字 */
    --bg-color: #000000; /* 纯黑背景 */
    --white: #1c1c1e; /* 用于卡片背景的深灰色 */
    --modal-bg: #1c1c1e;
    --border-radius: 12px;
    --btn-radius: 980px; /* Pill shape */
    --border-color: #38383a; /* 深色边框 */
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
}

.background-blur {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    background: radial-gradient(circle at 50% 30%, #1a2c4e 0%, #000000 60%); /* 深蓝到黑的渐变 */
    opacity: 0.8;
}

/* Navbar */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    height: 44px;
    background: rgba(28, 28, 30, 0.8); /* 深色半透明 */
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    z-index: 1000;
    border-bottom: 1px solid var(--border-color);
}

.nav-content {
    max-width: 980px;
    margin: 0 auto;
    height: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 20px;
}

.logo {
    display: flex;
    align-items: center;
    font-weight: 600;
    font-size: 1.1rem;
    color: var(--text-color);
}

.logo img {
    height: 24px;
    width: 24px;
    margin-right: 8px;
    border-radius: 6px;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-secondary); /* 默认为次要颜色 */
    font-size: 0.85rem;
    transition: color 0.3s;
}

.nav-links .btn {
    color: #ffffff !important;
}

.nav-links a:hover {
    color: var(--text-color); /* 悬停变亮 */
}

/* Hero Section */
.hero-section {
    padding-top: 100px;
    padding-bottom: 60px;
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
    padding-left: 20px;
    padding-right: 20px;
}

.app-icon-large img {
    width: 120px;
    height: 120px;
    border-radius: 28px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.5); /* 加深阴影 */
    margin-bottom: 24px;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 10px;
    letter-spacing: -0.02em;
    color: var(--text-color);
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    font-weight: 500;
    margin-bottom: 20px;
}

.hero-description {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 40px;
    line-height: 1.6;
}

.action-buttons {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
    margin-bottom: 60px;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 24px;
    border-radius: var(--btn-radius);
    text-decoration: none;
    font-weight: 500;
    font-size: 1rem;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
}

.btn-primary {
    background-color: var(--primary-color);
    color: #ffffff; /* 按钮文字保持白色 */
}

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: scale(1.02);
}

.btn-large {
    padding: 14px 40px;
    font-size: 1.1rem;
    min-width: 200px;
}

.btn-block {
    width: 100%;
}

.btn-sm {
    padding: 6px 16px;
    font-size: 0.85rem;
    min-width: auto;
    border-radius: 980px;
}

.platform-hint {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Features Grid */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 30px;
    margin-top: 40px;
    text-align: left;
}

.feature-item {
    background: rgba(28, 28, 30, 0.6); /* 深色半透明背景 */
    padding: 24px;
    border-radius: 18px;
    border: 1px solid var(--border-color);
}

.feature-item h3 {
    font-size: 1.1rem;
    margin-bottom: 8px;
    color: var(--text-color);
}

.feature-item p {
    font-size: 0.95rem;
    color: var(--text-secondary);
}

/* Footer */
.footer {
    background: #1c1c1e; /* 深灰色底部 */
    padding: 30px 20px;
    text-align: center;
    font-size: 0.8rem;
    color: var(--text-secondary);
    border-top: 1px solid var(--border-color);
}

.footer-links {
    margin-top: 10px;
    display: flex;
    justify-content: center;
    gap: 20px;
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
}

.footer-links a:hover {
    color: var(--text-color);
    text-decoration: underline;
}

/* Modal */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7); /* 加深背景遮罩 */
    backdrop-filter: blur(10px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    opacity: 0;
    animation: fadeIn 0.3s forwards;
}

@keyframes fadeIn {
    to { opacity: 1; }
}

.modal-content {
    background: var(--modal-bg);
    width: 90%;
    max-width: 400px;
    border-radius: 18px;
    padding: 24px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.5);
    transform: scale(0.95);
    animation: scaleUp 0.3s forwards;
    border: 1px solid var(--border-color);
}

@keyframes scaleUp {
    to { transform: scale(1); }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.modal-header h2 {
    font-size: 1.5rem;
    margin: 0;
    color: var(--text-color);
}

.close-btn {
    background: none;
    border: none;
    font-size: 24px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: color 0.2s;
}

.close-btn:hover {
    color: var(--text-color);
}

.modal-desc {
    color: var(--text-secondary);
    margin-bottom: 20px;
    font-size: 0.95rem;
}

.input-group {
    margin-bottom: 16px;
}

.input-group input {
    width: 100%;
    padding: 12px 16px;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    background-color: #2c2c2e; /* 深色输入框背景 */
    color: var(--text-color);
    font-size: 1rem;
    outline: none;
    transition: border-color 0.2s;
}

.input-group input:focus {
    border-color: var(--primary-color);
    background-color: #3a3a3c;
}

.agreement-group {
    margin-bottom: 20px;
    font-size: 0.85rem;
    color: var(--text-secondary);
    display: flex;
    align-items: flex-start;
    gap: 8px;
}

.agreement-group input {
    margin-top: 3px;
    accent-color: var(--primary-color);
}

.agreement-group a {
    color: var(--primary-color);
    text-decoration: none;
}

/* Responsive */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }
    .hero-subtitle {
        font-size: 1.2rem;
    }
}