/* ===== CSS VARIABLES ===== */
:root {
    /* Colors */
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary-color: #64748b;
    --accent-color: #f59e0b;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;

    /* Neutral Colors */
    --white: #ffffff;
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1e293b;
    --gray-900: #0f172a;

    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;

    /* Spacing */
    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 0.75rem;
    --spacing-4: 1rem;
    --spacing-5: 1.25rem;
    --spacing-6: 1.5rem;
    --spacing-8: 2rem;
    --spacing-10: 2.5rem;
    --spacing-12: 3rem;
    --spacing-16: 4rem;
    --spacing-20: 5rem;

    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.375rem;
    --radius-lg: 0.5rem;
    --radius-xl: 0.75rem;
    --radius-2xl: 1rem;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;

    /* Layout */
    --container-max-width: 1200px;
    --header-height: 70px;
}

/* ===== RESET & BASE STYLES ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--gray-700);
    background-color: var(--white);
    overflow-x: hidden;
}

.de_iv_adv {
    width: 100%;
    height: auto;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 5px 0;
    /* background-color: #F8F8F8; */
    margin: 80px 0 0px;
}

/* 底部广告位 */
.postionFixed {
    width: 100%;
    min-height: 60px;
    position: fixed;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: #F8F8F8;
    right: 0;
    left: 0;
    bottom: 0;
    z-index: 9999;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

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

button {
    border: none;
    background: none;
    cursor: pointer;
    font-family: inherit;
    transition: all var(--transition-fast);
}

ul {
    list-style: none;
}

/* ===== UTILITY CLASSES ===== */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-4);
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* ===== TYPOGRAPHY ===== */
h1,
h2,
h3,
h4,
h5,
h6 {
    font-weight: 600;
    line-height: 1.2;
    color: var(--gray-900);
    margin-bottom: var(--spacing-4);
}

h1 {
    font-size: var(--font-size-4xl);
}

h2 {
    font-size: var(--font-size-3xl);
}

h3 {
    font-size: var(--font-size-2xl);
}

h4 {
    font-size: var(--font-size-xl);
}

h5 {
    font-size: var(--font-size-lg);
}

h6 {
    font-size: var(--font-size-base);
}

p {
    margin-bottom: var(--spacing-4);
}

/* ===== BUTTONS ===== */
.cta-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-3) var(--spacing-6);
    background-color: var(--primary-color);
    color: var(--white);
    font-weight: 500;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    text-decoration: none;
}

.cta-button:hover {
    background-color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.secondary-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-3) var(--spacing-6);
    background-color: transparent;
    color: var(--primary-color);
    font-weight: 500;
    border: 2px solid var(--primary-color);
    border-radius: var(--radius-lg);
    transition: all var(--transition-normal);
    text-decoration: none;
}

.secondary-button:hover {
    background-color: var(--primary-color);
    color: var(--white);
    transform: translateY(-2px);
}

/* ===== SECTIONS ===== */
.section-title {
    text-align: center;
    margin-bottom: var(--spacing-4);
    color: var(--gray-900);
}

.section-description {
    text-align: center;
    color: var(--gray-600);
    max-width: 600px;
    margin: 0 auto var(--spacing-12);
    font-size: var(--font-size-lg);
}

/* ===== ANIMATIONS ===== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

.fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}

.fade-in {
    animation: fadeIn 0.6s ease-out;
}

/* ===== FOCUS STYLES ===== */
*:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

button:focus,
a:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* ===== LOADING STATES ===== */
.loading {
    opacity: 0.6;
    pointer-events: none;
}

.spinner {
    width: 20px;
    height: 20px;
    border: 2px solid var(--gray-300);
    border-top: 2px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% {
        transform: rotate(0deg);
    }

    100% {
        transform: rotate(360deg);
    }
}

/* ===== NEW HOMEPAGE SECTIONS ===== */

/* Stats Section */
.stats-section {
    padding: var(--spacing-16) 0;
    background: var(--primary-color);
    color: var(--white);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-8);
    text-align: center;
}

.stat-item {
    padding: var(--spacing-6);
}

.stat-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-4);
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-2);
    color: var(--white);
    min-height: 1.2em;
    /* 固定高度防止闪动 */
    line-height: 1.2;
    /* 防止数字变化时的布局跳动 */
    font-variant-numeric: tabular-nums;
}

.stat-label {
    font-size: 1.1rem;
    opacity: 0.9;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Reviews Section */
.reviews-section {
    padding: var(--spacing-16) 0;
    background: var(--white);
}

.reviews-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-8);
    margin-top: var(--spacing-12);
}

.review-card {
    background: var(--white);
    border-radius: var(--radius-xl);
    padding: var(--spacing-8);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--gray-200);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.review-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.review-stars {
    font-size: 1.2rem;
    margin-bottom: var(--spacing-4);
}

.review-text {
    font-size: 1.1rem;
    line-height: 1.6;
    color: var(--gray-700);
    margin-bottom: var(--spacing-6);
    font-style: italic;
}

.review-author {
    display: flex;
    align-items: center;
    gap: var(--spacing-4);
}

.author-avatar {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--primary-color);
    color: var(--white);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 1.1rem;
}

.author-name {
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: var(--spacing-1);
}

.author-role {
    font-size: 0.9rem;
    color: var(--gray-600);
}

/* Features Section */
.features-section {
    padding: var(--spacing-16) 0;
    background: var(--gray-50);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-8);
    margin-top: var(--spacing-12);
}

.feature-card {
    background: var(--white);
    border-radius: var(--radius-xl);
    padding: var(--spacing-8);
    text-align: center;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--gray-200);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-4);
}

.feature-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: var(--spacing-4);
}

.feature-description {
    color: var(--gray-700);
    line-height: 1.6;
}