/* 全局样式 */
:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --primary-light: #3b82f6;
    --background-color: #f8fafc;
    --text-color: #1f2937;
    --text-light: #6b7280;
    --white: #ffffff;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --header-height: 4rem;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    line-height: 1.5;
    color: var(--text-color);
    background-color: var(--background-color);
}

/* 容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* 导航栏 */
.navbar {
    background-color: var(--white);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    height: var(--header-height);
    border-bottom: 1px solid var(--border-color);
}

.nav-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--primary-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-logo i {
    font-size: 1.5rem;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-links a {
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    padding: 0.5rem 0;
    border-bottom: 2px solid transparent;
    transition: all 0.2s ease;
}

.nav-links a:hover {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

/* 语言选择器 */
.language-selector {
    position: relative;
    margin-left: 2rem;
}

.language-button {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    font-size: 0.95rem;
    color: var(--text-color);
    background-color: transparent;
    border: 1px solid var(--border-color);
    border-radius: 0.375rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

.language-button:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.language-button i {
    font-size: 1rem;
}

.language-options {
    position: absolute;
    top: calc(100% + 0.5rem);
    right: 0;
    background-color: var(--white);
    border: 1px solid var(--border-color);
    border-radius: 0.375rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    min-width: 150px;
    display: none;
}

.language-options.show {
    display: block;
}

.language-option {
    padding: 0.75rem 1rem;
    cursor: pointer;
    transition: all 0.2s ease;
    color: var(--text-color);
}

.language-option:hover {
    background-color: var(--background-color);
    color: var(--primary-color);
}

/* 移动菜单按钮 */
.mobile-menu-button {
    display: none;
    background: none;
    border: none;
    color: var(--text-color);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
}

@media (max-width: 768px) {
    .mobile-menu-button {
        display: block;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: var(--header-height);
        left: 0;
        right: 0;
        background-color: var(--white);
        padding: 1rem;
        flex-direction: column;
        gap: 1rem;
        border-top: 1px solid var(--border-color);
        box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    }

    .nav-links.show {
        display: flex;
    }

    .language-selector {
        margin-left: 0;
        width: 100%;
    }

    .language-button {
        width: 100%;
        justify-content: center;
    }

    .language-options {
        width: 100%;
    }
}

/* 主要内容区域 */
.main-content {
    margin-top: 4rem;
    padding: 2rem 0;
}

/* 计算器部分 */
.calculator-section {
    padding: 4rem 0;
    background-color: var(--white);
    border-radius: 1rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    margin: 2rem auto;
    max-width: 1000px;
}

.calculator-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    padding: 2rem;
}

.calculator-form {
    background-color: var(--background-color);
    border-radius: 0.75rem;
    padding: 2rem;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

.calculator-header {
    text-align: center;
    margin-bottom: 2rem;
    padding: 0 2rem;
}

.calculator-header h2 {
    color: var(--text-color);
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.calculator-header p {
    color: var(--text-light);
    font-size: 1.1rem;
    max-width: 600px;
    margin: 0 auto;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-color);
}

.form-input {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 1rem;
    transition: all 0.2s ease;
    background-color: var(--white);
}

.form-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-input:hover {
    border-color: var(--primary-light);
}

/* 结果显示部分 */
.results-section {
    margin-top: 2rem;
    padding: 2rem;
    background-color: #f8fafc;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.results-section h3 {
    color: #1e40af;
    font-size: 1.5rem;
    margin-bottom: 1rem;
    text-align: center;
}

.results-summary {
    font-size: 1.25rem;
    text-align: center;
    margin-bottom: 1.5rem;
    color: #1f2937;
}

#final-amount {
    font-weight: bold;
    color: #047857;
}

.results-description {
    text-align: center;
    color: #4b5563;
    margin-bottom: 2rem;
}

.chart-container {
    width: 100%;
    height: 400px;
    margin: 2rem 0;
}

.results-note {
    font-size: 0.875rem;
    color: #6b7280;
    text-align: center;
    font-style: italic;
    margin-top: 1rem;
}

/* 图表容器 */
.chart-section {
    grid-column: 1 / -1;
    background-color: var(--background-color);
    border-radius: 0.75rem;
    padding: 2rem;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

.chart-container {
    height: 400px;
    margin-top: 1rem;
}

/* 计算按钮 */
.btn-calculate {
    width: 100%;
    padding: 1rem;
    background-color: var(--primary-color);
    color: var(--white);
    border: none;
    border-radius: 0.5rem;
    font-size: 1.1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    margin-top: 1rem;
}

.btn-calculate:hover {
    background-color: var(--primary-dark);
    transform: translateY(-1px);
}

.btn-calculate:active {
    transform: translateY(0);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .calculator-grid {
        grid-template-columns: 1fr;
        padding: 1rem;
    }

    .calculator-section {
        margin: 1rem;
        padding: 2rem 0;
    }

    .calculator-form,
    .results-section {
        padding: 1.5rem;
    }

    .calculator-header h2 {
        font-size: 1.75rem;
    }

    .calculator-header p {
        font-size: 1rem;
    }

    .chart-container {
        height: 300px;
    }
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .mobile-menu-button {
        display: block;
    }

    .calculator-form {
        padding: 1.5rem;
    }

    .chart-container {
        height: 300px;
    }
}

/* 语言选择器 */
.language-selector {
    position: relative;
    display: inline-block;
}

.language-button {
    padding: 0.5rem 1rem;
    background-color: transparent;
    border: 1px solid var(--border-color);
    border-radius: 0.375rem;
    cursor: pointer;
}

.language-options {
    position: absolute;
    top: 100%;
    right: 0;
    background-color: white;
    border: 1px solid var(--border-color);
    border-radius: 0.375rem;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    display: none;
}

.language-options.show {
    display: block;
}

.language-option {
    padding: 0.5rem 1rem;
    cursor: pointer;
}

.language-option:hover {
    background-color: var(--background-color);
}

/* 动画效果 */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.animate-fade-in {
    animation: fadeIn 0.3s ease-out;
}

/* 工具提示 */
.tooltip {
    position: relative;
    display: inline-block;
}

.tooltip .tooltip-text {
    visibility: hidden;
    width: 200px;
    background-color: #333;
    color: white;
    text-align: center;
    border-radius: 0.375rem;
    padding: 0.5rem;
    position: absolute;
    z-index: 1;
    bottom: 125%;
    left: 50%;
    transform: translateX(-50%);
    opacity: 0;
    transition: opacity 0.2s;
}

.tooltip:hover .tooltip-text {
    visibility: visible;
    opacity: 1;
}

/* Header Styles */
.navbar {
    background-color: var(--white);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--box-shadow);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
}

.logo a {
    color: var(--primary-color);
    text-decoration: none;
    font-size: 1.5rem;
    font-weight: bold;
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a {
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-links a:hover {
    color: var(--primary-color);
}

.language-selector select {
    padding: 0.5rem;
    border-radius: var(--border-radius);
    border: 1px solid var(--light-gray);
    background-color: var(--white);
    cursor: pointer;
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-color);
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--white);
    padding: 8rem 0 4rem;
    text-align: center;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 20px;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1.5rem;
}

.hero p {
    font-size: 1.25rem;
    margin-bottom: 2rem;
}

.cta-button {
    display: inline-block;
    padding: 1rem 2rem;
    background-color: var(--white);
    color: var(--primary-color);
    text-decoration: none;
    border-radius: var(--border-radius);
    font-weight: bold;
    transition: transform 0.3s ease;
}

.cta-button:hover {
    transform: translateY(-2px);
}

/* Calculator Section */
.calculator-section {
    padding: 4rem 0;
    background-color: var(--white);
}

.calculator-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-top: 2rem;
}

.calculator-form {
    background-color: var(--background-color);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}

.input-group {
    margin-bottom: 1.5rem;
}

.input-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.input-group input,
.input-group select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--light-gray);
    border-radius: var(--border-radius);
    font-size: 1rem;
}

.calculate-btn {
    width: 100%;
    padding: 1rem;
    background-color: var(--primary-color);
    color: var(--white);
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: bold;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.calculate-btn:hover {
    background-color: var(--primary-dark);
}

.results-container {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
}

.result-card {
    background-color: var(--background-color);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--box-shadow);
}

.result-card h3 {
    font-size: 1rem;
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.result-card p {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

#chart-container {
    grid-column: 1 / -1;
    background-color: var(--background-color);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    margin-top: 1rem;
    min-height: 300px;
}

/* Features Section */
.features-section {
    padding: 4rem 0;
    background-color: var(--background-color);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.feature-card {
    background-color: var(--white);
    padding: 2rem;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--box-shadow);
}

.feature-card i {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

/* How It Works Section */
.how-it-works-section {
    padding: 4rem 0;
    background-color: var(--white);
}

.steps-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.step-card {
    position: relative;
    padding: 2rem;
    background-color: var(--background-color);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}

.step-number {
    position: absolute;
    top: -1rem;
    left: -1rem;
    width: 2.5rem;
    height: 2.5rem;
    background-color: var(--primary-color);
    color: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
}

/* Testimonials Section */
.testimonials-section {
    padding: 4rem 0;
    background-color: var(--background-color);
}

.testimonials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.testimonial-card {
    background-color: var(--white);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}

.testimonial-content {
    margin-bottom: 1.5rem;
}

.testimonial-author {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.testimonial-author img {
    width: 50px;
    height: 50px;
    border-radius: 50%;
}

/* FAQ Section */
.faq-section {
    padding: 4rem 0;
    background-color: var(--white);
}

.faq-grid {
    display: grid;
    gap: 1.5rem;
    margin-top: 2rem;
}

.faq-item {
    background-color: var(--background-color);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}

.faq-item h3 {
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

/* Footer */
.footer {
    background-color: var(--text-color);
    color: var(--white);
    padding: 4rem 0 2rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    margin-bottom: 1rem;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: var(--white);
    text-decoration: none;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

/* Responsive Design */
@media (max-width: 768px) {
    .navbar {
        padding: 1rem;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: var(--white);
        padding: 1rem;
        flex-direction: column;
        gap: 1rem;
        box-shadow: var(--box-shadow);
    }

    .nav-links.active {
        display: flex;
    }

    .mobile-menu-btn {
        display: block;
    }

    .calculator-grid {
        grid-template-columns: 1fr;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .hero p {
        font-size: 1rem;
    }
}

@media (max-width: 480px) {
    .results-container {
        grid-template-columns: 1fr;
    }

    .feature-card,
    .step-card,
    .testimonial-card {
        padding: 1.5rem;
    }
}