/* ==================== CSS Variables ==================== */
:root {
    --primary-blue: #3B82F6;
    --primary-blue-dark: #2563EB;
    --primary-blue-light: #60A5FA;
    --bg-gradient-start: #F0F4FF;
    --bg-gradient-end: #E8EEFF;
    --card-bg: #FFFFFF;
    --text-primary: #1F2937;
    --text-secondary: #6B7280;
    --text-muted: #9CA3AF;
    --border-color: #E5E7EB;
    --border-dashed: #C7D2E8;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
}

/* ==================== Reset & Base ==================== */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
    min-height: 100vh;
    color: var(--text-primary);
    line-height: 1.6;
}

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

/* ==================== Header ==================== */
.header {
    padding: 20px 0;
    position: sticky;
    top: 0;
    background: rgba(240, 244, 255, 0.9);
    backdrop-filter: blur(10px);
    z-index: 100;
    border-bottom: 1px solid rgba(229, 231, 235, 0.5);
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 4px;
    font-weight: 800;
    font-size: 1.5rem;
}

.logo-text {
    color: var(--text-primary);
}

.logo-ai {
    color: var(--primary-blue);
    position: relative;
}

.logo-ai::before {
    content: '';
    position: absolute;
    width: 28px;
    height: 28px;
    border: 2px solid var(--primary-blue);
    border-radius: 50%;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

.nav {
    display: flex;
    gap: 32px;
}

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    transition: color var(--transition-fast);
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-blue);
    transition: width var(--transition-normal);
}

.nav-link:hover {
    color: var(--primary-blue);
}

.nav-link:hover::after {
    width: 100%;
}

/* ==================== Hero Section ==================== */
.hero {
    padding: 60px 0 100px;
}

.hero-grid {
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 60px;
    align-items: center;
}

.hero-title {
    font-size: 3.2rem;
    font-weight: 800;
    line-height: 1.15;
    margin-bottom: 32px;
    letter-spacing: -0.02em;
}

.highlight {
    color: var(--primary-blue);
}

.hero-description {
    font-size: 1.05rem;
    color: var(--text-secondary);
    max-width: 540px;
    line-height: 1.7;
    margin-bottom: 48px;
}

.cta-text {
    color: var(--primary-blue);
    font-weight: 600;
}

/* ==================== Stats ==================== */
.stats {
    display: flex;
    gap: 40px;
}

.stat-item {
    position: relative;
    flex: 1;
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--text-primary);
    display: flex;
    align-items: baseline;
}

.stat-slash {
    color: var(--primary-blue);
    margin-right: 8px;
    font-weight: 400;
}

.stat-label {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-top: 8px;
    max-width: 200px;
}

.highlight-small {
    color: var(--primary-blue);
}

/* ==================== Try Section ==================== */
.hero-action {
    position: relative;
}

.try-header {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    margin-bottom: 20px;
}

.try-now-text {
    font-family: 'Comic Sans MS', 'Segoe Script', cursive, sans-serif;
    font-size: 2rem;
    color: var(--primary-blue);
    font-weight: 700;
    letter-spacing: 0.05em;
    text-shadow: 0 1px 2px rgba(59, 130, 246, 0.3);
}

.arrow-svg {
    width: 60px;
    height: 40px;
    transform: rotate(-10deg);
}

.detection-card {
    background: var(--card-bg);
    border-radius: var(--radius-xl);
    padding: 32px;
    box-shadow: var(--shadow-xl);
    width: 100%;
    border: 1px solid rgba(59, 130, 246, 0.1);
}

.card-header {
    margin-bottom: 32px;
}

.beta-badge {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-style: italic;
}

.card-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-top: 8px;
}

/* ==================== Upload Area ==================== */
.upload-area {
    border: 2px dashed var(--border-dashed);
    border-radius: var(--radius-lg);
    padding: 48px 24px;
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

.upload-area:hover {
    border-color: var(--primary-blue);
    background: rgba(59, 130, 246, 0.02);
}

.upload-area.dragover {
    border-color: var(--primary-blue);
    background: rgba(59, 130, 246, 0.05);
    transform: scale(1.01);
}

.upload-icon {
    position: relative;
    width: 64px;
    height: 64px;
}

.upload-icon svg {
    width: 100%;
    height: 100%;
}

.upload-plus {
    position: absolute;
    bottom: -4px;
    right: -4px;
    width: 24px;
    height: 24px;
    background: var(--primary-blue);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    font-weight: 600;
    box-shadow: var(--shadow-md);
}

.upload-text {
    font-size: 1rem;
    color: var(--text-primary);
}

.upload-link {
    color: var(--primary-blue);
    font-weight: 600;
    cursor: pointer;
    text-decoration: none;
    transition: color var(--transition-fast);
}

.upload-link:hover {
    color: var(--primary-blue-dark);
    text-decoration: underline;
}

.upload-hint {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.upload-limit {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* ==================== Preview Area ==================== */
.preview-area {
    position: relative;
    border-radius: var(--radius-lg);
    overflow: hidden;
    margin-bottom: 24px;
}

.preview-area img {
    width: 100%;
    max-height: 400px;
    object-fit: contain;
    background: #F9FAFB;
    border-radius: var(--radius-lg);
}

.remove-btn {
    position: absolute;
    top: 12px;
    right: 12px;
    width: 32px;
    height: 32px;
    border: none;
    background: rgba(0, 0, 0, 0.6);
    color: white;
    border-radius: 50%;
    font-size: 1.2rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.remove-btn:hover {
    background: rgba(239, 68, 68, 0.9);
    transform: scale(1.1);
}

/* ==================== Divider ==================== */
.divider {
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 28px 0;
}

.divider-text {
    background: #6B7280;
    color: white;
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
}

/* ==================== URL Input ==================== */
.url-input-area {
    display: flex;
    gap: 12px;
    background: var(--bg-gradient-start);
    padding: 8px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
}

.url-input {
    flex: 1;
    border: none;
    background: transparent;
    padding: 12px 16px;
    font-size: 1rem;
    color: var(--text-primary);
    outline: none;
}

.url-input::placeholder {
    color: var(--text-muted);
}

.url-btn {
    background: var(--primary-blue);
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
}

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

/* ==================== Analyze Button ==================== */
.analyze-btn {
    width: 100%;
    margin-top: 24px;
    padding: 16px 32px;
    background: linear-gradient(135deg, var(--primary-blue) 0%, var(--primary-blue-dark) 100%);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: all var(--transition-normal);
    box-shadow: 0 4px 14px rgba(59, 130, 246, 0.4);
}

.analyze-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.5);
}

.btn-icon {
    font-size: 1.2rem;
}

/* ==================== Result Area ==================== */
.result-area {
    margin-top: 32px;
    padding: 24px;
    background: linear-gradient(135deg, #F9FAFB 0%, #F3F4F6 100%);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

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

.result-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

.result-header h3 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin: 0;
}

.reset-btn {
    background: linear-gradient(135deg, var(--primary-blue) 0%, var(--primary-blue-dark) 100%);
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: var(--radius-md);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.3);
}

.reset-btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.4);
}

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

.result-indicator {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 20px;
}

.indicator-circle {
    width: 16px;
    height: 16px;
    border-radius: 50%;
    animation: pulse 1.5s infinite;
}

@keyframes pulse {

    0%,
    100% {
        transform: scale(1);
        opacity: 1;
    }

    50% {
        transform: scale(1.2);
        opacity: 0.7;
    }
}

.analyzing .indicator-circle {
    background: var(--primary-blue);
}

.ai-generated .indicator-circle {
    background: #EF4444;
    animation: none;
}

.uncertain .indicator-circle {
    background: #F59E0B;
    animation: none;
}

.human-made .indicator-circle {
    background: #10B981;
    animation: none;
}

.result-text {
    font-size: 1.1rem;
    font-weight: 600;
}

.analyzing .result-text {
    color: var(--primary-blue);
}

.ai-generated .result-text {
    color: #DC2626;
}

.uncertain .result-text {
    color: #D97706;
}

.human-made .result-text {
    color: #059669;
}

.result-details {
    margin-top: 16px;
}

.detail-item {
    display: flex;
    align-items: center;
    gap: 16px;
}

.detail-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    min-width: 100px;
}

.progress-bar {
    flex: 1;
    height: 8px;
    background: #E5E7EB;
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-blue) 0%, var(--primary-blue-dark) 100%);
    border-radius: 4px;
    transition: width 0.3s ease;
}

.detail-value {
    font-size: 1rem;
    font-weight: 700;
    color: var(--text-primary);
    min-width: 50px;
    text-align: right;
}

/* ==================== How It Works Section ==================== */
.how-it-works {
    padding: 100px 0;
    background: #F9FAFB;
}

.section-title-main {
    font-size: 3rem;
    font-weight: 800;
    text-align: center;
    line-height: 1.2;
    margin-bottom: 24px;
    color: var(--text-primary);
}

.circle-text {
    position: relative;
    display: inline-block;
    padding: 0 10px;
    z-index: 1;
}

.circle-text::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 110%;
    height: 130%;
    border: 3px solid var(--primary-blue);
    border-radius: 50% / 50%;
    z-index: -1;
    opacity: 0.6;
}

.section-desc-main {
    font-size: 1.1rem;
    color: var(--text-secondary);
    text-align: center;
    max-width: 800px;
    margin: 0 auto 60px;
    line-height: 1.8;
}

.steps-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 40px;
}

.step-card {
    text-align: center;
    transition: transform var(--transition-normal);
}

.step-card:hover {
    transform: translateY(-10px);
}

.step-image {
    background: white;
    border-radius: var(--radius-lg);
    padding: 20px;
    box-shadow: var(--shadow-lg);
    margin-bottom: 32px;
    aspect-ratio: 4/3;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.step-image img {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.step-title {
    font-size: 1.5rem;
    font-weight: 800;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.step-desc {
    font-size: 1rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ==================== AI Showcase Section ==================== */
.ai-showcase {
    padding: 100px 0;
    background: white;
}

.showcase-grid {
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 80px;
    align-items: center;
}

.showcase-image img {
    width: 100%;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xl);
}

.showcase-title {
    font-size: 2.5rem;
    font-weight: 800;
    line-height: 1.3;
    margin-bottom: 24px;
    color: var(--text-primary);
}

.showcase-desc {
    font-size: 1.1rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

/* ==================== AI Image Examples Section ==================== */
.ai-examples {
    padding: 100px 0;
    background: var(--bg-gradient-start);
}

.examples-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 32px;
    margin-top: 60px;
}

.example-card {
    background: white;
    border-radius: var(--radius-lg);
    padding: 24px;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    text-align: center;
    border: 1px solid rgba(229, 231, 235, 0.8);
}

.example-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: rgba(59, 130, 246, 0.2);
}

.example-image {
    width: 100%;
    height: 220px;
    margin-bottom: 24px;
    border-radius: var(--radius-md);
    overflow: hidden;
    background: #F9FAFB;
    display: flex;
    align-items: center;
    justify-content: center;
}

.example-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-normal);
}

.placeholder-image {
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: var(--radius-md);
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
    box-shadow: inset 0 2px 8px rgba(0, 0, 0, 0.1);
}

/* 不同类别的渐变背景 */
.placeholder-image.insurance {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
}

.placeholder-image.product {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
}

.placeholder-image.artwork {
    background: linear-gradient(135deg, #43e97b 0%, #38f9d7 100%);
}

.placeholder-image.profile {
    background: linear-gradient(135deg, #fa709a 0%, #fee140 100%);
}

.placeholder-image.news {
    background: linear-gradient(135deg, #30cfd0 0%, #330867 100%);
}

.placeholder-image.id {
    background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
}

/* 添加装饰性元素 */
.placeholder-image::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: float 6s ease-in-out infinite;
}

@keyframes float {
    0%, 100% {
        transform: translate(0, 0) rotate(0deg);
    }
    50% {
        transform: translate(20px, 20px) rotate(180deg);
    }
}

.placeholder-icon {
    font-size: 4rem;
    margin-bottom: 16px;
    opacity: 0.9;
    position: relative;
    z-index: 1;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.placeholder-text {
    font-size: 1.1rem;
    color: white;
    font-weight: 600;
    text-align: center;
    padding: 0 24px;
    position: relative;
    z-index: 1;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    background: rgba(0, 0, 0, 0.2);
    padding: 8px 16px;
    border-radius: 20px;
    backdrop-filter: blur(10px);
}

.example-card:hover .example-image img,
.example-card:hover .placeholder-image {
    transform: scale(1.05);
}

.example-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.example-desc {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ==================== Features Section ==================== */
.features {
    padding: 80px 0;
    background: white;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 800;
    text-align: center;
    margin-bottom: 48px;
    color: var(--text-primary);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 32px;
}

.feature-card {
    padding: 32px;
    background: var(--bg-gradient-start);
    border-radius: var(--radius-lg);
    text-align: center;
    transition: all var(--transition-normal);
    border: 1px solid transparent;
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(59, 130, 246, 0.2);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 16px;
}

.feature-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.feature-desc {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ==================== FAQ Section ==================== */
.faq-section {
    padding: 100px 0;
    background: white;
}

.faq-container {
    max-width: 800px;
    margin: 60px auto 0;
    background: #F9FAFB;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.faq-item {
    border-bottom: 1px solid var(--border-color);
}

.faq-item:last-child {
    border-bottom: none;
}

.faq-question {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 24px 32px;
    background: white;
    cursor: pointer;
    transition: all var(--transition-normal);
    user-select: none;
}

.faq-question:hover {
    background: var(--bg-gradient-start);
}

.faq-question span {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-primary);
    flex: 1;
}

.faq-toggle {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--primary-blue);
    cursor: pointer;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    transition: all var(--transition-normal);
    font-weight: 700;
}

.faq-toggle:hover {
    background: var(--primary-blue);
    color: white;
    transform: rotate(90deg);
}

.faq-question.active .faq-toggle {
    transform: rotate(45deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-normal), padding var(--transition-normal);
    background: white;
}

.faq-answer p {
    padding: 0 32px 24px;
    color: var(--text-secondary);
    line-height: 1.7;
    font-size: 0.95rem;
}

.faq-answer.active {
    max-height: 200px;
    padding: 0 32px 24px;
}

/* ==================== Footer ==================== */
.footer {
    padding: 60px 0;
    background: var(--text-primary);
    color: white;
}

.footer-content {
    text-align: center;
}

.footer-logo {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    font-weight: 800;
    font-size: 1.5rem;
    margin-bottom: 16px;
}

.footer-logo .logo-text {
    color: white;
}

.footer-logo .logo-ai {
    color: var(--primary-blue-light);
}

.footer-logo .logo-ai::before {
    border-color: var(--primary-blue-light);
}

.footer-desc {
    color: #9CA3AF;
    margin-bottom: 16px;
}

.footer-copyright {
    color: #6B7280;
    font-size: 0.85rem;
}

/* ==================== Responsive ==================== */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2.2rem;
    }

    .stats {
        flex-direction: column;
        gap: 32px;
    }

    .stat-number {
        font-size: 2.5rem;
    }

    .nav {
        display: none;
    }

    .detection-card {
        padding: 24px;
    }

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

    .url-input-area {
        flex-direction: column;
    }

    .url-btn {
        width: 100%;
    }

    .steps-grid {
        grid-template-columns: 1fr;
        gap: 60px;
    }

    .section-title-main {
        font-size: 2.2rem;
    }

    .showcase-grid {
        grid-template-columns: 1fr;
        gap: 40px;
        text-align: center;
    }

    .showcase-title {
        font-size: 1.8rem;
    }
}