/* ==========================================
   写代码的卓君 - 个人网站样式表
   zhuojun1024.com
   ========================================== */

/* CSS Variables */
:root {
    /* Colors */
    --color-bg-primary: #0a0a0f;
    --color-bg-secondary: #12121a;
    --color-bg-tertiary: #1a1a28;
    --color-bg-card: #151520;

    --color-text-primary: #ffffff;
    --color-text-secondary: #a0a0b8;
    --color-text-tertiary: #6b6b80;

    --color-accent-cyan: #00f5ff;
    --color-accent-purple: #7b2ff7;
    --color-accent-pink: #ff2a6d;
    --color-accent-green: #05ffa1;

    --color-gradient-primary: linear-gradient(135deg, #00f5ff 0%, #7b2ff7 100%);
    --color-gradient-secondary: linear-gradient(135deg, #7b2ff7 0%, #ff2a6d 100%);
    --color-gradient-tertiary: linear-gradient(135deg, #00f5ff 0%, #05ffa1 100%);

    --color-border: rgba(255, 255, 255, 0.08);
    --color-border-hover: rgba(0, 245, 255, 0.3);

    /* Typography */
    --font-primary: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-display: 'Orbitron', 'Noto Sans SC', sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    --spacing-4xl: 6rem;

    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;

    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    --shadow-glow-cyan: 0 0 20px rgba(0, 245, 255, 0.3);
    --shadow-glow-purple: 0 0 20px rgba(123, 47, 247, 0.3);

    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
    --transition-bounce: 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-primary);
    background-color: var(--color-bg-primary);
    color: var(--color-text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Particle Canvas */
#particle-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    pointer-events: none;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-xl);
}

@media (max-width: 768px) {
    .container {
        padding: 0 var(--spacing-md);
    }
}

/* ==========================================
   Navigation
   ========================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(10, 10, 15, 0.8);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--color-border);
    transition: var(--transition-base);
}

.navbar.scrolled {
    background: rgba(10, 10, 15, 0.95);
    box-shadow: var(--shadow-md);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-xl);
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-family: var(--font-display);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-text-primary);
    text-decoration: none;
}

.logo-bracket {
    color: var(--color-accent-cyan);
    font-family: var(--font-mono);
}

.logo-text {
    background: var(--color-gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.nav-link {
    color: var(--color-text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    transition: var(--transition-base);
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-text-primary);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 20px;
    height: 2px;
    background: var(--color-gradient-primary);
    border-radius: var(--radius-full);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: var(--spacing-sm);
}

.toggle-line {
    width: 24px;
    height: 2px;
    background: var(--color-text-primary);
    transition: var(--transition-base);
    border-radius: var(--radius-full);
}

.nav-toggle.active .toggle-line:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.nav-toggle.active .toggle-line:nth-child(2) {
    opacity: 0;
}

.nav-toggle.active .toggle-line:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

@media (max-width: 768px) {
    .nav-toggle {
        display: flex;
    }

    .nav-menu {
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        background: rgba(10, 10, 15, 0.98);
        backdrop-filter: blur(20px);
        flex-direction: column;
        padding: var(--spacing-xl);
        gap: var(--spacing-md);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: var(--transition-base);
        border-bottom: 1px solid var(--color-border);
    }

    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-link {
        width: 100%;
        text-align: center;
        padding: var(--spacing-md);
    }
}

/* ==========================================
   Hero Section
   ========================================== */
.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    position: relative;
    padding: var(--spacing-4xl) 0 var(--spacing-3xl);
    overflow: hidden;
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-xl);
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-greeting {
    margin-bottom: var(--spacing-lg);
}

.greeting-prefix {
    font-family: var(--font-mono);
    color: var(--color-accent-cyan);
    font-size: 1rem;
}

.hero-title {
    font-family: var(--font-display);
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: var(--spacing-lg);
}

.title-line {
    display: block;
    color: var(--color-text-primary);
}

.title-highlight {
    display: block;
    background: var(--color-gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: glow 3s ease-in-out infinite;
}

@keyframes glow {
    0%, 100% {
        filter: drop-shadow(0 0 10px rgba(0, 245, 255, 0.3));
    }
    50% {
        filter: drop-shadow(0 0 20px rgba(0, 245, 255, 0.6));
    }
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
    min-height: 3rem; /* 防止打字机换行导致的高度抖动 */
}

.subtitle-prefix {
    color: var(--color-text-secondary);
}

.typing-text {
    color: var(--color-accent-cyan);
    font-family: var(--font-mono);
}

.typing-cursor {
    color: var(--color-accent-cyan);
    animation: blink 1s step-end infinite;
}

@keyframes blink {
    50% {
        opacity: 0;
    }
}

.hero-description {
    color: var(--color-text-secondary);
    font-size: 1.05rem;
    max-width: 500px;
    margin-bottom: var(--spacing-2xl);
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: 0.875rem 1.75rem;
    font-size: 0.95rem;
    font-weight: 600;
    text-decoration: none;
    border-radius: var(--radius-md);
    border: none;
    cursor: pointer;
    transition: var(--transition-base);
    font-family: var(--font-primary);
}

.btn-primary {
    background: var(--color-gradient-primary);
    color: var(--color-bg-primary);
    box-shadow: var(--shadow-glow-cyan);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 0 30px rgba(0, 245, 255, 0.5);
}

.btn-secondary {
    background: transparent;
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
}

.btn-secondary:hover {
    border-color: var(--color-accent-cyan);
    background: rgba(0, 245, 255, 0.05);
}

.btn-icon {
    width: 18px;
    height: 18px;
}

/* Code Window */
.hero-visual {
    position: relative;
}

.code-window {
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    animation: float 6s ease-in-out infinite;
    max-width: 100%;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-10px);
    }
}

.code-window-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--color-bg-tertiary);
    border-bottom: 1px solid var(--color-border);
}

.window-dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
}

.window-dot.red {
    background: #ff5f56;
}

.window-dot.yellow {
    background: #ffbd2e;
}

.window-dot.green {
    background: #27c93f;
}

.window-title {
    margin-left: var(--spacing-md);
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--color-text-tertiary);
}

.code-window-body {
    padding: var(--spacing-lg);
    font-family: var(--font-mono);
    font-size: 0.9rem;
    line-height: 1.6;
    overflow-x: auto;
}

.code-window-body pre {
    white-space: pre-wrap;
    word-break: break-all;
    overflow-x: visible;
}

.code-keyword {
    color: #c678dd;
}

.code-variable {
    color: #e5c07b;
}

.code-property {
    color: #e06c75;
}

.code-string {
    color: #98c379;
}

/* Floating Elements */
.floating-elements {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    pointer-events: none;
}

.float-item {
    position: absolute;
    width: 48px;
    height: 48px;
    border-radius: var(--radius-lg);
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-accent-cyan);
}

.float-item svg {
    width: 24px;
    height: 24px;
}

.float-1 {
    top: -20px;
    right: -20px;
    animation: float-slow 8s ease-in-out infinite;
}

.float-2 {
    bottom: 40px;
    left: -30px;
    animation: float-slow 10s ease-in-out infinite reverse;
}

.float-3 {
    bottom: -20px;
    right: 40px;
    animation: float-slow 7s ease-in-out infinite;
}

@keyframes float-slow {
    0%, 100% {
        transform: translateY(0) rotate(0deg);
    }
    50% {
        transform: translateY(-15px) rotate(5deg);
    }
}

/* Scroll Indicator */
.hero-scroll {
    position: absolute;
    bottom: var(--spacing-2xl);
    left: 50%;
    transform: translateX(-50%);
    z-index: 1;
}

.scroll-indicator {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--color-text-tertiary);
    font-size: 0.8rem;
}

.scroll-arrow {
    width: 20px;
    height: 20px;
    border-right: 2px solid var(--color-accent-cyan);
    border-bottom: 2px solid var(--color-accent-cyan);
    transform: rotate(45deg);
    animation: scroll-bounce 2s ease-in-out infinite;
}

@keyframes scroll-bounce {
    0%, 100% {
        transform: rotate(45deg) translateY(0);
    }
    50% {
        transform: rotate(45deg) translateY(5px);
    }
}

@media (max-width: 992px) {
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-description {
        margin-left: auto;
        margin-right: auto;
    }

    .hero-buttons {
        justify-content: center;
    }

    .hero-visual {
        max-width: 500px;
        margin: 0 auto;
    }
}

/* Hide scroll indicator on H5/mobile devices */
@media (max-width: 768px) {
    .hero-scroll {
        display: none;
    }

    .hero-subtitle {
        font-size: 0.9rem;
        flex-wrap: nowrap;
        overflow: hidden;
    }

    .typing-text {
        white-space: nowrap;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }

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

    .code-window-body {
        font-size: 0.75rem;
        padding: var(--spacing-md);
    }

    /* Hide floating elements on small screens to prevent clipping */
    .floating-elements {
        display: none;
    }
}

/* ==========================================
   Section Styles
   ========================================== */
section {
    padding: var(--spacing-4xl) 0;
    position: relative;
    z-index: 1;
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
}

.section-tag {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--color-accent-cyan);
    text-transform: uppercase;
    letter-spacing: 2px;
    display: block;
    margin-bottom: var(--spacing-md);
}

.section-title {
    font-family: var(--font-display);
    font-size: clamp(2rem, 4vw, 2.5rem);
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
}

.section-line {
    width: 60px;
    height: 3px;
    background: var(--color-gradient-primary);
    margin: 0 auto;
    border-radius: var(--radius-full);
}

/* ==========================================
   About Section
   ========================================== */
.about {
    background: var(--color-bg-secondary);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: var(--spacing-3xl);
    align-items: center;
}

.about-image {
    display: flex;
    justify-content: center;
}

.image-frame {
    position: relative;
}

.avatar-container {
    position: relative;
    width: 200px;
    height: 200px;
}

.avatar-ring {
    position: absolute;
    top: -10px;
    left: -10px;
    right: -10px;
    bottom: -10px;
    border: 2px solid transparent;
    border-top-color: var(--color-accent-cyan);
    border-right-color: var(--color-accent-purple);
    border-radius: 50%;
    animation: spin 10s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.avatar-placeholder {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    background: var(--color-bg-tertiary);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.avatar-placeholder svg {
    width: 120px;
    height: 120px;
}

.about-text {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.about-heading {
    font-size: 1.5rem;
    font-weight: 600;
    background: var(--color-gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.about-paragraph {
    color: var(--color-text-secondary);
    line-height: 1.8;
}

.about-stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

.stat-item {
    text-align: center;
    padding: var(--spacing-lg);
    background: var(--color-bg-card);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border);
    transition: var(--transition-base);
}

.stat-item:hover {
    border-color: var(--color-border-hover);
    transform: translateY(-5px);
}

.stat-number {
    display: block;
    font-family: var(--font-display);
    font-size: 2rem;
    font-weight: 700;
    background: var(--color-gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    display: block;
    font-size: 0.85rem;
    color: var(--color-text-tertiary);
    margin-top: var(--spacing-xs);
}

@media (max-width: 768px) {
    .about-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .about-stats {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* ==========================================
   Skills Section
   ========================================== */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-2xl);
}

.skill-category {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    transition: var(--transition-base);
}

.skill-category:hover {
    border-color: var(--color-border-hover);
    box-shadow: var(--shadow-md);
}

.category-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--color-border);
}

.category-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
}

.category-icon svg {
    width: 24px;
    height: 24px;
}

.category-icon.frontend {
    background: rgba(0, 245, 255, 0.1);
    color: var(--color-accent-cyan);
}

.category-icon.backend {
    background: rgba(123, 47, 247, 0.1);
    color: var(--color-accent-purple);
}

.category-icon.ai {
    background: rgba(255, 42, 109, 0.1);
    color: var(--color-accent-pink);
}

.category-icon.tools {
    background: rgba(5, 255, 161, 0.1);
    color: var(--color-accent-green);
}

.category-title {
    font-size: 1.25rem;
    font-weight: 600;
}

.skill-items {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.skill-item {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.skill-name {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
}

.skill-bar {
    height: 6px;
    background: var(--color-bg-tertiary);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.skill-progress {
    height: 100%;
    background: var(--color-gradient-primary);
    border-radius: var(--radius-full);
    width: 0;
    transition: width 1.5s ease-out;
}

.skill-progress.animated {
    /* Width set by data-level attribute */
}

@media (max-width: 768px) {
    .skills-grid {
        grid-template-columns: 1fr;
    }
}

/* ==========================================
   Projects Section
   ========================================== */
.projects {
    background: var(--color-bg-secondary);
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-xl);
}

.project-card {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: var(--transition-base);
}

.project-card:hover {
    transform: translateY(-5px);
    border-color: var(--color-border-hover);
    box-shadow: var(--shadow-lg);
}

.project-image {
    position: relative;
    height: 200px;
    overflow: hidden;
}

.project-placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.project-placeholder svg {
    width: 64px;
    height: 64px;
    color: var(--color-text-tertiary);
}

.project-placeholder.ai-dashboard {
    background: linear-gradient(135deg, rgba(0, 245, 255, 0.1), rgba(123, 47, 247, 0.1));
}

.project-placeholder.chat-app {
    background: linear-gradient(135deg, rgba(123, 47, 247, 0.1), rgba(255, 42, 109, 0.1));
}

.project-placeholder.e-commerce {
    background: linear-gradient(135deg, rgba(255, 42, 109, 0.1), rgba(5, 255, 161, 0.1));
}

.project-placeholder.design-system {
    background: linear-gradient(135deg, rgba(5, 255, 161, 0.1), rgba(0, 245, 255, 0.1));
}

.project-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(10, 10, 15, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: var(--transition-base);
}

.project-card:hover .project-overlay {
    opacity: 1;
}

.project-link {
    color: var(--color-accent-cyan);
    text-decoration: none;
    font-weight: 600;
    padding: var(--spacing-md) var(--spacing-xl);
    border: 1px solid var(--color-accent-cyan);
    border-radius: var(--radius-md);
    transition: var(--transition-base);
}

.project-link:hover {
    background: rgba(0, 245, 255, 0.1);
}

.project-info {
    padding: var(--spacing-xl);
}

.project-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

.project-description {
    color: var(--color-text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: var(--spacing-lg);
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.tag {
    font-size: 0.8rem;
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--color-bg-tertiary);
    color: var(--color-text-secondary);
    border-radius: var(--radius-sm);
    font-family: var(--font-mono);
}

.projects-cta {
    text-align: center;
    margin-top: var(--spacing-2xl);
}

.projects-cta .btn {
    display: inline-flex;
}

@media (max-width: 768px) {
    .projects-grid {
        grid-template-columns: 1fr;
    }
}

/* ==========================================
   AI Research Section
   ========================================== */
.research-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-xl);
}

.research-card {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    transition: var(--transition-base);
}

.research-card:hover {
    border-color: var(--color-border-hover);
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.research-icon {
    width: 56px;
    height: 56px;
    border-radius: var(--radius-lg);
    background: rgba(0, 245, 255, 0.1);
    color: var(--color-accent-cyan);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-lg);
}

.research-icon svg {
    width: 28px;
    height: 28px;
}

.research-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

.research-description {
    color: var(--color-text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: var(--spacing-lg);
}

.research-topics {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.topic-tag {
    font-size: 0.8rem;
    padding: var(--spacing-xs) var(--spacing-sm);
    background: rgba(0, 245, 255, 0.1);
    color: var(--color-accent-cyan);
    border-radius: var(--radius-sm);
    font-family: var(--font-mono);
}

@media (max-width: 768px) {
    .research-grid {
        grid-template-columns: 1fr;
    }
}

/* ==========================================
   Blog Section
   ========================================== */
.blog {
    background: var(--color-bg-secondary);
}

.blog-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-xl);
}

.blog-card {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    transition: var(--transition-base);
}

.blog-card:hover {
    border-color: var(--color-border-hover);
    transform: translateY(-3px);
}

.blog-date {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--color-accent-cyan);
    margin-bottom: var(--spacing-md);
}

.blog-title {
    font-size: 1.15rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    line-height: 1.4;
}

.blog-excerpt {
    color: var(--color-text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
    margin-bottom: var(--spacing-lg);
}

.blog-read-more {
    color: var(--color-accent-cyan);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: var(--transition-base);
}

.blog-read-more:hover {
    color: var(--color-text-primary);
}

.blog-cta {
    text-align: center;
    margin-top: var(--spacing-2xl);
}

@media (max-width: 768px) {
    .blog-grid {
        grid-template-columns: 1fr;
    }
}

/* ==========================================
   Contact Section
   ========================================== */
.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
}

.contact-heading {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: var(--spacing-lg);
}

.contact-description {
    color: var(--color-text-secondary);
    line-height: 1.8;
    margin-bottom: var(--spacing-2xl);
}

.contact-methods {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.contact-method {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.method-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-md);
    background: var(--color-bg-tertiary);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-accent-cyan);
    flex-shrink: 0;
}

.method-icon svg {
    width: 20px;
    height: 20px;
}

.method-info {
    display: flex;
    flex-direction: column;
}

.method-label {
    font-size: 0.85rem;
    color: var(--color-text-tertiary);
    margin-bottom: var(--spacing-xs);
}

.method-value {
    color: var(--color-text-primary);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition-base);
}

.method-value:hover {
    color: var(--color-accent-cyan);
}

.contact-form-wrapper {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.form-group label {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--color-text-secondary);
}

.form-group input,
.form-group textarea {
    padding: 0.875rem 1rem;
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    font-family: var(--font-primary);
    font-size: 0.95rem;
    transition: var(--transition-base);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--color-accent-cyan);
    box-shadow: 0 0 0 3px rgba(0, 245, 255, 0.1);
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

.btn-submit {
    align-self: flex-start;
}

@media (max-width: 768px) {
    .contact-content {
        grid-template-columns: 1fr;
    }
}

/* ==========================================
   Footer
   ========================================== */
.footer {
    background: var(--color-bg-secondary);
    border-top: 1px solid var(--color-border);
    padding: var(--spacing-3xl) 0 var(--spacing-xl);
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-2xl);
    margin-bottom: var(--spacing-2xl);
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-family: var(--font-display);
    font-size: 1.25rem;
    font-weight: 700;
}

.footer-tagline {
    color: var(--color-text-tertiary);
    font-size: 0.9rem;
    margin-top: var(--spacing-sm);
}

.footer-links {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-lg);
}

.footer-links a {
    color: var(--color-text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    transition: var(--transition-base);
}

.footer-links a:hover {
    color: var(--color-accent-cyan);
}

.footer-social {
    display: flex;
    gap: var(--spacing-md);
}

.social-link {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-md);
    background: var(--color-bg-tertiary);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-secondary);
    transition: var(--transition-base);
}

.social-link:hover {
    background: var(--color-accent-cyan);
    color: var(--color-bg-primary);
}

.social-link svg {
    width: 18px;
    height: 18px;
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--color-border);
}

.footer-bottom p {
    color: var(--color-text-tertiary);
    font-size: 0.85rem;
    margin-bottom: var(--spacing-sm);
}

.footer-built {
    font-size: 0.8rem !important;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.footer-built a {
    color: var(--color-text-tertiary);
    text-decoration: none;
    transition: color var(--transition-base);
}

.footer-built a:hover {
    color: var(--color-accent-cyan);
}

.beian-icon {
    height: 14px;
    width: auto;
    display: inline-block;
    vertical-align: middle;
}

/* ==========================================
   Back to Top Button
   ========================================== */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 48px;
    height: 48px;
    border-radius: var(--radius-md);
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    color: var(--color-text-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: var(--transition-base);
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    background: var(--color-accent-cyan);
    color: var(--color-bg-primary);
    border-color: var(--color-accent-cyan);
}

.back-to-top svg {
    width: 20px;
    height: 20px;
}

/* ==========================================
   Loading Screen
   ========================================== */
.loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--color-bg-primary);
    z-index: 10000;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: opacity 0.8s ease, visibility 0.8s ease;
}

.loading-screen.hidden {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

.loading-content {
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-2xl);
}

.loading-core {
    position: relative;
    width: 120px;
    height: 120px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.core-ring {
    position: absolute;
    border-radius: 50%;
    border: 2px solid transparent;
}

.ring-1 {
    width: 100%;
    height: 100%;
    border-top-color: var(--color-accent-cyan);
    border-bottom-color: var(--color-accent-cyan);
    animation: spin-reverse 3s linear infinite;
}

.ring-2 {
    width: 80%;
    height: 80%;
    border-left-color: var(--color-accent-purple);
    border-right-color: var(--color-accent-purple);
    animation: spin 2s linear infinite;
}

.ring-3 {
    width: 60%;
    height: 60%;
    border-top-color: var(--color-accent-pink);
    border-bottom-color: var(--color-accent-pink);
    animation: spin-reverse 1.5s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

@keyframes spin-reverse {
    to {
        transform: rotate(-360deg);
    }
}

.core-icon {
    width: 40px;
    height: 40px;
    color: var(--color-accent-cyan);
    z-index: 1;
}

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

.loading-text-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    font-family: var(--font-mono);
    font-size: 1rem;
    color: var(--color-text-secondary);
}

.loading-word {
    color: var(--color-accent-cyan);
}

.loading-dots {
    display: inline-flex;
    gap: 4px;
}

.loading-dots .dot {
    animation: dot-blink 1.4s infinite both;
}

.loading-dots .dot:nth-child(1) {
    animation-delay: 0s;
}

.loading-dots .dot:nth-child(2) {
    animation-delay: 0.2s;
}

.loading-dots .dot:nth-child(3) {
    animation-delay: 0.4s;
}

@keyframes dot-blink {
    0%, 20% {
        opacity: 0;
    }
    40% {
        opacity: 1;
    }
    60%, 100% {
        opacity: 0;
    }
}

.loading-progress {
    width: 200px;
    height: 2px;
    background: var(--color-bg-tertiary);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background: var(--color-gradient-primary);
    width: 0%;
    transition: width 0.3s ease;
    box-shadow: 0 0 10px rgba(0, 245, 255, 0.5);
}

/* ==========================================
   Animations & Utilities
   ========================================== */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--color-bg-primary);
}

::-webkit-scrollbar-thumb {
    background: var(--color-bg-tertiary);
    border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-accent-purple);
}

/* Selection */
::selection {
    background: rgba(0, 245, 255, 0.3);
    color: var(--color-text-primary);
}

/* Focus styles */
:focus-visible {
    outline: 2px solid var(--color-accent-cyan);
    outline-offset: 2px;
}