/* ==========================================================================
   GZTONGCHEN.COM - Main Stylesheet
   Tesla-style design with rich animations
   ========================================================================== */

/* CSS Variables
   ========================================================================== */
:root {
  --color-bg: #0a0e1a;
  --color-bg-2: #0d1224;
  --color-bg-3: #111733;
  --color-surface: rgba(255, 255, 255, 0.04);
  --color-surface-2: rgba(255, 255, 255, 0.06);
  --color-border: rgba(255, 255, 255, 0.08);
  --color-border-2: rgba(255, 255, 255, 0.12);
  --color-text: #e6ebff;
  --color-text-2: #a0a8c5;
  --color-text-3: #6c7693;
  --color-primary: #00d4ff;
  --color-primary-2: #0095b3;
  --color-accent: #7b2ff7;
  --color-accent-2: #5a1dba;
  --color-success: #00f5a0;
  --color-warning: #ffb800;
  --color-danger: #ff4d6d;
  --gradient-primary: linear-gradient(135deg, #00d4ff 0%, #7b2ff7 100%);
  --gradient-primary-soft: linear-gradient(135deg, rgba(0,212,255,0.15) 0%, rgba(123,47,247,0.15) 100%);
  --gradient-dark: linear-gradient(180deg, #0a0e1a 0%, #0d1224 100%);
  --gradient-glow: radial-gradient(circle, rgba(0,212,255,0.15) 0%, transparent 70%);
  --gradient-glow-2: radial-gradient(circle, rgba(123,47,247,0.2) 0%, transparent 70%);
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.3);
  --shadow-md: 0 8px 32px rgba(0,0,0,0.4);
  --shadow-lg: 0 16px 64px rgba(0,0,0,0.5);
  --shadow-glow: 0 0 40px rgba(0,212,255,0.3);
  --shadow-glow-2: 0 0 40px rgba(123,47,247,0.3);
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --radius-full: 9999px;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, 'Noto Sans', sans-serif;
  --font-mono: 'SF Mono', 'Monaco', 'Cascadia Code', 'Roboto Mono', Consolas, 'Courier New', monospace;
  --container-w: 1280px;
  --header-h: 72px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: all 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  position: relative;
}

/* Page load animation */
body.loading {
  overflow: hidden;
}

body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100vh;
  background: var(--color-bg);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.4s ease;
}

img, svg, video {
  max-width: 100%;
  display: block;
}

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

ul, ol {
  list-style: none;
}

button {
  font-family: inherit;
  font-size: inherit;
  border: none;
  background: none;
  cursor: pointer;
  color: inherit;
}

input, textarea, select {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
}

/* Typography
   ========================================================================== */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--color-text);
}

h1 {
  font-size: clamp(2.5rem, 6vw, 5rem);
  font-weight: 800;
  letter-spacing: -0.04em;
}

h2 {
  font-size: clamp(2rem, 4vw, 3.5rem);
  font-weight: 700;
}

h3 {
  font-size: clamp(1.5rem, 3vw, 2.25rem);
  font-weight: 600;
}

h4 {
  font-size: 1.5rem;
  font-weight: 600;
}

h5 {
  font-size: 1.25rem;
  font-weight: 600;
}

p {
  color: var(--color-text-2);
  line-height: 1.7;
}

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

.text-mono {
  font-family: var(--font-mono);
  letter-spacing: 0;
}

.text-muted { color: var(--color-text-2); }
.text-dim { color: var(--color-text-3); }
.text-primary { color: var(--color-primary); }
.text-accent { color: var(--color-accent); }

/* Layout
   ========================================================================== */
.container {
  width: 100%;
  max-width: var(--container-w);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 120px 0;
  position: relative;
}

.section-sm {
  padding: 80px 0;
}

.section-lg {
  padding: 160px 0;
}

.grid {
  display: grid;
  gap: 24px;
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

.flex { display: flex; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.flex-between { display: flex; align-items: center; justify-content: space-between; }
.flex-col { display: flex; flex-direction: column; }

.gap-1 { gap: 8px; }
.gap-2 { gap: 16px; }
.gap-3 { gap: 24px; }
.gap-4 { gap: 32px; }

/* Buttons
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 28px;
  border-radius: var(--radius-full);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.01em;
  text-decoration: none;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
  white-space: nowrap;
  border: 1px solid transparent;
}

.btn svg {
  width: 18px;
  height: 18px;
  transition: var(--transition);
}

.btn-primary {
  background: var(--gradient-primary);
  color: #fff;
  box-shadow: 0 4px 20px rgba(0, 212, 255, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 32px rgba(0, 212, 255, 0.5);
}

.btn-primary:hover svg {
  transform: translateX(4px);
}

.btn-outline {
  background: transparent;
  color: var(--color-text);
  border: 1px solid var(--color-border-2);
}

.btn-outline:hover {
  background: var(--color-surface);
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.btn-ghost {
  background: var(--color-surface);
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.btn-ghost:hover {
  background: var(--color-surface-2);
  border-color: var(--color-border-2);
}

.btn-sm { padding: 10px 20px; font-size: 13px; }
.btn-lg { padding: 18px 36px; font-size: 16px; }

/* Cards
   ========================================================================== */
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 32px;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.card:hover {
  transform: translateY(-4px);
  border-color: var(--color-border-2);
  background: var(--color-surface-2);
  box-shadow: var(--shadow-lg);
}

.card-glow::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 80%;
  height: 1px;
  background: var(--gradient-primary);
  opacity: 0;
  transition: var(--transition);
}

.card-glow:hover::before {
  opacity: 1;
}

.card-glass {
  background: rgba(13, 18, 36, 0.6);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
}

/* Section Headers
   ========================================================================== */
.section-header {
  text-align: center;
  max-width: 800px;
  margin: 0 auto 80px;
  position: relative;
}

.section-eyebrow {
  display: inline-block;
  padding: 6px 16px;
  border-radius: var(--radius-full);
  background: var(--gradient-primary-soft);
  border: 1px solid rgba(0, 212, 255, 0.2);
  color: var(--color-primary);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 24px;
}

.section-title {
  margin-bottom: 24px;
  position: relative;
}

.section-subtitle {
  color: var(--color-text-2);
  font-size: 18px;
  line-height: 1.7;
}

/* Background Effects
   ========================================================================== */
.bg-grid {
  position: relative;
}

.bg-grid::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
  z-index: 0;
  mask-image: radial-gradient(ellipse at center, black 0%, transparent 70%);
  -webkit-mask-image: radial-gradient(ellipse at center, black 0%, transparent 70%);
}

.bg-glow {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  pointer-events: none;
  z-index: 0;
  opacity: 0.5;
}

.bg-glow-1 {
  top: 10%;
  left: 10%;
  width: 500px;
  height: 500px;
  background: var(--gradient-glow);
}

.bg-glow-2 {
  bottom: 20%;
  right: 10%;
  width: 600px;
  height: 600px;
  background: var(--gradient-glow-2);
}

/* Animations
   ========================================================================== */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(40px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInDown {
  from { opacity: 0; transform: translateY(-40px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInLeft {
  from { opacity: 0; transform: translateX(-40px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes fadeInRight {
  from { opacity: 0; transform: translateX(40px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes scaleIn {
  from { opacity: 0; transform: scale(0.9); }
  to { opacity: 1; transform: scale(1); }
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-20px); }
}

@keyframes rotate {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

@keyframes shimmer {
  0% { background-position: -200% 0; }
  100% { background-position: 200% 0; }
}

@keyframes glow {
  0%, 100% { box-shadow: 0 0 20px rgba(0, 212, 255, 0.3); }
  50% { box-shadow: 0 0 40px rgba(0, 212, 255, 0.6); }
}

@keyframes blink {
  0%, 50% { opacity: 1; }
  51%, 100% { opacity: 0; }
}

@keyframes marquee {
  0% { transform: translateX(0); }
  100% { transform: translateX(-50%); }
}

/* Reveal animations */
.reveal {
  opacity: 0;
  transform: translateY(40px);
  transition: opacity 0.8s ease, transform 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

.reveal.active {
  opacity: 1;
  transform: translateY(0);
}

.reveal-delay-1 { transition-delay: 0.1s; }
.reveal-delay-2 { transition-delay: 0.2s; }
.reveal-delay-3 { transition-delay: 0.3s; }
.reveal-delay-4 { transition-delay: 0.4s; }
.reveal-delay-5 { transition-delay: 0.5s; }

/* Code-style elements (Tesla/Computer science aesthetic) */
.code-block {
  font-family: var(--font-mono);
  background: rgba(0, 0, 0, 0.4);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 20px;
  font-size: 14px;
  line-height: 1.6;
  overflow-x: auto;
  position: relative;
}

.code-block::before {
  content: '● ● ●';
  position: absolute;
  top: 12px;
  left: 20px;
  color: var(--color-text-3);
  font-size: 10px;
  letter-spacing: 2px;
}

.code-block pre {
  margin: 16px 0 0;
  white-space: pre;
}

.code-block .c-kw { color: #ff79c6; }
.code-block .c-str { color: #f1fa8c; }
.code-block .c-num { color: #bd93f9; }
.code-block .c-com { color: #6272a4; font-style: italic; }
.code-block .c-fn { color: #50fa7b; }
.code-block .c-var { color: #8be9fd; }

/* Utility classes
   ========================================================================== */
.hidden { display: none !important; }
.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;
}

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.w-full { width: 100%; }
.h-full { height: 100%; }

.mt-1 { margin-top: 8px; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }
.mt-4 { margin-top: 32px; }
.mt-5 { margin-top: 48px; }
.mt-6 { margin-top: 64px; }

.mb-1 { margin-bottom: 8px; }
.mb-2 { margin-bottom: 16px; }
.mb-3 { margin-bottom: 24px; }
.mb-4 { margin-bottom: 32px; }
.mb-5 { margin-bottom: 48px; }
.mb-6 { margin-bottom: 64px; }

.p-1 { padding: 8px; }
.p-2 { padding: 16px; }
.p-3 { padding: 24px; }
.p-4 { padding: 32px; }

.opacity-50 { opacity: 0.5; }
.opacity-70 { opacity: 0.7; }
.opacity-80 { opacity: 0.8; }

.relative { position: relative; }
.absolute { position: absolute; }
.fixed { position: fixed; }

.z-10 { z-index: 10; }
.z-20 { z-index: 20; }
.z-50 { z-index: 50; }
.z-100 { z-index: 100; }