/* =========================================
   VARIABLES & RESET
   ========================================= */
:root {
  /* Colors - White & Professional Tone */
  --bg-color: #FFFFFF;
  --bg-light: #F4F6F9;
  --bg-dark: #1A1C20;
  
  --text-main: #111111;
  --text-sub: #555555;
  --text-light: #888888;
  
  --primary: #2D3436; /* Soft Black for buttons */
  --accent: #FF5A5F;  /* Point Color (Emphasis) */
  --border: #E0E4E8;
  
  /* Layout */
  --container-width: 1100px;
  --header-height: 70px;
  
  /* Font Families */
  --font-sans: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }

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

a { text-decoration: none; color: inherit; transition: all 0.3s ease; }
ul { list-style: none; }
img { max-width: 100%; display: block; }

/* =========================================
   UTILITIES
   ========================================= */
.container {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 24px;
}
.text-center { text-align: center; }
.pc-only { display: none; }
.mob-only { display: block; }
.mob-hide { display: none; }
.mb-50 { margin-bottom: 50px; }

@media (min-width: 992px) {
  .pc-only { display: flex; }
  .mob-only { display: none; }
  .mob-hide { display: inline; }
}

/* Scroll Animation */
[data-scroll] {
  opacity: 0;
  transform: translateY(40px);
  transition: all 0.8s cubic-bezier(0.22, 1, 0.36, 1);
}
[data-scroll].scrolled {
  opacity: 1;
  transform: translateY(0);
}

/* =========================================
   NAVIGATION
   ========================================= */
.navbar {
  position: fixed; top: 0; left: 0; width: 100%;
  height: var(--header-height);
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  z-index: 1000;
  border-bottom: 1px solid rgba(0,0,0,0.05);
}
.nav-inner {
  display: flex; justify-content: space-between; align-items: center; height: 100%;
}
.logo {
  font-size: 1.5rem; font-weight: 800; letter-spacing: -0.02em; color: var(--text-main);
}
.dot { color: var(--accent); }

.nav-links { gap: 32px; align-items: center; }
.nav-links a {
  font-weight: 600; font-size: 1rem; color: var(--text-sub);
}
.nav-links a:hover { color: var(--text-main); }
.nav-btn {
  background: var(--text-main); color: #fff !important;
  padding: 10px 24px; border-radius: 50px; font-size: 0.95rem;
}
.nav-btn:hover { background: var(--accent); transform: translateY(-2px); }

/* Mobile Menu Button */
.menu-btn {
  background: none; border: none; cursor: pointer; width: 30px; height: 20px;
  position: relative; z-index: 1002;
}
.menu-btn span {
  display: block; width: 100%; height: 2px; background: #000;
  position: absolute; left: 0; transition: 0.3s;
}
.menu-btn span:nth-child(1) { top: 0; }
.menu-btn span:nth-child(2) { top: 9px; }
.menu-btn span:nth-child(3) { top: 18px; }

.menu-btn.open span:nth-child(1) { transform: rotate(45deg); top: 9px; }
.menu-btn.open span:nth-child(2) { opacity: 0; }
.menu-btn.open span:nth-child(3) { transform: rotate(-45deg); top: 9px; }

/* Mobile Drawer */
.mobile-drawer {
  position: fixed; top: 0; right: -100%; width: 100%; height: 100vh;
  background: #fff; z-index: 1001; padding: 100px 30px;
  display: flex; flex-direction: column; gap: 30px;
  transition: 0.4s ease;
}
.mobile-drawer.active { right: 0; }
.m-link { font-size: 1.5rem; font-weight: 700; border-bottom: 1px solid #eee; padding-bottom: 20px; }
.m-link.highlight { color: var(--accent); border-bottom: none; }

/* =========================================
   HERO SECTION
   ========================================= */
.hero {
  padding-top: 140px; padding-bottom: 80px;
  min-height: 100vh; display: flex; align-items: center;
  position: relative; overflow: hidden;
}
.bg-decoration {
  position: absolute; top: -20%; right: -10%; width: 600px; height: 600px;
  background: radial-gradient(circle, rgba(255, 90, 95, 0.05) 0%, transparent 70%);
  z-index: -1; pointer-events: none;
}

.hero-container {
  display: grid; grid-template-columns: 1fr; gap: 50px;
}
@media (min-width: 992px) {
  .hero-container { grid-template-columns: 1.1fr 0.9fr; align-items: center; }
}

.capsule {
  display: inline-block; padding: 6px 14px; background: #F0F2F5;
  color: #555; border-radius: 20px; font-weight: 700; font-size: 0.85rem;
  margin-bottom: 24px; letter-spacing: -0.01em;
}
.hero-text h1 {
  font-size: clamp(2.5rem, 5vw, 4.2rem);
  line-height: 1.15; font-weight: 800; letter-spacing: -0.03em; margin-bottom: 24px;
}
.highlight {
  background: linear-gradient(180deg, transparent 65%, rgba(255, 90, 95, 0.2) 65%);
}
.hero-desc {
  font-size: 1.15rem; color: var(--text-sub); margin-bottom: 40px; max-width: 500px;
}

.btn-group { display: flex; gap: 16px; align-items: center; }
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 18px 36px; border-radius: 12px; font-weight: 700; font-size: 1rem;
}
.btn-black { background: var(--text-main); color: #fff; box-shadow: 0 10px 20px rgba(0,0,0,0.1); }
.btn-black:hover { transform: translateY(-4px); box-shadow: 0 15px 30px rgba(0,0,0,0.15); background: var(--accent); }
.btn-text { color: var(--text-main); text-decoration: underline; padding: 0; }

/* HERO VISUAL (3D) */
.hero-visual {
  height: 400px; display: flex; flex-direction: column; align-items: center; justify-content: center;
  perspective: 1000px;
}
.layer-stack {
  position: relative; width: 280px; height: 320px;
  transform-style: preserve-3d;
  transform: rotateX(55deg) rotateZ(-35deg);
  transition: transform 0.5s ease;
  animation: float 6s ease-in-out infinite;
}
@media(max-width: 768px) {
  /* Mobile: Less dramatic rotation for better visibility */
  .hero-visual { height: 350px; perspective: 800px; }
  .layer-stack { transform: rotateX(40deg) rotateZ(-20deg); }
}

@keyframes float {
  0%, 100% { transform: rotateX(55deg) rotateZ(-35deg) translateY(0); }
  50% { transform: rotateX(55deg) rotateZ(-35deg) translateY(-20px); }
}

.layer {
  position: absolute; top: 0; left: 0; width: 100%; height: 100%;
  border-radius: 20px;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  transition: 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  box-shadow: 10px 10px 30px rgba(0,0,0,0.05);
  border: 1px solid rgba(0,0,0,0.05);
}

.layer-top { background: #fff; transform: translateZ(100px); border: 2px solid var(--text-main); z-index: 3; }
.layer-mid { background: rgba(255, 255, 255, 0.9); transform: translateZ(50px); border: 1px dashed var(--accent); color: var(--accent); z-index: 2; }
.layer-bottom { background: #f8f9fa; transform: translateZ(0); z-index: 1; color: #999; }

/* Hover Effect: Explode Layers */
.hero-visual:hover .layer-stack { transform: rotateX(55deg) rotateZ(-35deg) scale(0.9); }
.hero-visual:hover .layer-top { transform: translateZ(160px); }
.hero-visual:hover .layer-mid { transform: translateZ(80px); }
.hero-visual:hover .layer-bottom { transform: translateZ(0); }

.layer-tag {
  position: absolute; top: -10px; left: 20px; background: #000; color: #fff;
  font-size: 0.6rem; padding: 4px 8px; font-weight: 700; border-radius: 4px;
}
.layer-mid .layer-tag { background: var(--accent); }

.layer-content { text-align: center; display: flex; flex-direction: column; gap: 5px; font-size: 0.9rem; }
.connect-lines {
  position: absolute; width: 2px; height: 100%; background: var(--accent); opacity: 0.2; transform: rotate(45deg);
}
.mini-ui-bar { width: 60px; height: 6px; background: #eee; border-radius: 10px; margin: 5px auto; }
.w-70 { width: 40px; }

.visual-caption { margin-top: 40px; font-size: 0.8rem; color: #999; text-align: center; }

/* =========================================
   SECTIONS GENERAL
   ========================================= */
.section { padding: 100px 0; }
.bg-gray { background: #F8F9FA; }
.bg-light { background: #F4F6F9; }
.bg-dark { background: #111; color: #fff; }

.sec-subtitle {
  display: block; font-size: 0.8rem; font-weight: 800; color: var(--accent);
  letter-spacing: 0.1em; margin-bottom: 12px;
}
.sec-title {
  font-size: clamp(2rem, 4vw, 3rem); font-weight: 800; margin-bottom: 20px; line-height: 1.2;
}
.sec-desc { font-size: 1.1rem; color: var(--text-sub); max-width: 700px; margin: 0 auto; margin-bottom: 50px; }

/* Grid Systems */
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 30px; }
.grid-4 { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 30px; }

/* Cards */
.card {
  padding: 40px 30px; border-radius: 20px; border: 1px solid transparent; transition: 0.3s;
}
.card:hover { background: #fff; box-shadow: 0 20px 40px rgba(0,0,0,0.08); border-color: var(--border); transform: translateY(-5px); }
.emoji { font-size: 3rem; margin-bottom: 20px; }
.card h3 { font-size: 1.3rem; margin-bottom: 10px; font-weight: 700; }
.card p { color: var(--text-sub); font-size: 0.95rem; }

/* Split Layout */
.split-layout { display: grid; gap: 60px; }
@media(min-width: 992px) {
  .split-layout { grid-template-columns: 1fr 1fr; align-items: center; }
  .reverse-mob { grid-template-columns: 1fr 1fr; } /* Logic diagram on left for PC */
}

/* Logic Diagram SVG */
.split-visual {
  background: #fff; border-radius: 30px; height: 350px; border: 1px solid var(--border);
  display: flex; align-items: center; justify-content: center; position: relative;
  box-shadow: 0 20px 50px rgba(0,0,0,0.05);
}
.logic-diagram { position: relative; width: 100%; height: 100%; }
.node {
  position: absolute; background: #fff; border: 2px solid #000; padding: 8px 16px;
  border-radius: 50px; font-weight: 700; font-size: 0.85rem; z-index: 2;
}
.n1 { top: 50px; left: 50px; }
.n2 { bottom: 50px; left: 50px; }
.n3 { top: 140px; right: 50px; }
.n-center { 
  top: 50%; left: 50%; transform: translate(-50%, -50%);
  background: #000; color: #fff; border-color: #000; z-index: 3;
}

.svg-connect {
  position: absolute; top: 0; left: 0; width: 100%; height: 100%; z-index: 1;
}
.svg-connect line {
  stroke: #ddd; stroke-width: 2; stroke-dasharray: 5;
  animation: dash 1s linear infinite;
}
@keyframes dash { to { stroke-dashoffset: -10; } }

.feature-list li {
  margin-bottom: 20px; padding-left: 20px; border-left: 3px solid var(--accent);
}
.feature-list strong { color: var(--text-main); font-size: 1.1rem; }

/* Tech Items (Dark Section) */
.op-70 { opacity: 0.7; color: #ccc; }
.tech-item {
  background: rgba(255,255,255,0.05); padding: 30px; border-radius: 16px; border: 1px solid rgba(255,255,255,0.1);
}
.tech-num {
  font-family: var(--font-mono); font-size: 2rem; opacity: 0.3; font-weight: 800; margin-bottom: 10px;
}
.tech-item h3 { font-size: 1.3rem; margin-bottom: 10px; color: #fff; }
.tech-item p { color: #aaa; font-size: 0.9rem; }

/* Use Case / Review */
.review-box {
  background: #fff; border: 1px solid var(--border); padding: 50px;
  border-radius: 30px; position: relative; text-align: center; max-width: 900px; margin: 0 auto;
}
.quote-mark {
  font-size: 6rem; line-height: 0; color: var(--accent); opacity: 0.2;
  font-family: serif; position: absolute; top: 40px; left: 50%; transform: translateX(-50%);
}
.review-box h3 {
  font-size: clamp(1.2rem, 2.5vw, 1.6rem); font-weight: 500; line-height: 1.6; margin-bottom: 30px; position: relative;
}
.reviewer strong { display: block; font-size: 1.1rem; margin-bottom: 4px; }
.reviewer span { font-size: 0.9rem; color: var(--text-sub); }

/* FAQ */
.small-container { max-width: 800px; }
.faq-item {
  background: #fff; border: 1px solid var(--border); border-radius: 12px;
  padding: 24px; margin-bottom: 16px;
}
.faq-q { font-weight: 700; font-size: 1.1rem; margin-bottom: 10px; color: var(--text-main); }
.faq-a { color: var(--text-sub); font-size: 0.95rem; line-height: 1.6; }

/* CTA */
.cta-section { background: var(--text-main); color: #fff; padding: 120px 0; }
.align-center { text-align: center; display: flex; flex-direction: column; align-items: center; }
.cta-title { font-size: clamp(2rem, 5vw, 3.5rem); margin-bottom: 16px; font-weight: 800; }
.cta-desc { font-size: 1.2rem; color: #aaa; margin-bottom: 40px; }

.download-btns { display: flex; gap: 20px; flex-wrap: wrap; justify-content: center; }
.btn-large { padding: 20px 40px; font-size: 1.1rem; border-radius: 12px; }
.btn-white { background: #fff; color: #000; }
.btn-white:hover { background: #eee; transform: translateY(-3px); }
.btn-outline-white { border: 1px solid rgba(255,255,255,0.3); color: #fff; }
.btn-outline-white:hover { border-color: #fff; background: rgba(255,255,255,0.1); }
.os-icon { margin-right: 8px; }
.cta-note { margin-top: 30px; font-size: 0.8rem; opacity: 0.5; }

/* Footer */
footer { padding: 60px 0; background: #fff; border-top: 1px solid var(--border); }
.footer-inner { display: flex; flex-direction: column; gap: 30px; margin-bottom: 40px; }
@media(min-width: 768px) {
  .footer-inner { flex-direction: row; justify-content: space-between; }
}
.f-logo { font-weight: 800; font-size: 1.2rem; margin-bottom: 10px; }
.f-info p { font-size: 0.85rem; color: #777; line-height: 1.6; }
.f-links a { font-size: 0.85rem; margin-right: 20px; color: #555; font-weight: 600; }
.copyright { font-size: 0.8rem; color: #999; border-top: 1px solid #eee; padding-top: 20px; }