/* =========================================
   1. Variables & Reset (Design System)
   ========================================= */
:root {
  /* Colors */
  --color-bg: #f8f9fc;
  --color-text-main: #2d3748;
  --color-text-sub: #718096;
  --color-primary: #4e54c8;
  --color-secondary: #8f94fb;
  --color-accent: #00d2ff;
  --color-white: #ffffff;
  --color-glass: rgba(255, 255, 255, 0.7);
  --color-glass-border: rgba(255, 255, 255, 0.4);

  /* Fonts */
  --font-main: 'Poppins', 'Noto Sans JP', sans-serif;
  
  /* Spacing */
  --spacing-sm: 8px;
  --spacing-md: 24px;
  --spacing-lg: 48px;
  --spacing-xl: 120px;

  /* UI */
  --radius-md: 12px;
  --radius-lg: 20px;
  --shadow-sm: 0 4px 6px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px; /* Header height offset */
}

body {
  font-family: var(--font-main);
  background-color: var(--color-bg);
  color: var(--color-text-main);
  line-height: 1.8;
  overflow-x: hidden;
  position: relative;
}

/* =========================================
   2. Utilities & Components
   ========================================= */
.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

.section {
  padding: var(--spacing-xl) 0;
  position: relative;
  z-index: 10;
}

/* Section Title with Gradient Underline */
.section-title {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: var(--spacing-lg);
  position: relative;
  display: inline-block;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.section-title::after {
  content: '';
  display: block;
  width: 60px;
  height: 4px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  margin-top: 10px;
  border-radius: 2px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 32px;
  border-radius: 50px;
  font-weight: 600;
  text-decoration: none;
  transition: var(--transition);
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: var(--color-white);
  box-shadow: 0 4px 15px rgba(78, 84, 200, 0.4);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(78, 84, 200, 0.6);
}

.btn-secondary {
  background: var(--color-white);
  color: var(--color-text-main);
  border: 1px solid #e2e8f0;
}

.btn-secondary:hover {
  background: #f7fafc;
  transform: translateY(-2px);
}

/* =========================================
   3. Header & Nav (Glassmorphism)
   ========================================= */
header {
  position: fixed;
  top: 0;
  width: 100%;
  height: 80px;
  z-index: 1000;
  transition: var(--transition);
  display: flex;
  align-items: center;
}

/* JSで付与するクラス：スクロール時の変化 */
header.scrolled {
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px); /* すりガラス効果 */
  box-shadow: var(--shadow-sm);
  height: 70px; /* 少し縮める */
}

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

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text-main);
  text-decoration: none;
}

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

.nav-list {
  display: flex;
  gap: 40px;
  list-style: none;
}

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

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

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

.nav-button {
  padding: 8px 20px;
  background: var(--color-text-main);
  color: white;
  border-radius: 20px;
  text-decoration: none;
  font-size: 0.9rem;
  transition: var(--transition);
}

.nav-button:hover {
  background: var(--color-primary);
}

/* =========================================
   4. Hero Section
   ========================================= */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: 80px;
  position: relative;
}

.hero-content {
  max-width: 800px;
}

.hero-tag {
  display: inline-block;
  background: rgba(78, 84, 200, 0.1);
  color: var(--color-primary);
  padding: 6px 16px;
  border-radius: 20px;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 20px;
}

.hero h1 {
  font-size: 4rem; /* 大きくインパクトを */
  line-height: 1.1;
  margin-bottom: 24px;
  letter-spacing: -0.02em;
}

.text-gradient {
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p {
  font-size: 1.1rem;
  color: var(--color-text-sub);
  margin-bottom: 40px;
  max-width: 600px;
}

.hero-actions {
  display: flex;
  gap: 16px;
}

/* Animated Blobs Background */
.background-blobs {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  overflow: hidden;
}

.blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.4;
  animation: float 10s infinite alternate;
}

.blob-1 {
  width: 500px;
  height: 500px;
  background: #ff9a9e;
  top: -10%;
  right: -10%;
}

.blob-2 {
  width: 600px;
  height: 600px;
  background: #a18cd1;
  bottom: -10%;
  left: -20%;
  animation-delay: -5s;
}

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

/* =========================================
   5. Content Cards (Glass & Hover)
   ========================================= */
.card, .project-card, .skill-card {
  background: var(--color-glass);
  backdrop-filter: blur(10px);
  border: 1px solid var(--color-glass-border);
  border-radius: var(--radius-lg);
  padding: 40px;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.card:hover, .project-card:hover, .skill-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-lg);
  border-color: rgba(78, 84, 200, 0.2);
}

/* Skills Grid */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 30px;
}

.skill-icon {
  font-size: 3rem;
  margin-bottom: 20px;
}

.tag {
  display: inline-block;
  font-size: 0.8rem;
  padding: 4px 12px;
  background: #edf2f7;
  border-radius: 12px;
  margin-top: 10px;
  color: var(--color-text-sub);
}

/* Output (Projects) */
.output-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 40px;
}

.project-category {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-primary);
  font-weight: 700;
  display: block;
  margin-bottom: 10px;
}

.project-desc {
  color: var(--color-text-sub);
  margin-bottom: 20px;
  font-size: 0.95rem;
}

.tech-stack {
  display: flex;
  gap: 10px;
  margin-bottom: 24px;
}

.tech-stack span {
  font-size: 0.75rem;
  padding: 4px 10px;
  border: 1px solid #e2e8f0;
  border-radius: 20px;
  color: var(--color-text-sub);
}

.card-links a {
  margin-right: 20px;
  font-weight: 600;
  color: var(--color-text-main);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: 0.2s;
}

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

/* Goal List */
.goal-list {
  list-style: none;
}
.goal-list li {
  padding: 15px 0;
  border-bottom: 1px solid #edf2f7;
  position: relative;
  padding-left: 30px;
}
.goal-list li::before {
  content: '✔';
  position: absolute;
  left: 0;
  color: var(--color-primary);
}

/* Footer */
footer {
  text-align: center;
  padding: 40px 0;
  color: var(--color-text-sub);
  font-size: 0.9rem;
  margin-top: 80px;
}

/* =========================================
   6. Animation Utility
   ========================================= */
.fade-up {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.8s cubic-bezier(0.2, 0.8, 0.2, 1), transform 0.8s cubic-bezier(0.2, 0.8, 0.2, 1);
}

.fade-up.show {
  opacity: 1;
  transform: translateY(0);
}

/* Responsive */
@media (max-width: 768px) {
  .hero h1 { font-size: 2.5rem; }
  .section { padding: 80px 0; }
  .nav-list { display: none; } /* 本番ではハンバーガーメニュー実装推奨 */
  .grid-2 { grid-template-columns: 1fr; }
}