:root {
  --primary-color: #6200ea;
  --primary-light: #9d46ff;
  --primary-dark: #0a00b6;
  --secondary-color: #03dac6;
  --background-color: #f5f5f5;
  --surface-color: #ffffff;
  --text-primary: #000000;
  --text-secondary: rgba(0, 0, 0, 0.6);
  --text-hint: rgba(0, 0, 0, 0.38);
  --shadow-2: 0 3px 6px rgba(0,0,0,0.16), 0 3px 6px rgba(0,0,0,0.23);
  --shadow-4: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);
  --radius-md: 8px;
  --font-main: 'Roboto', 'Helvetica Neue', sans-serif;
}

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

body {
  background-color: var(--background-color);
  color: var(--text-primary);
  font-family: var(--font-main);
  line-height: 1.6;
}

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

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

/* App Bar */
.app-bar {
  background-color: var(--primary-color);
  color: #fff;
  padding: 16px 0;
  box-shadow: var(--shadow-2);
  position: sticky;
  top: 0;
  z-index: 100;
}
.app-bar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.brand {
  display: flex;
  align-items: center;
  gap: 16px;
  font-size: 1.25rem;
  font-weight: 500;
}
.brand img { width: 40px; height: 40px; border-radius: 50%; box-shadow: 0 2px 4px rgba(0,0,0,0.2); }

/* Hero Card */
.hero-section {
  padding: 60px 0;
  background: var(--primary-color);
  color: #fff;
  margin-bottom: 40px;
  border-radius: 0 0 40px 40px;
  box-shadow: var(--shadow-2);
}
.hero-card {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}
.hero-content h1 {
  font-size: 3rem;
  margin-bottom: 16px;
  font-weight: 300;
}
.hero-content p {
  font-size: 1.1rem;
  margin-bottom: 32px;
  opacity: 0.9;
  max-width: 500px;
}
.fab-container {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}
.btn-raised {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: 28px;
  background-color: var(--secondary-color);
  color: #000;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 1px;
  box-shadow: var(--shadow-2);
}
.btn-raised:hover {
  background-color: #66fff9;
  box-shadow: var(--shadow-4);
  transform: translateY(-2px);
}
.btn-raised img { width: 24px; }
.btn-flat {
  color: #fff;
  padding: 12px 24px;
  text-transform: uppercase;
  font-weight: 500;
  letter-spacing: 1px;
}
.btn-flat:hover { background-color: rgba(255,255,255,0.1); border-radius: 4px; }

.hero-image {
  border-radius: 16px;
  box-shadow: var(--shadow-4);
  transform: rotate(-3deg);
  transition: transform 0.3s;
}
.hero-image:hover { transform: rotate(0); }

/* Section Header */
.section-title {
  text-align: center;
  font-size: 2rem;
  color: var(--primary-color);
  margin-bottom: 40px;
  font-weight: 300;
  position: relative;
}
.section-title::after {
  content: '';
  display: block;
  width: 60px;
  height: 4px;
  background-color: var(--secondary-color);
  margin: 8px auto 0;
}

/* Feature Cards */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
  padding-bottom: 60px;
}
.md-card {
  background: var(--surface-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-2);
  padding: 24px;
  transition: box-shadow 0.3s;
}
.md-card:hover { box-shadow: var(--shadow-4); }
.card-title {
  font-size: 1.25rem;
  margin-bottom: 12px;
  color: var(--primary-dark);
}
.card-text { color: var(--text-secondary); }

/* Gallery Chips */
.gallery-scroll {
  display: flex;
  overflow-x: auto;
  gap: 16px;
  padding: 16px 4px 32px;
}
.gallery-scroll img {
  height: 400px;
  width: auto;
  border-radius: 12px;
  box-shadow: var(--shadow-2);
  flex-shrink: 0;
}

/* List Items (Posts) */
.list-group {
  max-width: 800px;
  margin: 0 auto 60px;
  background: var(--surface-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-2);
}
.list-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 24px;
  border-bottom: 1px solid #eee;
  transition: background 0.2s;
}
.list-item:last-child { border-bottom: none; }
.list-item:hover { background-color: rgba(98, 0, 234, 0.04); }
.item-title { font-weight: 500; font-size: 1.1rem; }
.item-meta { color: var(--text-hint); font-size: 0.9rem; }

/* Chips (Friends) */
.chip-group {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  padding-bottom: 60px;
}
.chip {
  display: inline-flex;
  align-items: center;
  height: 32px;
  padding: 0 12px;
  border-radius: 16px;
  background-color: #e0e0e0;
  color: var(--text-primary);
  font-size: 0.875rem;
  transition: background 0.3s;
}
.chip:hover { background-color: #d1c4e9; }
.chip img {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  margin-left: -8px;
  margin-right: 8px;
}

/* Comments */
.comment-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
  padding-bottom: 60px;
}
.comment-card {
  background: var(--surface-color);
  padding: 16px;
  border-left: 4px solid var(--secondary-color);
  box-shadow: var(--shadow-2);
}
.comment-header { font-weight: bold; margin-bottom: 8px; color: var(--primary-color); }

/* Footer */
.footer {
  background-color: #333;
  color: #fff;
  padding: 40px 0;
  text-align: center;
  margin-top: auto;
}

@media (max-width: 768px) {
  .hero-card { grid-template-columns: 1fr; text-align: center; }
  .fab-container { justify-content: center; }
  .hero-image { max-width: 80%; margin: 0 auto; }
}