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

body {
  font-family: Arial, sans-serif;
  line-height: 1.6;
  background: #1e1e1e; /* nền tối dịu nhẹ */
  color: #e0e0e0;
}

/* Header */
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 2rem 3rem;
  background: #1e1e1e; 
  border-bottom: 1px solid #444;
}

header h1 {
  font-size: 2rem;
  color: #fff;
}

.header-right {
  display: flex;
  gap: 1rem;
  align-items: center;
}

.icon-btn {
  font-size: 1.3rem;
  color: #2d89ef;
  text-decoration: none;
  transition: color 0.3s ease;
}

.icon-btn:hover {
  color: #1a5fb4;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  border: 2px solid #2d89ef;
  border-radius: 25px;
  color: #2d89ef;
  text-decoration: none;
  font-weight: bold;
  transition: all 0.3s ease;
}

.btn:hover {
  background: #2d89ef;
  color: #fff;
}

/* Section */
section {
  padding: 2rem 1rem;
  max-width: 900px;
  margin: auto;
}

section h2 {
  margin-bottom: 1rem;
  border-bottom: 2px solid #3a3a3a;
  display: inline-block;
  padding-bottom: 0.3rem;
  color: #fff;
}

/* Skills pills */
.skills {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
  padding: 0;
}

.skills li {
  background: #2d89ef;
  color: #fff;
  padding: 0.6rem 1.2rem;
  border-radius: 20px;
  font-size: 0.9rem;
  transition: transform 0.2s ease, background 0.3s ease;
}

.skills li:hover {
  transform: scale(1.1);
  background: #3aa0ff;
}

/* Projects */
.project-card {
  background: #f2f2f2; /* sáng dịu mắt */
  color: #222;
  padding: 1.5rem;
  margin-bottom: 2rem;
  border-radius: 12px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.4);
}

.project-card h3 {
  margin-bottom: 0.5rem;
}

.project-section-title {
  font-weight: bold;
  margin-top: 0.8rem;
  margin-bottom: 0.3rem;
  color: #2d89ef;
}

.project-intro {
  margin-bottom: 0.8rem;
  color: #444;
}

.project-tech {
  margin-left: 1.5rem;
  margin-bottom: 1rem;
}

/* Video */
.video-container {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  margin-bottom: 1rem;
}

.video-container iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border-radius: 8px;
}

/* Buttons */
.buttons {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

a {
  color: #2d89ef;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* Footer */
footer {
  text-align: center;
  background: #1e1e1e;
  color: #bbb;
  padding: 1rem;
  margin-top: 2rem;
}

/* Responsive */
@media (max-width: 600px) {
  header {
    flex-direction: column;
    align-items: flex-start;
    gap: 1rem;
  }

  header h1 {
    font-size: 1.8rem;
  }

  .buttons {
    flex-direction: column;
  }

  .btn {
    text-align: center;
  }
}