body {
  margin: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: url('./assets/bg.jpg') center/cover fixed no-repeat;
}

.header {
  background-color: rgba(244, 244, 244, 0.7);
  backdrop-filter: blur(5px);
  padding: 0 20px;
  display: flex;
  align-items: center;
  gap: 15px;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 10px rgba(0,0,0,0.2);
}

.hidden { display: none !important; }

.container {
  display: flex;
  height: calc(100vh - 60px);
}

.sidebar {
  width: 220px;
  padding: 20px;
  background-color: rgba(244, 244, 244, 0.3);
  backdrop-filter: blur(10px);
  box-shadow: 2px 0 5px rgba(0,0,0,0.1);
}

.sidebar li {
  margin: 15px 0;
  cursor: pointer;
  padding: 8px;
  border-radius: 4px;
}
.sidebar li:hover { background: rgba(26, 115, 232, 0.1); }

.email-list {
  flex: 1;
  padding: 20px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.email-item {
  background: white;
  padding: 15px 20px;
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  transition: transform 0.2s, box-shadow 0.2s;
}
.email-item:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
  background: #fdfdfd;
}
.email-item.lu {
  font-weight: normal;
  background: rgba(255, 255, 255, 0.8);
  opacity: 0.8;
}

.email-view {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin: 20px;
  padding: 30px;
  background: white;
  border-radius: 12px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.2);
  overflow-y: auto;
}

.btn-download {
  display: block;
  width: 250px;
  margin: 15px auto 0;
  background: black;
  color: white !important;
  padding: 10px 20px;
  border: none;
  border-radius: 4px;
  font-weight: 500;
  font-family: inherit;
  cursor: pointer;
  box-shadow: 0 1px 3px rgba(0,0,0,0.12);
}
.btn-download:hover {
  background: #333;
  transform: scale(1.02);
  transition: 0.2s;
}

#mailSubject {
  text-align: center;
  font-size: 28px;
  font-weight: bold;
  margin: 0;
}
.email-info {
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: #666;
  margin-top: 10px;
  font-size: 24px;
  border-bottom: 1px solid rgba(0,0,0,0.5);
}
#mailSender { padding-bottom: 10px; }
#mailBody {
  margin-top: 20px;
  font-size: 16px;
  line-height: 1.6;
  white-space: pre-wrap;
}
#backbt {
  align-self: flex-start;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 18px;
  border-radius: 20px;
  border: 1.5px solid #ddd;
  background: white;
  color: #333;
  font-size: 14px;
  font-weight: 500;
  font-family: inherit;
  box-shadow: 0 2px 6px rgba(0,0,0,0.08);
  transition: background 0.2s, box-shadow 0.2s, transform 0.15s;
}
#backbt:hover {
  background: #f1f3f4;
  box-shadow: 0 4px 12px rgba(0,0,0,0.12);
  transform: translateX(-2px);
}