main.css

* {
  margin: 0;
  padding: 0;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  font-weight: unset;
  font-size: var(--size_nho);
  /* background-color: var(--nen_body); */
}

:root {
  --size_thuong: 20px;
  --size_nho: 16px;
  --nen_body: #05258a;
  --nen_header: #011257;
  --size_logo: 40px;
}

.header {
  width: 100vw;
  height: 50px;
  display: block;
  background: linear-gradient(90deg, #5890f6, #ab93ff);
  position: fixed;
}

#header_logo {
  height: var(--size_logo);
  position: absolute;
  left: 4%;
  top: calc(50% - var(--size_logo) / 2);
}
#header_logo_name {
  position: absolute;
  top: calc(50% - var(--size_nho) / 2);
  left: 10%;
}
/* 
.header {
  width: 100%;
  height: 50px;
  background: var(--nen_header);
  background-image: linear-gradient(90deg, #5890f6, #ab93ff);
  background-size: 100vw;
  color: black;
  /* position: fixed;
}

#header_logo {
  background: unset;
  background-position: center;
}
.header_logo {
  height: calc(var(--size_nho) * 2);
  background: unset;
}

#header_item {
  margin: 0 20px;
  background: unset;
}
#header_item:hover {
  color: #fa9c82;
}

#login_button {
  font-weight: lighter;
  margin-left: 10%;
  padding: 6px 10px;
  background-color: unset;
  background: #fa9c82;
  border-radius: 8px;
  box-sizing: border-box;
} */