:root {
  --mau-nen: #f8f9fa;
  --mau-nen-chinh: #ffffff;
  --mau-chu-chinh: #212529;
  --mau-chu-phu: #6c757d;
  --mau-chu-dao: #4a3f35;
  --mau-diem-nhan: #d99a7a;
  --mau-vien: #dee2e6;
  --mau-loi: #dc3545;
  
  --kieu-chu:
    "Segoe UI",
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    sans-serif;
  --khoang-cach-nho: 0.5rem;
  --khoang-cach-vua: 1rem;
  --khoang-cach-lon: 1.5rem;
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--kieu-chu);
  background-color: var(--mau-nen);
  color: var(--mau-chu-chinh);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

/* Màn Đăng nhập */
.trang-dang-nhap {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: var(--khoang-cach-vua);
  background-color: #fff8f2;
}

.khung-dang-nhap {
  background: white;
  padding: calc(var(--khoang-cach-lon) * 2);
  border-radius: 1rem;
  box-shadow: 0 10px 30px rgba(0,0,0,0.05);
  width: 100%;
  max-width: 420px;
  text-align: center;
}

.bieu-tuong-lon {
  font-size: 4rem;
  margin-bottom: var(--khoang-cach-nho);
}

.ve-trang-chu {
  display: inline-block;
  margin-bottom: var(--khoang-cach-vua);
  text-decoration: none;
  color: var(--mau-chu-phu);
  font-weight: 500;
}

.ve-trang-chu:hover {
  color: var(--mau-diem-nhan);
}

.khung-dang-nhap h1 {
  margin-top: 0;
  margin-bottom: var(--khoang-cach-nho);
  color: var(--mau-chu-dao);
}

.khung-dang-nhap p {
  color: var(--mau-chu-phu);
  margin-bottom: var(--khoang-cach-lon);
}

/* Forms */
form {
  display: flex;
  flex-direction: column;
  gap: var(--khoang-cach-vua);
  text-align: left;
}

label {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  font-weight: 600;
  color: var(--mau-chu-dao);
}

input, textarea {
  padding: 0.75rem 1rem;
  border: 1px solid var(--mau-vien);
  border-radius: 0.5rem;
  font-family: inherit;
  font-size: 1rem;
  transition: all 0.2s;
  background-color: #fcfcfc;
}

input:focus, textarea:focus {
  outline: none;
  border-color: var(--mau-diem-nhan);
  box-shadow: 0 0 0 3px rgba(217, 154, 122, 0.15);
  background-color: white;
}

.luoi-hai-cot {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--khoang-cach-vua);
}

.lua-chon {
  flex-direction: row;
  align-items: center;
  gap: 0.75rem;
  cursor: pointer;
}

.lua-chon input[type="checkbox"] {
  width: 1.2rem;
  height: 1.2rem;
  cursor: pointer;
}

/* Nút bấm */
.nut-chinh, .nut-phu, .nut-van-ban {
  padding: 0.75rem 1.5rem;
  border-radius: 0.5rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: all 0.2s;
  display: inline-block;
  text-align: center;
  text-decoration: none;
}

.nut-chinh {
  background-color: var(--mau-chu-dao);
  color: white;
}

.nut-chinh:hover {
  background-color: var(--mau-diem-nhan);
}

.nut-phu {
  background-color: white;
  border: 1px solid var(--mau-vien);
  color: var(--mau-chu-chinh);
}

.nut-phu:hover {
  background-color: var(--mau-nen);
  border-color: var(--mau-chu-phu);
}

.nut-van-ban {
  background: none;
  color: var(--mau-chu-phu);
  padding: 0.5rem 1rem;
}

.nut-van-ban:hover {
  color: var(--mau-chu-dao);
  background: rgba(0,0,0,0.05);
}

/* Khung Ứng dụng Quản lý */
.ung-dung {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.dau-quan-ly {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--khoang-cach-vua) calc(var(--khoang-cach-lon) * 1.5);
  background: white;
  border-bottom: 1px solid var(--mau-vien);
}

.dau-quan-ly .thuong-hieu {
  font-weight: 800;
  font-size: 1.2rem;
  color: var(--mau-chu-dao);
  text-decoration: none;
  margin-bottom: 0.25rem;
  display: block;
}

.dau-quan-ly p {
  margin: 0;
  color: var(--mau-chu-phu);
  font-size: 0.9rem;
}

.dieu-huong-quan-ly {
  display: flex;
  gap: var(--khoang-cach-lon);
  padding: 0 calc(var(--khoang-cach-lon) * 1.5);
  background: white;
  border-bottom: 1px solid var(--mau-vien);
  overflow-x: auto;
}

.dieu-huong-quan-ly button {
  background: none;
  border: none;
  padding: calc(var(--khoang-cach-vua) * 1.25) 0;
  font-weight: 600;
  color: var(--mau-chu-phu);
  cursor: pointer;
  border-bottom: 3px solid transparent;
  transition: all 0.2s;
  white-space: nowrap;
}

.dieu-huong-quan-ly button:hover {
  color: var(--mau-chu-dao);
}

.dieu-huong-quan-ly button[aria-current="page"] {
  color: var(--mau-diem-nhan);
  border-bottom-color: var(--mau-diem-nhan);
}

.noi-dung-quan-ly {
  padding: calc(var(--khoang-cach-lon) * 2) calc(var(--khoang-cach-lon) * 1.5);
  flex: 1;
  max-width: 1200px;
  margin: 0 auto;
  width: 100%;
}

.tieu-de-man {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: calc(var(--khoang-cach-lon) * 2);
}

.tieu-de-man h1 {
  margin: 0 0 0.5rem 0;
  color: var(--mau-chu-dao);
}

.tieu-de-man p {
  margin: 0;
  color: var(--mau-chu-phu);
}

/* Dialogs */
.hop-thoai {
  border: none;
  border-radius: 1rem;
  padding: 0;
  width: 90%;
  max-width: 700px;
  box-shadow: 0 20px 50px rgba(0,0,0,0.15);
}

.hop-thoai::backdrop {
  background: rgba(0,0,0,0.5);
  backdrop-filter: blur(4px);
}

.hop-thoai__khung {
  padding: calc(var(--khoang-cach-lon) * 1.5);
}

.hop-thoai__dau {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: calc(var(--khoang-cach-lon) * 1.5);
}

.hop-thoai__dau h2 {
  margin: 0;
  color: var(--mau-chu-dao);
}

.nut-dong {
  background: none;
  border: none;
  font-size: 2rem;
  line-height: 1;
  color: var(--mau-chu-phu);
  cursor: pointer;
}

.nut-dong:hover {
  color: var(--mau-chu-chinh);
}

.hop-thoai__hanh-dong {
  display: flex;
  justify-content: flex-end;
  gap: var(--khoang-cach-vua);
  margin-top: calc(var(--khoang-cach-lon) * 1.5);
  padding-top: var(--khoang-cach-lon);
  border-top: 1px solid var(--mau-vien);
}

/* Tiện ích */
.da-hien {
  animation: hienLen 0.4s ease forwards;
}

@keyframes hienLen {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.thong-bao {
  position: fixed;
  bottom: var(--khoang-cach-lon);
  left: 50%;
  transform: translateX(-50%);
  background: var(--mau-chu-dao);
  color: white;
  padding: var(--khoang-cach-vua) calc(var(--khoang-cach-vua) * 2);
  border-radius: 9999px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.2);
  z-index: 9999;
  font-weight: 500;
}

.dang-xu-ly {
  position: fixed;
  top: 0; left: 0; right: 0; bottom: 0;
  background: rgba(255,255,255,0.8);
  backdrop-filter: blur(4px);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 10000;
  font-weight: 600;
  color: var(--mau-chu-dao);
}

@media (max-width: 768px) {
  .luoi-hai-cot {
    grid-template-columns: 1fr;
  }
  
  .tieu-de-man {
    flex-direction: column;
    gap: var(--khoang-cach-vua);
  }
}