/* hoc.vietup.com.au — nền tối phát sáng (teal + cam VietUp), đọc tốt trên điện thoại */
:root {
  --nen: #0B1514;
  --nen-2: #102120;
  --mat: #142826;
  --vien: rgba(255, 255, 255, .09);
  --chu: #E8F2F1;
  --chu-phu: #A3B9B7;
  --teal: #1F8B85;
  --teal-sang: #34C1B7;
  --cam: #EA580C;
  --cam-sang: #FB923C;
  --do: #F87171;
  --bo: 16px;
  --rong: 1080px;
  color-scheme: dark;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--nen); color: var(--chu);
  font: 16px/1.65 "Be Vietnam Pro", system-ui, -apple-system, "Segoe UI", sans-serif;
  overflow-x: hidden;
}
a { color: var(--teal-sang); }
img { max-width: 100%; height: auto; }
h1, h2, h3 { line-height: 1.25; margin: 0 0 .5em; letter-spacing: -.01em; }
.an-chu { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
:focus-visible { outline: 2px solid var(--cam-sang); outline-offset: 2px; }

.dai-nhap { background: #B91C1C; color: #fff; text-align: center; font-weight: 700; font-size: 13px; padding: 6px 16px; }

/* ---------- Đầu trang ---------- */
.dau {
  position: sticky; top: 0; z-index: 10; display: flex; align-items: center; justify-content: space-between; gap: 12px;
  padding: 10px max(16px, calc((100% - var(--rong)) / 2)); background: rgba(11, 21, 20, .82);
  backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px); border-bottom: 1px solid var(--vien);
}
.logo { display: flex; align-items: center; gap: 10px; color: var(--chu); text-decoration: none; min-width: 0; }
.logo span { display: flex; flex-direction: column; line-height: 1.2; min-width: 0; }
.logo b { font-size: 15px; }
.logo i { font-style: normal; font-size: 12px; color: var(--chu-phu); white-space: nowrap; }
.dau nav { display: flex; gap: 4px; }
.dau nav a { color: var(--chu-phu); text-decoration: none; font-size: 14px; padding: 6px 10px; border-radius: 8px; white-space: nowrap; }
.dau nav a:hover { color: var(--chu); background: var(--mat); }

.dai-dien { border-radius: 50%; object-fit: cover; flex: none; }
.dai-dien.chu {
  display: inline-grid; place-items: center; font-weight: 800; color: #fff;
  background: linear-gradient(135deg, var(--teal), var(--cam));
}
.dai-dien.nho { width: 36px; height: 36px; font-size: 14px; }
.dai-dien.vua { width: 28px; height: 28px; font-size: 12px; }
.dai-dien.lon { width: 96px; height: 96px; font-size: 34px; box-shadow: 0 0 0 4px var(--nen), 0 0 0 6px var(--teal); }

/* ---------- Nút ---------- */
.nut {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px; min-height: 48px; padding: 0 22px;
  border-radius: 12px; font: inherit; font-weight: 700; text-decoration: none; cursor: pointer; border: 0;
  transition: transform .15s, box-shadow .15s, background .15s;
}
.nut:active { transform: translateY(1px); }
.nut-cam { background: linear-gradient(135deg, var(--cam), #F97316); color: #fff; box-shadow: 0 8px 28px -8px rgba(234, 88, 12, .7); }
.nut-cam:hover { box-shadow: 0 10px 34px -6px rgba(234, 88, 12, .85); }
.nut-cam[disabled] { opacity: .6; cursor: wait; }
.nut-vien { background: transparent; color: var(--chu); border: 1px solid rgba(255, 255, 255, .22); }
.nut-vien:hover { background: var(--mat); }

/* ---------- Hero ---------- */
.hero { position: relative; overflow: hidden; padding: 56px 16px 64px; border-bottom: 1px solid var(--vien); }
.hero-sang {
  position: absolute; inset: -20% -10% auto; height: 140%; pointer-events: none;
  background:
    radial-gradient(40% 45% at 18% 30%, rgba(31, 139, 133, .45), transparent 70%),
    radial-gradient(35% 40% at 85% 20%, rgba(234, 88, 12, .35), transparent 70%),
    radial-gradient(30% 30% at 60% 90%, rgba(52, 193, 183, .18), transparent 70%);
  filter: blur(10px);
}
.hero-noi { position: relative; max-width: var(--rong); margin: 0 auto; }
.kicker {
  display: inline-flex; align-items: center; gap: 8px; margin: 0 0 18px; padding: 4px 14px 4px 4px; border-radius: 99px;
  background: rgba(255, 255, 255, .06); border: 1px solid var(--vien); font-size: 13px; color: var(--chu-phu);
}
.hero h1 { font-size: clamp(32px, 6.4vw, 60px); font-weight: 800; max-width: 15ch; }
.sang { background: linear-gradient(90deg, var(--cam-sang), #FDBA74 45%, var(--teal-sang)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero-phu { font-size: clamp(16px, 2.2vw, 19px); color: var(--chu-phu); max-width: 46ch; margin: 0 0 26px; }
.hero-nut { display: flex; flex-wrap: wrap; gap: 12px; }
.hero-dem { margin: 22px 0 0; font-size: 14px; color: var(--chu-phu); }
.hero-dem b { color: var(--chu); }

/* ---------- Khối ---------- */
.khoi { max-width: var(--rong); margin: 0 auto; padding: 56px 16px; }
.khoi-dau { margin-bottom: 18px; }
.kicker-nho { text-transform: uppercase; letter-spacing: .14em; font-size: 12px; font-weight: 700; color: var(--cam-sang); margin: 0 0 8px; }
.khoi h2 { font-size: clamp(24px, 4vw, 34px); }
.phu { color: var(--chu-phu); margin: 0; }

.o-tim input {
  width: 100%; min-height: 52px; padding: 0 18px; border-radius: 14px; font: inherit; font-size: 17px;
  background: var(--nen-2); color: var(--chu); border: 1px solid rgba(255, 255, 255, .16);
}
.o-tim input:focus { border-color: var(--teal-sang); outline: none; box-shadow: 0 0 0 4px rgba(52, 193, 183, .15); }
.chips { display: flex; gap: 8px; overflow-x: auto; padding: 14px 0 6px; scrollbar-width: none; }
.chips::-webkit-scrollbar { display: none; }
.chip {
  flex: none; min-height: 38px; padding: 0 16px; border-radius: 99px; border: 1px solid var(--vien); cursor: pointer;
  background: var(--nen-2); color: var(--chu-phu); font: inherit; font-size: 14px; font-weight: 600;
}
.chip.bat { background: var(--teal); border-color: var(--teal); color: #fff; }

.luoi { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 14px; margin-top: 14px; }
.the {
  position: relative; display: flex; flex-direction: column; gap: 8px; padding: 18px; border-radius: var(--bo); text-decoration: none; color: var(--chu);
  background: linear-gradient(180deg, rgba(255, 255, 255, .045), rgba(255, 255, 255, .015)); border: 1px solid var(--vien);
  transition: border-color .15s, transform .15s, box-shadow .15s;
}
.the:hover { border-color: rgba(52, 193, 183, .45); transform: translateY(-2px); box-shadow: 0 14px 40px -18px rgba(31, 139, 133, .6); }
.the.khop { border-color: var(--cam-sang); box-shadow: 0 0 0 3px rgba(251, 146, 60, .25); }
.the[hidden] { display: none; }
.the b { font-size: 17px; line-height: 1.35; }
.the-mo { color: var(--chu-phu); font-size: 14px; line-height: 1.5; }
.the-tren { display: flex; gap: 6px; flex-wrap: wrap; }
.the-duoi { margin-top: auto; padding-top: 6px; display: flex; justify-content: space-between; align-items: center; }
.mui { color: var(--cam-sang); font-weight: 700; }
.luoi-sap .the { opacity: .8; }
.tieu-sap { margin: 34px 0 0; font-size: 18px; color: var(--chu-phu); }
.khong-thay { margin-top: 18px; color: var(--chu-phu); }

.nhan { display: inline-block; font-size: 12px; font-weight: 700; padding: 3px 10px; border-radius: 99px; background: rgba(52, 193, 183, .14); color: var(--teal-sang); }
.nhan-skill { background: rgba(167, 139, 250, .16); color: #C4B5FD; }
.nhan-video { background: rgba(251, 146, 60, .16); color: var(--cam-sang); }
.nhan-tiem { background: rgba(250, 204, 21, .14); color: #FDE68A; }
.nhan-vietup { background: rgba(96, 165, 250, .16); color: #93C5FD; }
.nhan-sap { background: rgba(255, 255, 255, .08); color: var(--chu-phu); }
.nhan-nhap { background: rgba(248, 113, 113, .18); color: var(--do); }
.tu-khoa { font-size: 13px; color: var(--chu-phu); }
.tu-khoa b { color: var(--chu); letter-spacing: .04em; background: rgba(234, 88, 12, .18); padding: 2px 8px; border-radius: 6px; margin-left: 2px; }

/* ---------- Khoá học + về mình ---------- */
.khoi-khoa { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; align-items: start; }
.khoa-chu p { color: var(--chu-phu); }
.ds-gon { padding-left: 0; list-style: none; }
.ds-gon li { padding-left: 28px; position: relative; margin: 8px 0; }
.ds-gon li::before { content: "✓"; position: absolute; left: 0; color: var(--teal-sang); font-weight: 800; }
.khoi-ve { display: flex; gap: 24px; align-items: flex-start; border-top: 1px solid var(--vien); }
.khoi-ve p { color: var(--chu-phu); }

/* ---------- Form để lại liên lạc ---------- */
.form-lead {
  padding: 22px; border-radius: 20px; background: var(--nen-2); border: 1px solid rgba(52, 193, 183, .25);
  box-shadow: 0 20px 60px -30px rgba(31, 139, 133, .6);
}
.form-lead h3 { font-size: 20px; }
.form-lead .phu { margin-bottom: 14px; font-size: 14px; }
.o-luoi { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 12px; }
.o { display: flex; flex-direction: column; gap: 6px; font-size: 14px; font-weight: 600; min-width: 0; }
.rong { grid-column: 1 / -1; }
.o input, .o select, .o textarea {
  width: 100%; min-height: 48px; padding: 10px 14px; border-radius: 12px; font: inherit; font-size: 16px; font-weight: 400;
  background: var(--nen); color: var(--chu); border: 1px solid rgba(255, 255, 255, .16);
}
.o textarea { resize: vertical; }
.o input:focus, .o select:focus, .o textarea:focus { outline: none; border-color: var(--teal-sang); box-shadow: 0 0 0 4px rgba(52, 193, 183, .15); }
.o .sai { border-color: var(--do); }
.goi-y { margin: -4px 0 0; font-size: 13px; color: var(--chu-phu); }
.o-an { position: absolute; left: -9999px; width: 1px; height: 1px; overflow: hidden; }
.dong-y { display: flex; gap: 10px; align-items: flex-start; margin: 16px 0 8px; font-size: 14px; color: var(--chu-phu); cursor: pointer; }
.dong-y input { width: 22px; height: 22px; flex: none; margin-top: 1px; accent-color: var(--cam); }
.dong-y.sai span { color: var(--do); }
.rieng { font-size: 12px; color: var(--chu-phu); margin: 0 0 14px; }
.form-lead .nut { width: 100%; }
.bao { margin: 12px 0 0; font-size: 14px; min-height: 1em; }
.bao.loi { color: var(--do); }
.bao.ok { color: var(--teal-sang); font-weight: 600; }
.form-lead.xong .o-luoi, .form-lead.xong .dong-y, .form-lead.xong .rieng, .form-lead.xong .nut, .form-lead.xong .phu { display: none; }

/* ---------- Trang tài liệu ---------- */
.trang-tl { max-width: 760px; margin: 0 auto; padding: 24px 16px 56px; }
.ve-kho { display: inline-block; color: var(--chu-phu); text-decoration: none; font-size: 14px; margin-bottom: 18px; }
.tl-dau { padding-bottom: 20px; margin-bottom: 24px; border-bottom: 1px solid var(--vien); }
.tl-nhan { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; margin: 0 0 14px; }
.tl-dau h1 { font-size: clamp(26px, 5vw, 38px); font-weight: 800; }
.tl-mo { color: var(--chu-phu); font-size: 17px; margin: 0; }
.tl-ngay { color: var(--chu-phu); font-size: 13px; margin: 12px 0 0; }
.dem-lenh { background: rgba(234, 88, 12, .12); border: 1px solid rgba(234, 88, 12, .3); padding: 10px 14px; border-radius: 12px; font-size: 14px; }

.bai { font-size: 17px; overflow-wrap: anywhere; }
.bai h2 { font-size: 23px; margin-top: 1.8em; padding-top: .2em; scroll-margin-top: 80px; }
.bai h3 { font-size: 19px; margin-top: 1.5em; scroll-margin-top: 80px; }
.bai p { margin: 0 0 1em; }
.bai ul, .bai ol { padding-left: 1.3em; margin: 0 0 1em; }
.bai li { margin: .35em 0; }
.bai hr { border: 0; border-top: 1px solid var(--vien); margin: 2em 0; }
.bai code { background: rgba(255, 255, 255, .08); padding: 1px 6px; border-radius: 6px; font-size: .92em; }
.bai strong { color: #fff; }
.bai pre.ma { background: var(--nen-2); padding: 14px; border-radius: 12px; overflow-x: auto; font-size: 14px; }
.bai figure { margin: 1em 0; }
.bai figure img { border-radius: 12px; }

/* Bảng trong bài: khung tự cuộn ngang, khổ 375px không làm tràn trang */
.bang-cuon { overflow-x: auto; -webkit-overflow-scrolling: touch; margin: 16px 0 20px; border-radius: 14px; border: 1px solid rgba(52, 193, 183, .28); background: var(--nen-2); }
.bang-cuon table { border-collapse: collapse; width: 100%; min-width: 520px; font-size: 15px; line-height: 1.5; overflow-wrap: normal; }
.bang-cuon th, .bang-cuon td { padding: 10px 12px; text-align: left; vertical-align: top; border-bottom: 1px solid var(--vien); }
.bang-cuon th { background: rgba(31, 139, 133, .18); color: #fff; font-weight: 700; white-space: nowrap; }
.bang-cuon tbody tr:last-child td { border-bottom: 0; }
.bang-cuon tbody tr:nth-child(even) td { background: rgba(255, 255, 255, .025); }
.bang-cuon td:first-child { font-weight: 600; color: #fff; }
.bang-cuon .canh-center { text-align: center; }
.bang-cuon .canh-right { text-align: right; }

.lenh { margin: 16px 0 20px; border-radius: 14px; background: var(--nen-2); border: 1px solid rgba(52, 193, 183, .28); overflow: hidden; }
.lenh-dau { display: flex; align-items: center; gap: 10px; padding: 8px 8px 8px 12px; background: rgba(31, 139, 133, .16); border-bottom: 1px solid rgba(52, 193, 183, .2); }
.lenh-dau b { flex: 1; font-size: 15px; line-height: 1.35; min-width: 0; }
.lenh-so { flex: none; width: 26px; height: 26px; display: grid; place-items: center; border-radius: 8px; background: var(--teal); color: #fff; font-size: 13px; font-weight: 800; }
.nut-chep {
  flex: none; min-height: 40px; min-width: 76px; padding: 0 14px; border-radius: 10px; border: 0; cursor: pointer;
  background: var(--cam); color: #fff; font: inherit; font-size: 14px; font-weight: 700;
}
.nut-chep.da { background: var(--teal); }
.lenh pre { margin: 0; padding: 14px; white-space: pre-wrap; word-break: break-word; font: 15px/1.6 "Be Vietnam Pro", system-ui, sans-serif; color: var(--chu); }

.hop { border-radius: 14px; padding: 14px 16px; margin: 16px 0; border-left: 4px solid var(--teal-sang); background: rgba(52, 193, 183, .08); }
.hop p { margin: 0 0 .5em; }
.hop p:last-child { margin: 0; }
.hop-canh { border-left-color: var(--cam-sang); background: rgba(234, 88, 12, .1); }
.hop-sap { margin-bottom: 22px; }

.ds-viec { list-style: none; padding-left: 0 !important; }
.ds-viec ul { list-style: none; padding-left: 34px; }
.viec label { display: flex; gap: 12px; align-items: flex-start; padding: 10px 12px; border-radius: 12px; background: rgba(255, 255, 255, .03); border: 1px solid var(--vien); cursor: pointer; }
.viec input { width: 22px; height: 22px; flex: none; margin-top: 3px; accent-color: var(--teal); }
.viec input:checked + span { color: var(--chu-phu); text-decoration: line-through; text-decoration-color: rgba(255, 255, 255, .3); }

.trang-tl .form-lead { margin-top: 36px; }
.tl-khac { margin-top: 48px; }
.tl-khac h2 { font-size: 20px; }

/* ---------- Chân trang ---------- */
.chan { border-top: 1px solid var(--vien); padding: 28px 16px 40px; text-align: center; color: var(--chu-phu); font-size: 14px; }
.chan p { margin: 4px 0; }
.chan a { color: var(--chu-phu); }
.chan .nho { font-size: 12px; opacity: .7; }

@media (max-width: 760px) {
  .dau nav a:not(:first-child) { display: none; }
  .khoi-khoa { grid-template-columns: 1fr; }
  .khoi-ve { flex-direction: column; }
  .o-luoi { grid-template-columns: 1fr; }
  .hero { padding: 40px 16px 48px; }
  .khoi { padding: 44px 16px; }
  .form-lead { padding: 18px; }
}
@media (prefers-reduced-motion: reduce) { * { transition: none !important; scroll-behavior: auto !important; } }