body { font-family: 'Inter', sans-serif; }

h1, h2, h3, .font-display, nav .font-bold {
    font-family: 'Rajdhani', 'Inter', sans-serif;
    letter-spacing: 0.02em;
}

.dark body {
    background-color: #0a0b1a;
    background-image:
        radial-gradient(ellipse 900px 500px at 15% -10%, rgba(201, 160, 79, 0.10), transparent 60%),
        radial-gradient(ellipse 700px 500px at 90% 10%, rgba(114, 92, 158, 0.16), transparent 55%),
        radial-gradient(1.5px 1.5px at 20px 40px, rgba(255,255,255,0.5), transparent),
        radial-gradient(1px 1px at 90px 120px, rgba(255,255,255,0.4), transparent),
        radial-gradient(1.5px 1.5px at 160px 30px, rgba(255,255,255,0.35), transparent),
        radial-gradient(1px 1px at 230px 90px, rgba(255,255,255,0.3), transparent),
        radial-gradient(1.5px 1.5px at 300px 150px, rgba(255,255,255,0.4), transparent),
        radial-gradient(1px 1px at 370px 60px, rgba(255,255,255,0.3), transparent);
    background-repeat: no-repeat, no-repeat, repeat, repeat, repeat, repeat, repeat, repeat;
    background-size: auto, auto, 400px 400px, 400px 400px, 400px 400px, 400px 400px, 400px 400px, 400px 400px;
    background-attachment: fixed;
}

::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: #cbd5e1; border-radius: 10px; }
.dark ::-webkit-scrollbar-thumb { background: #b8903f; }
::-webkit-scrollbar-thumb:hover { background: #94a3b8; }
.dark ::-webkit-scrollbar-thumb:hover { background: #d4af6a; }

.tab-content { display: none; }
.tab-content.active { display: block; animation: fadeIn 0.3s ease-in-out; }

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

.modal-overlay {
    backdrop-filter: blur(4px);
}

/* ======================================================================
   HSR-STYLE: góc vát chéo đặc trưng (dùng cho card môn học, panel modal,
   nút hành động chính) + viền vàng phát sáng nhẹ khi hover.
   ====================================================================== */
.hsr-panel {
    clip-path: polygon(0 12px, 12px 0, 100% 0, 100% calc(100% - 12px), calc(100% - 12px) 100%, 0 100%);
    position: relative;
}
.dark .hsr-panel {
    background-color: #14162e;
    border: 1px solid rgba(201, 160, 79, 0.35);
}
.dark .hsr-panel:hover {
    border-color: rgba(212, 175, 106, 0.75);
    box-shadow: 0 0 18px rgba(201, 160, 79, 0.25);
}

.hsr-btn {
    clip-path: polygon(10px 0, 100% 0, 100% calc(100% - 10px), calc(100% - 10px) 100%, 0 100%, 0 10px);
}
.dark .hsr-btn.bg-indigo-600 {
    background: linear-gradient(135deg, #d4af6a, #96793f);
    color: #14162e;
    text-shadow: none;
    box-shadow: 0 0 14px rgba(212, 175, 106, 0.35);
}
.dark .hsr-btn.bg-indigo-600:hover {
    background: linear-gradient(135deg, #e8c987, #b8903f);
    box-shadow: 0 0 20px rgba(212, 175, 106, 0.55);
}

.hsr-divider {
    height: 1px;
    background: linear-gradient(90deg, transparent, rgba(212, 175, 106, 0.6), transparent);
}

.container input {
position: absolute;
opacity: 0;
cursor: pointer;
height: 0;
width: 0;
}

.container {
display: flex;
flex-direction: column;
align-items: center;
position: relative;
cursor: pointer;
user-select: none;
}

.simple-text {
position: absolute;
bottom: -60px; 
width: 120px;
text-align: center;
color: #ffd700;
font-size: 16pt;
font-weight: 800;
font-family: monospace;
text-shadow: 0 0 10px rgba(255, 215, 0, 0.5);
transition: all 0.3s ease;
}

.torch {
display: flex;
justify-content: center;
height: 150px;
}

.head,
.stick {
position: absolute;
width: 30px;
transform-style: preserve-3d;
transform: rotateX(-30deg) rotateY(45deg);
}

.stick {
position: relative;
height: 120px;
}

.face {
position: absolute;
transform-style: preserve-3d;
width: 30px;
height: 30px;
display: grid;
grid-template-columns: 50% 50%;
grid-template-rows: 50% 50%;
background-color: #000000;
}

.top {
transform: rotateX(90deg) translateZ(15px);
}

.left {
transform: rotateY(-90deg) translateZ(15px);
}

.right {
transform: rotateY(0deg) translateZ(15px);
}

.top div,
.left div,
.right div {
width: 102%;
height: 102%;
}

.top div:nth-child(1),
.left div:nth-child(3),
.right div:nth-child(3) {
background-color: #ffff97aa;
}

.top div:nth-child(2),
.left div:nth-child(1),
.right div:nth-child(1) {
background-color: #ffd800aa;
}

.top div:nth-child(3),
.left div:nth-child(4),
.right div:nth-child(4) {
background-color: #ffffffaa;
}

.top div:nth-child(4),
.left div:nth-child(2),
.right div:nth-child(2) {
background-color: #ff8f00aa;
}

.side {
position: absolute;
width: 30px;
height: 120px;
display: grid;
grid-template-columns: 50% 50%;
grid-template-rows: repeat(8, 12.5%);
cursor: pointer;
translate: 0 12px;
}

.side-left {
transform: rotateY(-90deg) translateZ(15px) translateY(8px);
}

.side-right {
transform: rotateY(0deg) translateZ(15px) translateY(8px);
}

.side-left div,
.side-right div {
width: 103%;
height: 103%;
}

.side div:nth-child(1) {
background-color: #443622;
}

.side div:nth-child(2),
.side div:nth-child(2) {
background-color: #2e2517;
}

.side div:nth-child(3),
.side div:nth-child(5) {
background-color: #4b3b23;
}

.side div:nth-child(4),
.side div:nth-child(10) {
background-color: #251e12;
}

.side div:nth-child(6) {
background-color: #292115;
}

.side div:nth-child(7) {
background-color: #4b3c26;
}

.side div:nth-child(8) {
background-color: #292115;
}

.side div:nth-child(9) {
background-color: #4b3a21;
}

.side div:nth-child(11),
.side div:nth-child(15) {
background-color: #3d311d;
}

.side div:nth-child(12) {
background-color: #2c2315;
}

.side div:nth-child(13) {
background-color: #493a22;
}

.side div:nth-child(14) {
background-color: #2b2114;
}

.side div:nth-child(16) {
background-color: #271e10;
}

.light-effect {
position: absolute;
top: -20px;
left: -35px;
width: 100px;
height: 100px;
background: radial-gradient(
    circle at center,
    rgba(255, 223, 89, 0.9) 0%,
    rgba(255, 183, 43, 0.4) 30%,
    transparent 70%
);
filter: blur(8px);
opacity: 0;
transition: opacity 0.3s ease;
pointer-events: none;
}

.particles {
position: absolute;
top: -10px;
left: -20px;
width: 70px;
height: 70px;
pointer-events: none;
}

.particles span {
position: absolute;
width: 3px;
height: 3px;
background: #ffd700;
border-radius: 50%;
opacity: 0;
pointer-events: none;
box-shadow: 0 0 10px #ffd700;
filter: blur(1px);
}

@keyframes particleFloat {
0% {
    transform: translate(0, 0) scale(1) rotate(0deg);
    opacity: 0;
}
20% {
    opacity: 1;
}
100% {
    transform: translate(calc(var(--x) * 20px), calc(var(--y) * -40px)) scale(0)
    rotate(360deg);
    opacity: 0;
}
}

.particles span:nth-child(1) { --x: 1; --y: 1; }
.particles span:nth-child(2) { --x: -1; --y: 1; }
.particles span:nth-child(3) { --x: 0.5; --y: 1; }
.particles span:nth-child(4) { --x: -0.5; --y: 1; }
.particles span:nth-child(5) { --x: 0.7; --y: 1; }
.particles span:nth-child(6) { --x: -0.7; --y: 1; }
.particles span:nth-child(7) { --x: 0.3; --y: 1; }
.particles span:nth-child(8) { --x: -0.3; --y: 1; }

.container input:checked ~ .torch .light-effect {
opacity: 1;
animation: flicker 4s infinite;
}

.container input:checked ~ .torch .particles span {
animation: particleFloat 2s infinite;
}

.container input:checked ~ .torch .particles span:nth-child(1) { animation-delay: 0s; }
.container input:checked ~ .torch .particles span:nth-child(2) { animation-delay: 0.2s; }
.container input:checked ~ .torch .particles span:nth-child(3) { animation-delay: 0.4s; }
.container input:checked ~ .torch .particles span:nth-child(4) { animation-delay: 0.6s; }
.container input:checked ~ .torch .particles span:nth-child(5) { animation-delay: 0.8s; }
.container input:checked ~ .torch .particles span:nth-child(6) { animation-delay: 1s; }
.container input:checked ~ .torch .particles span:nth-child(7) { animation-delay: 1.2s; }
.container input:checked ~ .torch .particles span:nth-child(8) { animation-delay: 1.4s; }

@keyframes flicker {
0%,
100% { opacity: 1; }
50% { opacity: 0.8; }
25%,
75% { opacity: 0.9; }
}

.container:hover .torch {
transform: scale(1.05) rotate(2deg);
transition: all 0.3s ease;
}

.container:hover .simple-text {
transform: scale(1.1);
text-shadow:
    0 0 15px rgba(255, 215, 0, 0.7),
    0 0 30px rgba(255, 215, 0, 0.4);
letter-spacing: 2px;
}

.container input:checked ~ .torch .face {
filter: drop-shadow(0px 0px 8px rgb(255, 255, 255))
    drop-shadow(0px 0px 20px rgba(255, 237, 156, 0.8))
    drop-shadow(0px 0px 40px rgba(255, 227, 101, 0.5));
transition: filter 0.3s ease;
}

.container input:checked ~ .torch .side {
filter: brightness(1.3);
transition: filter 0.3s ease;
}

.glow-effect {
position: absolute;
top: -30px;
left: -45px;
width: 120px;
height: 120px;
background: radial-gradient(
    circle at center,
    rgba(255, 160, 0, 0.4) 0%,
    rgba(255, 120, 0, 0.2) 30%,
    transparent 70%
);
filter: blur(15px);
opacity: 0;
transition: opacity 0.3s ease;
pointer-events: none;
animation: glowPulse 3s infinite;
}

.smoke {
position: absolute;
top: -20px;
left: -10px;
width: 50px;
height: 50px;
pointer-events: none;
}

.smoke span {
position: absolute;
width: 4px;
height: 4px;
background: rgba(255, 255, 255, 0.3);
border-radius: 50%;
filter: blur(2px);
opacity: 0;
pointer-events: none;
}

@keyframes glowPulse {
0%,
100% { transform: scale(1); opacity: 0.3; }
50% { transform: scale(1.1); opacity: 0.5; }
}

@keyframes smokeRise {
0% { transform: translate(0, 0) scale(1); opacity: 0; }
20% { opacity: 0.5; }
100% { transform: translate(calc(var(--x) * 30px), calc(var(--y) * -60px)) scale(3); opacity: 0; }
}

.smoke span:nth-child(1) { --x: 0.5; --y: 1; }
.smoke span:nth-child(2) { --x: -0.5; --y: 1; }
.smoke span:nth-child(3) { --x: 0.2; --y: 1; }
.smoke span:nth-child(4) { --x: -0.2; --y: 1; }

.container input:checked ~ .torch .smoke span { animation: smokeRise 3s infinite; }
.container input:checked ~ .torch .smoke span:nth-child(1) { animation-delay: 0s; }
.container input:checked ~ .torch .smoke span:nth-child(2) { animation-delay: 0.8s; }
.container input:checked ~ .torch .smoke span:nth-child(3) { animation-delay: 1.6s; }
.container input:checked ~ .torch .smoke span:nth-child(4) { animation-delay: 2.4s; }

.container input:checked ~ .torch .glow-effect { opacity: 1; }
.face div { transition: all 0.3s ease; }
.side div { transition: all 0.3s ease; }

.container input:checked ~ .torch .side div {
filter: brightness(1.3);
box-shadow: inset 0 0 5px rgba(255, 183, 43, 0.2);
}

#input-custom-color {
    -webkit-appearance: none;
    appearance: none;
    border: none;
    background: none;
}
#input-custom-color::-webkit-color-swatch-wrapper {
    padding: 0;
    border-radius: 0.5rem;
}
#input-custom-color::-webkit-color-swatch {
    border: 2px solid #e2e8f0;
    border-radius: 0.5rem;
}
.dark #input-custom-color::-webkit-color-swatch {
    border-color: #475569;
}
#custom-color-preview.selected {
    box-shadow: 0 0 0 2px #6366f1;
}

.page-loader-overlay {
    position: fixed;
    inset: 0;
    z-index: 9999;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #0b0d12;
    opacity: 1;
    visibility: visible;
    transition: opacity 0.5s ease, visibility 0.5s ease;
}
.page-loader-overlay.page-loader-hide {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

.tetris-loader-root {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 1.25rem 1.5rem;
  min-width: 13rem;
  border-radius: 0.9rem;
  background: #111318;
  box-shadow:
    0 14px 30px rgba(0, 0, 0, 0.7),
    0 0 0 1px rgba(255, 255, 255, 0.04);
  font-family:
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
}

.tetris-loader {
  display: flex;
  gap: 0.35rem;
  align-items: flex-end;
}

.tetris-block {
  --tetris-size: 2.2rem;
  width: var(--tetris-size);
  height: var(--tetris-size);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 0.95rem;
  text-transform: uppercase;
  color: #f6f7ff;
  background: linear-gradient(135deg, #5b68ff, #b54dff);
  border-radius: 0.45rem;
  box-shadow:
    0 8px 16px rgba(0, 0, 0, 0.7),
    0 0 0 2px rgba(8, 10, 26, 0.9),
    inset 0 0 0 1px rgba(255, 255, 255, 0.28);
  transform-origin: center;
  animation: tetris-loader-drop 2.4s cubic-bezier(0.25, 0.7, 0.2, 1.05) infinite;
}

.tetris-block:nth-child(1) {
  animation-delay: 0s;
}
.tetris-block:nth-child(2) {
  animation-delay: 0.15s;
}
.tetris-block:nth-child(3) {
  animation-delay: 0.3s;
}
.tetris-block:nth-child(4) {
  animation-delay: 0.45s;
}
.tetris-block:nth-child(5) {
  animation-delay: 0.6s;
}
.tetris-block:nth-child(6) {
  animation-delay: 0.75s;
}
.tetris-block:nth-child(7) {
  animation-delay: 0.9s;
}

@keyframes tetris-loader-drop {
  0% {
    opacity: 0;
    transform: translateY(-7rem) rotate(-90deg);
  }
  20% {
    opacity: 1;
    transform: translateY(-2rem) rotate(-40deg);
  }
  55% {
    transform: translateY(0) rotate(0deg);
  }
  65% {
    
    transform: translateY(0.35rem) rotate(0deg);
  }
  75% {
    transform: translateY(0) rotate(0deg);
  }
  100% {
    opacity: 1;
    transform: translateY(0) rotate(0deg);
  }
}

.tetris-loader-text {
  margin-top: 0.9rem;
  color: #c4cad9;
  font-size: 0.85rem;
  letter-spacing: 0.25em;
  text-transform: uppercase;
}

/* From Uiverse.io by shadyeljokers */
#modal-login .container {
  position: relative;
  width: 400px;
  height: 400px;
  display: flex;
  flex-direction: row;
  justify-content: center;
  align-items: center;
  border-radius: 50%;
  overflow: hidden;
  background: #1f293a;
  cursor: default;
  user-select: auto;
}

#modal-login .container span {
  position: absolute;
  left: 0;
  width: 32px;
  height: 6px;
  background: #2c4766;
  border-radius: 80px;
  transform-origin: 200px;
  transform: rotate(calc(var(--i) * (360deg / 50)));
  animation: modalLoginBlink 3s linear infinite;
  animation-delay: calc(var(--i) * (3s / 50));
}

@keyframes modalLoginBlink {
  0% {
    background: #d4af6a;
  }
  25% {
    background: #2c4766;
  }
}

#modal-login .login-box {
  position: absolute;
  width: 80%;
  max-width: 300px;
  z-index: 1;
  padding: 20px;
  border-radius: 20px;
}

#modal-login .login-box form {
  width: 100%;
  padding: 0 10px;
  box-sizing: border-box;
}

#modal-login .login-box h2 {
  font-size: 1.8em;
  color: #d4af6a;
  text-align: center;
  margin-bottom: 20px;
}

#modal-login .input-box {
  position: relative;
  margin: 25px 0;
}

#modal-login .login-box input {
  position: static;
  opacity: 1;
  cursor: text;
  width: 100%;
  height: 45px;
  background: transparent;
  border: 2px solid #2c4766;
  outline: none;
  border-radius: 40px;
  font-size: 1em;
  color: #fff;
  padding: 0 15px;
  transition: 0.5s ease;
  box-sizing: border-box;
}

#modal-login #pass-input {
  padding-right: 45px;
}

#modal-login .login-box input:focus {
  border-color: #d4af6a;
}

#modal-login .login-box input:valid ~ label,
#modal-login .login-box input:focus ~ label {
  top: -10px;
  font-size: 0.8em;
  background: #1f293a;
  padding: 0 6px;
  color: #d4af6a;
}

#modal-login .login-box label {
  position: absolute;
  top: 50%;
  left: 15px;
  transform: translateY(-50%);
  font-size: 1em;
  pointer-events: none;
  transition: 0.5s ease;
  color: #fff;
}

#modal-login .login-box .btn {
  width: 100%;
  height: 45px;
  background: #d4af6a;
  border: none;
  outline: none;
  border-radius: 40px;
  cursor: pointer;
  font-size: 1em;
  color: #1f293a;
  font-weight: 600;
  margin-top: 10px;
}

#modal-login .toggle-password {
  position: absolute;
  right: 15px;
  top: 50%;
  transform: translateY(-50%);
  cursor: pointer;
  color: #fff;
  width: 20px;
  height: 20px;
  transition: 0.3s ease;
}

#modal-login .toggle-password:hover {
  color: #d4af6a;
}

/* From Uiverse.io by Bastiennnn */
#view-code-content .card {
  width: 100%;
  height: 100%;
  min-height: 60vh;
  max-height: 85vh;
  display: flex;
  flex-direction: column;
  background-color: #24233b;
  border-radius: 8px;
  z-index: 1;
  box-shadow: 0px 10px 10px rgb(73, 70, 92);
  transition: 0.5s;
}

#view-code-content .card:hover {
  box-shadow: 0px 10px 10px black;
}

#view-code-content .top {
  display: flex;
  align-items: center;
  padding-left: 10px;
  transform: none;
}

#view-code-content .top > div {
  width: auto;
  height: auto;
  background-color: transparent;
}

#view-code-content .circle {
  padding: 0 4px;
}

#view-code-content .circle2 {
  display: inline-block;
  align-items: center;
  width: 10px;
  height: 10px;
  padding: 1px;
  border-radius: 5px;
}

#view-code-content .red {
  background-color: #ff605c;
}

#view-code-content .yellow {
  background-color: #ffbd44;
}

#view-code-content .green {
  background-color: #00ca4e;
}

#view-code-content .header {
  margin: 5px;
  margin-top: 5px;
  border-radius: 5px;
  flex-shrink: 0;
}

#view-code-content #title2 {
  color: white;
  padding-left: 50px;
  font-size: 15px;
}

#view-code-content .code-container {
  text-align: center;
  flex: 1;
  min-height: 0;
  display: flex;
  padding: 0 10px 10px;
}
#view-code-content #code {
  width: 100%;
  height: 100%;
  resize: none;
  background-color: rgb(73, 70, 92);
  border-radius: 5px;
  border: none;
  color: white;
  padding: 10px;
}
#view-code-content #code:focus {
  outline: none !important;
}


/* ==========================================================================
   Chống gian lận khi làm bài kiểm tra: không cho bôi đen/chọn văn bản đề bài,
   câu hỏi, đáp án bên trong modal làm bài (không ảnh hưởng các phần khác của
   trang). Lưu ý: đây chỉ là biện pháp cản trở ở mức giao diện, không thể
   ngăn chặn tuyệt đối người dùng có chủ đích (xem thêm ghi chú trong script.js).
   ========================================================================== */
#modal-quiz-taking,
#modal-quiz-taking * {
    -webkit-user-select: none !important;
    -moz-user-select: none !important;
    -ms-user-select: none !important;
    user-select: none !important;
    -webkit-touch-callout: none !important;
    -webkit-user-drag: none !important;
}

/* Vẫn cho phép gõ chữ bình thường trong ô trả lời tự luận. */
#modal-quiz-taking textarea.quiz-answer-input {
    -webkit-user-select: text !important;
    -moz-user-select: text !important;
    -ms-user-select: text !important;
    user-select: text !important;
}

/* Lớp phủ cảnh báo khi phát hiện mở DevTools trong lúc đang làm bài. */
#quiz-devtools-warning-overlay {
    position: fixed;
    inset: 0;
    z-index: 9999;
    background: rgba(15, 23, 42, 0.96);
    color: #fff;
    display: none;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 24px;
    font-family: 'Inter', sans-serif;
}
#quiz-devtools-warning-overlay.visible {
    display: flex;
}
#quiz-devtools-warning-overlay i {
    font-size: 48px;
    color: #f87171;
    margin-bottom: 16px;
}


/* Ô làm bài kiểm tra: phủ toàn màn hình, bỏ góc vát của hsr-panel */
#modal-quiz-taking #quiz-container {
    clip-path: none !important;
    border-radius: 0 !important;
    width: 100vw;
    height: 100vh;
    height: 100dvh;
}
#modal-quiz-taking #quiz-questions-container .quiz-question-item {
    width: 100%;
    max-width: 56rem;
    margin-left: auto;
    margin-right: auto;
}
#modal-quiz-taking .quiz-question-item.quiz-q-hidden {
    display: none;
}

/* Bảng số câu hỏi khi làm bài: trắng = chưa trả lời, xanh = đã trả lời */
.quiz-nav-grid {
    display: grid;
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 8px;
}
.quiz-nav-btn {
    height: 44px;
    border-radius: 8px;
    border: 1px solid #94a3b8;
    background: #ffffff;
    color: #0f172a;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.15s, transform 0.1s;
}
.quiz-nav-btn:hover { transform: translateY(-1px); }
.quiz-nav-btn.answered {
    background: #22c55e;
    border-color: #16a34a;
    color: #ffffff;
}
.quiz-nav-btn.current {
    outline: 3px solid #f59e0b;
    outline-offset: 2px;
}
.quiz-nav-legend {
    display: inline-block;
    width: 18px;
    height: 18px;
    border-radius: 4px;
}
@media (max-width: 768px) {
    #modal-quiz-taking #quiz-navigator-panel { width: 14rem; padding: 1rem; }
    .quiz-nav-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

/* Nút Nộp bài mờ đi khi còn câu chưa trả lời (vẫn bấm được để báo câu còn thiếu) */
#quiz-submit-btn.quiz-submit-incomplete {
    opacity: 0.45;
    cursor: not-allowed;
    filter: grayscale(0.4);
}