:root{--color-primary:#6cb5e6;--color-secondary:#2ecc71;--primary-red:#a31d1d;--color-background:#ecf0f1;--text-color:#fff;--color-red--:#80241a;font-size:62.5%}@keyframes gradient{0%{background-position:0 50%}50%{background-position:100% 50%}to{background-position:0 50%}}.music-player{position:fixed;left:2rem;top:24rem;width:32rem;max-height:calc(100vh - 24rem - 2rem);background-color:hsla(0,0%,100%,.95);border-radius:1.2rem;box-shadow:0 .4rem 2rem rgba(0,0,0,.15);padding:1.5rem;z-index:1000;transition:all .3s ease;border:1px solid #e0e0e0;display:flex;flex-direction:column}.music-player.minimized{width:20rem;padding:1rem}.music-player.minimized .music-player-header{margin-bottom:0}.music-player-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:1rem}.music-player-header h3{margin:0;font-size:1.4rem;font-weight:700;color:#333}.music-player-header .minimize-btn{background:none;border:none;font-size:1.8rem;cursor:pointer;padding:0;width:2.4rem;height:2.4rem;display:flex;align-items:center;justify-content:center}.song-info{margin-bottom:1rem}.song-info .song-title{font-size:1.2rem;color:#666;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;font-weight:500}.song-info .song-counter{font-size:1rem;color:#999;margin-top:.2rem}.progress-container{margin-bottom:1rem}.progress-container .progress-bar{width:100%;height:.4rem;border-radius:.2rem;outline:none;cursor:pointer}.progress-container .time-display{display:flex;justify-content:space-between;font-size:1rem;color:#999;margin-top:.2rem}.controls{display:flex;align-items:center;gap:.8rem;margin-bottom:1rem}.controls .control-btn{background:#f0f0f0;border:none;border-radius:50%;width:3.2rem;min-width:3.2rem;height:3.2rem;cursor:pointer;display:flex;align-items:center;justify-content:center;font-size:1.4rem;aspect-ratio:1;line-height:1}.controls .control-btn.play-pause-btn{background:#a31d1d;color:#fff;width:4rem;min-width:4rem;height:4rem;font-size:1.8rem}.controls .volume-control{flex:1 1;display:flex;align-items:center;gap:.5rem;margin-left:.5rem}.controls .volume-control .volume-icon{font-size:1.2rem}.controls .volume-control .volume-slider{flex:1 1;height:.4rem;border-radius:.2rem;outline:none;cursor:pointer;max-width:9.6rem}.controls .volume-control .volume-percent{font-size:1rem;color:#999;min-width:3rem}.playlist-indicator{font-size:1rem;color:#999;text-align:center;margin-bottom:1rem}.playlist-container{border-top:1px solid #e0e0e0;padding-top:1rem;margin-top:1rem;max-height:30rem;overflow-y:auto;overflow-x:hidden}.playlist-container .playlist-header{font-size:1.2rem;font-weight:700;margin-bottom:.8rem;color:#333}.playlist-container .playlist{display:flex;flex-direction:column;gap:.4rem}.song-button{background:#f8f9fa;color:#333;border:1px solid #e0e0e0;border-radius:.6rem;padding:.8rem 1rem;cursor:pointer;text-align:left;font-size:1.1rem;transition:all .2s ease;display:flex;align-items:center;gap:.8rem;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.song-button:hover{background:#e9ecef}.song-button.current{background:#a31d1d;color:#fff;border:none}.song-button .song-number{min-width:2rem;font-size:1rem}.song-button .song-title{flex:1 1;overflow:hidden;text-overflow:ellipsis}@media screen and (max-width:768px){.music-player{left:1rem;top:19.2rem;width:28rem}.music-player.minimized{width:18rem}}@media screen and (max-width:480px){.music-player{left:.5rem;top:16rem;width:26rem}.music-player.minimized{width:16rem}}@media screen and (max-width:1800px){.music-player{display:none}}*{margin:0;padding:0;box-sizing:border-box}body{font-family:Arial,sans-serif;line-height:1.6;font-size:1.6rem}body:before{content:"";position:fixed;top:0;left:0;width:100%;height:100%;background-image:url(/img/logo.png);background-size:cover;background-position:50%;background-repeat:no-repeat;z-index:-1;opacity:.2}body{margin:0;padding:2rem;background-color:#fff}h1{text-align:center;color:var(--color-red--);font-size:2.4rem}.header-container{background-color:var(--primary-red);color:var(--text-color);display:flex;flex-direction:row;align-items:center;padding:1rem 6rem;width:100%}.header-container .logo{width:7rem;height:auto;margin-right:1.5rem}.header-container .header-content{display:flex;flex-direction:column;flex-grow:1}.header-container .header-content .main-title{display:flex;justify-content:space-between;width:100%;font-weight:700;margin-bottom:.5rem}.header-container .header-content .main-title .title-left,.header-container .header-content .main-title .title-right{font-size:2.4rem;text-transform:uppercase}.header-container .header-content .subtitle{font-size:1.4rem;text-transform:uppercase;font-weight:700;color:#fff017}#history-screen,#login-screen,#review-screen,#settings-screen,.container{max-width:100rem;margin:7rem auto 0;background:#fff;padding:5rem;border-radius:2rem;box-shadow:0 0 2rem rgba(245,9,9,.1)}.login-form label{display:inline-block;width:100rem;margin:1.2rem 0 .5rem;font-size:1.6rem;font-weight:700}.login-form input,.login-form select{width:calc(100% - .5rem);padding:1rem;margin-bottom:1rem;border:.1rem solid #504b4b;border-radius:.2rem;font-size:1.6rem}.login-form button{display:block;width:50%;padding:1rem;color:#fff;border:none;border-radius:.4rem;cursor:pointer;font-size:2.4rem;margin:2rem auto;transition:background-color .3s;box-shadow:0 .4rem 1.5rem rgba(74,79,83,.3);text-align:center;font-weight:700;text-transform:uppercase;letter-spacing:.1rem;background:linear-gradient(90deg,var(--color-red--),#a55b68);background-size:200% 200%;animation:gradient 5s ease infinite}.login-form button:hover{background:linear-gradient(90deg,#5153b1,#4c6a8d);background-size:200% 200%;animation:gradient 3s ease infinite;box-shadow:0 .6rem 2rem rgba(74,79,83,.5);transform:translateY(-.2rem)}.admin-login{margin-top:3rem;border-top:.2rem solid var(--color-red--);padding-top:2rem}.admin-login h2{text-align:center;color:var(--color-red--);margin-bottom:2rem;font-size:2.4rem}.admin-login label{display:inline-block;width:100%;margin:1.2rem 0 .5rem;font-size:1.6rem}.admin-login input{width:calc(100% - 4rem);padding:1rem;margin-bottom:1rem;border:.1rem solid #504b4b;border-radius:.2rem;font-size:1.6rem}.admin-login button{display:block;width:50%;padding:1rem;color:#fff;border:none;border-radius:.4rem;cursor:pointer;font-size:2.4rem;margin:2rem auto;transition:background-color .3s;box-shadow:0 .4rem 1.5rem rgba(74,79,83,.3);text-align:center;text-decoration:none;font-weight:700;text-transform:uppercase;letter-spacing:.1rem;background:linear-gradient(90deg,#7e2020,#a55b68);background-size:200% 200%;animation:gradient 5s ease infinite}.admin-login button:hover{background:linear-gradient(90deg,#5153b1,#4c6a8d);background-size:200% 200%;animation:gradient 3s ease infinite;box-shadow:0 .6rem 2rem rgba(74,79,83,.5);transform:translateY(-.2rem)}#backBtn{background:linear-gradient(90deg,#24039b,#3f51b5);color:#fff;cursor:pointer;font-size:2.4rem;padding:1.5rem 3rem;border:none;border-radius:.6rem;box-shadow:0 .4rem 1.5rem rgba(36,3,155,.3);text-transform:uppercase;letter-spacing:.1rem;transition:all .3s ease}#backBtn:hover{background:linear-gradient(90deg,#1a237e,#3f51b5);box-shadow:0 .6rem 2rem rgba(36,3,155,.5);transform:translateY(-.2rem)}#backBtn:disabled{background:#860e0e;cursor:not-allowed;box-shadow:none;color:#ccc}#backBtn:disabled,#settingsBtn{font-size:2.4rem;padding:1.5rem 3rem;border:none;border-radius:.6rem}#settingsBtn{background:linear-gradient(90deg,#801a08,#b71c1c);color:#fff;cursor:pointer;box-shadow:0 .4rem 1.5rem rgba(128,26,8,.3);text-transform:uppercase;letter-spacing:.1rem;transition:all .3s ease}#settingsBtn:hover{background:linear-gradient(90deg,#6a1b9a,#b71c1c);box-shadow:0 .6rem 2rem rgba(128,26,8,.5);transform:translateY(-.2rem)}#historyBtn{background:linear-gradient(90deg,#616161,#757575);color:#fff;cursor:pointer;font-size:2.4rem;padding:1.5rem 3rem;border:none;border-radius:.6rem;box-shadow:0 .4rem 1.5rem rgba(97,97,97,.3);text-transform:uppercase;letter-spacing:.1rem;transition:all .3s ease}#historyBtn:hover{background:linear-gradient(90deg,#424242,#616161);box-shadow:0 .6rem 2rem rgba(97,97,97,.5);transform:translateY(-.2rem)}#historyBtn:disabled{background:#1f1414;cursor:not-allowed;font-size:2.4rem;padding:1.5rem 3rem;border:none;border-radius:.6rem;box-shadow:none;color:#ccc}table{width:100%;border-collapse:collapse;margin-top:2rem}table td,table th{padding:1rem;text-align:left;border:.1rem solid #ddd}table th{background-color:#f2f2f2}.dialog-overlay{position:fixed;top:0;left:0;right:0;bottom:0;background-color:rgba(0,0,0,.5);display:flex;align-items:center;justify-content:center;z-index:1000;animation:fadeIn .2s ease-in-out}@keyframes fadeIn{0%{opacity:0}to{opacity:1}}@keyframes slideIn{0%{transform:translateY(-1.25rem);opacity:0}to{transform:translateY(0);opacity:1}}.dialog-header{display:flex;justify-content:space-between;align-items:center;padding:2rem;border-bottom:.1rem solid #ddd}.dialog-header h2{margin:0;font-size:2.4rem;color:var(--color-red--)}.dialog-header .dialog-close{background:none;border:none;font-size:3.2rem;cursor:pointer;color:#666;padding:0;width:3.2rem;height:3.2rem;display:flex;align-items:center;justify-content:center;border-radius:.4rem;transition:background-color .2s}.dialog-header .dialog-close:hover{background-color:#f0f0f0;color:#000}.dialog-content{padding:2rem}.dialog-content label{display:block;margin:1rem 0 .5rem;font-weight:700}.dialog-content input,.dialog-content select,.dialog-content textarea{width:100%;padding:.8rem;margin-bottom:1rem;border:.1rem solid #ccc;border-radius:.4rem;box-sizing:border-box}.dialog-content #options{display:flex;flex-direction:column;gap:1rem}.dialog-footer{display:flex;justify-content:flex-end;gap:1rem;padding:2rem;border-top:.1rem solid #ddd}.dialog-footer button{padding:1rem 2rem;border:none;border-radius:.4rem;cursor:pointer;font-size:1.6rem;transition:background-color .2s}.dialog-footer button:first-of-type{background-color:#4caf50;color:#fff}.dialog-footer button:first-of-type:hover{background-color:#45a049}.dialog-footer button:last-of-type{background-color:#801a08;color:#fff}.dialog-footer button:last-of-type:hover{background-color:#9a2525}.history-item{border:.1rem solid #ddd;padding:1rem;margin-bottom:1rem;border-radius:.4rem;background-color:#f9f9f9}.history-item button{padding:.5rem 1rem;margin:.5rem .5rem 0 0;border:none;border-radius:.4rem;cursor:pointer}.history-item button:first-of-type{background-color:#2196f3;color:#fff}.history-item button:first-of-type:hover{background-color:#1976d2}.history-item button:last-of-type{background-color:#4caf50;color:#fff}.history-item button:last-of-type:hover{background-color:#45a049}.print-history-btn{margin:1rem;padding:.8rem 1.6rem;background-color:#4caf50;color:#fff;border:none;border-radius:.4rem;cursor:pointer}.print-history-btn:hover{background-color:#45a049}#test-mode-selection .button-group{display:flex;justify-content:center;gap:2rem;margin:2rem 0;flex-direction:column}#test-mode-selection button{padding:4.5rem 7rem;font-size:3.8rem;font-weight:700;color:#fff;background-color:#a31d1d;border:none;border-radius:.5rem;box-shadow:0 .4rem 1.5rem rgba(74,79,83,.3);cursor:pointer;transition:all .3s ease}#test-mode-selection button:hover{background:linear-gradient(90deg,#155294,#0096cc);box-shadow:0 .6rem 2rem rgba(7,8,10,.5);transform:translateY(-.2rem)}#test-mode-selection button:active{transform:translateY(.1rem);box-shadow:0 .2rem 1rem rgba(0,123,255,.2)}#review-screen .question-block{margin-bottom:2rem}#review-screen .question{font-size:1.8rem;font-weight:700;margin-bottom:1rem}#review-screen .choices-container{margin-left:2rem}#review-screen .choice{font-size:1.6rem;margin-bottom:.8rem}#review-screen .choice.correct{color:#1e27a5;font-weight:700}#quiz-container{margin-bottom:2rem;margin-right:2rem}#question-nav{position:fixed;right:5rem;top:30rem;width:38rem;max-height:70vh;display:grid;grid-template-columns:repeat(5,5.5rem);grid-gap:.8rem;gap:.8rem;overflow-y:auto;z-index:100;padding:1rem;box-sizing:border-box}.nav-btn{width:5rem;height:5rem;min-width:5rem;min-height:5rem;background-color:#fff;border:.1rem solid #ccc;border-radius:.5rem;display:flex;flex-direction:column;align-items:center;justify-content:center;cursor:pointer;font-size:1.8rem;transition:background-color .3s;position:relative;box-sizing:border-box}.nav-btn.answered{background-color:green;color:#fff}.nav-btn.answered:hover{background-color:#006400}.nav-btn.correct{background-color:#4caf50;color:#fff}.nav-btn.correct:hover{background-color:#388e3c}.nav-btn.incorrect{background-color:red;color:#fff}.nav-btn.incorrect:hover{background-color:darkred}.nav-btn:hover{background-color:#e0e0e0}.nav-btn .status{font-size:1.2rem;margin-top:.5rem}.question-block{margin-bottom:2rem;padding:1rem;border:.1rem solid #ddd;border-radius:.4rem}.question-block .question{font-weight:700;margin-bottom:1rem}.question-block .choices-container{margin-left:2rem}.question-block .choices-container label{display:block}.question-block .choices-container .choice{margin:.5rem 0}.question-block .choices-container .choice input[type=radio]{margin-right:1rem;transform:scale(1.5);cursor:pointer}.question-block .choices-container .choice.correct,.question-block .choices-container .choice.incorrect{padding:.4rem .8rem;margin-left:-1.2rem;border-left:.4rem solid}.question-block .choices-container .choice.correct{background-color:#d4edda;border-color:#4caf50}.question-block .choices-container .choice.incorrect{background-color:#f8d7da;border-color:#dc3545}#result{font-size:1.875rem;font-weight:700;margin-top:1.25rem;color:green;text-align:center;position:relative;z-index:10}.button-group{text-align:center;margin-bottom:2rem}.button-group button{padding:1rem 2rem;margin:0 1rem;border:none;border-radius:.4rem;cursor:pointer}#submitBtn{background:linear-gradient(90deg,#2196f3,#42a5f5);color:#fff;cursor:pointer;font-size:2.4rem;padding:1.5rem 3rem;border:none;border-radius:.6rem;box-shadow:0 .4rem 1.5rem rgba(33,150,243,.3);text-transform:uppercase;letter-spacing:.1rem;transition:all .3s ease}#submitBtn:hover{background:linear-gradient(90deg,#1976d2,#2196f3);box-shadow:0 .6rem 2rem rgba(33,150,243,.5);transform:translateY(-.2rem)}#fixed-timer{position:fixed;right:6rem;bottom:6rem;transform:translateY(-50%);background:linear-gradient(135deg,#121111,#533423);color:#fff;padding:1.2rem 2.4rem;border-radius:.7rem;font-family:Arial,sans-serif;font-weight:700;font-size:2.24rem;z-index:1000;box-shadow:0 .4rem 1.5rem rgba(0,0,0,.1);display:flex;align-items:center;gap:1rem;transition:transform .3s ease,box-shadow .3s ease}#fixed-timer:hover{transform:translateY(-50%) scale(1.05);box-shadow:0 .6rem 2rem rgba(0,0,0,.4)}#fixed-time,#fixed-timer{font-size:1.6rem;letter-spacing:.2rem}#fixed-time{font-weight:700}@media screen and (max-width:96rem){#submitBtn{margin-bottom:3.2rem}#fixed-timer{position:-webkit-sticky;position:sticky;bottom:0;margin-top:3.2rem}}@media screen and (max-width:48rem){.header-container{flex-direction:column;padding:1rem}.header-container .logo{margin-right:0;margin-bottom:1rem}.header-container .main-title{flex-direction:column}.header-container .main-title .title-left,.header-container .main-title .title-right{font-size:1.8rem;text-align:center}.header-container .main-title .title-right{margin-top:.5rem;text-align:center}.header-container .subtitle{font-size:1.2rem;text-align:center}}@media screen and (max-width:37.5rem){body{padding:1rem}body:before{top:8rem;left:1rem;width:95%;height:80%;opacity:.1}#history-screen,#login-screen,#review-screen,#settings-screen,.container{padding:2rem;margin-top:5rem;border-radius:1rem}.tieu-de{padding:2rem}.dong-to{font-size:2.4rem;margin-left:1rem}.dong-nho{font-size:1.4rem;margin-left:1rem}.logo-tieu-de img.logo{height:6rem}.login-form label{width:100%;font-size:1.92rem}.login-form input,.login-form select{width:100%;padding:1.2rem;font-size:1.6rem}.login-form button{padding:1.2rem;font-size:1.92rem}#quiz-container{margin-right:0}#quiz-container,.question{font-size:1.8rem}.choice{font-size:1.6rem}.choice input[type=radio]{transform:scale(1.2)}#question-nav{position:fixed;top:auto;bottom:2rem;right:1rem;width:100%;max-width:30rem;height:auto;grid-template-columns:repeat(5,5rem);gap:.5rem;padding:.5rem;background:hsla(0,0%,100%,.9);border-radius:.8rem;z-index:1000}.nav-btn{width:5rem;height:5rem;min-width:5rem;min-height:5rem;font-size:1.6rem;border-radius:.4rem}.nav-btn .status{font-size:1rem}#fixed-time{font-size:1.92rem}#test-mode-selection .button-group{flex-direction:column;gap:1.5rem}#test-mode-selection button{padding:2rem 4rem;font-size:2.4rem}#test-mode-selection button:active{transform:translateY(.1rem);box-shadow:0 .2rem 1rem rgba(0,123,255,.2)}#review-screen button{padding:1.2rem 2.4rem;font-size:1.6rem;font-weight:700;color:#fff;background:linear-gradient(90deg,#0c3115,#087020);border:none;border-radius:.8rem;box-shadow:0 .4rem 1.5rem rgba(40,167,69,.3);cursor:pointer;transition:all .3s ease}#review-screen button:hover{background:linear-gradient(90deg,#1e7e34,#28a745);box-shadow:0 .6rem 2rem rgba(40,167,69,.5);transform:translateY(-.2rem)}#review-screen button:active{transform:translateY(.1rem);box-shadow:0 .2rem 1rem rgba(40,167,69,.2)}#review-screen .question-block{margin-bottom:2rem}#review-screen .question{font-weight:700;margin-bottom:1rem}#review-screen .choices-container{margin-left:2rem}#review-screen .choice{margin-bottom:.8rem}#review-screen .choice.correct{color:#1e27a5;font-weight:700}.nav-btn,button{touch-action:manipulation;-webkit-tap-highlight-color:rgba(0,0,0,0)}}.quiz-nav-buttons{text-align:right;margin-bottom:2rem}.back-btn{background-color:#6c757d;margin-right:.625rem}.back-btn,.logout-btn{color:#fff;border:none;padding:.5rem 1rem;border-radius:.25rem;cursor:pointer}.logout-btn{background-color:#dc3545}.edit-btn{background-color:#2196f3;color:#fff;border:none;padding:.5rem 1rem;border-radius:.4rem;cursor:pointer}.edit-btn:hover{background-color:#1976d2}.delete-btn{color:#fff;border:none;padding:.5rem 1rem;border-radius:.4rem;cursor:pointer}.delete-btn,.delete-btn:hover{background-color:#801a08}.admin-actions{display:flex;gap:.25rem;justify-content:center;flex-wrap:wrap}@media screen and (max-width:1800px){#question-nav{display:none}}dialog{margin:auto;position:relative;background:#fff;border-radius:.8rem;padding:0;max-width:60rem;width:90%;max-height:90vh;overflow-y:auto;box-shadow:0 .4rem 1.5rem rgba(0,0,0,.3);animation:slideIn .3s ease-out;border:none}dialog::-webkit-backdrop{background:transparent}dialog::backdrop{background:transparent}