@import "https://fonts.googleapis.com/css2?family=Crimson+Pro:wght@300;400;600&family=DM+Mono:wght@300;400;500&family=Libre+Baskerville:wght@400;700&display=swap";:root{--color-paper:#fdfbf7;--color-ink:#1a1412;--color-charcoal:#3e3836;--color-accent:#c17e5d;--color-accent-dark:#8b5a40;--color-muted:#e8e4df;--color-border:#d4cec5;--color-success:#2d5f3f;--color-success-bg:#ebf4ef;--color-error:#a85e3a;--color-error-bg:#fdf0eb;--font-display:"Libre Baskerville", serif;--font-body:"Crimson Pro", serif;--font-mono:"DM Mono", monospace;--shadow-soft:0 2px 24px #1a14120a;--shadow-medium:0 8px 40px #1a141214;--shadow-strong:0 16px 64px #1a14121f}*{box-sizing:border-box;margin:0;padding:0}body{font-family:var(--font-body);background:var(--color-paper);color:var(--color-ink);min-height:100vh;line-height:1.6;overflow-x:hidden}body:before{content:"";pointer-events:none;z-index:0;background-image:repeating-linear-gradient(0deg,#0000,#0000 2px,#1a141202 2px 4px);width:100%;height:100%;position:fixed;top:0;left:0}#root{z-index:1;min-height:100vh;position:relative}nav{-webkit-backdrop-filter:blur(20px);backdrop-filter:blur(20px);border-bottom:1px solid var(--color-border);z-index:100;background:#fdfbf7eb;position:fixed;top:0;left:0;right:0}.nav-container{justify-content:space-between;align-items:center;max-width:1100px;height:68px;margin:0 auto;padding:0 40px;display:flex}.logo{font-family:var(--font-display);letter-spacing:-.02em;color:var(--color-ink);align-items:center;gap:10px;font-size:20px;font-weight:700;text-decoration:none;display:flex}.logo img{object-fit:contain;width:30px;height:30px}.nav-right{align-items:center;gap:16px;display:flex}.lang-switcher{background:var(--color-muted);border-radius:6px;gap:3px;padding:3px;display:flex}.lang-btn{font-family:var(--font-mono);letter-spacing:.05em;color:var(--color-charcoal);cursor:pointer;text-transform:uppercase;background:0 0;border:none;border-radius:4px;padding:5px 10px;font-size:11px;transition:all .2s}.lang-btn.active{color:var(--color-ink);box-shadow:var(--shadow-soft);background:#fff}.lang-btn:hover:not(.active){color:var(--color-ink)}.nav-user{color:var(--color-charcoal);font-size:15px}.btn-logout{font-family:var(--font-body);color:var(--color-charcoal);border:1px solid var(--color-border);cursor:pointer;background:0 0;border-radius:6px;padding:7px 14px;font-size:14px;transition:all .2s}.btn-logout:hover{border-color:var(--color-accent);color:var(--color-accent)}.page-wrapper{min-height:100vh;padding-top:68px}.auth-page{justify-content:center;align-items:center;min-height:100vh;padding:100px 24px 60px;display:flex}.auth-card{border:1px solid var(--color-border);box-shadow:var(--shadow-strong);background:#fff;border-radius:16px;width:100%;max-width:440px;overflow:hidden}.auth-header{background:linear-gradient(135deg, var(--color-ink) 0%, var(--color-charcoal) 100%);padding:36px 40px}.auth-header-label{font-family:var(--font-mono);letter-spacing:.15em;text-transform:uppercase;color:var(--color-accent);margin-bottom:10px;font-size:10px}.auth-header h1{font-family:var(--font-display);color:#fff;margin-bottom:6px;font-size:26px;font-weight:700}.auth-header p{color:#fff9;font-size:15px}.auth-body{padding:36px 40px}.form-group{margin-bottom:18px}.form-group label{font-family:var(--font-mono);letter-spacing:.1em;text-transform:uppercase;color:var(--color-charcoal);margin-bottom:7px;font-size:10px;display:block}.form-group input,.form-group select{border:2px solid var(--color-border);width:100%;font-family:var(--font-body);color:var(--color-ink);background:var(--color-paper);appearance:none;border-radius:8px;padding:12px 15px;font-size:17px;transition:all .2s}.form-group input:focus,.form-group select:focus{border-color:var(--color-accent);outline:none;box-shadow:0 0 0 4px #c17e5d1a}.form-group select{cursor:pointer;background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%233E3836' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");background-position:right 14px center;background-repeat:no-repeat;padding-right:40px}.form-row{grid-template-columns:1fr 1fr;gap:14px;display:grid}.password-wrap{position:relative}.password-wrap input{border:2px solid var(--color-border);width:100%;font-family:var(--font-body);color:var(--color-ink);background:var(--color-paper);appearance:none;border-radius:8px;padding:12px 44px 12px 15px;font-size:17px;transition:all .2s}.password-wrap input:focus{border-color:var(--color-accent);outline:none;box-shadow:0 0 0 4px #c17e5d1a}.password-toggle{cursor:pointer;color:var(--color-charcoal);opacity:.5;background:0 0;border:none;border-radius:4px;justify-content:center;align-items:center;padding:4px;transition:opacity .2s;display:flex;position:absolute;top:50%;right:13px;transform:translateY(-50%)}.password-toggle:hover{opacity:1;color:var(--color-accent)}.btn-primary{background:var(--color-accent);color:#fff;width:100%;font-family:var(--font-body);cursor:pointer;border:none;border-radius:8px;margin-top:6px;padding:14px 24px;font-size:17px;font-weight:600;transition:all .2s}.btn-primary:hover:not(:disabled){background:var(--color-accent-dark);box-shadow:var(--shadow-medium);transform:translateY(-1px)}.btn-primary:disabled{opacity:.65;cursor:not-allowed}.auth-switch{text-align:center;color:var(--color-charcoal);margin-top:18px;font-size:15px}.auth-switch button{color:var(--color-accent);cursor:pointer;font-family:var(--font-body);text-underline-offset:3px;background:0 0;border:none;margin-left:4px;font-size:15px;font-weight:600;text-decoration:underline}.auth-switch button:hover{color:var(--color-accent-dark)}.error-msg{background:var(--color-error-bg);color:var(--color-error);border:1px solid #a85e3a4d;border-radius:8px;margin-bottom:18px;padding:12px 16px;font-size:15px}.dashboard-page{max-width:960px;margin:0 auto;padding:50px 40px}.dashboard-hero{border-bottom:1px solid var(--color-border);grid-template-columns:1fr auto;align-items:start;gap:40px;margin-bottom:48px;padding-bottom:40px;display:grid}.greeting-label{font-family:var(--font-mono);letter-spacing:.15em;text-transform:uppercase;color:var(--color-accent);margin-bottom:10px;font-size:11px}.greeting-name{font-family:var(--font-display);letter-spacing:-.02em;color:var(--color-ink);margin-bottom:10px;font-size:46px;font-weight:700;line-height:1.1}.greeting-class{color:var(--color-charcoal);font-size:19px;font-weight:300}.btn-start{background:var(--color-accent);color:#fff;font-family:var(--font-display);cursor:pointer;white-space:nowrap;box-shadow:var(--shadow-soft);border:none;border-radius:10px;padding:18px 36px;font-size:17px;font-weight:700;transition:all .3s}.btn-start:hover:not(:disabled){background:var(--color-accent-dark);box-shadow:var(--shadow-medium);transform:translateY(-2px)}.btn-start:disabled{opacity:.65;cursor:not-allowed}.stats-grid{grid-template-columns:repeat(3,1fr);gap:20px;margin-bottom:40px;display:grid}.stat-card{border:1px solid var(--color-border);background:#fff;border-radius:12px;padding:26px;transition:all .3s}.stat-card:hover{border-color:var(--color-accent);box-shadow:var(--shadow-soft)}.stat-number{font-family:var(--font-display);color:var(--color-accent);letter-spacing:-.02em;margin-bottom:6px;font-size:38px;font-weight:700}.stat-label{font-family:var(--font-mono);letter-spacing:.1em;text-transform:uppercase;color:var(--color-charcoal);font-size:10px}.attempts-section{border:1px solid var(--color-border);background:#fff;border-radius:12px;overflow:hidden}.attempts-header{border-bottom:1px solid var(--color-border);background:linear-gradient(135deg, var(--color-ink) 0%, var(--color-charcoal) 100%);padding:22px 28px}.attempts-header h3{font-family:var(--font-display);color:#fff;font-size:17px;font-weight:700}.attempt-item{border-bottom:1px solid var(--color-border)}.attempt-item:last-child{border-bottom:none}.attempt-item--open{background:var(--color-paper)}.attempt-row{cursor:pointer;text-align:left;background:0 0;border:none;justify-content:space-between;align-items:center;gap:16px;width:100%;padding:13px 24px;transition:background .18s;display:flex}.attempt-row:hover{background:#c17e5d0a}.attempt-item--open .attempt-row{background:#c17e5d0f}.attempt-row-left{align-items:center;gap:10px;min-width:0;display:flex}.attempt-chevron{color:var(--color-charcoal);opacity:.5;flex-shrink:0;transition:transform .25s cubic-bezier(.16,1,.3,1),opacity .2s}.attempt-chevron--open{opacity:1;color:var(--color-accent);transform:rotate(180deg)}.attempt-date{font-family:var(--font-mono);color:var(--color-charcoal);white-space:nowrap;font-size:12px}.attempt-row-badges{flex-shrink:0;align-items:center;gap:6px;display:flex}.attempt-detail{max-height:0;transition:max-height .35s cubic-bezier(.16,1,.3,1);overflow:hidden}.attempt-detail-inner{padding:0 24px 20px 46px}.attempt-detail-loading{color:var(--color-charcoal);align-items:center;gap:10px;padding:8px 0;font-size:14px;display:flex}.attempt-detail-muted{color:var(--color-charcoal);opacity:.6;font-size:15px}.attempt-detail-grid{flex-direction:column;gap:16px;display:flex}.attempt-detail-label{font-family:var(--font-mono);letter-spacing:.1em;text-transform:uppercase;color:var(--color-charcoal);opacity:.7;margin-bottom:6px;font-size:10px}.attempt-detail-task{font-family:var(--font-body);color:var(--color-ink);font-size:16px;line-height:1.65}.attempt-answers-row{flex-wrap:wrap;gap:12px;display:flex}.attempt-answer-box{border:1px solid var(--color-border);background:#fff;border-radius:8px;flex:1;min-width:90px;padding:12px 16px}.attempt-answer-val{font-family:var(--font-mono);font-size:20px;font-weight:500}.val-correct{color:var(--color-success)}.val-wrong{color:var(--color-error)}.val-neutral{color:var(--color-ink)}.attempt-detail-section{flex-direction:column;display:flex}.attempt-detail-explanation{font-family:var(--font-body);color:var(--color-charcoal);white-space:pre-line;border:1px solid var(--color-border);border-left:3px solid var(--color-accent);background:#fff;border-radius:8px;padding:14px 16px;font-size:15px;line-height:1.75}.badge{font-family:var(--font-mono);letter-spacing:.05em;border-radius:20px;padding:3px 9px;font-size:10px}.badge-success{background:var(--color-success-bg);color:var(--color-success)}.badge-error{background:var(--color-error-bg);color:var(--color-error)}.badge-pending{background:var(--color-muted);color:var(--color-charcoal)}.task-page{flex-direction:column;max-width:1200px;height:calc(100vh - 68px);margin:0 auto;padding:36px 40px;display:flex;overflow:hidden}.task-nav{flex-shrink:0;align-items:center;gap:14px;margin-bottom:20px;display:flex}.task-layout{flex:1;grid-template-columns:1fr;gap:24px;min-height:0;display:grid}.task-layout--split{grid-template-columns:1fr 1fr}.task-right-panel{flex-direction:column;gap:16px;min-height:0;display:flex}.task-right-panel .explanation-card{flex-direction:column;flex:1;min-height:0;margin-bottom:0;display:flex;overflow:hidden}.task-right-panel .explanation-body{scrollbar-width:thin;scrollbar-color:var(--color-border) transparent;flex:1;overflow-y:auto}.task-right-panel .vote-card{flex-shrink:0;margin-bottom:0}.task-right-panel .btn-next{flex-shrink:0}.back-btn{border:1px solid var(--color-border);font-family:var(--font-body);color:var(--color-charcoal);cursor:pointer;background:0 0;border-radius:8px;align-items:center;gap:6px;padding:8px 14px;font-size:15px;transition:all .2s;display:flex}.back-btn:hover{border-color:var(--color-accent);color:var(--color-accent)}.task-card{border:1px solid var(--color-border);box-shadow:var(--shadow-strong);background:#fff;border-radius:16px;flex-direction:column;min-height:0;margin-bottom:0;display:flex;overflow:hidden}.task-layout .task-card{height:100%}.task-card .task-body{scrollbar-width:thin;scrollbar-color:var(--color-border) transparent;flex:1;overflow-y:auto}.task-card-header{background:linear-gradient(135deg, var(--color-ink) 0%, var(--color-charcoal) 100%);padding:26px 34px}.task-card-label{font-family:var(--font-mono);letter-spacing:.15em;text-transform:uppercase;color:var(--color-accent);margin-bottom:7px;font-size:10px}.task-card-header h2{font-family:var(--font-display);color:#fff;font-size:19px;font-weight:700}.task-body{padding:34px}.task-description{color:var(--color-ink);margin-bottom:30px;font-size:20px;line-height:1.75}.answer-label{font-family:var(--font-mono);letter-spacing:.1em;text-transform:uppercase;color:var(--color-charcoal);margin-bottom:9px;font-size:10px;display:block}.answer-input{border:2px solid var(--color-border);width:100%;font-family:var(--font-body);color:var(--color-ink);background:var(--color-paper);-moz-appearance:textfield;border-radius:8px;padding:14px 18px;font-size:22px;transition:all .2s}.answer-input::-webkit-inner-spin-button{-webkit-appearance:none;margin:0}.answer-input::-webkit-outer-spin-button{-webkit-appearance:none;margin:0}.answer-input:focus{border-color:var(--color-accent);outline:none;box-shadow:0 0 0 4px #c17e5d1a}.answer-input:disabled{opacity:.7;cursor:not-allowed}.result-card{border:1px solid;border-radius:10px;margin-bottom:20px;padding:22px}.result-correct{background:var(--color-success-bg);border-color:#2d5f3f4d}.result-wrong{background:var(--color-error-bg);border-color:#a85e3a4d}.result-heading{font-family:var(--font-display);margin-bottom:14px;font-size:19px;font-weight:700}.result-correct .result-heading{color:var(--color-success)}.result-wrong .result-heading{color:var(--color-error)}.result-row{border-bottom:1px solid #0000000f;justify-content:space-between;align-items:center;padding:8px 0;font-size:17px;display:flex}.result-row:last-child{border-bottom:none}.result-row-label{color:var(--color-charcoal)}.result-row-value{font-family:var(--font-mono);color:var(--color-ink);font-size:18px;font-weight:500}.explanation-card{border:1px solid var(--color-border);background:linear-gradient(135deg,#f8f6f2 0%,#fdfbf7 100%);border-radius:12px;margin-bottom:20px;overflow:hidden}.explanation-header{border-bottom:1px solid var(--color-border);align-items:center;gap:12px;padding:18px 26px;display:flex}.explanation-icon{background:linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-dark) 100%);color:#fff;border-radius:8px;flex-shrink:0;justify-content:center;align-items:center;width:34px;height:34px;font-size:15px;font-weight:700;display:flex}.explanation-title{font-family:var(--font-display);color:var(--color-ink);font-size:17px;font-weight:700}.explanation-body{padding:22px 26px}.explanation-loading{color:var(--color-charcoal);align-items:center;gap:12px;font-size:16px;display:flex}.spinner{border:2px solid var(--color-border);border-top-color:var(--color-accent);border-radius:50%;flex-shrink:0;width:20px;height:20px;animation:.8s linear infinite spin}@keyframes spin{to{transform:rotate(360deg)}}.explanation-text{color:var(--color-charcoal);white-space:pre-line;font-size:17px;line-height:1.85}.model-answer-row{border-top:1px solid var(--color-border);color:var(--color-charcoal);align-items:center;gap:10px;margin-top:16px;padding-top:16px;font-size:15px;display:flex}.model-answer-val{font-family:var(--font-mono);color:var(--color-ink);font-size:16px;font-weight:500}.model-correct-badge{font-family:var(--font-mono);letter-spacing:.05em;border-radius:12px;padding:3px 8px;font-size:10px}.vote-card{border:1px solid var(--color-border);text-align:center;background:#fff;border-radius:12px;margin-bottom:20px;padding:26px}.vote-question{font-family:var(--font-display);color:var(--color-ink);margin-bottom:18px;font-size:17px}.vote-buttons{justify-content:center;gap:14px;display:flex}.vote-btn{border:2px solid var(--color-border);font-family:var(--font-body);cursor:pointer;color:var(--color-charcoal);background:#fff;border-radius:10px;align-items:center;gap:9px;padding:13px 28px;font-size:16px;font-weight:600;transition:all .25s;display:flex}.vote-btn:hover{border-color:var(--color-accent);color:var(--color-accent);transform:translateY(-2px)}.vote-btn.selected-like{background:var(--color-success-bg);border-color:var(--color-success);color:var(--color-success)}.vote-btn.selected-dislike{background:var(--color-error-bg);border-color:var(--color-error);color:var(--color-error)}.vote-btn:disabled{cursor:not-allowed;opacity:.85;transform:none}.vote-icon{width:22px;height:22px}.btn-next{background:var(--color-ink);color:#fff;width:100%;font-family:var(--font-display);cursor:pointer;border:none;border-radius:10px;justify-content:center;align-items:center;gap:10px;padding:17px 32px;font-size:17px;font-weight:700;transition:all .3s;display:flex}.btn-next:hover{background:var(--color-charcoal);box-shadow:var(--shadow-medium);transform:translateY(-2px)}.no-tasks{text-align:center;padding:60px 40px}.no-tasks-emoji{margin-bottom:20px;font-size:64px}.no-tasks h2{font-family:var(--font-display);color:var(--color-ink);margin-bottom:12px;font-size:30px}.no-tasks p{color:var(--color-charcoal);font-size:18px}.calc-toggle-btn{border:1px solid var(--color-border);font-family:var(--font-body);color:var(--color-charcoal);cursor:pointer;background:0 0;border-radius:8px;justify-content:center;align-items:center;gap:7px;width:100%;margin-top:14px;padding:8px 14px;font-size:15px;transition:all .2s;display:flex}.calc-toggle-btn:hover{border-color:var(--color-accent);color:var(--color-accent)}.calc-toggle-btn.active{border-color:var(--color-accent);color:var(--color-accent);background:#c17e5d0f}.calc-toggle-icon{font-size:16px}.calc-card{border:1px solid var(--color-border);box-shadow:var(--shadow-medium);background:#fff;border-radius:14px;flex-direction:column;display:flex;overflow:hidden}.calc-header{border-bottom:1px solid var(--color-border);background:linear-gradient(135deg, var(--color-ink) 0%, var(--color-charcoal) 100%);justify-content:space-between;align-items:center;padding:14px 18px;display:flex}.calc-title{font-family:var(--font-mono);letter-spacing:.12em;text-transform:uppercase;color:#ffffffb3;font-size:11px}.calc-use-btn{font-family:var(--font-mono);letter-spacing:.06em;background:var(--color-accent);color:#fff;cursor:pointer;text-transform:uppercase;border:none;border-radius:5px;padding:5px 12px;font-size:11px;transition:background .2s}.calc-use-btn:hover{background:var(--color-accent-dark)}.calc-display{background:var(--color-paper);border-bottom:1px solid var(--color-border);text-align:right;padding:16px 20px 12px}.calc-expr{font-family:var(--font-mono);color:var(--color-charcoal);opacity:.7;text-overflow:ellipsis;white-space:nowrap;min-height:18px;margin-bottom:4px;font-size:12px;overflow:hidden}.calc-num{font-family:var(--font-mono);color:var(--color-ink);letter-spacing:-.02em;text-overflow:ellipsis;white-space:nowrap;font-size:32px;font-weight:400;overflow:hidden}.calc-grid{background:var(--color-border);grid-template-columns:repeat(4,1fr);gap:1px;padding:0;display:grid}.calc-btn{height:54px;font-family:var(--font-mono);color:var(--color-ink);cursor:pointer;background:#fff;border:none;justify-content:center;align-items:center;padding:0;font-size:16px;font-weight:400;transition:background .15s;display:flex}.calc-btn:hover{background:var(--color-paper)}.calc-btn:active{background:var(--color-muted)}.calc-btn--zero{grid-column:span 2}.calc-btn--op{color:var(--color-accent);background:#faf6f2;font-size:18px}.calc-btn--op:hover{background:#f5ede5}.calc-btn--action{background:var(--color-muted);color:var(--color-charcoal);font-size:14px}.calc-btn--action:hover{background:#ddd8d2}.calc-btn--eq{background:var(--color-accent);color:#fff;font-size:18px}.calc-btn--eq:hover,.calc-btn--eq:active{background:var(--color-accent-dark)}.task-right-panel--answering{flex-direction:column;justify-content:flex-end;gap:0;min-height:0;display:flex}@keyframes fadeInUp{0%{opacity:0;transform:translateY(18px)}to{opacity:1;transform:translateY(0)}}.fade-in{animation:.4s cubic-bezier(.16,1,.3,1) both fadeInUp}@media (width<=768px){.nav-container{padding:0 20px}.dashboard-page,.task-page{padding:28px 18px}.dashboard-hero{grid-template-columns:1fr;gap:20px}.greeting-name{font-size:34px}.stats-grid{grid-template-columns:1fr}.task-body{padding:22px}.task-page{height:auto;overflow:visible}.task-layout--split{grid-template-columns:1fr}.task-right-panel .explanation-body{max-height:300px}.auth-header,.auth-body{padding:26px 24px}.form-row{grid-template-columns:1fr}.vote-buttons{flex-direction:column}.attempt-detail-inner{padding:0 16px 16px 36px}.attempt-answers-row{gap:8px}}