:root{--font-family-base:-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", "Pretendard", "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;--duo-green:#58cc02;--duo-green-dark:#46a302;--duo-green-light:#89e219;--duo-green-bg:#e5f8d0;--duo-blue:#1cb0f6;--duo-blue-dark:#1899d6;--duo-blue-bg:#ddf4ff;--duo-orange:#ff9600;--duo-orange-dark:#e58400;--duo-yellow:#ffc800;--duo-yellow-dark:#e5b200;--duo-purple:#ce82ff;--duo-purple-dark:#b75dff;--duo-rose:#ff4b4b;--duo-rose-dark:#ea2b2b;--duo-card-bg:#fff;--duo-border:#e5e5e5;--duo-border-dark:#cecece;--duo-text-dark:#3c3c3c;--duo-text-muted:#777;--bg-gradient:#f7f7f7;--radius-large:24px;--radius-medium:16px;--radius-small:12px}*{box-sizing:border-box;font-family:var(--font-family-base);-webkit-tap-highlight-color:transparent;margin:0;padding:0}body{background-color:var(--bg-gradient);min-height:100vh;color:var(--duo-text-dark);justify-content:center;align-items:flex-start;padding:24px 16px;display:flex}.app-container{flex-direction:column;align-items:center;gap:20px;width:100%;max-width:1160px;margin:0 auto;display:flex}.main-tab-nav{border-radius:var(--radius-large);border:2px solid var(--duo-border);border-bottom:5px solid var(--duo-border-dark);scrollbar-width:none;background:#fff;gap:8px;width:100%;padding:8px;display:flex;overflow-x:auto;box-shadow:0 4px 12px #0000000a}.main-tab-nav::-webkit-scrollbar{display:none}.main-tab-btn{border-radius:var(--radius-medium);color:var(--duo-text-muted);cursor:pointer;white-space:nowrap;text-transform:uppercase;letter-spacing:.3px;background:0 0;border:2px solid #0000;border-bottom-width:4px;flex:1;padding:12px 18px;font-size:14px;font-weight:800;transition:all .15s}.main-tab-btn:hover{color:var(--duo-text-dark);background:#f1f1f1}.main-tab-btn.active{background:var(--duo-green);color:#fff;border-color:var(--duo-green-dark);border-bottom:4px solid var(--duo-green-dark);box-shadow:0 4px 0 var(--duo-green-dark)}.main-tab-btn.active:active{box-shadow:0 2px 0 var(--duo-green-dark);transform:translateY(2px)}.category-nav-wrapper{background:#fff;border:2px solid #e9ecef;border-bottom:5px solid #dee2e6;border-radius:24px;flex-direction:column;gap:12px;margin-bottom:24px;padding:16px 20px;display:flex;box-shadow:0 8px 24px #0000000d}.category-nav-group{flex-wrap:wrap;align-items:center;gap:8px;display:flex}.category-label{white-space:nowrap;letter-spacing:-.3px;border-radius:12px;padding:6px 12px;font-size:12px;font-weight:900}.nav-pill-btn{color:#4a5568;cursor:pointer;white-space:nowrap;background:#f8f9fa;border:2px solid #e9ecef;border-radius:14px;align-items:center;gap:6px;padding:9px 15px;font-size:14px;font-weight:800;transition:all .15s;display:inline-flex;box-shadow:0 3px #e2e8f0}.nav-pill-btn:hover{color:#2d3748;background:#edf2f7;transform:translateY(-1px)}.nav-pill-btn:active{transform:translateY(2px);box-shadow:0 1px #e2e8f0}.nav-pill-btn.active{color:#fff;background:#58cc02;border-color:#46a302;box-shadow:0 4px #46a302}.app-header{text-align:center;border-radius:var(--radius-large);border:2px solid var(--duo-border);border-bottom:5px solid var(--duo-border-dark);background:#fff;width:100%;padding:20px 24px}.app-title{color:var(--duo-green-dark);letter-spacing:-.5px;font-size:26px;font-weight:900}.user-manager-header-bar{border-radius:var(--radius-large);border:2px solid var(--duo-border);border-bottom:5px solid var(--duo-border-dark);background:#fff;justify-content:space-between;align-items:center;gap:12px;width:100%;margin-bottom:4px;padding:14px 20px;display:flex}.user-info-group{align-items:center;gap:10px;display:flex}.user-info-label{color:var(--duo-text-muted);font-size:14px;font-weight:800}.user-info-badge{color:var(--duo-blue-dark);background:var(--duo-blue-bg);border-radius:var(--radius-medium);border:2px solid var(--duo-blue);border-bottom:4px solid var(--duo-blue-dark);white-space:nowrap;padding:8px 18px;font-size:15px;font-weight:900}.user-actions-group{align-items:center;gap:10px;display:flex}.btn-user-edit{background:var(--duo-green);border:2px solid var(--duo-green-dark);border-bottom:4px solid var(--duo-green-dark);color:#fff;border-radius:var(--radius-medium);cursor:pointer;padding:9px 18px;font-size:13px;font-weight:900;transition:all .15s}.btn-user-edit:hover{background:var(--duo-green-light)}.btn-user-edit:active{border-bottom-width:2px;transform:translateY(2px)}.btn-user-logout{border:2px solid var(--duo-rose);border-bottom:4px solid var(--duo-rose-dark);color:var(--duo-rose);border-radius:var(--radius-medium);cursor:pointer;background:#fff;padding:9px 18px;font-size:13px;font-weight:900;transition:all .15s}.btn-user-logout:hover{background:var(--duo-rose);color:#fff}.btn-user-logout:active{border-bottom-width:2px;transform:translateY(2px)}.flashcard-wrapper{perspective:1200px;width:100%;max-width:820px;margin:4px auto}.flashcard{width:100%;min-height:360px;transform-style:preserve-3d;cursor:pointer;border-radius:28px;transition:transform .6s cubic-bezier(.34,1.56,.64,1);position:relative}.flashcard.flipped{transform:rotateY(180deg)}.card-face{backface-visibility:hidden;border:3px solid var(--duo-border);text-align:center;box-sizing:border-box;background:#fff;border-radius:28px;flex-direction:column;justify-content:center;align-items:center;width:100%;min-height:360px;padding:32px 24px;display:flex;box-shadow:0 10px #e5e5e5}.card-back{border-color:var(--duo-blue);box-shadow:0 10px 0 var(--duo-blue-dark);position:absolute;top:0;left:0;transform:rotateY(180deg)}.card-category-badge{background:var(--duo-green-bg);color:var(--duo-green-dark);border:2px solid var(--duo-green);border-radius:var(--radius-medium);padding:6px 16px;font-size:13px;font-weight:900;position:absolute;top:18px;left:20px}.word-en{color:var(--duo-text-dark);letter-spacing:-.5px;margin-top:10px;font-size:46px;font-weight:900}.word-phonics{color:var(--duo-blue-dark);margin-top:6px;font-size:20px;font-weight:800}.word-ko{color:var(--duo-rose-dark);margin-top:10px;font-size:46px;font-weight:900}.word-meaning-title{color:var(--duo-text-muted);font-size:15px;font-weight:800}.flip-hint{color:var(--duo-text-muted);font-size:13px;font-weight:800;position:absolute;bottom:16px}.audio-btn{background:var(--duo-blue);border:2px solid var(--duo-blue-dark);border-bottom:4px solid var(--duo-blue-dark);color:#fff;border-radius:var(--radius-medium);cursor:pointer;padding:12px 24px;font-size:15px;font-weight:900;transition:all .15s}.audio-btn:hover{background:#2cbdff}.audio-btn:active{border-bottom-width:2px;transform:translateY(2px)}.card-nav-buttons{border-radius:var(--radius-large);border:2px solid var(--duo-border);border-bottom:5px solid var(--duo-border-dark);background:#fff;justify-content:space-between;align-items:center;width:100%;margin-top:18px;padding:16px 22px;display:flex}.btn-nav{border:2px solid var(--duo-border);border-bottom:4px solid var(--duo-border-dark);border-radius:var(--radius-medium);color:var(--duo-text-dark);cursor:pointer;white-space:nowrap;background:#fff;padding:12px 22px;font-size:14px;font-weight:900;transition:all .15s}.btn-nav:hover{background:var(--duo-green);color:#fff;border-color:var(--duo-green-dark);border-bottom-color:var(--duo-green-dark)}.btn-nav:active{border-bottom-width:2px;transform:translateY(2px)}.card-counter{color:var(--duo-green-dark);margin:0 12px;font-size:20px;font-weight:900}.word-list-section{border-radius:var(--radius-large);border:2px solid var(--duo-border);border-bottom:5px solid var(--duo-border-dark);background:#fff;width:100%;padding:24px}.word-list-header{text-align:center;margin-bottom:20px}.word-list-subtitle{color:var(--duo-text-muted);margin-top:6px;font-size:14px;font-weight:700}.word-card-grid{flex-direction:column;gap:12px;display:flex}.word-list-item-card{border:2px solid var(--duo-border);border-bottom:4px solid var(--duo-border-dark);border-radius:var(--radius-medium);background:#fff;align-items:center;gap:16px;padding:16px 20px;transition:all .15s;display:flex}.word-list-item-card:hover{border-color:var(--duo-green);border-bottom-color:var(--duo-green-dark);transform:translateY(-2px)}.word-item-index{background:var(--duo-green);color:#fff;width:36px;height:36px;box-shadow:0 3px 0 var(--duo-green-dark);border-radius:50%;flex-shrink:0;justify-content:center;align-items:center;font-size:15px;font-weight:900;display:flex}.word-item-main{flex:1}.word-item-header{align-items:baseline;gap:10px;display:flex}.word-item-en{color:var(--duo-text-dark);font-size:22px;font-weight:900}.word-item-phonics{color:var(--duo-blue-dark);font-size:15px;font-weight:800}.word-item-meaning{color:var(--duo-rose-dark);margin-top:3px;font-size:17px;font-weight:900}.word-item-example{border-top:2px stroke var(--duo-border);margin-top:8px;padding-top:8px}.example-en-sm{color:var(--duo-text-dark);font-size:13px;font-weight:800}.example-ko-sm{color:var(--duo-text-muted);font-size:12px}.audio-btn-sm{border:2px solid var(--duo-blue);border-bottom:4px solid var(--duo-blue-dark);background:var(--duo-blue-bg);width:44px;height:44px;color:var(--duo-blue-dark);cursor:pointer;border-radius:50%;flex-shrink:0;justify-content:center;align-items:center;font-size:18px;transition:all .15s;display:flex}.audio-btn-sm:hover{background:var(--duo-blue);color:#fff}.audio-btn-sm:active{border-bottom-width:2px;transform:translateY(2px)}.quiz-container{width:100%}.quiz-tab-buttons{flex-wrap:wrap;gap:10px;margin-bottom:16px;display:flex}.tab-btn{border:2px solid var(--duo-border);border-bottom:4px solid var(--duo-border-dark);border-radius:var(--radius-medium);min-height:48px;color:var(--duo-text-muted);cursor:pointer;-webkit-user-select:none;user-select:none;background:#fff;flex:1;justify-content:center;align-items:center;gap:6px;padding:12px 18px;font-size:15px;font-weight:900;transition:all .15s;display:inline-flex}.tab-btn:hover{color:var(--duo-text-dark);background:#f8f9fa}.tab-btn:active{border-bottom-width:2px;transform:translateY(2px)}.tab-btn.active{background:var(--duo-purple);color:#fff;border-color:var(--duo-purple-dark);border-bottom-color:var(--duo-purple-dark);box-shadow:0 2px 0 var(--duo-purple-dark)}.quiz-card{border-radius:var(--radius-large);border:2px solid var(--duo-border);border-bottom:5px solid var(--duo-border-dark);background:#fff;padding:28px}.quiz-level-btn{border:2px solid var(--duo-border);border-bottom:4px solid var(--duo-border-dark);border-radius:var(--radius-small);min-height:44px;color:var(--duo-text-muted);cursor:pointer;-webkit-user-select:none;user-select:none;background:#fff;justify-content:center;align-items:center;gap:6px;padding:10px 16px;font-size:14px;font-weight:900;transition:all .15s;display:inline-flex}.quiz-level-btn:hover{color:var(--duo-text-dark);background:#f8f9fa}.quiz-level-btn:active{border-bottom-width:2px;transform:translateY(2px)}.quiz-level-btn.active{background:var(--duo-green);color:#fff;border-color:var(--duo-green-dark);border-bottom-color:var(--duo-green-dark);box-shadow:0 2px 0 var(--duo-green-dark)}.options-grid{grid-template-columns:1fr 1fr;gap:14px;display:grid}.option-btn{border:2px solid var(--duo-border);border-bottom:4px solid var(--duo-border-dark);border-radius:var(--radius-medium);min-height:64px;color:var(--duo-text-dark);cursor:pointer;text-align:center;-webkit-user-select:none;user-select:none;background:#fff;justify-content:center;align-items:center;padding:14px 20px;font-size:17px;font-weight:900;line-height:1.35;transition:all .15s;display:flex}.option-btn:hover{background:var(--duo-blue-bg);border-color:var(--duo-blue);border-bottom-color:var(--duo-blue-dark);color:var(--duo-blue-dark);transform:translateY(-2px)}.option-btn:active{border-bottom-width:2px;transform:translateY(2px)}.btn-unified-primary{background:var(--duo-green);border:2px solid var(--duo-green-dark);border-bottom:4px solid var(--duo-green-dark);color:#fff;cursor:pointer;-webkit-user-select:none;user-select:none;border-radius:14px;justify-content:center;align-items:center;gap:8px;min-height:48px;padding:12px 24px;font-size:15px;font-weight:900;transition:all .15s;display:inline-flex}.btn-unified-primary:hover{background:var(--duo-green-light)}.btn-unified-primary:active{border-bottom-width:2px;transform:translateY(2px)}.btn-unified-blue{background:var(--duo-blue);border:2px solid var(--duo-blue-dark);border-bottom:4px solid var(--duo-blue-dark);color:#fff;cursor:pointer;-webkit-user-select:none;user-select:none;border-radius:14px;justify-content:center;align-items:center;gap:8px;min-height:48px;padding:12px 24px;font-size:15px;font-weight:900;transition:all .15s;display:inline-flex}.btn-unified-blue:hover{background:#2cbdff}.btn-unified-blue:active{border-bottom-width:2px;transform:translateY(2px)}.btn-unified-secondary{border:2px solid var(--duo-border);border-bottom:4px solid var(--duo-border-dark);min-height:44px;color:var(--duo-text-dark);cursor:pointer;-webkit-user-select:none;user-select:none;background:#fff;border-radius:12px;justify-content:center;align-items:center;gap:6px;padding:10px 20px;font-size:14px;font-weight:800;transition:all .15s;display:inline-flex}.btn-unified-secondary:hover{background:#f8f9fa;border-color:#cbd5e1}.btn-unified-secondary:active{border-bottom-width:2px;transform:translateY(2px)}.btn-speed-item{cursor:pointer;color:#475569;-webkit-user-select:none;user-select:none;background:#f8fafc;border:2px solid #cbd5e1;border-bottom:3px solid #94a3b8;border-radius:10px;justify-content:center;align-items:center;min-width:64px;height:38px;padding:6px 12px;font-size:13px;font-weight:900;transition:all .15s;display:inline-flex}.btn-speed-item:hover{background:#e2e8f0}.btn-speed-item.active{color:#fff;background:#58cc02;border-color:#46a302 #46a302 #388e00;box-shadow:0 2px #388e00}.spelling-input{border:3px solid var(--duo-blue);border-bottom:5px solid var(--duo-blue-dark);border-radius:var(--radius-medium);text-align:center;width:100%;color:var(--duo-text-dark);background:#fff;padding:18px;font-size:22px;font-weight:900}@media (max-width:768px){body{-webkit-text-size-adjust:100%;padding:12px 8px}.app-container{padding:0 4px}.user-manager-header-bar{flex-direction:column;align-items:stretch;gap:10px;padding:12px 14px}.word-en{font-size:34px!important}.word-ko{font-size:20px!important;line-height:1.35!important}.flashcard,.card-face{min-height:320px;padding:24px 16px}.options-grid{grid-template-columns:1fr;gap:10px}.category-nav-group{flex-wrap:wrap;justify-content:center}}