:root{--bg-color:#f7f8fa;--card-bg:#fff;--text-color:#191f28;--gray-text:#8b95a1;--border-color:#e5e8eb;--topbar-bg:#f7f8fad9;--nav-bg:#fffffff5;--primary-color:#3182f6;--primary-light:#edf5ff;--hover-bg:#f9fafb;--active-bg:#f2f4f6;--shadow-sm:0 2px 10px #00000008;--shadow-md:0 6px 16px #0000000f}body.dark-mode{--bg-color:#121212;--card-bg:#1e1e1e;--text-color:#f3f4f6;--gray-text:#9ca3af;--border-color:#2c2c2c;--topbar-bg:#121212d9;--nav-bg:#1e1e1ef5;--primary-light:#1e293b;--hover-bg:#282828;--active-bg:#333;--shadow-sm:0 2px 10px #0003;--shadow-md:0 6px 16px #0000004d}*{box-sizing:border-box}body{background-color:var(--bg-color);color:var(--text-color);margin:0;font-family:Inter,Pretendard,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;transition:background-color .2s,color .2s}button{-webkit-tap-highlight-color:transparent;font-family:inherit}.gray-text{margin:0;color:var(--gray-text)!important}@keyframes fadeInUp{0%{opacity:0;transform:translateY(16px)}to{opacity:1;transform:translateY(0)}}@keyframes xpFill{0%{width:0%}to{width:35%}}.fade-in{animation:.35s ease-out forwards fadeInUp}.app{min-height:100vh;padding-bottom:90px}.container{width:min(720px,100% - 40px);margin:auto;animation:.4s ease-out forwards fadeInUp}.topbar{background-color:#0000;justify-content:space-between;align-items:center;width:min(720px,100% - 40px);height:72px;margin:auto;display:flex}.topbar .logo{letter-spacing:-1.5px;font-size:22px;font-weight:800}.logout-button{color:var(--gray-text);cursor:pointer;background:0 0;border:1px solid #0000;border-radius:8px;padding:8px 12px;transition:color .15s,background-color .15s,transform .1s}.logout-button:hover{color:var(--text-color);background-color:var(--hover-bg)}.logout-button:active{transform:scale(.94)}body.dark-mode .topbar .logout-button{background-color:var(--card-bg);border-color:var(--border-color)}.bottom-nav{border-top:1px solid var(--border-color);background:var(--nav-bg);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);justify-content:center;height:74px;display:flex;position:fixed;bottom:0;left:0;right:0}.bottom-nav button{width:90px;color:var(--gray-text);cursor:pointer;background:0 0;border:0;transition:color .15s,transform .1s}.bottom-nav button span{margin-bottom:4px;font-size:20px;transition:transform .2s cubic-bezier(.34,1.56,.64,1);display:block}.bottom-nav button:hover span{transform:translateY(-2px)}.bottom-nav button:active{transform:scale(.92)}.bottom-nav button.active{color:var(--primary-color)}.bottom-nav button.active span{transform:scale(1.1)}.login-page{background:radial-gradient(ellipse at 50% 0%, #3182f617, transparent 58%), var(--bg-color);justify-content:center;align-items:center;min-height:100svh;padding:32px 16px;display:flex}.login-content{border:1px solid var(--border-color);background:var(--card-bg);border-radius:24px;width:min(390px,100%);padding:38px 30px 30px;animation:.4s ease-out forwards fadeInUp;box-shadow:0 18px 60px #191f2814}body.dark-mode .login-content{box-shadow:0 18px 60px #0000003d}.login-brand{text-align:center;flex-direction:column;align-items:center;margin-bottom:30px;display:flex}.login-brand-mark{background:var(--primary-light);width:58px;height:58px;color:var(--primary-color);border-radius:18px;place-items:center;margin-bottom:17px;display:grid}.login-brand-mark svg{width:31px;height:31px}.login-brand-name{color:var(--text-color);letter-spacing:-1.3px;margin:0;font-size:27px;font-weight:800}.login-description{color:var(--gray-text);margin:9px 0 0;font-size:14px;line-height:1.5}.google-button{border:1px solid var(--border-color);background:var(--card-bg);width:100%;min-height:54px;color:var(--text-color);cursor:pointer;border-radius:13px;justify-content:center;align-items:center;gap:12px;padding:0 18px;font-size:15px;font-weight:650;transition:border-color .15s,background-color .15s,box-shadow .15s,transform .15s;display:flex;position:relative}.google-button:hover{background:var(--hover-bg);box-shadow:var(--shadow-sm);border-color:#c6cbd1}.google-button:active{transform:scale(.985)}.google-button:focus-visible,.guest-button:focus-visible,.guest-nickname-input:focus-visible{outline-offset:3px;outline:3px solid #3182f647}.google-icon{flex:0 0 20px;width:20px;height:20px}.login-divider{color:var(--gray-text);align-items:center;gap:12px;margin:23px 0;font-size:12px;display:flex}.login-divider:before,.login-divider:after{content:"";background:var(--border-color);flex:1;height:1px}.guest-login-panel{flex-direction:column;gap:10px;display:flex}.guest-label{color:var(--text-color);font-size:13px;font-weight:650}.guest-nickname-input{border:1px solid var(--border-color);background:var(--bg-color);width:100%;min-height:48px;color:var(--text-color);font:inherit;border-radius:12px;outline:none;padding:0 14px;font-size:14px;transition:border-color .15s,box-shadow .15s}.guest-nickname-input::placeholder{color:var(--gray-text)}.guest-nickname-input:focus{border-color:var(--primary-color);box-shadow:0 0 0 3px #3182f61a}.guest-button{border:1px solid var(--border-color);background:var(--hover-bg);width:100%;min-height:48px;color:var(--text-color);cursor:pointer;border-radius:12px;padding:0 16px;font-size:14px;font-weight:650;transition:background-color .15s,transform .15s}.guest-button:hover{background:var(--active-bg)}.guest-button:active{transform:scale(.985)}@media (width<=420px){.login-content{border-radius:20px;padding:32px 22px 24px}}.page-header,.welcome{padding:30px 0 20px}.welcome h1,.page-header h1{letter-spacing:-1px;margin:0 0 8px;font-size:30px}.small-text{color:var(--gray-text);margin:0 0 8px;font-size:14px}.level-card{background:var(--card-bg);box-shadow:var(--shadow-sm);border-radius:20px;padding:26px;transition:transform .2s,box-shadow 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span:hover{color:var(--primary-color)}.study-card{border:1px solid var(--border-color);background:var(--card-bg);text-align:left;cursor:pointer;width:100%;box-shadow:var(--shadow-sm);border-radius:18px;align-items:center;gap:16px;padding:20px;transition:transform .15s cubic-bezier(.2,0,0,1),box-shadow .15s,background-color .15s;display:flex}.study-card:hover{box-shadow:var(--shadow-md);transform:translateY(-2px)}.study-card:active{transform:scale(.97)translateY(0)}.study-icon{background:var(--primary-light);width:48px;height:48px;color:var(--primary-color);border-radius:14px;justify-content:center;align-items:center;font-size:22px;transition:transform .2s cubic-bezier(.34,1.56,.64,1);display:flex}.study-card:hover .study-icon{transform:scale(1.08)rotate(-4deg)}.study-info{flex:1}.study-info h3{margin:0 0 5px;font-size:16px}.study-info p{color:var(--gray-text);margin:0;font-size:13px}.arrow{color:var(--gray-text);font-size:28px;transition:transform .15s,color .15s}.study-card:hover 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20px;font-size:14px;line-height:1.5}.course-footer{justify-content:space-between;align-items:center;display:flex}.course-footer span{color:var(--gray-text);font-size:12px;font-weight:600}.start-btn{background:var(--primary-color);color:#fff;cursor:pointer;border:0;border-radius:10px;padding:8px 16px;font-weight:600;transition:transform .1s,background-color .15s}.start-btn:active{transform:scale(.95)}.start-btn.secondary{background:var(--border-color);color:var(--text-color)}.start-btn.secondary:hover{background:var(--hover-bg)}.ranking-podium{justify-content:center;align-items:flex-end;gap:16px;margin:20px 0 30px;display:flex}.podium-item{background:var(--card-bg);border:1px solid var(--border-color);text-align:center;width:100px;box-shadow:var(--shadow-sm);border-radius:16px;flex-direction:column;align-items:center;padding:16px;display:flex}.podium-item.rank-1{border:2px solid gold;justify-content:center;height:140px}.podium-item.rank-2{justify-content:center;height:120px}.podium-item.rank-3{justify-content:center;height:110px}.podium-badge{margin-bottom:6px;font-size:24px}.podium-name{margin-bottom:4px;font-size:14px}.podium-xp{color:var(--gray-text);font-size:11px}.ranking-list{background:var(--card-bg);box-shadow:var(--shadow-sm);border:1px solid var(--border-color);border-radius:18px;overflow:hidden}.ranking-item{align-items:center;gap:16px;padding:16px 20px;display:flex}.ranking-item+.ranking-item{border-top:1px solid var(--border-color)}.ranking-item.my-rank{background:var(--primary-light)}.rank-num{width:24px;color:var(--text-color);font-size:16px;font-weight:700}.rank-user{flex:1}.rank-user strong{font-size:15px}.rank-user p{color:var(--gray-text);margin:2px 0 0;font-size:12px}.rank-xp{color:var(--primary-color);font-size:14px;font-weight:700}.profile-header{text-align:center;padding:30px 0 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var(--border-color);box-shadow:var(--shadow-sm);border-radius:18px;flex-direction:column;gap:6px;margin:30px 0 40px;padding:24px;display:flex}.result-xp-card .label{color:var(--gray-text);font-size:14px}.result-xp-card .value{color:var(--primary-color);font-size:28px}.empty-state{text-align:center;padding:28px 20px}.empty-state p{margin:0;font-size:14px}@media (width<=600px){.welcome h1,.page-header h1{font-size:24px}.level-card{padding:22px}.container,.topbar{width:calc(100% - 28px)}}body.dark-mode .study-card{color:#fff;background-color:#1e1e1e;border-color:#3a3a3a}body.dark-mode .study-card .study-info h3{color:#fff}body.dark-mode .study-card .study-info p{color:#d1d5db}body.dark-mode .study-card .arrow{color:#e5e7eb}body.dark-mode .study-card:hover{background-color:#282828}body.dark-mode .study-card:active{background-color:#333}