:root{font-family:system-ui,Avenir,Helvetica,Arial,sans-serif;line-height:1.5;font-weight:400;color-scheme:light dark;color:#ffffffde;background-color:#242424;font-synthesis:none;text-rendering:optimizeLegibility;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}a{font-weight:500;color:#646cff;text-decoration:inherit}a:hover{color:#535bf2}body{margin:0;display:flex;place-items:center;min-width:320px;min-height:100vh}h1{font-size:3.2em;line-height:1.1}button{border-radius:8px;border:1px solid transparent;padding:.6em 1.2em;font-size:1em;font-weight:500;font-family:inherit;background-color:#1a1a1a;cursor:pointer;transition:border-color .25s}button:hover{border-color:#646cff}button:focus,button:focus-visible{outline:4px auto -webkit-focus-ring-color}@media(prefers-color-scheme:light){:root{color:#213547;background-color:#fff}a:hover{color:#747bff}button{background-color:#f9f9f9}}:root{--color-primary: #2563eb;--color-primary-dark: #1d4ed8;--color-primary-light: #3b82f6;--color-primary-bg: #eff6ff;--color-white: #ffffff;--color-gray-50: #f9fafb;--color-gray-100: #f3f4f6;--color-gray-200: #e5e7eb;--color-gray-300: #d1d5db;--color-gray-400: #9ca3af;--color-gray-500: #6b7280;--color-gray-600: #4b5563;--color-gray-700: #374151;--color-gray-800: #1f2937;--color-gray-900: #111827;--color-success: #10b981;--color-success-bg: #d1fae5;--color-error: #ef4444;--color-error-bg: #fee2e2;--color-warning: #f59e0b;--color-warning-bg: #fef3c7;--space-xs: .25rem;--space-sm: .5rem;--space-md: 1rem;--space-lg: 1.5rem;--space-xl: 2rem;--space-2xl: 3rem;--space-3xl: 4rem;--font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;--font-size-xs: .75rem;--font-size-sm: .875rem;--font-size-base: 1rem;--font-size-lg: 1.125rem;--font-size-xl: 1.25rem;--font-size-2xl: 1.5rem;--font-size-3xl: 2rem;--font-size-4xl: 2.5rem;--radius-sm: 4px;--radius-md: 6px;--radius-lg: 8px;--radius-xl: 12px;--shadow-sm: 0 1px 2px 0 rgb(0 0 0 / .05);--shadow-md: 0 4px 6px -1px rgb(0 0 0 / .1);--shadow-lg: 0 10px 15px -3px rgb(0 0 0 / .1);--transition-fast: .15s ease;--transition-base: .2s ease;--transition-slow: .3s ease}*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}html{font-size:16px;scroll-behavior:smooth}body{font-family:var(--font-family);color:var(--color-gray-900);background:var(--color-white);line-height:1.6;min-height:100vh}.container{width:100%;max-width:1200px;margin:0 auto;padding:0 4vw}.container-narrow{width:100%;max-width:900px;margin:0 auto;padding:0 4vw}.container-wide{width:100%;max-width:1400px;margin:0 auto;padding:0 3vw}.container-full{width:100%;padding:0 4vw}.flex{display:flex}.flex-col{flex-direction:column}.flex-wrap{flex-wrap:wrap}.flex-center{align-items:center;justify-content:center}.flex-between{justify-content:space-between}.flex-start{justify-content:flex-start}.flex-end{justify-content:flex-end}.items-center{align-items:center}.items-start{align-items:flex-start}.items-stretch{align-items:stretch}.grid{display:flex;flex-wrap:wrap;gap:2vw}.grid-2>*{flex:1 1 calc(50% - 1vw);min-width:280px}.grid-3>*{flex:1 1 calc(33.333% - 1.5vw);min-width:280px}.grid-4>*{flex:1 1 calc(25% - 1.5vw);min-width:240px}.full-height{min-height:100vh}.half-height{min-height:50vh}.section{padding:8vh 0}.section-sm{padding:4vh 0}.section-lg{padding:12vh 0}.gap-xs{gap:.5vw}.gap-sm{gap:1vw}.gap-md{gap:2vw}.gap-lg{gap:3vw}.gap-xl{gap:4vw}.mt-sm{margin-top:2vh}.mt-md{margin-top:4vh}.mt-lg{margin-top:6vh}.mb-sm{margin-bottom:2vh}.mb-md{margin-bottom:4vh}.mb-lg{margin-bottom:6vh}.text-center{text-align:center}.text-left{text-align:left}.text-right{text-align:right}.app-layout{display:flex;flex-direction:column;min-height:100vh}.app-main{flex:1}@media(max-width:768px){.container{width:95%;padding:0 2.5vw}.grid-2>*,.grid-3>*,.grid-4>*{flex:1 1 100%}.section{padding:6vh 0}.hide-mobile{display:none}}@media(min-width:769px){.hide-desktop{display:none}}.btn{display:inline-flex;align-items:center;justify-content:center;padding:var(--space-md) var(--space-xl);font-size:var(--font-size-base);font-weight:600;border-radius:var(--radius-md);border:2px solid transparent;cursor:pointer;transition:all var(--transition-base);text-decoration:none;gap:var(--space-sm)}.btn:disabled{opacity:.5;cursor:not-allowed}.btn-primary{background:var(--color-primary);color:var(--color-white);border-color:var(--color-primary)}.btn-primary:hover:not(:disabled){background:var(--color-primary-dark);border-color:var(--color-primary-dark)}.btn-outline{background:transparent;color:var(--color-primary);border-color:var(--color-primary)}.btn-outline:hover:not(:disabled){background:var(--color-primary-bg)}.btn-secondary{background:var(--color-gray-100);color:var(--color-gray-700);border-color:var(--color-gray-200)}.btn-secondary:hover:not(:disabled){background:var(--color-gray-200)}.btn-lg{padding:var(--space-lg) var(--space-2xl);font-size:var(--font-size-lg)}.btn-sm{padding:var(--space-sm) var(--space-md);font-size:var(--font-size-sm)}.card{background:var(--color-white);border:1px solid var(--color-gray-200);border-radius:var(--radius-lg);padding:var(--space-xl);transition:box-shadow var(--transition-base)}.card:hover{box-shadow:var(--shadow-md)}.card-header{margin-bottom:var(--space-lg)}.card-title{font-size:var(--font-size-xl);font-weight:600;color:var(--color-gray-900)}.card-description{color:var(--color-gray-600);margin-top:var(--space-sm)}.input-group{margin-bottom:var(--space-lg)}.input-label{display:block;font-size:var(--font-size-sm);font-weight:500;color:var(--color-gray-700);margin-bottom:var(--space-sm)}.input{width:100%;padding:var(--space-md);font-size:var(--font-size-base);border:2px solid var(--color-gray-200);border-radius:var(--radius-md);transition:border-color var(--transition-base);background:var(--color-white)}.input:focus{outline:none;border-color:var(--color-primary)}.input:disabled{background:var(--color-gray-100);cursor:not-allowed}.choice{display:flex;align-items:flex-start;padding:var(--space-md) var(--space-lg);border:2px solid var(--color-gray-200);border-radius:var(--radius-lg);cursor:pointer;transition:all var(--transition-base);gap:var(--space-md)}.choice:hover{border-color:var(--color-primary-light);background:var(--color-gray-50)}.choice.selected{border-color:var(--color-primary);background:var(--color-primary-bg)}.choice.correct{border-color:var(--color-success);background:var(--color-success-bg)}.choice.incorrect{border-color:var(--color-error);background:var(--color-error-bg)}.choice-letter{width:28px;height:28px;display:flex;align-items:center;justify-content:center;border-radius:50%;background:var(--color-gray-100);font-weight:600;font-size:var(--font-size-sm);flex-shrink:0}.choice.selected .choice-letter{background:var(--color-primary);color:var(--color-white)}.choice-text{flex:1;line-height:1.5}.progress-bar{width:100%;height:8px;background:var(--color-gray-200);border-radius:var(--radius-sm);overflow:hidden}.progress-fill{height:100%;background:var(--color-primary);transition:width var(--transition-slow)}.progress-fill.success{background:var(--color-success)}.badge{display:inline-flex;align-items:center;padding:var(--space-xs) var(--space-sm);font-size:var(--font-size-xs);font-weight:600;border-radius:var(--radius-sm)}.badge-primary{background:var(--color-primary-bg);color:var(--color-primary)}.badge-success{background:var(--color-success-bg);color:var(--color-success)}.badge-error{background:var(--color-error-bg);color:var(--color-error)}h1,h2,h3,h4,h5,h6{font-weight:600;line-height:1.3;color:var(--color-gray-900)}h1{font-size:clamp(2rem,5vw,var(--font-size-4xl))}h2{font-size:clamp(1.5rem,4vw,var(--font-size-3xl))}h3{font-size:var(--font-size-2xl)}h4{font-size:var(--font-size-xl)}.text-muted{color:var(--color-gray-600)}.text-sm{font-size:var(--font-size-sm)}.text-lg{font-size:var(--font-size-lg)}a{color:var(--color-primary);text-decoration:none;transition:color var(--transition-fast)}a:hover{color:var(--color-primary-dark)}.spinner{width:24px;height:24px;border:3px solid var(--color-gray-200);border-top-color:var(--color-primary);border-radius:50%;animation:spin .8s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}.alert{padding:var(--space-md) var(--space-lg);border-radius:var(--radius-md);margin-bottom:var(--space-lg)}.alert-success{background:var(--color-success-bg);color:#065f46;border:1px solid var(--color-success)}.alert-error{background:var(--color-error-bg);color:#991b1b;border:1px solid var(--color-error)}.alert-warning{background:var(--color-warning-bg);color:#92400e;border:1px solid var(--color-warning)}.header{position:sticky;top:0;background:var(--color-white);border-bottom:1px solid var(--color-gray-200);z-index:100}.header-container{width:90%;max-width:1200px;margin:0 auto;padding:var(--space-md) 0;display:flex;align-items:center;justify-content:space-between;gap:var(--space-xl)}.header-logo{text-decoration:none}.logo-text{font-size:var(--font-size-xl);font-weight:700;color:var(--color-primary)}.header-nav{display:flex;align-items:center;gap:var(--space-lg)}.nav-link{font-size:var(--font-size-base);font-weight:500;color:var(--color-gray-600);text-decoration:none;padding:var(--space-sm) var(--space-md);border-radius:var(--radius-md);transition:all var(--transition-fast)}.nav-link:hover{color:var(--color-primary);background:var(--color-gray-50)}.nav-link.active{color:var(--color-primary);background:var(--color-primary-bg)}.header-actions{display:flex;align-items:center;gap:var(--space-md)}.user-menu{display:flex;align-items:center;gap:var(--space-sm)}.user-name{font-weight:500;color:var(--color-gray-700)}@media(max-width:768px){.header-container{width:95%;padding:var(--space-sm) 0}.header-nav{display:none}.header-actions .btn{padding:var(--space-sm) var(--space-md);font-size:var(--font-size-sm)}}.footer{background:var(--color-gray-900);color:var(--color-gray-300);padding:6vh 0 2vh;margin-top:auto}.footer-container{width:90%;max-width:1200px;margin:0 auto;display:flex;justify-content:space-between;flex-wrap:wrap;gap:4vw}.footer-brand{max-width:280px}.footer-logo{font-size:var(--font-size-xl);font-weight:700;color:var(--color-white)}.footer-tagline{margin-top:var(--space-sm);color:var(--color-gray-400)}.footer-links{display:flex;gap:4vw}.footer-column{display:flex;flex-direction:column;gap:var(--space-sm)}.footer-column h4{color:var(--color-white);font-size:var(--font-size-sm);font-weight:600;margin-bottom:var(--space-sm)}.footer-column a{color:var(--color-gray-400);font-size:var(--font-size-sm);transition:color var(--transition-fast)}.footer-column a:hover{color:var(--color-white)}.footer-bottom{width:90%;max-width:1200px;margin:4vh auto 0;padding-top:2vh;border-top:1px solid var(--color-gray-800);text-align:center}.footer-bottom p{font-size:var(--font-size-sm);color:var(--color-gray-500)}@media(max-width:768px){.footer-container{flex-direction:column;gap:3vh}.footer-links{flex-wrap:wrap;gap:3vw}.footer-column{min-width:120px}}.orgo-buddy-container{position:fixed;bottom:var(--space-lg);right:var(--space-lg);z-index:1000;font-family:var(--font-family)}.orgo-buddy-fab{display:flex;align-items:center;gap:var(--space-sm);padding:var(--space-md) var(--space-lg);background:var(--color-primary);color:var(--color-white);border:none;border-radius:50px;cursor:pointer;box-shadow:var(--shadow-lg);transition:all var(--transition-base);font-weight:600;font-size:var(--font-size-base)}.orgo-buddy-fab:hover{background:var(--color-primary-dark);transform:translateY(-2px);box-shadow:0 6px 20px #2563eb4d}.orgo-buddy-fab.hidden{display:none}.fab-icon{font-size:1.25rem}.fab-label{font-size:var(--font-size-sm)}.orgo-buddy-panel{position:absolute;bottom:70px;right:0;width:380px;max-width:calc(100vw - 32px);height:500px;max-height:calc(100vh - 120px);background:var(--color-white);border-radius:var(--radius-xl);box-shadow:0 10px 40px #00000026;display:flex;flex-direction:column;overflow:hidden;animation:slideUp .2s ease-out}@keyframes slideUp{0%{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}.orgo-buddy-header{display:flex;align-items:center;justify-content:space-between;padding:var(--space-md) var(--space-lg);background:var(--color-primary);color:var(--color-white)}.orgo-buddy-title{display:flex;align-items:center;gap:var(--space-sm);font-weight:600;font-size:var(--font-size-base)}.orgo-buddy-icon{font-size:1.25rem}.orgo-buddy-controls{display:flex;gap:var(--space-xs)}.control-btn{width:28px;height:28px;display:flex;align-items:center;justify-content:center;background:#fff3;border:none;border-radius:var(--radius-sm);color:var(--color-white);cursor:pointer;font-size:var(--font-size-sm);transition:background var(--transition-fast)}.control-btn:hover{background:#ffffff4d}.orgo-buddy-messages{flex:1;overflow-y:auto;padding:var(--space-md);display:flex;flex-direction:column;gap:var(--space-md);background:var(--color-gray-50)}.chat-message{max-width:85%;animation:fadeIn .2s ease-out}@keyframes fadeIn{0%{opacity:0}to{opacity:1}}.chat-message.user{align-self:flex-end}.chat-message.assistant{align-self:flex-start}.message-content{padding:var(--space-md);border-radius:var(--radius-lg);line-height:1.6;font-size:var(--font-size-sm)}.chat-message.user .message-content{background:var(--color-primary);color:var(--color-white);border-bottom-right-radius:var(--radius-sm)}.chat-message.assistant .message-content{background:var(--color-white);color:var(--color-gray-800);border:1px solid var(--color-gray-200);border-bottom-left-radius:var(--radius-sm)}.message-content strong{font-weight:600}.message-content em{font-style:italic}.message-content code{background:var(--color-gray-100);padding:2px 6px;border-radius:var(--radius-sm);font-family:monospace;font-size:.9em}.chat-message.user .message-content code{background:#fff3}.message-bullet,.message-numbered{display:flex;gap:var(--space-sm);margin:var(--space-xs) 0}.bullet-icon,.number-icon{flex-shrink:0;width:1.2em}.message-image-placeholder{display:inline-flex;align-items:center;gap:var(--space-xs);padding:var(--space-sm) var(--space-md);background:var(--color-gray-100);border-radius:var(--radius-md);margin:var(--space-sm) 0;font-size:var(--font-size-sm);color:var(--color-gray-600)}.image-icon{font-size:1.2em}.cursor-blink{animation:blink 1s infinite;color:var(--color-primary)}@keyframes blink{0%,50%{opacity:1}51%,to{opacity:0}}.orgo-buddy-typing{display:flex;gap:4px;padding:var(--space-md);background:var(--color-white);border:1px solid var(--color-gray-200);border-radius:var(--radius-lg);border-bottom-left-radius:var(--radius-sm);width:fit-content}.typing-dot{width:8px;height:8px;background:var(--color-gray-400);border-radius:50%;animation:typingBounce 1.4s infinite ease-in-out}.typing-dot:nth-child(1){animation-delay:0s}.typing-dot:nth-child(2){animation-delay:.2s}.typing-dot:nth-child(3){animation-delay:.4s}@keyframes typingBounce{0%,80%,to{transform:translateY(0)}40%{transform:translateY(-6px)}}.orgo-buddy-input-area{display:flex;gap:var(--space-sm);padding:var(--space-md);border-top:1px solid var(--color-gray-200);background:var(--color-white)}.orgo-buddy-input{flex:1;padding:var(--space-sm) var(--space-md);border:2px solid var(--color-gray-200);border-radius:var(--radius-lg);font-size:var(--font-size-sm);transition:border-color var(--transition-fast);background:var(--color-white)}.orgo-buddy-input:focus{outline:none;border-color:var(--color-primary)}.orgo-buddy-input:disabled{background:var(--color-gray-100)}.orgo-buddy-send{padding:var(--space-sm) var(--space-lg);background:var(--color-primary);color:var(--color-white);border:none;border-radius:var(--radius-lg);font-weight:600;font-size:var(--font-size-sm);cursor:pointer;transition:background var(--transition-fast)}.orgo-buddy-send:hover:not(:disabled){background:var(--color-primary-dark)}.orgo-buddy-send:disabled{opacity:.5;cursor:not-allowed}@media(max-width:480px){.orgo-buddy-container{bottom:var(--space-md);right:var(--space-md)}.orgo-buddy-panel{width:calc(100vw - 32px);height:calc(100vh - 100px);bottom:60px}.orgo-buddy-fab{padding:var(--space-sm) var(--space-md)}.fab-label{display:none}}.hero{min-height:90vh;display:flex;align-items:center;justify-content:center;background:linear-gradient(180deg,var(--color-gray-50) 0%,var(--color-white) 100%);padding:0 5vw}.hero-content{max-width:800px;text-align:center}.hero-content h1{margin-bottom:var(--space-lg)}.hero-subtitle{font-size:clamp(1rem,2vw,1.25rem);color:var(--color-gray-600);line-height:1.7;margin-bottom:var(--space-xl);max-width:600px;margin-left:auto;margin-right:auto}.hero-actions{display:flex;gap:var(--space-md);justify-content:center;flex-wrap:wrap}.hero-stats{display:flex;justify-content:center;gap:4vw;margin-top:6vh;flex-wrap:wrap}.stat{text-align:center}.stat-number{display:block;font-size:var(--font-size-2xl);font-weight:700;color:var(--color-primary)}.stat-label{display:block;font-size:var(--font-size-sm);color:var(--color-gray-500);margin-top:var(--space-xs)}.features{background:var(--color-white)}.section-header h2{margin-bottom:var(--space-sm)}.section-header .text-muted{max-width:500px;margin:0 auto}.feature-card{text-align:center;padding:var(--space-2xl)}.feature-icon{font-size:2.5rem;margin-bottom:var(--space-lg)}.feature-title{font-size:var(--font-size-xl);margin-bottom:var(--space-sm)}.feature-description{line-height:1.6}.topics{background:var(--color-gray-50)}.topics-grid{display:flex;flex-wrap:wrap;gap:var(--space-md);justify-content:center;max-width:800px;margin:0 auto}.topic-item{display:flex;align-items:center;justify-content:space-between;background:var(--color-white);padding:var(--space-md) var(--space-lg);border-radius:var(--radius-lg);border:1px solid var(--color-gray-200);min-width:280px;flex:1 1 calc(50% - var(--space-md))}.topic-name{font-weight:500;color:var(--color-gray-800)}.topic-count{font-size:var(--font-size-xs)}.cta{background:var(--color-primary);color:var(--color-white)}.cta h2{color:var(--color-white)}.cta .text-muted{color:#fffc}.cta .btn-primary{background:var(--color-white);color:var(--color-primary)}.cta .btn-primary:hover{background:var(--color-gray-100)}@media(max-width:768px){.hero{min-height:80vh;padding:4vh 5vw}.hero-stats{gap:2vw}.stat-number{font-size:var(--font-size-xl)}.topic-item{flex:1 1 100%}}.practice-page{min-height:100vh;padding:4vh 4vw;background:var(--color-gray-50);width:100%}.practice-header{text-align:center;margin-bottom:var(--space-xl)}.practice-header h1{margin-bottom:var(--space-sm)}.loading-state{display:flex;flex-direction:column;align-items:center;justify-content:center;padding:10vh 0;gap:var(--space-md)}.loading-state .spinner{width:40px;height:40px}.mode-selector{display:flex;gap:var(--space-md);margin-bottom:var(--space-xl)}.mode-btn{flex:1;display:flex;align-items:center;gap:var(--space-md);padding:var(--space-lg);background:var(--color-white);border:2px solid var(--color-gray-200);border-radius:var(--radius-lg);cursor:pointer;transition:all var(--transition-base);text-align:left}.mode-btn:hover{border-color:var(--color-primary-light)}.mode-btn.active{border-color:var(--color-primary);background:var(--color-primary-bg)}.mode-icon{font-size:1.5rem}.mode-btn div{display:flex;flex-direction:column}.mode-btn strong{color:var(--color-gray-900)}.mode-btn .text-sm{margin-top:var(--space-xs)}.courses-list{display:flex;flex-direction:column;gap:var(--space-md)}.course-card{background:var(--color-white);border:1px solid var(--color-gray-200);border-radius:var(--radius-lg);overflow:hidden}.course-header{display:flex;align-items:center;gap:var(--space-md);padding:var(--space-lg);cursor:pointer;transition:background var(--transition-fast)}.course-header:hover{background:var(--color-gray-50)}.course-header h3{flex:1;font-size:var(--font-size-lg);margin:0}.expand-icon{color:var(--color-gray-400);font-size:var(--font-size-sm)}.course-content{padding:0 var(--space-lg) var(--space-lg);border-top:1px solid var(--color-gray-100)}.course-actions{display:flex;gap:var(--space-sm);margin-bottom:var(--space-md);padding-top:var(--space-md)}.topics-list{display:flex;flex-direction:column;gap:var(--space-sm)}.topic-checkbox{display:flex;align-items:center;gap:var(--space-md);padding:var(--space-sm) var(--space-md);border-radius:var(--radius-md);cursor:pointer;transition:background var(--transition-fast)}.topic-checkbox:hover{background:var(--color-gray-50)}.topic-checkbox input[type=checkbox]{width:18px;height:18px;accent-color:var(--color-primary)}.topic-title{color:var(--color-gray-700)}.practice-footer{display:flex;align-items:center;justify-content:space-between;margin-top:var(--space-xl);padding:var(--space-lg);background:var(--color-white);border-radius:var(--radius-lg);box-shadow:var(--shadow-md);position:sticky;bottom:var(--space-md)}.selected-count{color:var(--color-gray-600)}.selected-count strong{color:var(--color-primary);font-size:var(--font-size-xl)}.question-page{min-height:100vh;padding:4vh 4vw;width:100%}.question-container{max-width:900px;margin:0 auto;width:100%}.question-progress{display:flex;align-items:center;justify-content:space-between;margin-bottom:var(--space-lg)}.question-number{font-weight:600;color:var(--color-gray-700)}.question-timer{font-size:var(--font-size-sm);color:var(--color-gray-500)}.question-card{background:var(--color-white);border-radius:var(--radius-xl);padding:var(--space-2xl);box-shadow:var(--shadow-md)}.question-image{max-width:100%;border-radius:var(--radius-md);margin-bottom:var(--space-lg)}.question-text{font-size:var(--font-size-lg);line-height:1.7;color:var(--color-gray-900);margin-bottom:var(--space-xl)}.choices-list{display:flex;flex-direction:column;gap:var(--space-md);margin-bottom:var(--space-xl)}.question-actions{display:flex;gap:var(--space-md);justify-content:flex-end}.feedback-section{margin-top:var(--space-xl);padding:var(--space-lg);border-radius:var(--radius-lg)}.feedback-section.correct{background:var(--color-success-bg);border:1px solid var(--color-success)}.feedback-section.incorrect{background:var(--color-error-bg);border:1px solid var(--color-error)}.feedback-header{display:flex;align-items:center;gap:var(--space-sm);font-weight:600;margin-bottom:var(--space-md)}.explanation-text{line-height:1.7;color:var(--color-gray-700)}.explanation-steps{display:flex;flex-direction:column;gap:var(--space-lg);margin-top:var(--space-lg);padding-top:var(--space-lg);border-top:1px solid var(--color-gray-200)}.explanation-step{background:var(--color-white);border:1px solid var(--color-gray-200);border-radius:var(--radius-lg);padding:var(--space-lg)}.step-number{display:inline-block;background:var(--color-primary);color:var(--color-white);font-weight:600;font-size:var(--font-size-sm);padding:var(--space-xs) var(--space-md);border-radius:var(--radius-md);margin-bottom:var(--space-md)}.explanation-step-image{max-width:100%;border-radius:var(--radius-md);display:block}.step-caption{margin-top:var(--space-md);color:var(--color-gray-600);font-size:var(--font-size-sm);line-height:1.5}.explain-btn{margin-top:var(--space-lg);width:100%}@media(max-width:768px){.mode-selector{flex-direction:column}.practice-footer{flex-direction:column;gap:var(--space-md);text-align:center}.practice-footer .btn{width:100%}.question-card{padding:var(--space-lg)}}.auth-page{min-height:100vh;display:flex;align-items:center;justify-content:center;padding:5vh 4vw;background:var(--color-gray-50);width:100%}.auth-container{width:100%;max-width:440px;background:var(--color-white);padding:var(--space-2xl);border-radius:var(--radius-xl);box-shadow:var(--shadow-lg)}@media(max-width:480px){.input-row{flex-direction:column;gap:0}}.auth-header{text-align:center;margin-bottom:var(--space-xl)}.auth-header h1{font-size:var(--font-size-2xl);margin-bottom:var(--space-sm)}.auth-form{margin-bottom:var(--space-lg)}.input-row{display:flex;gap:var(--space-md)}.input-row .input-group{flex:1}.auth-footer{text-align:center;padding-top:var(--space-lg);border-top:1px solid var(--color-gray-200)}.auth-footer p{color:var(--color-gray-600);font-size:var(--font-size-sm)}