:root{--primary-color: #2f3e46;--secondary-color: #3e5053;--accent-color: #84dcc6;--background-color: #f0f2f5;--text-color: #333;--white: #fff;--button-bg: var(--primary-color);--button-hover-bg: var(--secondary-color);--button-text: var(--white);--auth-bg: var(--white);--header-bg: var(--primary-color);--header-text: var(--white);--footer-bg: var(--primary-color);--footer-text: var(--white);--sidebar-bg: var(--primary-color);--sidebar-text: var(--white);--exercise-bg: var(--white);--exercise-text: var(--text-color);--profile-ct: #f0f2f5;--profile-bg: var(--white);--profile-b: var(--primary-color);--profile-text: var(--text-color);--nav-b: var(--primary-color);--viewer-bg: var(--white);--viewer-text: var(--text-color);--course-card-bg: var(--white);--course-card-text: #000000de;--course-card-border: #d0d0d0;--splash-bg: rgba(255,255,255,.95)}html[data-theme=dark]{--primary-color: #1e1e1e;--secondary-color: #333;--accent-color: #84dcc6;--background-color: #121212;--text-color: #e0e0e0;--white: #ccc;--nav-b: #4a4a4a;--button-bg: var(--primary-color);--button-hover-bg: var(--secondary-color);--button-text: var(--white);--auth-bg: #181818;--profile-ct: #abaaaa21;--profile-b: #bac6c712;--header-bg: var(--primary-color);--header-text: var(--white);--footer-bg: var(--primary-color);--footer-text: var(--white);--sidebar-bg: var(--primary-color);--sidebar-text: var(--white);--exercise-bg: #1e1e1e;--exercise-text: var(--white);--profile-bg: #1e1e1e;--profile-text: var(--white);--viewer-bg: #212020;--viewer-text: var(--white);--course-card-bg: #1f1f1f;--course-card-text: #000000b0;--course-card-border: #333333;--splash-bg: rgba(30,30,30,.95)}.course-selection{display:flex;flex-wrap:wrap;justify-content:center;gap:1.5rem;text-align:center;width:100%;box-sizing:border-box;margin-top:0}.course-card{background-color:var(--course-card-bg);color:var(--course-card-text);border:1px solid var(--course-card-border, #ccc);padding:1.5rem 1rem;border-radius:.5rem;text-align:center;text-decoration:none;width:300px;max-width:90vw;display:flex;flex-direction:column;align-items:center;gap:1rem;box-sizing:border-box;transition:transform .2s ease,box-shadow .2s ease}.course-card:hover{transform:translateY(-2px);box-shadow:0 4px 12px #0000001f}.course-card-img{width:100%;max-width:180px;height:120px;object-fit:contain;margin-bottom:.5rem;display:block}.course-card h2{font-size:1.3rem;margin:0}.course-card p{font-size:.95rem;color:var(--course-card-text-secondary, #666)}button{padding:.625rem 1.25rem;font-size:1rem;background-color:var(--profile-b);border:none;color:var(--white);border-radius:.3125rem;cursor:pointer;transition:background-color .2s ease}button:hover{background-color:var(--secondary-color)}.nav-buttons button:disabled{opacity:.5;cursor:not-allowed}.loading-skeleton{width:100%;border-radius:.5rem;background:linear-gradient(90deg,#f0f0f0 25%,#e0e0e0,#f0f0f0 75%);background-size:200% 100%;animation:shimmer 1.2s infinite linear}@keyframes shimmer{0%{background-position:-200px 0}to{background-position:200px 0}}.fade-in{opacity:0;transition:opacity .4s}.fade-in.visible{opacity:1}.course-card--tables{box-shadow:0 0 0 4px #b6f5e2 inset;background:linear-gradient(135deg,#e8fff6 60%,#b6f5e2);transition:background .4s,box-shadow .4s}.course-card--tables:hover{background:linear-gradient(135deg,#b6f5e2 80%,#e8fff6);box-shadow:0 0 0 6px #7be9c7 inset}.course-card--presentations{box-shadow:0 0 0 4px #ffd6d6 inset;background:linear-gradient(135deg,#fff0f0 60%,#ffd6d6);transition:background .4s,box-shadow .4s}.course-card--presentations:hover{background:linear-gradient(135deg,#ffd6d6 80%,#fff0f0);box-shadow:0 0 0 6px #ffb3b3 inset}.course-card--text{box-shadow:0 0 0 4px #d6d6ff inset;background:linear-gradient(135deg,#f0f0ff 60%,#d6d6ff);transition:background .4s,box-shadow .4s}.course-card--text:hover{background:linear-gradient(135deg,#d6d6ff 80%,#f0f0ff);box-shadow:0 0 0 6px #b3b3ff inset}.splash-screen{position:fixed;inset:0;background:#0009;display:flex;justify-content:center;align-items:center;z-index:9999;opacity:0;pointer-events:none;transition:opacity .3s ease}.splash-screen.splash-visible{opacity:1;pointer-events:auto}.splash-screen.splash-hide{opacity:0;pointer-events:none}.spinner-circle{transform-origin:50% 50%;animation:spin .9s linear infinite}@keyframes spin{0%{transform:rotate(0)}to{transform:rotate(360deg)}}.splash-spinner{display:flex;align-items:center;justify-content:center}.splash-spinner svg{display:block}.splash-spinner circle{stroke:#fff;stroke-width:5;stroke-linecap:round;transform-origin:50% 50%}.btn-icon{width:1.2em;height:1.2em;vertical-align:middle;margin-right:.5em;margin-bottom:0;display:inline-block;position:relative;top:-.08em;filter:grayscale(.2) brightness(.95);opacity:.85;transition:opacity .2s}button:disabled .btn-icon{opacity:.5}.splash-inner{display:flex;flex-direction:column;align-items:center;justify-content:center;padding:2.5rem 3.5rem;background:#fffffff2;border-radius:1.5rem;box-shadow:0 8px 32px #2c3e501a;animation:splash-pop .6s cubic-bezier(.23,1.02,.56,.98)}@keyframes splash-pop{0%{transform:scale(.92) translateY(30px);opacity:0}to{transform:scale(1) translateY(0);opacity:1}}.splash-logo-anim{margin-bottom:1.5rem}.splash-title{font-size:1.25rem;font-weight:600;color:#2f3e46;letter-spacing:.01em;text-shadow:0 2px 8px rgba(44,62,80,.07)}.nav-btns-flex{display:flex;justify-content:space-between;gap:1em}.nav-btn-hidden{visibility:hidden}.lightbox-overlay{position:fixed;top:0;left:0;width:100%;height:100%;background:#000000d9;display:flex;justify-content:center;align-items:center;z-index:10000;opacity:0;pointer-events:none;transition:opacity .3s ease}.lightbox-overlay.active{opacity:1;pointer-events:auto}.lightbox-image{max-width:90%;max-height:90%;border-radius:4px;box-shadow:0 0 20px #00000080;transform:scale(.9);transition:transform .3s ease}.lightbox-overlay.active .lightbox-image{transform:scale(1)}.lightbox-close{position:absolute;top:20px;right:30px;color:#fff;font-size:40px;cursor:pointer;-webkit-user-select:none;user-select:none}:root{--header-height: 4rem;--footer-height: 2.5rem}body,html{height:100%;overflow-x:hidden}.container{display:flex;height:100vh;width:100%;overflow:hidden;max-width:100vw;box-sizing:border-box;padding-top:var(--header-height);padding-bottom:var(--footer-height);min-height:calc(100vh - var(--header-height) - var(--footer-height));overflow-x:hidden}.header{position:fixed;top:0;left:0;width:100%;height:var(--header-height);display:flex;align-items:center;background-color:var(--primary-color);color:var(--white);padding:0 1rem;z-index:1000;box-shadow:0 2px 8px #0000000a}.footer{position:fixed;bottom:0;left:0;width:100%;height:var(--footer-height);display:flex;justify-content:center;align-items:center;gap:1.5em;background-color:var(--primary-color);color:var(--white);text-align:center;font-size:.95rem;line-height:var(--footer-height);z-index:1000;box-shadow:0 -2px 8px #0000000a}.header-content{display:flex;align-items:center;width:100%}.course-title{margin:0;font-size:1.5rem}.course-title-button{display:flex;align-items:center;gap:.5rem;background:none;color:var(--white);border:none;font-size:1.5rem;cursor:pointer;padding:0;transition:color .2s;text-align:left}.course-title-button:hover{color:var(--accent-color)}.course-title-button .logo{width:30px;height:30px;object-fit:contain}.login-button,.profile-button{background-color:var(--primary-color);color:var(--white);border:none;padding:.5rem 1rem;border-radius:.25rem;cursor:pointer;transition:background-color .2s}.login-button:hover,.profile-button:hover{background-color:var(--secondary-color)}.main-content{display:flex;justify-content:center;align-items:center;flex-grow:1;background-color:var(--background-color);padding:.5rem;height:calc(100vh - 5rem);margin-top:1rem;width:100%;max-width:100vw;box-sizing:border-box;padding-top:var(--header-height);padding-bottom:var(--footer-height);min-height:calc(100vh - var(--header-height) - var(--footer-height));overflow-x:hidden;overflow-y:hidden}body>main{padding-top:var(--header-height);padding-bottom:var(--footer-height);min-height:calc(100vh - var(--header-height) - var(--footer-height));box-sizing:border-box}body>main,.container,.main-content{padding-top:var(--header-height);padding-bottom:var(--footer-height);min-height:calc(100vh - var(--header-height) - var(--footer-height));box-sizing:border-box;width:100%;max-width:100vw;overflow-x:hidden}.logo-container{display:flex;align-items:center;gap:.5rem}.logo{width:40px;height:40px;object-fit:contain}.toggle-icons-button{order:3;display:none;background-color:var(--primary-color);color:var(--white);border:none;padding:.5rem 1rem;border-radius:.25rem;cursor:pointer;font-size:1.25rem;position:relative;z-index:11001;margin-left:.5rem}.toggle-icons-button:hover{background-color:var(--secondary-color)}#auth-profile-btn{order:2;margin-left:auto;display:flex;align-items:center}