/* ═══════════════════════════════════════════════════════
   Prepapython — Style principal
   ═══════════════════════════════════════════════════════ */

:root {
    --bg:#0d1117;--panel:#161b22;--border:#30363d;
    --blue:#58a6ff;--green:#3fb950;--yellow:#d29922;
    --red:#f85149;--purple:#bc8cff;--text:#e6edf3;--muted:#8b949e;
}

*{box-sizing:border-box;}
body{background:var(--bg);color:var(--text);font-family:'Segoe UI',system-ui,sans-serif;margin:0;}

/* Scrollbar */
::-webkit-scrollbar{width:5px;height:5px;}
::-webkit-scrollbar-track{background:var(--bg);}
::-webkit-scrollbar-thumb{background:var(--border);border-radius:3px;}

/* Skip to content (accessibility) */
.skip-link{
    position:absolute;top:-40px;left:0;background:var(--blue);color:#fff;
    padding:8px 16px;z-index:100000;font-size:14px;font-weight:600;
    transition:top .2s;
}
.skip-link:focus{top:0;}

/* Layout */
.app{display:flex;flex-direction:column;height:100vh;overflow:hidden;}
.header{background:var(--panel);border-bottom:1px solid var(--border);padding:10px 20px;display:flex;align-items:center;justify-content:space-between;flex-shrink:0;}
.main-layout{display:flex;flex:1;overflow:hidden;}
.sidebar{width:220px;flex-shrink:0;background:var(--panel);border-right:1px solid var(--border);overflow-y:auto;display:flex;flex-direction:column;}
.ex-list{width:280px;flex-shrink:0;border-right:1px solid var(--border);overflow-y:auto;padding:12px;}
.content{flex:1;overflow-y:auto;}

/* Navigation */
.nav-section{padding:12px;}
.nav-label{font-size:10px;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);margin-bottom:6px;padding:0 6px;}
.nav-btn{display:flex;align-items:center;gap:8px;width:100%;text-align:left;padding:7px 10px;border-radius:6px;font-size:13px;color:var(--text);border:none;background:none;cursor:pointer;transition:background .15s;}
.nav-btn:hover,.nav-btn:focus-visible{background:#21262d;outline:2px solid var(--blue);outline-offset:-2px;}
.nav-btn.active{background:#1f6feb1a;color:var(--blue);font-weight:600;border-left:3px solid var(--blue);padding-left:7px;}

/* Exercise cards */
.ex-card{background:var(--panel);border:1px solid var(--border);border-radius:10px;padding:12px;margin-bottom:8px;cursor:pointer;transition:border-color .15s,background .15s;}
.ex-card:hover,.ex-card:focus-visible{border-color:#58a6ff55;outline:none;}
.ex-card.active{border-color:var(--blue);background:#1f6feb0d;}
.ex-card-title{font-size:13px;font-weight:600;color:var(--text);margin-bottom:2px;}
.ex-card-sub{font-size:11px;color:var(--muted);margin-bottom:6px;}
.ex-section-lbl{font-size:10px;font-weight:700;text-transform:uppercase;letter-spacing:.07em;padding:10px 2px 6px;display:flex;align-items:center;justify-content:space-between;}

/* Badges */
.badge{display:inline-block;font-size:10px;font-weight:700;padding:2px 8px;border-radius:12px;}
.badge-deb{background:#3fb95022;color:var(--green);}
.badge-int{background:#d2992222;color:var(--yellow);}
.badge-avd{background:#f8514922;color:var(--red);}

/* Content area */
.content-inner{max-width:820px;padding:20px 24px 40px;}

/* Professor bubble */
.prof-bubble{display:flex;align-items:flex-start;gap:14px;margin-bottom:24px;}
.prof-avatar{width:46px;height:46px;border-radius:50%;background:linear-gradient(135deg,#1f6feb,#58a6ff);display:flex;align-items:center;justify-content:center;font-size:22px;flex-shrink:0;}
.prof-msg{background:#1f6feb0f;border:1px solid #1f6feb30;border-radius:14px;border-top-left-radius:4px;padding:14px 16px;flex:1;}
.prof-name{font-size:11px;color:var(--muted);margin-top:6px;}

/* Tabs */
.tabs{display:flex;border-bottom:1px solid var(--border);margin-bottom:16px;gap:2px;}
.tab-btn{padding:8px 16px;font-size:13px;color:var(--muted);border:none;background:none;cursor:pointer;border-bottom:2px solid transparent;transition:all .15s;}
.tab-btn:hover,.tab-btn:focus-visible{color:var(--text);}
.tab-btn.active{color:var(--blue);border-bottom-color:var(--blue);}
.tab-btn[role="tab"]{outline:none;}
.tab-btn[role="tab"]:focus-visible{box-shadow:0 0 0 2px var(--blue);}

/* Boxes */
.theory-box{background:var(--panel);border:1px solid var(--border);border-left:3px solid var(--green);border-radius:10px;padding:16px;margin-bottom:14px;}
.problem-box{background:var(--panel);border:1px solid var(--border);border-left:3px solid var(--blue);border-radius:10px;padding:16px;margin-bottom:14px;}
.hint-item{background:#d299221a;border:1px solid #d2992233;border-left:3px solid var(--yellow);border-radius:8px;padding:10px 14px;font-size:13px;}
.complexity-box{background:var(--panel);border:1px solid var(--border);border-left:3px solid var(--purple);border-radius:10px;padding:16px;}

/* Buttons */
.btn{padding:7px 14px;border-radius:6px;font-size:13px;cursor:pointer;border:none;transition:all .15s;font-weight:500;}
.btn:focus-visible{outline:2px solid var(--blue);outline-offset:2px;}
.btn-primary{background:#1f6feb;color:white;}
.btn-primary:hover{background:#388bfd;}
.btn-primary:disabled{background:var(--border);color:var(--muted);cursor:not-allowed;}
.btn-ghost{background:#21262d;color:var(--text);border:1px solid var(--border);}
.btn-ghost:hover{border-color:var(--blue);}
.btn-hint{background:#d299221a;color:var(--yellow);border:1px solid #d2992244;}
.btn-hint:hover{background:#d2992233;}
.btn-hint:disabled{opacity:.5;cursor:not-allowed;}
.btn-solution{background:#f849221a;color:var(--red);border:1px solid #f8514944;}
.btn-solution:hover{background:#f8514922;}
.btn-success{background:#3fb95022;color:var(--green);border:1px solid #3fb95044;}
.btn-purple{background:#bc8cff22;color:var(--purple);border:1px solid #bc8cff44;}
.btn-purple:hover{background:#bc8cff33;}

/* Code editor */
.editor-wrap{border:1px solid var(--border);border-radius:10px;overflow:hidden;transition:border-color .2s;}
.editor-wrap:focus-within{border-color:var(--blue);box-shadow:0 0 0 3px #1f6feb18;}
.editor-topbar{background:#161b22;border-bottom:1px solid var(--border);padding:7px 14px;display:flex;align-items:center;justify-content:space-between;}
.editor-dots{display:flex;gap:6px;}
.editor-dot{width:12px;height:12px;border-radius:50%;}
.editor-lang-badge{font-size:10px;font-weight:700;letter-spacing:.06em;padding:2px 8px;border-radius:10px;background:#21262d;color:var(--blue);font-family:monospace;}
.code-editor{width:100%;font-family:'Fira Code','Courier New',monospace;font-size:13.5px;background:#010409;color:var(--text);border:none;border-radius:0;padding:18px 20px;resize:vertical;min-height:220px;outline:none;line-height:1.75;tab-size:4;letter-spacing:.01em;}

/* Terminal output */
.terminal-wrap{border:1px solid var(--border);border-radius:10px;overflow:hidden;transition:border-color .2s;}
.terminal-topbar{background:#0a0f14;border-bottom:1px solid var(--border);padding:7px 14px;display:flex;align-items:center;gap:10px;}
.terminal-title{font-size:11px;color:var(--muted);font-family:monospace;flex:1;text-align:center;}
.output-box{background:#0a0f14;border:none;border-radius:0;padding:16px 20px;min-height:120px;font-family:'Fira Code','Courier New',monospace;font-size:13px;white-space:pre-wrap;word-break:break-all;line-height:1.7;}
.output-box.ok{color:var(--green);}
.output-box.err{color:var(--red);}
.output-box.idle{color:var(--muted);font-style:italic;}

/* Progress bar */
.progress-bar{height:4px;background:var(--border);border-radius:4px;overflow:hidden;}
.progress-fill{height:100%;background:linear-gradient(90deg,var(--blue),var(--purple));transition:width .4s;}

/* Loading overlay */
.loading-overlay{position:fixed;inset:0;background:#0d1117ee;z-index:999;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:16px;}
.spinner{width:40px;height:40px;border:3px solid var(--border);border-top-color:var(--blue);border-radius:50%;animation:spin 1s linear infinite;}
@keyframes spin{to{transform:rotate(360deg);}}

/* Topic grid */
.topic-grid{display:grid;grid-template-columns:1fr 1fr;gap:12px;}
.topic-card{background:var(--panel);border:1px solid var(--border);border-radius:12px;padding:16px;cursor:pointer;transition:border-color .2s,transform .15s;}
.topic-card:hover,.topic-card:focus-visible{transform:translateY(-2px);outline:2px solid var(--blue);}
.topic-card:last-child{grid-column:span 2;}

/* Code highlighting */
pre[class*="language-"]{margin:0;border-radius:8px;font-size:13px;}

/* Utility classes */
.section-label{font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:.06em;color:var(--muted);margin-bottom:8px;}
.inline-code{background:#21262d;padding:1px 6px;border-radius:4px;font-family:'Fira Code',monospace;font-size:12px;color:var(--blue);}
h2{font-size:20px;font-weight:700;}
h3{font-size:14px;font-weight:600;}
.status-pill{font-size:11px;padding:3px 10px;border-radius:12px;font-weight:600;}
.status-loading{background:#d2992222;color:var(--yellow);}
.status-ready{background:#3fb95022;color:var(--green);}
.status-error{background:#f8514922;color:var(--red);}
.text-sm{font-size:13px;} .text-xs{font-size:11px;}
.text-muted{color:var(--muted);} .text-blue{color:var(--blue);}
.text-green{color:var(--green);} .text-yellow{color:var(--yellow);}
.text-purple{color:var(--purple);} .leading-relaxed{line-height:1.7;}
.mb-2{margin-bottom:8px;} .mb-3{margin-bottom:12px;} .mb-4{margin-bottom:16px;} .mt-2{margin-top:8px;}

/* SQL data tables */
.sql-tables-wrap{margin-bottom:16px;}
.sql-table-name{font-size:11px;font-weight:700;color:var(--blue);margin:10px 0 4px 0;font-family:monospace;}
.sql-data-table{width:100%;border-collapse:collapse;border:1px solid var(--border);border-radius:8px;overflow:hidden;margin-bottom:8px;}
.sql-data-table th{background:#21262d;color:var(--blue);font-weight:600;padding:8px 12px;text-align:left;font-size:12px;font-family:monospace;}
.sql-data-table td{padding:7px 12px;border-top:1px solid var(--border);font-size:12px;font-family:monospace;color:var(--text);}
.sql-data-table tr:nth-child(even) td{background:#ffffff08;}

/* SQL result */
.sql-result-wrap{padding:12px 16px;overflow-x:auto;}
.sql-result-table{width:100%;border-collapse:collapse;font-size:12.5px;font-family:'Fira Code','Courier New',monospace;}
.sql-result-table thead tr{border-bottom:2px solid var(--border);}
.sql-result-table th{padding:8px 16px;text-align:left;color:var(--yellow);font-weight:700;white-space:nowrap;background:#0d1117;}
.sql-result-table td{padding:6px 16px;border-bottom:1px solid #ffffff07;color:var(--text);white-space:nowrap;}
.sql-result-table tr:hover td{background:#ffffff05;}
.sql-result-count{font-size:11px;color:var(--muted);padding:6px 16px 10px;border-top:1px solid var(--border);margin-top:4px;}
.output-box.sql-out{background:#0a0f14;padding:0;min-height:80px;}

/* SQL nav */
.sql-nav-bar{display:flex;align-items:center;gap:8px;background:#161b22;border:1px solid var(--border);border-radius:8px;padding:8px 14px;margin-bottom:12px;}
.sql-nav-counter{flex:1;text-align:center;font-size:13px;font-weight:700;color:var(--yellow);}
.btn-nav{padding:5px 12px;border-radius:6px;font-size:12px;cursor:pointer;border:1px solid var(--border);background:#21262d;color:var(--text);}
.btn-nav:hover{border-color:var(--yellow);color:var(--yellow);}
.btn-nav:disabled{opacity:.4;cursor:not-allowed;}

/* Algo du jour card */
.adj-card{background:linear-gradient(135deg,#1f6feb11,#bc8cff11);border:1px solid var(--purple);border-radius:10px;padding:12px;margin-bottom:4px;cursor:pointer;transition:border-color .15s;}
.adj-card:hover{border-color:var(--blue);}
.adj-card.active{background:linear-gradient(135deg,#1f6feb1a,#bc8cff1a);}

/* SQL du jour card */
.sdj-card{background:linear-gradient(135deg,#d2992211,#92400e11);border:1px solid var(--yellow);border-radius:10px;padding:12px;margin-bottom:4px;cursor:pointer;transition:border-color .15s;}
.sdj-card:hover{border-color:var(--blue);}
.sdj-card.active{background:linear-gradient(135deg,#d299221a,#92400e1a);}
.btn-sql{background:#d2992222;color:var(--yellow);border:1px solid #d2992244;}
.btn-sql:hover{background:#d2992233;}

/* ═══════════════════════════════════════════════════════
   PAYWALL
   ═══════════════════════════════════════════════════════ */
#paywall{position:fixed;inset:0;z-index:10000;background:var(--bg);display:flex;align-items:center;justify-content:center;padding:20px;overflow-y:auto;}
.pw-card{background:var(--panel);border:1px solid var(--border);border-radius:20px;max-width:460px;width:100%;padding:40px 36px;text-align:center;position:relative;box-shadow:0 24px 80px #00000088;}
.pw-logo{font-size:40px;margin-bottom:10px;}
.pw-brand{font-size:22px;font-weight:800;color:var(--blue);letter-spacing:-.5px;margin-bottom:4px;}
.pw-tagline{font-size:13px;color:var(--muted);margin-bottom:28px;}
.pw-features{text-align:left;background:var(--bg);border-radius:12px;padding:16px 18px;margin-bottom:24px;}
.pw-feature{display:flex;align-items:flex-start;gap:10px;font-size:13px;color:var(--text);padding:5px 0;}
.pw-feature-icon{color:var(--green);font-size:14px;flex-shrink:0;margin-top:1px;}
.pw-price-box{background:linear-gradient(135deg,#1f6feb22,#58a6ff11);border:1px solid #58a6ff33;border-radius:14px;padding:18px;margin-bottom:24px;}
.pw-price{font-size:42px;font-weight:800;color:var(--text);letter-spacing:-1px;}
.pw-price sup{font-size:18px;font-weight:600;vertical-align:super;}
.pw-price-label{font-size:12px;color:var(--muted);margin-top:2px;}
.pw-price-trial{font-size:11px;color:var(--green);margin-top:4px;}
#paypal-button-container{margin-bottom:16px;min-height:50px;}
.pw-restore-link{font-size:12px;color:var(--muted);cursor:pointer;text-decoration:underline;display:block;margin-bottom:10px;}
.pw-restore-link:hover{color:var(--blue);}
.pw-restore-zone{display:none;margin-top:10px;}
.pw-restore-input{width:100%;background:#0d1117;border:1px solid var(--border);border-radius:8px;padding:8px 12px;color:var(--text);font-size:12px;font-family:monospace;margin-bottom:8px;}
.pw-restore-input::placeholder{color:var(--muted);}
.pw-restore-input:focus{outline:none;border-color:var(--blue);}
.pw-legal{font-size:10px;color:#8b949e88;line-height:1.5;margin-top:12px;}
.pw-secure{display:flex;align-items:center;justify-content:center;gap:6px;font-size:11px;color:var(--muted);margin-bottom:20px;}

/* Logout button */
#btn-logout{display:none;padding:4px 10px;font-size:11px;border-radius:6px;border:1px solid var(--border);background:transparent;color:var(--muted);cursor:pointer;transition:all .15s;}
#btn-logout:hover{border-color:var(--red);color:var(--red);}

/* Mobile hamburger */
.mobile-menu-btn{display:none;background:none;border:1px solid var(--border);color:var(--text);padding:6px 10px;border-radius:6px;cursor:pointer;font-size:18px;}
.mobile-menu-btn:focus-visible{outline:2px solid var(--blue);}

/* ═══════════════════════════════════════════════════════
   RESPONSIVE — Mobile first breakpoints
   ═══════════════════════════════════════════════════════ */

/* Tablet: < 1024px */
@media (max-width: 1024px) {
    .sidebar{width:180px;}
    .ex-list{width:240px;}
    .content-inner{padding:16px 18px 30px;}
}

/* Mobile landscape: < 768px */
@media (max-width: 768px) {
    .main-layout{flex-direction:column;}

    .sidebar{
        width:100%;height:auto;flex-shrink:0;
        border-right:none;border-bottom:1px solid var(--border);
        overflow-x:auto;overflow-y:hidden;
        flex-direction:row;padding:0;
        display:none;
    }
    .sidebar.open{display:flex;flex-wrap:wrap;}
    .sidebar .nav-section{display:flex;flex-wrap:wrap;gap:4px;padding:8px;}
    .sidebar .nav-label{display:none;}
    .sidebar .nav-btn{width:auto;padding:6px 12px;font-size:12px;}

    .mobile-menu-btn{display:block;}

    .ex-list{
        width:100%;border-right:none;border-bottom:1px solid var(--border);
        max-height:200px;overflow-y:auto;
    }
    .ex-list:empty{display:none;}

    .content{overflow-y:auto;}
    .content-inner{padding:12px 14px 30px;}

    .topic-grid{grid-template-columns:1fr;}
    .topic-card:last-child{grid-column:span 1;}

    .header{padding:8px 14px;flex-wrap:wrap;gap:8px;}

    .code-editor{min-height:150px;font-size:12px;padding:12px 14px;}
    .output-box{min-height:80px;padding:12px 14px;}

    .prof-bubble{flex-direction:column;gap:10px;}
    .prof-avatar{width:36px;height:36px;font-size:18px;}

    .tabs{overflow-x:auto;}
    .tab-btn{white-space:nowrap;padding:6px 12px;font-size:12px;}

    /* SQL nav compact */
    .sql-nav-bar{flex-wrap:wrap;gap:4px;padding:6px 10px;}
    .sql-nav-counter{font-size:11px;}

    /* Paywall responsive */
    .pw-card{padding:24px 20px;}
    .pw-price{font-size:32px;}
}

/* Mobile portrait: < 480px */
@media (max-width: 480px) {
    .header .progress-bar{display:none;}
    #prog-text{display:none;}
    .status-pill{font-size:9px;padding:2px 6px;}
    .editor-topbar{padding:5px 10px;}
    .editor-dots{display:none;}
}