:root{--bg:#faf6f0;--card:#fffcf7;--warm:#c2703e;--warm-light:#f5e6d4;--warm-dark:#8a4a24;--warm-bg:#fef8f2;--olive:#5a6e3c;--olive-light:#e8edde;--olive-dark:#3d4d27;--red:#b84838;--red-light:#fce4e0;--ink:#2c2420;--text:#453a32;--dim:#8a7e74;--border:rgba(180,165,148,0.35);--mono:'JetBrains Mono',monospace;--serif:'Lora',Georgia,serif;--body:'Source Sans 3',sans-serif;--radius:10px;--radius-lg:14px}
*{margin:0;padding:0;box-sizing:border-box}
body{background:var(--bg);color:var(--text);font-family:var(--body);line-height:1.7;font-size:16px}
::selection{background:var(--warm-light);color:var(--warm-dark)}
.container{max-width:920px;margin:0 auto;padding:32px 28px 80px}

.top-nav{display:flex;justify-content:space-between;align-items:center;margin-bottom:24px;padding-bottom:14px;border-bottom:1px solid var(--border);gap:10px;flex-wrap:wrap}
.top-nav a{font-family:var(--mono);font-size:0.82rem;font-weight:600;color:var(--warm);text-decoration:none;transition:color 0.2s}
.top-nav a:hover{color:var(--warm-dark)}
.top-nav .task-num{font-family:var(--mono);font-size:0.78rem;color:var(--dim);font-weight:600;display:inline-flex;align-items:center;gap:8px}

h1{font-family:var(--serif);font-size:1.95rem;font-weight:700;color:var(--ink);letter-spacing:-0.01em;margin-bottom:6px;line-height:1.25}
h1 .num{color:var(--warm)}

.meta{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:22px;margin-top:10px}
.tag{display:inline-block;padding:3px 10px;border-radius:6px;font-size:0.7rem;font-weight:700;text-transform:uppercase;letter-spacing:0.04em;background:var(--warm-light);color:var(--warm-dark);font-family:var(--mono)}
.tag.olive{background:var(--olive-light);color:var(--olive)}
.tag.time{background:rgba(180,165,148,0.2);color:var(--dim)}

.description{background:var(--card);border:1px solid var(--border);border-radius:var(--radius-lg);padding:18px 22px;margin-bottom:24px}
.description p{font-size:0.94rem;color:var(--text);margin:0 0 10px}
.description p:last-child{margin:0}
.description strong{color:var(--ink)}
.description code{background:rgba(194,112,62,0.12);padding:1px 6px;border-radius:4px;font-family:var(--mono);font-size:0.83rem;color:var(--warm-dark)}

.kotlin-code-wrap{margin-bottom:18px}

.lang-tabs{display:flex;gap:2px;margin-bottom:14px;border-bottom:2px solid var(--border)}
.lang-tab{padding:8px 18px;border:none;background:none;font-family:var(--mono);font-size:0.82rem;font-weight:600;color:var(--dim);cursor:pointer;border-bottom:2px solid transparent;margin-bottom:-2px;transition:all 0.2s;letter-spacing:0.02em}
.lang-tab:hover{color:var(--warm)}
.lang-tab.active{color:var(--warm-dark);border-bottom-color:var(--warm)}
.hidden{display:none !important}
.lang-stack{display:grid;grid-template-columns:1fr}
.lang-stack > [data-lang-pane]{grid-row:1;grid-column:1;transition:opacity 0.15s}
.lang-stack > [data-lang-pane].lang-pane-inactive{visibility:hidden;pointer-events:none;opacity:0}

.tests-block{background:var(--card);border:1px solid var(--border);border-left:3px solid var(--olive);border-radius:var(--radius);padding:16px 22px;margin-bottom:24px}
.tests-block h3{font-family:var(--mono);font-size:0.72rem;font-weight:700;color:var(--olive);text-transform:uppercase;letter-spacing:0.06em;margin-bottom:10px}
.tests-block ol{margin:0;padding-left:22px}
.tests-block li{font-size:0.9rem;color:var(--text);margin-bottom:6px;line-height:1.55}
.tests-block li:last-child{margin-bottom:0}
.tests-block li strong{color:var(--ink)}
.tests-block code{background:rgba(90,110,60,0.1);padding:1px 5px;border-radius:3px;font-family:var(--mono);font-size:0.82rem;color:var(--olive-dark)}

.actions{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:14px}
.btn{padding:8px 16px;border-radius:var(--radius);border:1.5px solid var(--border);background:var(--card);color:var(--text);font-family:var(--body);font-size:0.85rem;font-weight:600;cursor:pointer;transition:all 0.2s}
.btn:hover{border-color:var(--warm);color:var(--warm-dark)}

.box{border-radius:var(--radius);padding:14px 18px;margin-bottom:14px;transition:all 0.2s}
.box.hidden{display:none}
.box .label{font-size:0.68rem;font-weight:700;text-transform:uppercase;letter-spacing:0.06em;margin-bottom:6px;font-family:var(--mono)}
.box.hint{background:var(--warm-light);border:1px solid rgba(194,112,62,0.2)}
.box.hint .label{color:var(--warm)}
.box.hint p{color:var(--warm-dark)}
.box.solution{background:var(--olive-light);border:1px solid rgba(90,110,60,0.2)}
.box.solution .label{color:var(--olive)}
.box p{font-size:0.9rem;margin:0 0 8px;color:var(--olive-dark)}
.box p:last-of-type{margin:0}
.box pre{background:#2c2420;border-radius:6px;padding:14px 16px;margin-top:10px;font-family:var(--mono);font-size:0.78rem;line-height:1.55;color:#e8ddd0;overflow-x:auto;white-space:pre}

.task-nav{display:flex;justify-content:space-between;margin-top:36px;padding-top:24px;border-top:1px solid var(--border);gap:10px}
.task-nav a{font-family:var(--mono);font-size:0.82rem;color:var(--warm);text-decoration:none;font-weight:600;padding:9px 16px;border:1.5px solid var(--border);border-radius:var(--radius);background:var(--card);transition:all 0.2s}
.task-nav a:hover{border-color:var(--warm);background:var(--warm-bg)}
.task-nav a.disabled{color:var(--dim);pointer-events:none;opacity:0.4}

.status-badge{display:inline-block;padding:3px 9px;border-radius:6px;font-family:var(--mono);font-size:0.68rem;font-weight:700;background:rgba(180,165,148,0.2);color:var(--dim);text-transform:uppercase;letter-spacing:0.04em}
.status-badge.solved{background:var(--olive-light);color:var(--olive)}

header.hub{text-align:center;margin-bottom:36px}
header.hub h1{font-size:2.4rem;margin-bottom:8px}
header.hub .sub{color:var(--dim);font-size:0.95rem;max-width:560px;margin:0 auto}

.progress-summary{background:var(--card);border:1px solid var(--border);border-radius:var(--radius-lg);padding:18px 22px;margin-bottom:36px;display:flex;justify-content:space-between;align-items:center;gap:14px;flex-wrap:wrap}
.progress-summary .text{font-family:var(--mono);font-size:0.88rem;color:var(--text)}
.progress-summary .text strong{color:var(--ink);font-size:1.05rem}
.progress-summary .reset{font-family:var(--mono);font-size:0.74rem;color:var(--dim);background:none;border:1px solid var(--border);padding:5px 12px;border-radius:6px;cursor:pointer;transition:all 0.2s}
.progress-summary .reset:hover{color:var(--red);border-color:var(--red)}
.progress-bar{flex:1;min-width:200px;height:6px;background:rgba(180,165,148,0.2);border-radius:3px;overflow:hidden}
.progress-fill{height:100%;background:linear-gradient(90deg,var(--warm),var(--olive));border-radius:3px;transition:width 0.4s}

.day-section{margin-bottom:32px}
.day-label{font-family:var(--mono);font-size:0.7rem;font-weight:700;color:var(--warm);text-transform:uppercase;letter-spacing:0.08em;margin-bottom:6px}
.day-title{font-family:var(--serif);font-size:1.3rem;font-weight:700;color:var(--ink);margin-bottom:14px}
.task-list{display:grid;grid-template-columns:1fr;gap:10px}
@media(min-width:720px){.task-list{grid-template-columns:1fr 1fr}}
.task-card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:16px 20px;text-decoration:none;color:inherit;transition:all 0.2s;display:flex;flex-direction:column;gap:4px;position:relative;overflow:hidden}
.task-card::before{content:"";position:absolute;left:0;top:0;bottom:0;width:3px;background:var(--warm);opacity:0;transition:opacity 0.2s}
.task-card:hover{border-color:var(--warm);transform:translateY(-1px);box-shadow:0 4px 14px rgba(194,112,62,0.06)}
.task-card:hover::before{opacity:1}
.task-card.solved::before{background:var(--olive);opacity:1}
.task-card .head{display:flex;justify-content:space-between;align-items:baseline;gap:8px}
.task-card .num{font-family:var(--mono);font-size:0.7rem;color:var(--warm);font-weight:700;text-transform:uppercase;letter-spacing:0.06em}
.task-card h3{font-family:var(--serif);font-size:1.05rem;color:var(--ink);font-weight:600;margin:4px 0;line-height:1.35}
.task-card .meta-row{display:flex;gap:6px;flex-wrap:wrap;margin-top:6px}

@media(max-width:640px){.container{padding:20px 16px 60px}h1{font-size:1.55rem}header.hub h1{font-size:1.85rem}.top-nav a,.top-nav .task-num{font-size:0.74rem}}