/* FirstHack reader: tutorials and course lessons. Learning blocks, quiz, progress bar, text size. */

/* comfortable line length on wide screens */
.ls-art{max-width:760px}
.ls-art,.with-side .article{font-size:calc(1em * var(--rd-scale,1))}

/* reading progress */
.rd-bar{position:fixed;left:0;top:0;height:3px;width:0;z-index:200;background:linear-gradient(90deg,#dc2733,#9c0e19);transition:width .1s linear;pointer-events:none}

/* text size */
.rd-tools{display:flex;justify-content:flex-end;align-items:center;gap:6px;margin:-4px 0 10px;font-size:13px;color:var(--text-faint,#8a909c)}
.rd-tools button{width:34px;height:30px;border:1px solid var(--border,#e4e5e9);border-radius:8px;background:var(--surface,#fff);color:var(--text,#14161a);cursor:pointer;font:600 13px/1 var(--font,inherit)}
.rd-tools button:hover{border-color:var(--blue,#c1121f);color:var(--blue,#c1121f)}

/* "on this page": current section */
.ls-onpage a.rd-on,.side a.rd-on{color:var(--blue,#c1121f)!important;font-weight:600}

/* ---- boxes: learn / key points / mistakes ---- */
.lb{border:1px solid var(--border,#e4e5e9);border-radius:16px;padding:16px 18px 6px;margin:22px 0;background:var(--surface,#fff)}
.lb-h{display:flex;align-items:center;gap:10px;font-weight:700;font-size:1.02em;margin-bottom:8px;color:var(--text,#14161a)}
.lb-ic{width:30px;height:30px;border-radius:9px;display:grid;place-items:center;font-size:16px;flex:0 0 auto}
.lb-body>*:first-child{margin-top:0}
.lb-body ul,.lb-body ol{padding-left:1.2em}
.lb-body li{margin:4px 0}
.lb-learn{background:linear-gradient(180deg,#f3f7ff,var(--surface,#fff));border-color:#d9e4fb}
.lb-learn .lb-ic{background:#e3ecff}
.lb-keypoints{background:linear-gradient(180deg,#f1fbf5,var(--surface,#fff));border-color:#cfeedd}
.lb-keypoints .lb-ic{background:#dcf5e7}
.lb-mistakes{background:linear-gradient(180deg,#fff7ec,var(--surface,#fff));border-color:#f6dfbd}
.lb-mistakes .lb-ic{background:#ffecd0}
[data-theme="dark"] .lb-learn,[data-theme="dark"] .lb-keypoints,[data-theme="dark"] .lb-mistakes{background:var(--surface,#16181d)}
[data-theme="dark"] .lb-learn .lb-ic,[data-theme="dark"] .lb-keypoints .lb-ic,[data-theme="dark"] .lb-mistakes .lb-ic{background:rgba(255,255,255,.07)}

/* ---- exercises ---- */
.lb-ex{border-left:4px solid var(--blue,#c1121f);padding-bottom:12px}
.lb-num{display:inline-flex;align-items:center;height:24px;padding:0 9px;border-radius:999px;background:var(--blue-tint,#fdecee);color:var(--blue,#c1121f);font-size:12px;font-weight:700;letter-spacing:.02em}
.lb-det{margin-top:8px;border:1px solid var(--border,#e4e5e9);border-radius:11px;background:var(--bg,#fbfbfc)}
.lb-det summary{cursor:pointer;list-style:none;padding:10px 14px;font-weight:600;font-size:.94em;color:var(--text-dim,#5b6170);display:flex;align-items:center;gap:8px}
.lb-det summary::-webkit-details-marker{display:none}
.lb-det summary::before{content:"";width:8px;height:8px;border-right:2px solid currentColor;border-bottom:2px solid currentColor;transform:rotate(-45deg);transition:transform .15s}
.lb-det[open] summary::before{transform:rotate(45deg)}
.lb-det[open] summary{color:var(--text,#14161a)}
.lb-sol summary{color:var(--blue,#c1121f)}
.lb-det-b{padding:0 14px 6px}

/* ---- viva / interview ---- */
.viva{display:grid;gap:8px;margin:14px 0 22px}
.viva-q{border:1px solid var(--border,#e4e5e9);border-radius:12px;background:var(--surface,#fff)}
.viva-q summary{cursor:pointer;list-style:none;display:flex;gap:12px;align-items:flex-start;padding:13px 14px;font-weight:600}
.viva-q summary::-webkit-details-marker{display:none}
.viva-q summary::after{content:"+";margin-left:auto;font-size:20px;line-height:1;color:var(--text-faint,#8a909c);flex:0 0 auto}
.viva-q[open] summary::after{content:"−"}
.viva-q[open]{border-color:color-mix(in srgb,var(--blue,#c1121f) 35%,var(--border,#e4e5e9))}
.viva-n{flex:0 0 auto;min-width:30px;height:24px;border-radius:7px;display:grid;place-items:center;font-size:12px;font-weight:700;background:var(--surface-2,#f2f3f5);color:var(--text-dim,#5b6170)}
.viva-a{padding:0 14px 4px 56px;color:var(--text,#14161a)}
@media (max-width:520px){ .viva-a{padding-left:14px} }

/* ---- quiz ---- */
.quiz{display:grid;gap:14px;margin:14px 0 26px}
.qz-q{border:1px solid var(--border,#e4e5e9);border-radius:16px;padding:14px 16px;background:var(--surface,#fff)}
.qz-t{display:flex;gap:10px;align-items:flex-start;font-weight:600;margin:0 0 12px}
.qz-n{flex:0 0 auto;width:26px;height:26px;border-radius:50%;display:grid;place-items:center;font-size:13px;background:var(--text,#14161a);color:var(--surface,#fff)}
.qz-opts{display:grid;gap:8px}
.qz-o{display:flex;align-items:flex-start;gap:10px;width:100%;text-align:left;padding:11px 12px;border:1.5px solid var(--border,#e4e5e9);border-radius:12px;background:var(--surface,#fff);
  color:var(--text,#14161a);font:inherit;font-size:.96em;cursor:pointer;transition:border-color .12s,background .12s}
.qz-o:hover:not([disabled]){border-color:color-mix(in srgb,var(--blue,#c1121f) 45%,var(--border,#e4e5e9))}
.qz-l{flex:0 0 auto;width:24px;height:24px;border-radius:7px;display:grid;place-items:center;font-size:12px;font-weight:700;background:var(--surface-2,#f2f3f5);color:var(--text-dim,#5b6170)}
.qz-o[disabled]{cursor:default}
.qz-o.ok{border-color:#1f9d55;background:#ecf8f1}.qz-o.ok .qz-l{background:#1f9d55;color:#fff}
.qz-o.bad{border-color:#c1121f;background:#fdecee}.qz-o.bad .qz-l{background:#c1121f;color:#fff}
[data-theme="dark"] .qz-o.ok{background:rgba(31,157,85,.15)}[data-theme="dark"] .qz-o.bad{background:rgba(193,18,31,.15)}
.qz-exp{margin-top:10px;padding:10px 12px;border-radius:10px;background:var(--surface-2,#f2f3f5);font-size:.94em;line-height:1.55}
.qz-score{display:flex;align-items:center;gap:12px;padding:14px 16px;border-radius:14px;font-weight:600;background:linear-gradient(135deg,#fff5f6,#fff);border:1px solid #f3c9cc}
[data-theme="dark"] .qz-score{background:var(--surface,#16181d)}
.qz-score b{font-size:22px;color:var(--blue,#c1121f)}
.qz-score button{margin-left:auto;border:1px solid var(--border,#e4e5e9);background:var(--surface,#fff);border-radius:9px;padding:8px 12px;font:600 13px/1 var(--font,inherit);cursor:pointer;color:var(--text,#14161a)}
.qz-ns{color:var(--text-faint,#8a909c);font-size:13px}

@media (max-width:520px){
  .lb{padding:14px 14px 4px;border-radius:14px}
  .qz-q{padding:12px}
}
@media print{ .rd-bar,.rd-tools{display:none} .lb-det,.viva-q{break-inside:avoid} details{display:block} }
.qz-tx,.lb-tt{min-width:0;flex:1}