/* =============================================================
   C Programming Course — Light Theme Stylesheet
   Matches ABCL TECH main site (white bg, green accent #39b549)
   Shared across all lecture and index pages.
   ============================================================= */

:root {
    --bg: #ffffff;
    --bg-soft: #f8f9fa;
    --bg-card: #ffffff;
    --bg-code: #0f172a;         /* dark code block for contrast */
    --bg-output: #f1f5f9;
    --text: #1a1a1a;
    --text-soft: #555;
    --text-mute: #6b7280;
    --border: #e5e7eb;
    --border-strong: #d1d5db;

    --accent: #39b549;           /* site green */
    --accent-hover: #2d8c3a;
    --accent-soft: #e6f4e8;
    --accent-dark: #1f6e2a;

    --blue: #2563eb;             /* for links/highlights */
    --blue-soft: #eff6ff;
    --purple: #7c3aed;
    --purple-soft: #f5f3ff;
    --orange: #ea580c;
    --orange-soft: #fff7ed;
    --red: #dc2626;
    --red-soft: #fef2f2;
    --yellow: #ca8a04;
    --yellow-soft: #fefce8;

    --radius: 10px;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.05);
    --shadow: 0 4px 12px rgba(0,0,0,0.06);
    --shadow-lg: 0 12px 30px rgba(0,0,0,0.08);
}

/* ---------- Base ---------- */
body {
    font-family: 'Roboto', 'Hind Siliguri', sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
}

h1, h2, h3, h4, h5 {
    font-family: 'Roboto', 'Hind Siliguri', sans-serif;
    color: #0f172a;
    font-weight: 700;
    line-height: 1.3;
}

h2 { font-size: 1.6rem; margin-bottom: 1rem; }
h3 { font-size: 1.2rem; margin-bottom: 0.8rem; }

p { margin-bottom: 1rem; color: #374151; }

strong { color: #0f172a; font-weight: 700; }

code {
    background: var(--accent-soft);
    color: var(--accent-dark);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.9em;
    font-family: 'JetBrains Mono', 'Courier New', monospace;
    font-weight: 500;
}

/* ---------- Bengali ---------- */
.bn {
    font-family: 'Hind Siliguri', 'Noto Sans Bengali', sans-serif;
    color: #374151;
    line-height: 1.85;
}
.bn-inline {
    font-family: 'Hind Siliguri', sans-serif;
    color: var(--accent-dark);
    background: var(--accent-soft);
    padding: 1px 6px;
    border-radius: 4px;
    font-size: 0.95em;
}
.bangla-note {
    background: linear-gradient(135deg, var(--accent-soft), #ecfdf5);
    border-left: 4px solid var(--accent);
    padding: 0.9rem 1.1rem;
    border-radius: 0 8px 8px 0;
    margin: 1rem 0;
    font-family: 'Hind Siliguri', 'Roboto', sans-serif;
    color: #14532d;
    line-height: 1.85;
}
.bangla-note::before {
    content: "🇧🇩 বাংলায় বুঝি";
    display: block;
    font-size: 0.72rem;
    color: var(--accent-dark);
    font-weight: 700;
    letter-spacing: 1px;
    text-transform: uppercase;
    margin-bottom: 0.35rem;
    font-family: 'Roboto', sans-serif;
}

/* ---------- Layout ---------- */
html, body { overflow-x: hidden; }
main { padding-top: 0; padding-bottom: 0.5rem; }

.course-container {
    max-width: 980px;
    margin: 0 auto 1rem;
    padding: 0 1.2rem 1.5rem;
}

/* Page hero sits flush with the site nav — match AI Foundations */
body > main:first-of-type,
.course-container:first-child { margin-top: 0; }

/* Standard spacing before footer */
.nav-buttons { margin-bottom: 1rem; }
.summary     { margin-bottom: 1.2rem; }

/* Adsense slot spacing */
.ad-slot {
    margin: 2rem 0;
    min-height: 90px;
    display: flex; align-items: center; justify-content: center;
    background: var(--bg-soft);
    border: 1px dashed var(--border);
    border-radius: 8px;
    color: var(--text-mute);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 1.5px;
    overflow: hidden;
}
.ad-slot ins { display: block; width: 100%; min-height: 90px; }

/* ---------- Module Header (Hero — matches AI Foundations full-bleed dark hero) ---------- */
.module-header {
    background: linear-gradient(135deg, #020c1a 0%, #0d1f3c 50%, #0a2818 100%);
    color: #e2e8f0;
    /* Escape the .course-container max-width and span the full viewport */
    width: 100vw;
    margin-left: calc(50% - 50vw);
    margin-right: calc(50% - 50vw);
    margin-top: 0;
    margin-bottom: 1.8rem;
    padding: 2.4rem max(1.4rem, calc(50vw - 410px)) 2rem;
    border-radius: 0;
    border-bottom: none;
    position: relative;
    overflow: hidden;
}
.module-header::before {
    content: '';
    position: absolute; inset: 0;
    background: radial-gradient(ellipse 60% 50% at 50% 30%, rgba(57,181,73,0.12) 0%, transparent 70%);
    pointer-events: none;
}
.module-header > * { position: relative; z-index: 1; }

.breadcrumb {
    font-size: 0.8rem;
    color: #94a3b8;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 0.7rem;
}
.breadcrumb a { color: #4ade80; }
.breadcrumb a:hover { text-decoration: underline; }
.module-header strong { color: #f1f5f9; }

.module-title {
    font-size: clamp(1.7rem, 4vw, 2.5rem);
    color: #f1f5f9;
    letter-spacing: -0.01em;
}
.module-subtitle {
    color: #94a3b8;
    font-size: 1.05rem;
    margin-top: 0.6rem;
}
.meta-row {
    display: flex; flex-wrap: wrap; gap: 0.6rem;
    margin-top: 1rem; font-size: 0.85rem;
}
.module-header .meta-chip {
    background: rgba(255,255,255,0.07);
    border: 1px solid rgba(255,255,255,0.13);
    color: #cbd5e1;
}
.module-header .meta-chip i { color: #4ade80; }
/* Default meta-chip (when used outside the dark hero) */
.meta-chip {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.3rem 0.7rem;
    background: var(--bg-soft);
    border: 1px solid var(--border);
    border-radius: 50px;
    color: var(--text-soft);
}
.meta-chip i { color: var(--accent); }

/* ---------- Content Blocks ---------- */
.content-block {
    margin-bottom: 2.4rem;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.8rem;
    box-shadow: var(--shadow-sm);
    transition: box-shadow 0.2s;
}
.content-block:hover {
    box-shadow: var(--shadow);
}
.content-block.key-concept {
    border-left: 5px solid var(--accent);
}
.content-block.practice {
    background: linear-gradient(135deg, #fffbeb, var(--bg));
    border-color: #fde68a;
}

/* Section titles inside a block */
.section-title {
    color: var(--accent-dark);
    text-transform: uppercase;
    font-size: 0.75rem;
    letter-spacing: 1.5px;
    margin: 1.5rem 0 0.6rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 0.45rem;
}
.section-title i { color: var(--accent); }
.section-title:first-child { margin-top: 0.5rem; }

/* ---------- Code Block with Run button ---------- */
.code-block {
    margin: 1.2rem 0;
    background: var(--bg-code);
    border-radius: var(--radius);
    overflow: hidden;
    border: 1px solid #1e293b;
    box-shadow: var(--shadow);
}
.code-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.5rem 0.9rem;
    background: #020617;
    border-bottom: 1px solid #1e293b;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.76rem;
    color: #64748b;
}
.code-header .dots { display: flex; gap: 5px; }
.code-header .dots span {
    width: 11px; height: 11px; border-radius: 50%;
}
.code-header .r { background: #ff5f57; }
.code-header .y { background: #febc2e; }
.code-header .g { background: #28c840; }
.code-header .filename { font-family: 'JetBrains Mono', monospace; color: #94a3b8; }
.code-block pre {
    margin: 0;
    padding: 1.1rem 1.2rem;
    overflow-x: auto;
    background: transparent;
    border: none;
    color: #e2e8f0;
    font-family: 'JetBrains Mono', 'Courier New', monospace;
    font-size: 0.88rem;
    line-height: 1.6;
}
.code-block pre code {
    background: transparent;
    color: inherit;
    padding: 0;
    font-family: inherit;
    font-size: inherit;
    font-weight: normal;
}
.kw  { color: #c084fc; }
.str { color: #86efac; }
.fn  { color: #7dd3fc; }
.num { color: #fbbf24; }
.cmt { color: #64748b; font-style: italic; }

.code-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    padding: 0.6rem 0.9rem;
    background: #020617;
    border-top: 1px solid #1e293b;
}
.code-actions button {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.4rem 0.9rem;
    border-radius: 6px;
    border: 1px solid transparent;
    font-family: 'Roboto', sans-serif;
    font-size: 0.82rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.15s;
}
.run-btn {
    background: var(--accent);
    color: white;
}
.run-btn:hover  { background: var(--accent-hover); }
.run-btn:disabled { opacity: 0.65; cursor: wait; }

.copy-btn {
    background: transparent;
    color: #cbd5e1;
    border-color: #334155;
}
.copy-btn:hover { background: #1e293b; color: white; }
.copy-btn.copied { background: var(--accent); color: white; border-color: var(--accent); }

.gdb-btn {
    background: transparent;
    color: #cbd5e1;
    border-color: #334155;
    margin-left: auto;
}
.gdb-btn:hover { background: #1e293b; color: white; }

.spinner {
    width: 11px; height: 11px;
    border: 2px solid rgba(255,255,255,0.3);
    border-top-color: white;
    border-radius: 50%;
    display: inline-block;
    animation: spin 0.6s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

.code-output {
    margin: 0;
    padding: 0.9rem 1.2rem;
    background: var(--bg-output);
    color: #0f172a;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    white-space: pre-wrap;
    word-break: break-word;
    border-top: 2px solid var(--border);
    max-height: 320px;
    overflow-y: auto;
}
.code-output::before {
    content: "▶ Output (আউটপুট)";
    display: block;
    font-size: 0.7rem;
    color: var(--accent-dark);
    font-weight: 700;
    letter-spacing: 1.5px;
    text-transform: uppercase;
    margin-bottom: 0.4rem;
    font-family: 'Roboto', sans-serif;
}
.code-output.success { border-top-color: var(--accent); }
.code-output.error   { border-top-color: var(--red); color: var(--red); background: var(--red-soft); }
.code-output.running { color: var(--blue); }

/* ---------- Practice / Answer ---------- */
.problem-list {
    list-style: none;
    counter-reset: prob;
    padding: 0;
    margin: 0.5rem 0;
}
.problem-list > li {
    counter-increment: prob;
    position: relative;
    padding: 1rem 0 1rem 3rem;
    border-bottom: 1px dashed var(--border);
}
.problem-list > li:last-child { border-bottom: none; }
.problem-list > li::before {
    content: counter(prob, decimal-leading-zero);
    position: absolute; left: 0; top: 1rem;
    background: var(--accent);
    color: white;
    font-weight: 700;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.78rem;
    padding: 0.15rem 0.5rem;
    border-radius: 6px;
}
.problem-list .q-text {
    color: var(--text);
    font-weight: 500;
    margin-bottom: 0.3rem;
}
.problem-list .q-bn {
    font-family: 'Hind Siliguri', sans-serif;
    color: #4b5563;
    font-size: 0.93em;
    margin-bottom: 0.5rem;
    line-height: 1.7;
}

details.answer {
    margin-top: 0.5rem;
    background: var(--bg-soft);
    border: 1px solid var(--border);
    border-radius: 8px;
}
details.answer[open] {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-soft);
}
details.answer summary {
    cursor: pointer;
    padding: 0.6rem 1rem;
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--accent-dark);
    list-style: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    user-select: none;
}
details.answer summary::before {
    content: '▶';
    font-size: 0.7rem;
    transition: transform 0.2s;
}
details.answer[open] summary::before { transform: rotate(90deg); }
details.answer summary::-webkit-details-marker { display: none; }
details.answer .answer-body {
    padding: 0 1rem 1rem;
}

/* ---------- Callouts ---------- */
.callout {
    padding: 1rem 1.2rem;
    border-radius: 8px;
    margin: 1rem 0;
    font-size: 0.95rem;
    border-left: 4px solid;
    background: var(--bg-soft);
}
.callout strong:first-child {
    display: block;
    margin-bottom: 0.35rem;
    font-size: 0.95em;
    letter-spacing: 0.5px;
}
.callout.tip    { border-color: var(--accent);  background: var(--accent-soft); }
.callout.tip strong:first-child    { color: var(--accent-dark); }
.callout.warn   { border-color: var(--orange);  background: var(--orange-soft); }
.callout.warn strong:first-child   { color: var(--orange); }
.callout.danger { border-color: var(--red);     background: var(--red-soft); }
.callout.danger strong:first-child { color: var(--red); }
.callout.note   { border-color: var(--blue);    background: var(--blue-soft); }
.callout.note strong:first-child   { color: var(--blue); }
.callout.proof  { border-color: var(--purple);  background: var(--purple-soft); }
.callout.proof strong:first-child  { color: var(--purple); }

/* ---------- Tables ---------- */
.ctable {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0;
    margin: 1rem 0;
    font-size: 0.92rem;
    background: white;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}
.ctable th, .ctable td {
    text-align: left;
    padding: 0.7rem 0.95rem;
    border-bottom: 1px solid var(--border);
    vertical-align: top;
}
.ctable th {
    background: var(--bg-soft);
    color: var(--text);
    font-weight: 700;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.8px;
}
.ctable tr:last-child td { border-bottom: none; }
.ctable tr:hover td { background: var(--accent-soft); }
.ctable code { font-size: 0.85em; }

/* ---------- Visualizations ---------- */
.viz {
    margin: 1.2rem 0;
    padding: 1rem;
    background: var(--bg-soft);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    text-align: center;
}
.viz svg { max-width: 100%; height: auto; }
.viz-caption {
    display: block;
    margin-top: 0.6rem;
    font-size: 0.85rem;
    color: var(--text-mute);
    font-style: italic;
}

/* ---------- Comparison grid ---------- */
.comparison-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin: 1.2rem 0;
}
.comparison-card {
    padding: 1.2rem;
    border-radius: 8px;
    border: 1px solid var(--border);
    background: white;
    box-shadow: var(--shadow-sm);
}
.comparison-card h4 { font-size: 1rem; margin-bottom: 0.6rem; }
.comparison-card.good { border-top: 4px solid var(--accent); }
.comparison-card.bad  { border-top: 4px solid var(--red); }
.comparison-card.neutral { border-top: 4px solid var(--blue); }
.comparison-card ul { list-style: none; padding: 0; }
.comparison-card li {
    padding: 0.3rem 0 0.3rem 1.3rem;
    position: relative;
    color: var(--text-soft);
    font-size: 0.9rem;
}
.comparison-card.good li::before { content: '✓'; color: var(--accent); position: absolute; left: 0; font-weight: 700; }
.comparison-card.bad li::before  { content: '✗'; color: var(--red); position: absolute; left: 0; font-weight: 700; }
.comparison-card.neutral li::before { content: '●'; color: var(--blue); position: absolute; left: 0; }
@media (max-width: 720px) { .comparison-grid { grid-template-columns: 1fr; } }

/* ---------- Info chips grid ---------- */
.chip-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
    gap: 0.8rem;
    margin: 0.8rem 0;
}
.info-chip {
    display: flex;
    gap: 0.8rem;
    padding: 0.9rem 1rem;
    background: var(--bg-soft);
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 0.92rem;
}
.info-chip i {
    color: var(--accent);
    font-size: 1.3rem;
    flex-shrink: 0;
    margin-top: 2px;
}

/* ---------- Checklist / plain list ---------- */
ul.checklist, ul.plain { list-style: none; padding: 0; margin: 0.4rem 0 1rem; }
ul.checklist li {
    padding: 0.35rem 0 0.35rem 1.7rem;
    position: relative;
    color: #374151;
}
ul.checklist li::before {
    content: '✓';
    position: absolute; left: 0;
    color: var(--accent);
    font-weight: 700;
}
ul.plain li {
    padding: 0.3rem 0 0.3rem 1.3rem;
    position: relative;
    color: #374151;
}
ul.plain li::before {
    content: '▸';
    position: absolute; left: 0;
    color: var(--accent);
}

/* ---------- Timeline ---------- */
.timeline {
    margin: 1rem 0;
    border-left: 3px solid var(--accent);
    padding: 0.3rem 0 0.3rem 1.3rem;
}
.tl-item {
    display: flex;
    gap: 1rem;
    padding: 0.45rem 0;
    color: #374151;
    font-size: 0.93rem;
    position: relative;
}
.tl-year {
    font-family: 'JetBrains Mono', monospace;
    color: var(--accent-dark);
    font-weight: 700;
    min-width: 60px;
    flex-shrink: 0;
    background: var(--accent-soft);
    padding: 0.15rem 0.5rem;
    border-radius: 4px;
    font-size: 0.82rem;
    text-align: center;
    align-self: flex-start;
}

/* ---------- Summary / Next ---------- */
.summary {
    margin-top: 1.5rem;
    padding: 1.5rem 1.8rem;
    background: linear-gradient(135deg, var(--accent-soft), #ecfdf5);
    border: 1px solid var(--accent);
    border-radius: var(--radius);
}
.summary h3 { color: var(--accent-dark); margin-bottom: 0.7rem; }
.summary .next-class {
    margin-top: 0.8rem;
    color: var(--accent-dark) !important;
    font-style: italic;
}

/* ---------- Navigation buttons ---------- */
.nav-buttons {
    display: flex;
    justify-content: space-between;
    gap: 0.8rem;
    margin-top: 1.5rem;
    padding-top: 1.2rem;
    border-top: 1px solid var(--border);
}
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.75rem 1.3rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.92rem;
    transition: all 0.2s;
}
.btn-primary {
    background: var(--accent);
    color: white;
}
.btn-primary:hover {
    background: var(--accent-hover);
    color: white;
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}
.btn-outline {
    background: white;
    color: var(--text);
    border: 1px solid var(--border-strong);
}
.btn-outline:hover {
    border-color: var(--accent);
    color: var(--accent-dark);
}

/* ---------- Responsive ---------- */
@media (max-width: 640px) {
    .course-container { padding: 0.8rem; }
    .content-block { padding: 1.2rem; }
    .module-title { font-size: 1.7rem; }
    .nav-buttons { flex-direction: column; }
    .btn { justify-content: center; }
    .code-actions { justify-content: flex-start; }
    .gdb-btn { margin-left: 0; }
}