:root {
  --bg: #fbfbf8;
  --text: #171717;
  --muted: #666;
  --light: #e5e5df;
  --accent: #1f5eff;
  --dark: #171717;
  --max: 1100px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Inter", sans-serif;
  line-height: 1.6;
}

/* =========================
   CONTAINER
========================= */

.container {
  width: min(calc(100% - 40px), var(--max));
  margin: 0 auto;
}


/* =========================
   HEADER
========================= */

.site-header {
  border-bottom: 1px solid var(--light);
  background: var(--bg);
}

.nav {
  min-height: 76px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 30px;
}

.brand {
  color: var(--text);
  text-decoration: none;
  font-weight: 600;
}

nav {
  display: flex;
  align-items: center;
  gap: 26px;
}

nav a {
  color: var(--text);
  text-decoration: none;
  font-size: 0.95rem;
}

nav a:hover {
  color: var(--accent);
}


/* =========================
   SECTIONS
========================= */

.section {
  padding: 80px 0;
}

.section-heading {
  display: flex;
  align-items: baseline;
  gap: 16px;
  margin-bottom: 34px;
}

.section-heading span {
  color: var(--accent);
  font-family: "DM Mono", monospace;
  font-size: 0.85rem;
}

.section-heading h2 {
  margin: 0;
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  line-height: 1.2;
}


/* =========================
   PROJECT / INTRO
========================= */

.project {
  border-top: 1px solid var(--light);
  padding-top: 30px;
}

.project-meta {
  margin-bottom: 14px;
  color: var(--muted);
  font-family: "DM Mono", monospace;
  font-size: 0.75rem;
  letter-spacing: 0.05em;
}

.project h1 {
  margin: 0 0 18px;
  font-size: clamp(2rem, 5vw, 3.8rem);
  line-height: 1.1;
}

.project h3 {
  margin: 0 0 8px;
  font-size: 1.25rem;
}

.project-lead {
  max-width: 760px;
  font-size: 1.12rem;
}


/* =========================
   PYTHON TOPICS
========================= */

.topic-list {
  border-top: 1px solid var(--light);
}

.topic {
  display: grid;
  grid-template-columns: 60px 1fr;
  gap: 20px;

  padding: 24px 0;

  border-bottom: 1px solid var(--light);

  color: var(--text);
  text-decoration: none;

  transition:
    padding-left 0.15s ease,
    color 0.15s ease;
}

.topic:hover {
  padding-left: 8px;
}

.topic:hover h3 {
  color: var(--accent);
}

.topic-number {
  padding-top: 3px;

  color: var(--accent);

  font-family: "DM Mono", monospace;
  font-size: 0.9rem;
}

.topic h3 {
  margin: 0 0 5px;

  font-size: 1.05rem;
  line-height: 1.4;

  transition: color 0.15s ease;
}

.topic p {
  margin: 0;

  color: var(--muted);

  font-size: 0.95rem;
}


/* =========================
   PYTHON EDITOR
========================= */

.python-editor {
  margin-top: 30px;
}


/* =========================
   CODE EDITOR
========================= */

#code {
  display: block;

  width: 100%;
  min-height: 320px;

  padding: 20px;

  resize: vertical;

  border: 1px solid #292929;
  border-radius: 6px;

  background: var(--dark);
  color: #f4f4f4;

  font-family: "DM Mono", monospace;
  font-size: 0.9rem;
  line-height: 1.6;

  outline: none;

  tab-size: 4;
}

#code:focus {
  border-color: var(--accent);
}


/* =========================
   EDITOR BUTTONS
========================= */

.editor-actions {
  display: flex;
  align-items: center;
  gap: 10px;

  margin: 14px 0 24px;
}

button {
  border: 0;
  border-radius: 4px;

  padding: 11px 18px;

  background: var(--accent);
  color: white;

  font-family: "Inter", sans-serif;
  font-weight: 600;

  cursor: pointer;

  transition:
    opacity 0.15s ease,
    transform 0.15s ease;
}

button:hover:not(:disabled) {
  opacity: 0.9;
}

button:active:not(:disabled) {
  transform: translateY(1px);
}

button:disabled {
  cursor: wait;
  opacity: 0.55;
}

.secondary-button {
  border: 1px solid var(--light);

  background: transparent;
  color: var(--text);
}

.secondary-button:hover {
  background: #f1f1ed;
}


/* =========================
   OUTPUT
========================= */

.output-label {
  margin-bottom: 8px;

  color: var(--muted);

  font-family: "DM Mono", monospace;
  font-size: 0.75rem;
  letter-spacing: 0.05em;
}

#output {
  min-height: 110px;

  margin: 0;
  padding: 18px;

  overflow-x: auto;
  overflow-y: auto;

  border: 1px solid var(--light);

  background: white;

  color: var(--text);

  font-family: "DM Mono", monospace;
  font-size: 0.85rem;
  line-height: 1.6;

  /*
   * Preserve Python spaces and line breaks.
   * Important for pattern-printing exercises.
   */
  white-space: pre;
}


/* =========================
   PYODIDE RUNNABLE CODE
========================= */

.runnable {
  position: relative;
  margin: 0.75rem 0;
}


/* =========================
   RUN BAR
========================= */

.run-bar {
  display: flex;
  align-items: center;
  gap: 0.6rem;

  margin-top: -0.5rem;
  margin-bottom: 0.5rem;
}


/* =========================
   RUN BUTTON
========================= */

.run-btn {
  font-family: "DM Mono", monospace;
  font-size: 0.8rem;
  font-weight: 600;

  color: white;
  background: var(--accent);

  border: none;
  border-radius: 4px;

  padding: 0.4rem 0.9rem;

  cursor: pointer;

  transition:
    opacity 0.15s ease,
    transform 0.15s ease;

  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.run-btn:hover:not(:disabled) {
  opacity: 0.9;
}

.run-btn:active:not(:disabled) {
  transform: translateY(1px);
}

.run-btn:disabled {
  opacity: 0.5;
  cursor: wait;
}


/* =========================
   RUN STATUS
========================= */

.run-status {
  font-family: "DM Mono", monospace;
  font-size: 0.78rem;
  color: var(--muted);
}


/* =========================
   RUN OUTPUT WRAPPER
========================= */

.run-output-wrap {
  display: none;

  margin: 0.4rem 0 1rem 0;
}

.run-output-wrap.show {
  display: block;
}


/* =========================
   RUN OUTPUT LABEL
========================= */

.run-output-label {
  font-family: "DM Mono", monospace;
  font-size: 0.7rem;

  letter-spacing: 0.14em;
  text-transform: uppercase;

  color: var(--muted);

  margin-bottom: 0.3rem;
}


/* =========================
   RUN OUTPUT
========================= */

.run-output {
  font-family: "DM Mono", monospace;

  font-size: 0.88rem;
  line-height: 1.55;

  background: var(--dark);
  color: #f4f4f4;

  border-radius: 4px;

  padding: 0.85rem 1rem;

  /*
   * CRITICAL:
   * Preserve every space and newline
   * produced by Python.
   */
  white-space: pre;

  /*
   * Allow wide pattern output to scroll
   * instead of wrapping.
   */
  overflow-x: auto;
  overflow-y: auto;

  margin: 0;
}

.run-output.is-error {
  color: #ffb4b4;
}


/* =========================
   EDITABLE CODE CELLS
========================= */

.runnable textarea.code-editable {
  width: 100%;

  font-family: "DM Mono", monospace;
  font-size: 0.92rem;
  line-height: 1.55;

  background: var(--dark);

  border: 1px solid #292929;
  border-left: 3px solid var(--accent);

  border-radius: 4px;

  padding: 1rem 1.1rem;

  color: #f4f4f4;

  resize: vertical;

  min-height: 3.5rem;

  outline: none;

  tab-size: 4;
}

.runnable textarea.code-editable:focus {
  border-color: var(--accent);
}


/* =========================
   PYODIDE LOADING BANNER
========================= */

#pyodide-status {
  position: fixed;

  bottom: 1rem;
  right: 1rem;

  background: var(--dark);
  color: white;

  font-family: "DM Mono", monospace;
  font-size: 0.8rem;

  padding: 0.6rem 1rem;

  border-radius: 6px;

  z-index: 999;

  opacity: 0.92;

  transition: opacity 0.3s;
}

#pyodide-status.hidden {
  opacity: 0;
  pointer-events: none;
}


/* =========================
   FOOTER
========================= */

.site-footer {
  border-top: 1px solid var(--light);

  padding: 30px 0;

  color: var(--muted);
}

.site-footer p {
  margin: 0;
}


/* =========================
   MOBILE
========================= */

@media (max-width: 700px) {

  .container {
    width: min(calc(100% - 30px), var(--max));
  }

  .nav {
    align-items: flex-start;
    flex-direction: column;

    padding: 20px 0;
  }

  nav {
    gap: 16px;
    flex-wrap: wrap;
  }

  .section {
    padding: 55px 0;
  }

  .section-heading {
    margin-bottom: 26px;
  }

  .topic {
    grid-template-columns: 42px 1fr;
    gap: 12px;

    padding: 20px 0;
  }

  .topic:hover {
    padding-left: 0;
  }

  .topic h3 {
    font-size: 1rem;
  }

  .topic p {
    font-size: 0.9rem;
  }

  #code {
    min-height: 260px;

    padding: 16px;

    font-size: 0.82rem;
  }

  .editor-actions {
    flex-wrap: wrap;
  }

  .run-output {
    font-size: 0.82rem;
  }

  .runnable textarea.code-editable {
    font-size: 0.84rem;
  }
}