/* --- Root Variables for Easy Customization --- */
:root {
  --background-color: #f8f9fa; /* Soft, light gray background */
  --text-color: #343a40;       /* Dark gray for better readability than pure black */
  --primary-color: #005f73;    /* A deep, academic teal/blue */
  --secondary-color: #0a9396;  /* A brighter accent for links and highlights */
  --border-color: #dee2e6;      /* Subtle border color */
  --highlight-bg: #e9f5f5;      /* Light background for notes and definitions */

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-serif: 'Georgia', 'Times New Roman', serif;
}

/* --- General Layout & Typography --- */
body {
  max-width: 61.8rem; /* A slightly narrower width for better reading comfort */
  margin: auto;
  padding: 2rem 1rem;
  font-family: var(--font-serif);
  background-color: var(--background-color);
  color: var(--text-color);
  line-height: 1.75;
  font-size: 1.1em;
}

/* --- Headings --- */
.main-title {
  color: var(--primary-color);
  text-shadow: 1px 1px 3px rgba(0, 0, 0, 0.1);
}

h2 {
  font-family: var(--font-sans);
  color: var(--primary-color);
  border-bottom: 3px solid var(--border-color);
  padding-bottom: 0.5rem;
  margin-top: 2.5rem; /* More space between sections */
}

h3 {
  font-family: var(--font-sans);
  color: var(--primary-color);
}

/* --- Custom Styled Boxes (like tcolorbox) --- */
.tcolorbox, .definition, .definition-formal {
  background-color: var(--highlight-bg);
  border-left: 5px solid var(--secondary-color);
  padding: 1.5rem;
  margin: 1.5rem 0;
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.tcolorbox strong, .definition strong, .definition-formal strong {
  color: var(--primary-color);
  font-family: var(--font-sans);
}

/* --- Links and Lists --- */
a {
  color: var(--secondary-color);
  text-decoration: none;
  font-weight: bold;
  border-bottom: 2px dotted transparent;
  transition: all 0.3s ease;
}

a:hover {
  border-bottom: 2px solid var(--secondary-color);
}

ul {
  padding-left: 1.5rem;
}

li {
  margin-bottom: 0.5rem;
}

/* --- Interactive Canvas Section Styling --- */
.canvas-container {
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 0.5rem;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
  background-color: #fff;
}

#series-canvas {
  width: 100%;
  height: auto;
}

#startButton {
  background-color: var(--primary-color);
  font-family: var(--font-sans);
  font-weight: bold;
  font-size: 1rem;
  padding: 0.75rem 1.5rem;
  border-radius: 50px; /* Fully rounded button */
  box-shadow: 0 4px 10px rgba(0, 95, 115, 0.3);
  transition: all 0.3s ease;
}

#startButton:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 15px rgba(0, 95, 115, 0.4);
}

.info-box {
  font-family: var(--font-sans);
  background-color: #fff;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 0.75rem 1.25rem;
  text-align: left;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.info-box p {
  margin: 0.25rem 0;
}

.info-box span {
  font-weight: bold;
  color: var(--primary-color);
}

/* --- Flowchart Diagram Styling --- */

/* The main container for the flowchart */
.flowchart {
  text-align: center;
  margin: 3rem 0; /* Adds space around the diagram */
  position: relative;
}

/* Base styles for all boxes in the chart */
.flowchart-box {
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  font-family: var(--font-sans);
  font-weight: bold;
  box-shadow: 0 4px 12px rgba(0,0,0,0.08);
  display: inline-block; /* Allows centering and proper layout */
  position: relative;
  z-index: 2; /* Ensures boxes are above the lines */
}

/* Specific styling for the top "Sequence" box */
.parent-node {
  background-color: #cde2ff; /* Light blue background */
  color: #003d99; /* Dark blue text */
  border: 1px solid #99c2ff;
}

/* Styling for the two bottom boxes */
.child-node {
  background-color: #fff0d1; /* Light orange background */
  color: #7a4f01; /* Dark orange/brown text */
  border: 1px solid #ffe1a3;
}

/* This pseudo-element draws the short vertical line coming DOWN from the parent box */
.parent-node::after {
  content: '';
  position: absolute;
  left: 50%;
  bottom: -20px; /* Puts the line 20px below the box */
  transform: translateX(-50%);
  width: 2px;
  height: 20px;
  background-color: #adb5bd;
}

/* A container to hold the two child boxes */
.flowchart-children {
  display: flex;
  justify-content: center;
  gap: 5rem; /* The space between "Finite" and "Infinite" boxes */
  margin-top: 40px; /* Creates space for the connecting lines */
}

/* This pseudo-element draws the vertical lines coming UP from each child box */
.child-node::before {
  content: '';
  position: absolute;
  left: 50%;
  top: -20px; /* Puts the line 20px above the box */
  transform: translateX(-50%);
  width: 2px;
  height: 20px;
  background-color: #adb5bd;
}

/* This pseudo-element on the FIRST child draws the horizontal line connecting the two branches */
.child-node:first-child::after {
  content: '';
  position: absolute;
  left: 50%;
  top: -20px; /* Aligns it perfectly with the vertical lines */
  height: 2px;
  /* The width is calculated as 100% of the box + the gap between boxes */
  width: calc(100% + 5rem);
  background-color: #adb5bd;
  z-index: 1; /* Puts it behind the boxes but in front of the page */
}

.custom-underline {
  text-decoration: underline;

  /* You can also customize the underline! */
  text-decoration-color: #0a9396;   /* Make the line color match your theme */
  text-decoration-thickness: 2px;  /* Make the line thicker */
  text-decoration-style: wavy;     /* Or even make it wavy! */
}

/* --- START: Add these styles to the end of series.css --- */

/* Styles for lists in the new sections */
section ol, section ul {
  margin-left: 1.5rem;
  margin-bottom: 1rem;
}

section ol > li, section ul > li {
  margin-bottom: 1rem;
}

/* Base style for the new themed info boxes */
.info-box-themed {
  border-left: 5px solid;
  padding: 1rem 1.5rem;
  margin: 1.5rem 0;
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.info-box-themed h4 {
  font-family: var(--font-sans);
  font-size: 1.2rem;
  margin-top: 0;
  color: var(--text-color);
}

/* Yellow Box (for Rudin definitions) */
.info-box-yellow {
  background-color: #fffbeb;
  border-color: #f59e0b;
}

/* Green Box (for Fitzee definitions) */
.info-box-green {
  background-color: #f0fdf4;
  border-color: #22c55e;
}

/* Blue Box (for ChatGPT definitions) */
.info-box-blue {
  background-color: #eff6ff;
  border-color: #3b82f6;
}

/* Orange Box (for Geometric Series Theorem) */
.info-box-orange {
  background-color: #fff7ed;
  border-color: #f97316;
}

/* --- END: CSS styles --- */