:root {
  /* body */
  --color-bg: #f9fafb;
  --color-text: #222;

  /* Form's button */
  --color-on-primary: white;
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;

  /* Different level of grays */
  --color-gray-100: #f3f4f6;
  --color-gray-200: #e5e7eb;
  --color-gray-300: #d1d5db;
  --color-gray-400: #9ca3af;
  --color-gray-600: #4b5563;
  --color-gray-800: #111827;

  --color-collection-name: var(--color-gray-800);
  --color-completion-status: var(--color-gray-600);

  /* 
     1) Message of class "success" / "error"
     2) complete/incomplete status 
  */
  --color-success: #16a34a;
  --color-error: #b91c1c;

  --color-message-box-bg: #fef3c7;

  --radius-md: 0.5rem;
  --shadow-md: 0 1px 3px rgba(0, 0, 0, 0.05);

  --border-on-light-bg: 1px solid var(--color-gray-300);
}

/* Base reset */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: system-ui, sans-serif;
  line-height: 1.5;
  background: var(--color-bg);
  color: var(--color-text);
  padding: 1rem;
  max-width: 800px;
  margin: auto;
}

h1 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
  text-align: center;
}

/* Form styling */
form {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
  margin-bottom: 0.5rem;
  font-size: 1rem;

  label {
    font-weight: 600;
  }

  input[type="text"] {
    flex: 1;
    min-width: 200px;
    padding: 0.5rem 0.75rem;
    border: var(--border-on-light-bg);
    border-radius: var(--radius-md);
  }

  input[type="text"]:focus {
    border-color: var(--color-primary);
    outline: none;
    box-shadow: var(--shadow-md);
  }

  button {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: var(--radius-md);
    background-color: var(--color-primary);
    color: var(--color-on-primary);
    cursor: pointer;
    transition: background-color 0.2s ease;
  }

  button:hover {
    background-color: var(--color-primary-dark);
  }

  /* Screen reader only (to hide the label from normal view but make the label 
   accessible to screen readers) */
  .sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip-path: inset(50%); /* Note: clip 50% from all four sides, making it invisible */
    white-space: nowrap;
    border: none;
  }
}

/* User info section */
#user-info {
  display: flex;
  gap: 0 2rem;
  flex-wrap: wrap; /* wrap on small screens */
  justify-content: space-between;
  background-color: white;
  padding: 0.5rem 1rem;
  border: var(--border-on-light-bg);
  border-radius: var(--radius-md);

  box-shadow: var(--shadow-md);
  margin: 0.5rem 0;

  @media (max-width: 600px) {
    /* Stack user info vertically on narrow view */
    flex-direction: column;
  }

  > div {
    display: flex;
    gap: 0.25rem; /* space between label and value */
    align-items: center;
    font-weight: 500;
    color: var(--color-gray-800);
  }

  > div span:first-child {
    font-weight: 600;
    color: #4b5563;
  }
}

/* Message area */
#message {
  display: none; /* hidden by default */
  font-weight: 500;
  min-height: 1.5em; /* keeps space reserved */
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0rem 1rem;
  border: var(--border-on-light-bg);
  border-radius: var(--radius-md);
  background-color: var(--color-message-box-bg);
  font-size: 0.8rem;

  button {
    color: #92400e;
    padding: 0.2rem 0.5rem;
    background: none;
    border: none;
    font-size: 1.2rem;
    cursor: pointer;
    line-height: 1;
  }

  #message-text.error {
    color: var(--color-error);
  }

  #message-text.info {
    color: var(--color-primary);
  }

  #message-text.success {
    color: var(--color-success);
  }
}

/* Collection details container */
.collection-details {
  margin-bottom: 0;
  border: var(--border-on-light-bg);
  border-radius: var(--radius-md);

  padding: 0.5rem 1rem;
  background: white;
  box-shadow: var(--shadow-md);

  summary {
    display: flex;
    width: 100%;
    align-items: center;
    cursor: pointer;
  }

  /* Hide default summary marker */
  summary::marker {
    display: none;
    content: "";
  }

  /* Arrow before name */
  summary::before {
    content: "▶";
    display: flex;
    width: 1em;
    height: 1em;
    align-items: center;
    justify-content: center;
    margin-right: 0.5rem;
    transition: transform 0.2s ease;
  }

  /* Rotate arrow when open */
  &[open] summary::before {
    transform: rotate(90deg);
  }

  .collection-header {
    display: flex;
    gap: 0 0.5rem;
    width: 100%;

    @media (max-width: 600px) {
      /* Stack title and completion status vertically on narrow screens */
      flex-direction: column;
    }
  }

  .collection-name {
    flex: 1;
    min-width: 0;
    font-size: 1rem;
    font-weight: 500;
    color: var(--color-gray-800);
  }

  .collection-completion-status {
    font-size: 0.9rem;
    color: var(--color-completion-status);

    @media (max-width: 600px) {
      font-size: 0.75rem;
    }
  }
}

/* Katas list */
.katas-list {
  margin-top: 0.75rem;
  padding-left: 0rem;
}

/* Kata list item */
.kata-li {
  margin: 0.5rem 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
  column-gap: 1.5rem;
  border-bottom: 1px solid var(--color-gray-200);

  .kata-title a {
    color: #2563eb;
    text-decoration: none;

    &:hover {
      text-decoration: underline;
    }
  }

  .kata-completed.completed {
    color: var(--color-success);
    &::before {
      content: "Completed";

      @media (max-width: 600px) {
        content: "✔";
      }
    }
  }

  .kata-completed.incomplete {
    color: var(--color-error);

    &::before {
      content: "Incomplete";

      @media (max-width: 600px) {
        content: "✖";
      }
    }
  }
}