/* Layout */
  body, html {
    margin: 0; padding: 0; height: 100vh; font-family: 'Arial';
    width:100%;
    background: #ffffff;
    display: flex;
  }
  #container {
    display: flex;
    flex: 1;
    height: 100vh;
  }

  .panel {
    box-sizing: border-box;
    padding: 20px;
    overflow-y: auto;
  }

  /* Left: instructions */
  #instructions {
    width: 25%;
    background: #2c3e50;
    color: #ecf0f1;
    border-right: 2px solid #34495e;
    display: flex;
    flex-direction: column;
    place-items: center;
    font-size: 1.4rem;
  }
  #instructions h2 {
    margin-top: 0;
    font-weight: 700;
    border-bottom: 2px solid #2980b9;
    padding-bottom: 10px;
  }
  #instructions p {
    line-height: 1.5;
  }
  #instructions img{
    margin-bottom: 50px;
  }

  #img{
    width:100%;
  }

  /* Middle: code editor */
  #header{
    background: #2c3e50;
    color: #ecf0f1;
    padding: 20px;
    border-bottom: 2px solid #34495e;
    font-size: 1.6rem;
    line-height: 1.6;
    max-height: 40%;
    overflow-y: auto;
  }

  #header ul{
    padding-left: 20px;
    line-height: 1.6;
  }
  #code-editor {
    width: 40%;
    background: white;
    border-right: 2px solid #bdc3c7;
    display: flex;
    flex-direction: column;
  }
  #code-editor textarea {
    flex-grow: 1;
    font-family: 'Source Code Pro', monospace, monospace;
    font-size: 1.1rem;
    line-height: 1.4;
    border: none;
    padding: 15px;
    resize: none;
    outline: none;
    background: #fefefe;
    box-shadow: inset 0 0 8px rgba(0,0,0,0.05);
    border-radius: 8px;
    margin-bottom: 15px;
  }
  #code-editor .hint {
    font-size: 1.2rem;
    color: #7f8c8d;
    background: #ecf0f1;
    border-radius: 6px;
    padding: 10px;
    margin-bottom: 15px;
  }
  .run-btn {
    background: #27ae60;
    border: none;
    color: white;
    font-weight: 700;
    font-size: 1.2rem;
    padding: 12px;
    border-radius: 10px;
    cursor: pointer;
    transition: background 0.3s ease;
  }
  .run-btn:hover:not(:disabled) {
    background: #2ecc71;
  }
  .run-btn:disabled {
    background: #95a5a6;
    cursor: not-allowed;
  }
  .stop-btn {
    background: #c0392b;
    border: none;
    color: white;
    font-weight: 700;
    font-size: 1.2rem;
    padding: 12px;
    border-radius: 10px;
    cursor: pointer;
    transition: background 0.3s ease;
    margin-left: 10px;
  }
  .stop-btn:hover:not(:disabled) {
    background: #e74c3c;
  }
  .stop-btn:disabled {
    background: #95a5a6;
    cursor: not-allowed;
  }
  #dimensioninputs{
    display:flex;
    justify-content: space-around;
    margin:10px;
  }
  .inputset{
    font-family: 'Arial';
    font-size: 1.2rem;
    color: #000000;
    background: #ecf0f1;
    border-radius: 6px;
    padding: 10px;
    margin-bottom: 15px;
  }
  /* Right: grid */
  #grid-container {
    width: 35%;
    background: #ffffff;
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
    overflow-x: hidden;
  }
  #grid {
    display: grid;
    grid-template-columns: repeat(10, 40px);
    grid-template-rows: repeat(10, 40px);
    gap: 4px;
    background: #ecf0f1;
    padding: 10px;
    border-radius: 10px;
    box-shadow: 0 6px 15px rgba(0,0,0,0.1);
    margin-left:20px;
  }
  .cell {
    background: white;
    border-radius: 6px;
    box-shadow: inset 0 0 4px rgba(0,0,0,0.1);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 24px;
    user-select: none;
  }
  .turtle {
    font-size: 26px;
    transition: background-color 0.3s ease;
    background-color: #27ae60;
    border-radius: 6px;
    color: white;
  }
  #status {
    margin-top: 20px;
    font-size: 1rem;
    color: #34495e;
    min-height: 22px;
    font-weight: 600;
    user-select: none;
  }

  #output{
    width: 100%;
    height: 100%;
  }

  #console{
    width:100%;
    flex-grow: 1;
    font-family: 'Source Code Pro', monospace, monospace;
    font-size: 1.1rem;
    line-height: 1.4;
    border: none;
    resize: none;
    outline: none;
    background: #9b9b9b;
    box-shadow: inset 0 0 8px rgba(0,0,0,0.05);
    border-radius: 8px;
    padding:10px;
  }

.unit{
    background-color: #95a5a6;
    color:black;
    text-align: center;
    padding:10px;
    border-radius: 20px;
    font-size: 1.6rem;
    margin:15px;
    cursor:pointer;
}

.unit:hover{
    background-color: #889191;
}

.lessons{
    text-align: left;
}

.hiddenlessons{
    display:none;
}
.visiblelessons{
    display:block;
}
hr{
    min-width: 100%;
}