:root {
      --bg: #f4f4f4;
      --text: #222;
      --card: #fff;
      --subtask: #444;
      --pending-border: #007BFF;
      --completed-border: green;
      --btn-bg: red;
      --btn-color: white;
    }

    body.dark {
      --bg: #121212;
      --text: #f1f1f1;
      --card: #1f1f1f;
      --subtask: #ccc;
      --pending-border: #2196f3;
      --completed-border: #4caf50;
      --btn-bg: #e53935;
      --btn-color: white;
    }

    body {
      font-family: Arial, sans-serif;
      padding: 20px;
      background: var(--bg);
      color: var(--text);
      transition: background 0.3s, color 0.3s;
    }

    h1, h2 {
      text-align: center;
    }

    input, button {
      padding: 8px;
      margin: 5px;
      font-size: 16px;
      border-radius: 5px;
    }

    .task-container {
      display: flex;
      justify-content: space-around;
      flex-wrap: wrap;
      gap: 20px;
      margin-top: 20px;
    }

    .section {
      flex: 1 1 100%;
      max-width: 500px;
      background: var(--card);
      border-radius: 10px;
      padding: 15px;
      box-shadow: 0 0 10px rgba(0,0,0,0.1);
    }

    .task-item {
      border-left: 4px solid var(--pending-border);
      padding: 10px 35px 10px 10px;
      margin-bottom: 10px;
      background: inherit;
      position: relative;
      overflow: hidden;
      word-wrap: break-word;
    }

    .task-item.completed {
      border-left-color: var(--completed-border);
      text-decoration: line-through;
      opacity: 0.6;
    }

    .delete-btn {
      position: absolute;
      top: 10px;
      right: 10px;
      background: var(--btn-bg);
      color: var(--btn-color);
      border: none;
      padding: 4px 6px;
      border-radius: 4px;
      cursor: pointer;
    }

    .subtask {
      font-size: 14px;
      margin-left: 10px;
      color: var(--subtask);
    }

    #clock {
      text-align: center;
      font-size: 20px;
      margin-bottom: 10px;
      font-weight: bold;
    }

    .theme-toggle {
      position: fixed;
      top: 15px;
      right: 15px;
      z-index: 999;
    }

    @media (max-width: 600px) {
      .task-container {
        flex-direction: column;
        align-items: center;
      }
      input[type="text"], input[type="date"], input[type="time"] {
        width: 90%;
        max-width: 400px;
      }
    }