:root {
  --main-color: #2e8b8b;
  --light-bg: #F4F7F9;
  --header-bg: #edf2f7;
  --font-color: #333;
  --border-color: #ccc;
  --hover-bg: #ddd;
  --white: #fff;
  --shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
}

body {
  margin: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: var(--light-bg);
  color: var(--font-color);
}

/* ===== Toolbar ===== */
.toolbar {
  background-color: var(--main-color);
  padding: 10px 20px;
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--white);
  box-shadow: var(--shadow);
  flex-wrap: wrap;
  justify-content: space-between;
}

.toolbar select,
.toolbar button,
.toolbar input[type="file"],
.toolbar input[type="color"] {
  padding: 6px 12px;
  border: 1px solid var(--main-color);
  font-weight: bold;
  font-size: 16px;
  border-radius: 5px;
  transition: all 0.3s ease;
  background-color: var(--white);
  color: var(--main-color);
}

.toolbar select:focus,
.toolbar input[type="file"]:focus,
.toolbar input[type="color"]:focus {
  outline: none;
  border-color: #145f5f;
  box-shadow: 0 0 0 2px rgba(46, 139, 139, 0.3);
}

.toolbar button:hover,
.toolbar select:hover {
  background-color: var(--hover-bg);
  cursor: pointer;
}

.toolbar-icon-button {
  background-color: var(--white);
  color: var(--main-color);
  font-size: 18px;
  border: none;
  cursor: pointer;
  padding: 6px 10px;
  border-radius: 4px;
  transition: background-color 0.3s;
}

.toolbar-icon-button:hover {
  background-color: var(--hover-bg);
}

/* ===== Spreadsheet Grid ===== */
.spreadsheet {
  display: grid;
  grid-template-columns: 40px repeat(20, 100px);
  margin: 20px;
  background: var(--white);
  border-radius: 8px;
  overflow: auto;
  box-shadow: var(--shadow);
}

/* ===== Cell and Header Styling ===== */
.cell,
.header {
  border: 1px solid var(--border-color);
  padding: 8px;
  box-sizing: border-box;
  min-height: 24px;
  transition: background-color 0.2s ease;
}

.cell[contenteditable] {
  outline: none;
  background-color: var(--white);
}

.cell[contenteditable]:hover,
.cell[contenteditable]:focus {
  background-color: #e6f7ff;
  border-color: var(--main-color);
}

.header,
.row-header {
  background: var(--header-bg);
  font-weight: bold;
  text-align: center;
  color: var(--font-color);
}

/* ===== Sheet Container ===== */
.sheet-container {
  padding: 0px;
}

/* ===== New Sheet Button ===== */
.new-sheet-btn {
  color: var(--main-color);
  background-color: var(--white);
  font-weight: bold;
  border-radius: 4px;
  border: 2px solid var(--main-color);
  padding: 6px 14px;
  transition: all 0.3s ease;
}

.new-sheet-btn:hover {
  background-color: var(--main-color);
  color: var(--white);
  cursor: pointer;
}

/* ===== Responsive Design ===== */
@media (max-width: 768px) {
  .spreadsheet {
    grid-template-columns: 40px repeat(10, 100px);
    overflow-x: scroll;
  }

  .toolbar {
    flex-direction: column;
    align-items: stretch;
  }

  .toolbar select,
  .toolbar button,
  .toolbar input[type="file"],
  .toolbar input[type="color"] {
    width: 100%;
    max-width: 100%;
    margin-bottom: 8px;
  }

  .toolbar-icon-button {
    width: 100%;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .spreadsheet {
    grid-template-columns: 40px repeat(5, 100px);
  }
}