input内边距（padding）

input {
     width: 100%;
 }

input[type=text] {
          width: 100%;
          padding: 12px 20px;
          margin: 8px 0;
          box-sizing: border-box;
}

input[type=text] {
          border: 2px solid red;
          border-radius: 4px;
}

input[type=text] {
          border: none;
          border-bottom: 2px solid red;
}

input[type=text] {
      background-color: #3CBC8D;
      color: white;
}

input[type=text]:focus {
   background-color: lightblue;
}  

input[type=text]:focus {
   border: 3px solid #555;
}     

input[type=text] {
          background-color: white;
          background-image: url('searchicon.png');
          background-position: 10px 10px; 
          background-repeat: no-repeat;
          padding-left: 40px;
}

input[type=text] {
          -webkit-transition: width 0.4s ease-in-out;
          transition: width 0.4s ease-in-out;
}
input[type=text]:focus {
          width: 100%;
}

textarea {
          width: 100%;
          height: 150px;
          padding: 12px 20px;
          box-sizing: border-box;
          border: 2px solid #ccc;
          border-radius: 4px;
          background-color: #f8f8f8;
          resize: none;
}

select {
          width: 100%;
          padding: 16px 20px;
          border: none;
          border-radius: 4px;
          background-color: #f1f1f1;
}

input[type=button], input[type=submit], input[type=reset] {
          background-color: #4CAF50;
          border: none;
          color: white;
          padding: 16px 32px;
          text-decoration: none;
          margin: 4px 2px;
          cursor: pointer;
}
/* 提示:使用width:100%的全宽度按钮 */

@media screen and (max-width: 600px) {
     .col-25, .col-75, input[type=submit] {
            width: 100%;
            margin-top: 0;
     }
}