SVG ดร็อปดาวน์โดยใช้ css3

svg .shadow { 
  cursor:crosshair; 
  -moz-box-shadow: -5px -5px 5px #888;
  -webkit-box-shadow: -5px -5px 5px #888;
  box-shadow: -5px -5px 5px #888; 
}	

<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" baseProfile="full"  viewBox="0 0 120 70">	
    <rect class="shadow" x="10" y="10" width="100" height="50" fill="#c66" />
</svg>

/* Use -webkit- only if supporting: Chrome < 54, iOS < 9.3, Android < 4.4.4 */

.shadow {
  -webkit-filter: drop-shadow( 3px 3px 2px rgba(0, 0, 0, .7));
  filter: drop-shadow( 3px 3px 2px rgba(0, 0, 0, .7));
  /* Similar syntax to box-shadow */
}

<img src="https://upload.wikimedia.org/wikipedia/commons/c/ce/Star_wars2.svg" alt="" class="shadow" width="200">

<!-- Or -->

<svg class="shadow" ...>
    <rect x="10" y="10" width="200" height="100" fill="#bada55" />
</svg>

img.light-shadow{
  filter: drop-shadow(0px 3px 3px rgba(0, 0, 0, 0.4));
}

img.dark-shadow{
  filter: drop-shadow(0px 3px 3px rgba(0, 0, 0, 1));
}

<img class="light-shadow" src="https://cdn.sstatic.net/Sites/stackoverflow/company/img/logos/so/so-logo.svg" />
<img class="dark-shadow" src="https://cdn.sstatic.net/Sites/stackoverflow/company/img/logos/so/so-logo.svg" />

<svg xmlns="http://www.w3.org/2000/svg" width="640" height="70"
    xmlns:xlink="http://www.w3.org/1999/xlink">
  <defs>
  <filter id="Blur"><feGaussianBlur stdDeviation="0.8" /></filter>
  <text style="font-family:sans,helvetica;font-weight:bold;font-size:12pt"
      id="Text"><tspan x="12" y="19">
        Black text with white shadow
    </tspan></text>
  </defs>
  <rect style="fill:#8AB" width="640" height="70" />
  <use style="fill:white;" filter="url(#Blur)" xlink:href="#Text"
      transform="translate(1.8,.9)"/>
  <use style="fill:black;" xlink:href="#Text"/>
</svg>

<svg xmlns="http://www.w3.org/2000/svg" width="640" height="70"
    xmlns:xlink="http://www.w3.org/1999/xlink">
  <defs>
  <filter id="Blur"><feGaussianBlur stdDeviation="3" /></filter>
  <text style="font-family:sans,helvetica;font-weight:bold;font-size:12pt"
      id="Text"><tspan x="12" y="19">
        Black text with white shadow
    </tspan></text>
  </defs>
  <rect style="fill:#8AB" width="640" height="70" />
  <use style="fill:white;" filter="url(#Blur)" xlink:href="#Text"
      transform="translate(7,5)"/>
  <use style="fill:black;" xlink:href="#Text"/>
</svg>

<svg xmlns="http://www.w3.org/2000/svg" width="364" height="172"
    xmlns:xlink="http://www.w3.org/1999/xlink">
  <defs>
    <filter id="Blur"><feGaussianBlur stdDeviation="0.8" /></filter>
    <g transform="matrix(.7,0,0,.7,-117.450795,-335.320895)" id="Img">
        <g transform="matrix(12.997776,0,0,-12.997776,389.30313,662.04015)">
            <path d="m 0,0 -1.107,0 c -0.039,0 -0.067,0.044 -0.067,0.086 0,0.015 0.589,1.914 0.589,1.914 0.021,0.071 0.023,0.073 0.031,0.073 l 0.001,0 c 0.009,0 0.01,-0.002 0.031,-0.073 0,0 0.589,-1.899 0.589,-1.914 C 0.067,0.044 0.037,0 0,0 M 1.493,4.345 C 1.482,4.383 1.448,4.411 1.408,4.414 l -4.065,0 C -2.698,4.41 -2.731,4.383 -2.742,4.346 c 0,0 -2.247,-7.418 -2.247,-7.432 0,-0.037 0.029,-0.067 0.067,-0.067 l 2.687,0 c 0.021,0.008 0.037,0.028 0.042,0.051 l 0.313,1 c 0.01,0.025 0.033,0.042 0.061,0.043 l 2.479,0.002 c 0.027,-0.002 0.051,-0.021 0.061,-0.045 l 0.32,-1 c 0.005,-0.023 0.021,-0.044 0.042,-0.052 0,0 2.642,10e-4 2.644,10e-4 0.037,0 0.068,0.028 0.068,0.065 0,0.013 -2.302,7.433 -2.302,7.433" />
        </g>
        <g transform="matrix(12.997776,0,0,-12.997776,508.27177,644.93113)">
            <path d="m 0,0 -1.651,-0.001 c 0,0 -0.044,0.013 -0.044,0.063 l -10e-4,0.833 c 0,0.05 0.044,0.063 0.044,0.063 l 1.514,0 C 0.038,0.958 0.394,0.87 0.394,0.463 0.394,0.056 0,0 0,0 m 7.916,0.645 3.741,0 0,2.453 -4.81,0 C 6.397,3.098 5.764,2.866 5.401,2.597 5.038,2.328 4.513,1.715 4.513,0.87 c 0,-0.845 0.513,-1.502 0.513,-1.502 0.263,-0.326 0.925,-1.005 0.925,-1.005 0.015,-0.016 0.024,-0.037 0.024,-0.061 0,-0.051 -0.041,-0.092 -0.092,-0.092 l -3.705,0 c -0.451,0.002 -0.482,0.181 -0.482,0.207 0,0.046 0.056,0.075 0.056,0.075 0.169,0.081 0.514,0.35 0.514,0.35 0.732,0.57 0.82,1.352 0.82,1.771 0,0.42 -0.063,1.163 -0.814,1.814 C 1.521,3.078 0.57,3.096 0.57,3.096 l -5.287,0 c 0,0 0,-7.52 0,-7.522 0,-0.024 0.022,-0.043 0.046,-0.043 l 2.943,0 0,2.11 c 0,0.037 0.057,0 0.057,0 l 1.533,-1.54 c 0.545,-0.551 1.446,-0.57 1.446,-0.57 l 5.796,0.001 c 0.989,0 1.539,0.538 1.69,0.688 0.15,0.151 0.651,0.714 0.651,1.647 0,0.932 -0.426,1.409 -0.608,1.628 C 8.675,-0.309 8.029,0.375 7.894,0.517 7.878,0.53 7.868,0.55 7.868,0.572 c 0,0.033 0.019,0.064 0.048,0.073" />
        </g>
        <g transform="matrix(12.997776,0,0,-12.997776,306.99861,703.01559)">
            <path d="m 0,0 c 0.02,0 0.034,0.014 0.04,0.036 0,0 2.277,7.479 2.277,7.486 0,0.02 -0.012,0.042 -0.031,0.044 0,0 -2.805,0 -2.807,0 -0.014,0 -0.023,-0.011 -0.026,-0.026 0,-0.001 -0.581,-1.945 -0.581,-1.946 -0.004,-0.016 -0.012,-0.026 -0.026,-0.026 -0.014,0 -0.026,0.014 -0.028,0.026 L -1.79,7.541 c -0.002,0.013 -0.012,0.025 -0.026,0.025 -10e-4,0 -3.1,0.001 -3.1,0.001 -0.009,-0.002 -0.017,-0.01 -0.02,-0.018 0,0 -0.545,-1.954 -0.545,-1.954 -0.003,-0.017 -0.012,-0.027 -0.027,-0.027 -0.013,0 -0.024,0.01 -0.026,0.023 l -0.578,1.952 c -0.001,0.012 -0.011,0.022 -0.023,0.024 l -2.992,0 c -0.024,0 -0.044,-0.02 -0.044,-0.045 0,-0.004 10e-4,-0.012 10e-4,-0.012 0,0 2.31,-7.471 2.311,-7.474 C -6.853,0.014 -6.839,0 -6.819,0 c 0.003,0 2.485,-0.001 2.485,-0.001 0.015,0.002 0.03,0.019 0.034,0.037 10e-4,0 0.865,2.781 0.865,2.781 0.005,0.017 0.012,0.027 0.026,0.027 0.015,0 0.023,-0.012 0.027,-0.026 L -2.539,0.024 C -2.534,0.01 -2.521,0 -2.505,0 -2.503,0 0,0 0,0" />
        </g>
        <g transform="matrix(12.997776,0,0,-12.997776,278.90126,499.03369)">
            <path d="m 0,0 c -0.451,0 -1.083,-0.232 -1.446,-0.501 -0.363,-0.269 -0.888,-0.882 -0.888,-1.727 0,-0.845 0.513,-1.502 0.513,-1.502 0.263,-0.326 0.925,-1.01 0.925,-1.01 0.015,-0.016 0.024,-0.037 0.024,-0.06 0,-0.051 -0.041,-0.093 -0.092,-0.093 -0.008,0 -6.046,0 -6.046,0 l 0,-2.674 7.267,0 c 0.988,0 1.539,0.538 1.69,0.689 0.15,0.15 0.65,0.713 0.65,1.646 0,0.932 -0.425,1.414 -0.607,1.633 -0.162,0.196 -0.808,0.876 -0.943,1.017 -0.016,0.014 -0.026,0.034 -0.026,0.056 0,0.033 0.019,0.063 0.048,0.073 l 3.5,0 0,-5.114 2.691,0 0,5.101 3.267,0 0,2.466 L 0,0 Z" />
        </g>
        <g transform="matrix(12.997776,0,0,-12.997776,583.96822,539.30215)">
            <path d="m 0,0 -1.651,-0.001 c 0,0 -0.044,0.013 -0.044,0.063 l -10e-4,0.833 c 0,0.05 0.044,0.063 0.044,0.063 l 1.514,0 C 0.038,0.958 0.394,0.87 0.394,0.463 0.394,0.056 0,0 0,0 m 2.178,-1.79 c -0.45,0.002 -0.482,0.181 -0.482,0.207 0,0.046 0.056,0.075 0.056,0.075 0.169,0.081 0.514,0.35 0.514,0.35 0.732,0.57 0.82,1.352 0.82,1.771 0,0.42 -0.063,1.163 -0.814,1.814 C 1.521,3.078 0.57,3.098 0.57,3.098 l -5.287,0 c 0,0 0,-7.522 0,-7.524 0,-0.024 0.022,-0.043 0.046,-0.043 0.005,0 2.943,0 2.943,0 l 0,2.109 c 0,0.038 0.057,0 0.057,0 l 1.533,-1.539 c 0.545,-0.551 1.446,-0.57 1.446,-0.57 l 4.525,0 0,2.679 -3.655,0 z" />
        </g>
        <g transform="matrix(12.997776,0,0,-12.997776,466.86346,556.40203)">
            <path d="m 0,0 -1.107,0 c -0.041,0 -0.067,0.044 -0.067,0.086 0,0.016 0.589,1.914 0.589,1.914 0.021,0.071 0.027,0.073 0.031,0.073 l 0.001,0 c 0.004,0 0.01,-0.002 0.031,-0.073 0,0 0.589,-1.898 0.589,-1.914 C 0.067,0.044 0.04,0 0,0 M 1.49,4.347 C 1.479,4.385 1.446,4.412 1.405,4.414 l -4.065,0 C -2.7,4.412 -2.734,4.385 -2.745,4.348 c 0,0 -2.245,-7.42 -2.245,-7.434 0,-0.037 0.03,-0.067 0.067,-0.067 l 2.687,0 c 0.022,0.007 0.038,0.028 0.043,0.051 l 0.313,1.001 c 0.01,0.024 0.033,0.041 0.061,0.042 l 2.478,0 C 0.687,-2.061 0.71,-2.078 0.721,-2.102 l 0.32,-1 c 0.005,-0.023 0.021,-0.044 0.042,-0.052 0,0 2.642,10e-4 2.644,10e-4 0.037,0 0.067,0.028 0.067,0.066 0,0.012 -2.304,7.434 -2.304,7.434" />
        </g>
    </g>
  </defs>
  <rect style="fill:#8AB" width="364" height="172" />
  <use style="fill:white;" filter="url(#Blur)" xlink:href="#Img"
    transform="translate(1.8,.9)"/>
  <use style="fill:black;" xlink:href="#Img"/>
</svg>

// Does not works, with regular dynamic css styling:

shadow0.onchange = () => {
  rect1.style.filter = "filter:drop-shadow(0 0 " + shadow0.value + "rem black);"
}

// Okay! Inline styling, appending.

shadow1.onchange = () => {
  rect1.style += " ;filter:drop-shadow(0 0 " + shadow1.value + "rem black);"
  rect2.style += " ;filter:drop-shadow(0 0 " + shadow1.value + "rem black);"
}

<h4>
Does not works! 
<input id="shadow0" type="number" min="0" max="100" step="0.1">

 | Okay!
<input id="shadow1" type="number" min="0" max="100" step="0.1">

<svg viewBox="0 0 120 70">  
    <rect id="rect1" x="10" y="10" width="100" height="50" fill="#c66" />
    
    <!-- Inline style declaration does NOT works at svg level, no shadow at loading: -->
    <rect id="rect2" x="40" y="30" width="10" height="10" fill="#aaa" style="filter:drop-shadow(0 0 20rem black)" />
    
</svg>