diff --git a/Sangmin/3/css/progress.css b/Sangmin/3/css/progress.css
new file mode 100644
index 0000000..a00d259
--- /dev/null
+++ b/Sangmin/3/css/progress.css
@@ -0,0 +1,112 @@
+/* SOURCE: https://css-tricks.com/styling-cross-browser-compatible-range-inputs-css/ */
+
+input[type="range"] {
+  -webkit-appearance: none; /* Hides the slider so that custom slider can be made */
+  width: 100%; /* Specific width is required for Firefox. */
+  background: transparent; /* Otherwise white in Chrome */
+}
+
+input[type="range"]::-webkit-slider-thumb {
+  -webkit-appearance: none;
+}
+
+input[type="range"]:focus {
+  outline: none; /* Removes the blue border. You should probably do some kind of focus styling for accessibility reasons though. */
+}
+
+input[type="range"]::-ms-track {
+  width: 100%;
+  cursor: pointer;
+
+  /* Hides the slider so custom styles can be added */
+  background: transparent;
+  border-color: transparent;
+  color: transparent;
+}
+
+/* Special styling for WebKit/Blink */
+input[type="range"]::-webkit-slider-thumb {
+  -webkit-appearance: none;
+  border: 1px solid #000000;
+  height: 36px;
+  width: 16px;
+  border-radius: 3px;
+  background: #ffffff;
+  cursor: pointer;
+  margin-top: -14px; /* You need to specify a margin in Chrome, but in Firefox and IE it is automatic */
+  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d; /* Add cool effects to your sliders! */
+}
+
+/* All the same stuff for Firefox */
+input[type="range"]::-moz-range-thumb {
+  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
+  border: 1px solid #000000;
+  height: 36px;
+  width: 16px;
+  border-radius: 3px;
+  background: #ffffff;
+  cursor: pointer;
+}
+
+/* All the same stuff for IE */
+input[type="range"]::-ms-thumb {
+  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
+  border: 1px solid #000000;
+  height: 36px;
+  width: 16px;
+  border-radius: 3px;
+  background: #ffffff;
+  cursor: pointer;
+}
+
+input[type="range"]::-webkit-slider-runnable-track {
+  width: 100%;
+  height: 8.4px;
+  cursor: pointer;
+  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
+  background: #3071a9;
+  border-radius: 1.3px;
+  border: 0.2px solid #010101;
+}
+
+input[type="range"]:focus::-webkit-slider-runnable-track {
+  background: #367ebd;
+}
+
+input[type="range"]::-moz-range-track {
+  width: 100%;
+  height: 8.4px;
+  cursor: pointer;
+  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
+  background: #3071a9;
+  border-radius: 1.3px;
+  border: 0.2px solid #010101;
+}
+
+input[type="range"]::-ms-track {
+  width: 100%;
+  height: 8.4px;
+  cursor: pointer;
+  background: transparent;
+  border-color: transparent;
+  border-width: 16px 0;
+  color: transparent;
+}
+input[type="range"]::-ms-fill-lower {
+  background: #2a6495;
+  border: 0.2px solid #010101;
+  border-radius: 2.6px;
+  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
+}
+input[type="range"]:focus::-ms-fill-lower {
+  background: #3071a9;
+}
+input[type="range"]::-ms-fill-upper {
+  background: #3071a9;
+  border: 0.2px solid #010101;
+  border-radius: 2.6px;
+  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
+}
+input[type="range"]:focus::-ms-fill-upper {
+  background: #367ebd;
+}
diff --git a/Sangmin/3/css/style.css b/Sangmin/3/css/style.css
new file mode 100644
index 0000000..11db700
--- /dev/null
+++ b/Sangmin/3/css/style.css
@@ -0,0 +1,75 @@
+@import url("https://fonts.googleapis.com/css?family=Questrial&display=swap");
+
+* {
+  box-sizing: border-box;
+}
+
+body {
+  font-family: "Questrial", sans-serif;
+  background-color: #666;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  max-height: 100vh;
+  margin: 0;
+}
+
+h1 {
+  color: #fff;
+}
+
+.screen {
+  cursor: pointer;
+  width: 60%;
+  background-color: #000 !important;
+  border-top-left-radius: 10px;
+  border-top-right-radius: 10px;
+}
+
+.controls {
+  background: #333;
+  color: #fff;
+  width: 60%;
+  border-bottom-left-radius: 10px;
+  border-bottom-right-radius: 10px;
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  padding: 10px;
+}
+
+.controls .btn {
+  border: 0;
+  background: transparent;
+  cursor: pointer;
+}
+
+.controls .fa-play {
+  color: #28a745;
+}
+
+.controls .fa-stop {
+  color: #dc3545;
+}
+
+.controls .fa-pause {
+  color: #fff;
+}
+
+.controls .timestamp {
+  color: #fff;
+  font-weight: bold;
+  margin-left: 10px;
+}
+
+.btn:focus {
+  outline: 0;
+}
+
+@media (max-width: 800px) {
+  .screen,
+  .controls {
+    width: 90%;
+  }
+}
diff --git a/Sangmin/3/img/poster.png b/Sangmin/3/img/poster.png
new file mode 100644
index 0000000..a0d1413
Binary files /dev/null and b/Sangmin/3/img/poster.png differ
diff --git a/Sangmin/3/index.html b/Sangmin/3/index.html
new file mode 100644
index 0000000..5a48ba8
--- /dev/null
+++ b/Sangmin/3/index.html
@@ -0,0 +1,48 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
+    <title>Custom Video Player</title>
+    <link
+      href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css"
+      rel="stylesheet"
+      integrity="sha384-wvfXpqpZZVQGK6TAh5PVlGOfQNHSoD2xbE+QkPxCAFlNEevoEH3Sl0sibVcOQVnN"
+      crossorigin="anonymous"
+    />
+    <link rel="stylesheet" href="css/progress.css" />
+    <link rel="stylesheet" href="css/style.css" />
+  </head>
+  <body>
+    <h1>Custom Video Player</h1>
+    <video
+      src="videos/gone.mp4"
+      id="video"
+      class="screen"
+      poster="img/poster.png"
+    ></video>
+    <div class="controls">
+      <button class="btn" id="play">
+        <i class="fa fa-2x fa-play"></i>
+      </button>
+      <button class="btn" id="stop">
+        <i class="fa fa-2x fa-stop"></i>
+      </button>
+      <input
+        type="range"
+        id="progress"
+        class="progress"
+        min="0"
+        max="100"
+        step="0.1"
+        value="0"
+      />
+      <span class="timestamp" id="timestamp">00:00</span>
+    </div>
+
+    <script src="script.js"></script>
+  </body>
+</html>
+
+<!-- https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Video_and_audio_APIs -->
diff --git a/Sangmin/3/script.js b/Sangmin/3/script.js
new file mode 100644
index 0000000..60889e7
--- /dev/null
+++ b/Sangmin/3/script.js
@@ -0,0 +1,49 @@
+const video = document.querySelector("#video");
+
+const playBtn = document.querySelector("#play");
+const playBtnProperty = playBtn.querySelector("i");
+const stopBtn = document.querySelector("#stop");
+
+const progress = document.querySelector(".progress");
+const timestamp = document.querySelector(".timestamp");
+
+const PutToPlay = () => {
+  playBtnProperty.classList.remove("fa-play");
+  playBtnProperty.classList.add("fa-pause");
+};
+const PutToPause = () => {
+  playBtnProperty.classList.remove("fa-pause");
+  playBtnProperty.classList.add("fa-play");
+};
+
+const adjustVideoPlay = () => {
+  video.paused ? video.play() : video.pause();
+  video.paused ? PutToPause() : PutToPlay();
+};
+
+const resetTimestamp = () => {
+  video.currentTime = 0;
+  video.pause();
+  PutToPause();
+};
+
+const adjustProgressBar = () => {
+  progress.value = (video.currentTime / video.duration) * 100;
+
+  let minutes = String(Math.floor(video.currentTime / 60)).padStart(2, "0");
+  let seconds = String(Math.floor(video.currentTime % 60)).padStart(2, "0");
+
+  timestamp.innerHTML = `${minutes}:${seconds}`;
+};
+
+const updateProgress = () => {
+  video.currentTime = (progress.value * video.duration) / 100;
+};
+
+video.addEventListener("click", adjustVideoPlay);
+playBtn.addEventListener("click", adjustVideoPlay);
+stopBtn.addEventListener("click", resetTimestamp);
+
+video.addEventListener("timeupdate", adjustProgressBar);
+
+progress.addEventListener("change", updateProgress);
diff --git a/Sangmin/3/videos/gone.mp4 b/Sangmin/3/videos/gone.mp4
new file mode 100644
index 0000000..2e84739
Binary files /dev/null and b/Sangmin/3/videos/gone.mp4 differ