style.css

:root {
  --primary-color: #000;
  --secondary-color: #fff;
  --needle-color: #000;
  --clock-border-color: #d0d0d0;
  --bg-color: #eeeeee;
  --switch-theme-bg-color: #bebebe;
  --switch-theme-btn-color: #333;
  --relax-btn-hover: #e4e4e4;
  --timer-color: #fff;
}

/*Default styles begin*/
*, 
*::before, 
*::after {
    box-sizing: border-box;
}

html {
  font-family: 'Josefin Sans', sans-serif;
  font-size: 62.5%;
  transition: all 0.3s ease-in;
}

html[data-theme='dark'] {
  --primary-color: #ffffff;
  --secondary-color: #000000;
  --needle-color: #237b1d;
  --clock-border-color: #464646;
  --bg-color: #333333;
  --relax-btn-hover: #464646;
}

@media screen and (max-width: 767px) {
  html {
      font-size: 50%;
  }
}

body {
  margin: 0;
  font-size: 1.4rem;
  background-color: var(--bg-color);
  transition: all 0.4s ease;
}

h1, h2, h3, h4, p {
  margin: 0;
}

input, button, textarea, select {
  font: inherit;
}

a {
  text-decoration: none;
}

button {
  border: none;
  outline:none;
  cursor:pointer;
}
/*Default styles end*/

.container {
  margin: 0 auto;
  max-width: 1440px;
  width: calc(100% - 40px);
}


/*Theme switcher*/
.switch-wrapper {
  margin-top: 5rem;
  margin-right: 1.5rem;
  text-align: right;
}

.switch__checkbox {
  display: none;
}

.switch {
  position: relative;
  display: inline-block;
  width: 70px;
  height: 35px;
}

.switch__slider {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  display: flex;
  justify-content: space-around;
  align-items: center;
  cursor: pointer;
  background-color: var(--switch-theme-bg-color);
  border-radius: 46px;
  transition: all 0.4s ease;
}

.switch__slider::after {
  content: '';
  position: absolute;
  top: 8%;
  right: 50%;
  width: 32px;
  height: 29px;
  background-color: var(--switch-theme-btn-color);
  border-radius: 46px;
  transition: all 0.4s ease;
}

.theme-slider__day {
  display: inline-block;
  margin: 0 5px;
  width: 23px;
  height: 23px;
  background: url(assets/sun.svg) no-repeat center;
  background-size: cover;
}

.theme-slider__night {
  display: inline-block;
  margin: 0 5px;
  width: 23px;
  height: 23px;
  background: url(assets/moon.svg) no-repeat center;
  background-size: cover;
}

.switch__checkbox:checked + .switch__slider::after {
  transform: translateX(32px);
}

.switch__checkbox:not(:checked)+ .switch__slider > .theme-slider__day {
  visibility: hidden;
}

.switch__checkbox:checked + .switch__slider > .theme-slider__night {
  visibility: hidden;
}
/*theme switcher end*/

/*clock*/
.clock-container {
  display: flex;
  justify-content: center;
  align-items: center;
  margin-top: 7rem;
}

.clock-wrapper {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-direction: column;
}

.clock {
  position: relative;
  width: 200px;
  height: 200px;
  margin-bottom: 2rem;
  border: 2px solid var(--clock-border-color);
  border-radius: 50%;
}

.needle {
  position: absolute;
  top: 50%;
  left: 50%;
  height: 70px;
  width: 4px;
  background-color: var(--needle-color);
  border-radius: 7px 7px 0 0;
  transform-origin: bottom center;
  transition: all 0.05s;
  transition-timing-function: cubic-bezier(0.1, 2.7, 0.58, 1);
}

.needle.hour {
  transform: translate(-50%, -100%) rotate(0deg);
}

.needle.minute {
  transform: translate(-50%, -100%) rotate(0deg);
  height: 91px;
}

.needle.second {
  transform: translate(-50%, -100%) rotate(0deg);
  height: 93px;
  width: 2px;
  background-color: #882c2c;
}

.centre-point {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 10px;
  height: 10px;
  background-color: #882c2c;
  border-radius: 50%;
  transform: translate(-50%, -50%);
}

.centre-point::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 5px;
  height: 5px;
  background-color: var(--needle-color);
  border-radius: 50%;
  transform: translate(-50%, -50%);
}

.time {
  font-size: 50px;
  color: var(--primary-color);
  letter-spacing: 2.5px;
}

.date {
  margin-top: 0.5rem;
  color: #6da875;
  font-size: 18px;
  letter-spacing: 1px;
  text-transform: uppercase;
}
/*clock end*/

/*relax*/
.relax-container {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  margin-top: 60px;
}

.relax-btn {
  color: var(--primary-color);
  font-size: 3rem;
  padding: 10px 10px 7px 10px;
  border: 1px solid var(--primary-color);
  border-radius: 40px;
  background-color: var(--bg-color);
  /* background-color: transparent; */
  transition: all 0.4s ease;
}

.relax-btn:hover {
  background-color: var(--relax-btn-hover);
  transition: all 0.4s ease;
}

.input-container {
  margin-top: -70px;
  text-align: center;
  color: var(--primary-color);
  font-size: 3rem;
}

.relax-title {
  margin-bottom: 25px;
}

/* remove arrows in input*/
input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button {
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  margin: 0;
}
input[type="number"] {
  -moz-appearance: textfield;
}
/**/

.input-btn {
  width: 35px;
  height: 35px;
  background-color: var(--switch-theme-bg-color);
  border-radius: 50%;
}

.relax-input {
  text-align: center;
  width: 70px;
  height: 35px;
  outline: none;
  border-radius: 4px;
  padding: 4px 4px 0 4px;
}

.begin-btn {
  margin-top: 30px;
}

.stop-btn {
  margin-top: 30px;
}

.timer-block {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.timer {
  color: var(--timer-color);
  font-size: 30px;
  letter-spacing: 2px;
}

.relax-light {
  background-image: url(https://images.unsplash.com/2/02.jpg?ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&ixlib=rb-1.2.1&auto=format&fit=crop&w=1950&q=80);
  background-position: 50% 35%;
  background-size: 210vh;
  background-repeat: no-repeat;
}

.relax-dark {
  background-image: url(https://images.unsplash.com/photo-1452800185063-6db5e12b8e2e?ixlib=rb-1.2.1&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=1189&q=80);
  background-position: 50% 35%;
  background-size: 210vh;
  background-repeat: no-repeat;
}

.display-none {
  display: none;
}

.visibility-hidden {
  visibility: hidden;
}