*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    list-style: none;
    text-decoration: none;
}
body {
    background: #2c2f38;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    font-family: Arial, Helvetica, sans-serif;
}
.tabsPanel {
    width: 400px;
    height: 600px;
    box-shadow: 0 0 20px 0 rgba(0,0,0,0.8);
    display: flex;
    flex-direction: column;
    margin: 20px 0;
    background: #22272d;
}
.tabsLinks {
    display: flex;
    background: #191d22;
}
.tabsItem {
    flex-grow: 1;
    display: flex;
}
.tabsLink {
    padding: 15px;
    flex-grow: 1;
    display: flex;
    justify-content: center;
    color: #fff;
    text-transform: uppercase;
    letter-spacing: 1.5px;
    border-bottom: 3px solid #2c2f38;
    position: relative;
}
.tabsItem.active .tabsLink {
    border-bottom-color: #fff;
}
.tabsContent {
    flex-grow: 1;
    position: relative;
}
.clock, .stopwatch {
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    padding: 20px 0;
}
.tabsContentItem {
    z-index: 0;
    opacity: 0;
    transition: 0.5s;
    position: absolute;
    top: 0;
}
.tabsContentItem.active {
    z-index: 1;
    opacity: 1;
}
.tabsLink__span {
    display: none;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: #fff;
    right: 10px;
    position: absolute;
    transition: 0.5s;
}
.tabsLink__span.active {
    display: block;
}
.tabsLink__span.active_clear {
    display: block;
    background: red;
}
.arrowClock {
    --position: 15px;
    width: 250px;
    height: 250px;
    background: #434a53;
    border-radius: 50%;
    margin-bottom: 90px;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
}
.h {
    width: 2px;
    height: 100%;
    position: absolute;
}
.h::before {
    content: '';
    position: absolute;
    width: 100%;
    height: 35%;
    background: #0b0c0e;
    top: calc(55% - 35% + 6px);
}
.m {
    width: 2px;
    height: 100%;
    position: absolute;
}
.m::before {
    content: '';
    position: absolute;
    width: 100%;
    height: 45%;
    background: #22272d;
    top: calc(10% + 6px);
}
.s {
    width: 2px;
    height: 100%;
    position: absolute;
}
.s::before {
    content: '';
    position: absolute;
    width: 100%;
    height: 65%;
    background: #fff;
    top: 6px;
}
.arrowClockNumber {
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    position: absolute;
}
.arrowClockNumber__num {
    color: #fff;
    font-size: 22px;
    position: absolute;
}
.arrowClockNumber__num_12 {
    top: var(--position);
}
.arrowClockNumber__arr {
    position: absolute;
    width: 3px;
    height: 100%;
}
.arrowClockNumber__arr::before {
    content: '';
    display: block;
    height: 20px;
    background: #fff;
    width: 100%;
    margin-top: 8px;
}
.arrowClockNumber__arr_1 {
    transform: rotate(30deg);
}
.arrowClockNumber__arr_2 {
    transform: rotate(60deg);
}
.arrowClockNumber__arr_4 {
    transform: rotate(120deg);
}
.arrowClockNumber__arr_5 {
    transform: rotate(150deg);
}
.arrowClockNumber__arr_7 {
    transform: rotate(210deg);
}
.arrowClockNumber__arr_8 {
    transform: rotate(240deg);
}
.arrowClockNumber__arr_10 {
    transform: rotate(300deg);
}
.arrowClockNumber__arr_11 {
    transform: rotate(330deg);
}
.arrowClockNumber__num_3 {
    right: calc(var(--position) + 3px);
}
.arrowClockNumber__num_6 {
    bottom: var(--position);
}
.arrowClockNumber__num_9 {
    left: calc(var(--position) + 3px);
}

.numberClock {
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}
.numberClock::before, .numberClock::after {
    content: '';
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: #fff;
    display: block;
    position: absolute;
    animation: opacity 1s infinite;
}
.numberClock::before {
    top: 13px
}
.numberClock::after {
    bottom: 13px;
}
.hours, .minutes, .stopwatch__hours, .stopwatch__minutes, .stopwatch__seconds {
    padding: 10px 15px;
    background: #434a53;
    color: #fff;
    font-size: 25px;
    margin: 0 10px;
    border-radius: 6px;
}
.stopwatch__hours, .stopwatch__minutes, .stopwatch__seconds {
    width: 58px;
    text-align: center;
    margin: 0 0 10px;
}
.stopwatch__clock-description {
    padding: 5px 5px 10px;  
    text-align: center;
    color: #fff;
    background: #191d22;
    border-radius: 6px;
    text-transform: uppercase;
    margin: 0 5px;
}
.stopwatch__clock {
    display: flex;
    margin-bottom: 50px;
}
.stopwatch__btn {
    padding: 10px 15px;
    background: #fff;
    border-radius: 30px;
    border: none;
    font-size: 18px;
    text-transform: uppercase;
    color: #191d22;
    cursor: pointer;
    outline: none;
}


/* Добавляем keyframe на уроке*/

@keyframes opacity {
    0% {
        opacity: 1;
    }
    50% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}