*{
    margin:0;
    padding:0;
    box-sizing:border-box;
    font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
}

body{
    min-height:100vh;
    display:flex;
    align-items:center;
    justify-content:center;
    background: radial-gradient(circle at top, #87ceeb, #0d1f33);
    transition: background 0.4s;
}

.stopwatch-container{
    background: linear-gradient(160deg, #1e90ff, #00bfff);
    padding:40px 50px;
    border-radius:32px;
    text-align:center;
    box-shadow:0 20px 60px rgba(0,0,0,0.5);
    transition: transform 0.3s, box-shadow 0.3s;
}

.stopwatch-container:hover{
    transform: translateY(-6px);
    box-shadow:0 30px 80px rgba(0,0,0,0.6);
}

.mode-btns{
    display:flex;
    justify-content:center;
    gap:12px;
    margin-bottom:25px;
}

.mode-btns button{
    padding:6px 16px;
    border:none;
    border-radius:20px;
    cursor:pointer;
    font-size:13px;
    transition:0.3s;
}

.mode-btns button:hover{
    background:#1e90ff;
    color:#fff;
}

.time-display{
    font-size:40px;
    font-weight:700;
    color:#f0f8ff;
    margin-bottom:35px;
    letter-spacing:4px;
}

.time-display span{
    min-width:50px;
    display:inline-block;
}

.buttons{
    display:flex;
    justify-content:center;
    gap:20px;
}

.buttons button{
    padding:14px 36px;
    border:none;
    border-radius:50px;
    background:#00bfff;
    color:#fff;
    font-size:14px;
    font-weight:600;
    letter-spacing:1.5px;
    cursor:pointer;
    box-shadow:0 10px 25px rgba(0,0,0,0.4);
    transition:0.3s;
}

.buttons button:hover{
    background:#1e90ff;
    transform: translateY(-4px) scale(1.05);
}

.buttons button:active{
    transform: scale(0.95);
}

.dark{
    background: radial-gradient(circle at top, #020617, #000);
}

.dark .stopwatch-container{
    background: linear-gradient(160deg, #020617, #0b1220);
}

@media(max-width:480px){
    .time-display{
        font-size:32px;
        letter-spacing:2px;
    }
    .buttons{
        flex-direction:column;
        gap:14px;
    }
}