:root {
    --bg-color: #0f172a;
    --text-color: #f8fafc;
    --accent-color: #38bdf8;
    --accent-glow: rgba(56, 189, 248, 0.5);
    --secondary-bg: #1e293b;
    --font-family: 'Inter', sans-serif;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: var(--font-family);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    overflow: hidden;
}

.app-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
    padding: 2rem;
    background: var(--secondary-bg);
    border-radius: 24px;
    box-shadow: 0 20px 50px -12px rgba(0, 0, 0, 0.5);
    border: 1px solid rgba(255, 255, 255, 0.05);
}

/* Timer Circle & SVG */
.timer-circle {
    position: relative;
    width: 450px;
    height: 450px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.progress-ring {
    transform: rotate(-90deg);
    transform-origin: 50% 50%;
}

.progress-ring__circle {
    /* transition: stroke-dashoffset 0.1s linear; Removed for smooth JS animation */
    stroke-linecap: round;
    filter: drop-shadow(0 0 8px var(--accent-glow));
}

.time-display {
    position: absolute;
    font-size: 6rem;
    font-weight: 600;
    letter-spacing: -2px;
    text-shadow: 0 0 20px rgba(56, 189, 248, 0.3);
    font-variant-numeric: tabular-nums;
    /* Fixes jitter */
}

/* Controls */
.controls {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    width: 100%;
}

.input-group {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

input {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: white;
    padding: 0.8rem;
    border-radius: 12px;
    font-size: 1.5rem;
    width: 100px;
    text-align: center;
    outline: none;
    transition: all 0.3s ease;
}

input:focus {
    border-color: var(--accent-color);
    box-shadow: 0 0 0 2px var(--accent-glow);
}

/* Buttons */
.btn {
    padding: 1.2rem 3.5rem;
    border-radius: 50px;
    border: none;
    font-size: 1.3rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.btn-primary {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    color: #fff;
    box-shadow: 0 10px 20px -5px rgba(0, 242, 254, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 15px 30px -5px rgba(0, 242, 254, 0.6);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    background: rgba(255, 50, 50, 0.1);
    color: #ff4d4d;
    border: 1px solid rgba(255, 50, 50, 0.2);
}

.btn-secondary:hover {
    background: rgba(255, 50, 50, 0.2);
    box-shadow: 0 0 15px rgba(255, 50, 50, 0.2);
}

.hidden {
    display: none !important;
}

/* Pulse Animation for 00:00 */
@keyframes pulse-red {
    0% {
        box-shadow: 0 0 0 0 rgba(255, 0, 0, 0.7);
    }

    70% {
        box-shadow: 0 0 0 20px rgba(255, 0, 0, 0);
    }

    100% {
        box-shadow: 0 0 0 0 rgba(255, 0, 0, 0);
    }
}

.pulse-active {
    animation: pulse-red 1s infinite;
}