:root {
    --bg-color: #0f172a;
    --text-color: #f8fafc;
    --muted-color: #94a3b8;
    --timeline-bg: rgba(255, 255, 255, 0.1);
}

body, html {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

header {
    padding: 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 10;
}

.header-left, .header-right {
    display: flex;
    align-items: center;
    gap: 16px;
}

.back-btn {
    color: var(--muted-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1.1rem;
    transition: color 0.2s;
}

.back-btn:hover {
    color: var(--text-color);
}

.exercise-selector {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--text-color);
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 1rem;
    outline: none;
    cursor: pointer;
    backdrop-filter: blur(10px);
    appearance: none;
    -webkit-appearance: none;
    padding-right: 36px;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' fill='white' viewBox='0 0 16 16'%3E%3Cpath fill-rule='evenodd' d='M1.646 4.646a.5.5 0 0 1 .708 0L8 10.293l5.646-5.647a.5.5 0 0 1 .708.708l-6 6a.5.5 0 0 1-.708 0l-6-6a.5.5 0 0 1 0-.708z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
}

.exercise-selector option {
    background-color: var(--bg-color);
    color: var(--text-color);
}

.icon-btn {
    background: none;
    border: none;
    color: var(--muted-color);
    cursor: pointer;
    font-size: 1.5rem;
    transition: color 0.2s;
    padding: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.icon-btn:hover {
    color: var(--text-color);
}

.gift-btn {
    color: #FBBF24;
    display: none;
    animation: popIn 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards;
}

.gift-btn:hover {
    color: #FDE68A;
    transform: scale(1.1);
}

@keyframes popIn {
    0% { transform: scale(0); opacity: 0; }
    100% { transform: scale(1); opacity: 1; }
}

main {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    position: relative;
}

.breathe-container {
    position: relative;
    width: 240px;
    height: 240px;
    cursor: pointer;
    margin-bottom: 40px;
}

.breathe-glow {
    position: absolute;
    inset: -20px;
    border-radius: 50%;
    pointer-events: none;
    transition: box-shadow 0.1s linear;
}

.breathe-ring {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    will-change: transform, background;
    box-shadow: 0 10px 30px rgba(0,0,0,0.5);
}

.breathe-count {
    color: rgba(255,255,255,0.95);
    font-size: 4rem;
    font-weight: 700;
    line-height: 1;
    pointer-events: none;
    text-shadow: 0 2px 10px rgba(0,0,0,0.3);
}

.breathe-info {
    text-align: center;
    min-height: 80px;
}

.breathe-phase {
    font-size: 1.5rem;
    font-weight: 600;
    letter-spacing: 0.1em;
    margin-bottom: 8px;
    text-transform: uppercase;
}

.breathe-hint {
    color: var(--muted-color);
    font-size: 1.1rem;
}

.session-tracker {
    position: fixed;
    bottom: 70px;
    left: 0;
    width: 100%;
    display: flex;
    justify-content: center;
    gap: 12px;
    padding: 10px;
    box-sizing: border-box;
    z-index: 5;
}

.tracker-dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    opacity: 0;
    transform: scale(0);
    animation: dotIn 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards;
    box-shadow: 0 0 10px rgba(255,255,255,0.2);
}

@keyframes dotIn {
    to { opacity: 1; transform: scale(1); }
}

.timeline-container {
    width: 100%;
    height: 60px;
    background: rgba(0,0,0,0.3);
    position: fixed;
    bottom: 0;
    display: flex;
    align-items: center;
    padding: 0;
    z-index: 10;
}

.timeline-track {
    position: relative;
    width: 100%;
    height: 100%;
    background: var(--timeline-bg);
}

.timeline-progress {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.4));
    position: absolute;
    top: 0;
    left: 0;
    will-change: width, background-color;
    border-right: 2px solid white;
    box-shadow: 0 0 15px rgba(255,255,255,0.5);
}

.timeline-chart-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
}

.timeline-segment {
    height: 100%;
    opacity: 0.2;
    border-right: 1px solid rgba(255,255,255,0.1);
}

/* Modals */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.7);
    backdrop-filter: blur(5px);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 100;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.modal-overlay.active {
    display: flex;
    opacity: 1;
}

.modal-content {
    background: var(--bg-color);
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: 20px;
    padding: 32px;
    width: 90%;
    max-width: 400px;
    text-align: center;
    box-shadow: 0 25px 50px -12px rgba(0,0,0,0.5);
    position: relative;
    transform: translateY(20px);
    transition: transform 0.3s ease;
}

.modal-overlay.active .modal-content {
    transform: translateY(0);
}

.modal-close {
    position: absolute;
    top: 16px;
    right: 16px;
    background: none;
    border: none;
    color: var(--muted-color);
    cursor: pointer;
    font-size: 1.5rem;
}

.modal-close:hover {
    color: white;
}

/* Custom Config Styles */
.config-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-top: 24px;
    text-align: left;
}

.config-item label {
    display: block;
    margin-bottom: 8px;
    color: var(--muted-color);
    font-size: 0.9rem;
}

.config-item input {
    width: 100%;
    background: rgba(255,255,255,0.05);
    border: 1px solid rgba(255,255,255,0.2);
    padding: 10px;
    border-radius: 8px;
    color: white;
    font-size: 1.1rem;
    box-sizing: border-box;
}

.btn-primary {
    background: #0EA5E9;
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 30px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    margin-top: 24px;
    width: 100%;
    transition: background 0.2s;
}

.btn-primary:hover {
    background: #0284C7;
}

/* Stats Styles */
.stats-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-top: 24px;
}

.stat-box {
    background: rgba(255,255,255,0.05);
    border-radius: 12px;
    padding: 16px;
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: #0EA5E9;
    margin-bottom: 4px;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--muted-color);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}