:root {
    --bg-color: #000000;
    --text-color: #ffffff;
    --accent-color: #ffffff;
    --dim-text: #888888;
    --border-color: #333333;
    --font-main: '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-main);
    height: 100vh;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: background-color 0.5s ease;
}

/* Animations */
@keyframes breath {

    0%,
    100% {
        opacity: 0.8;
        transform: scale(1);
    }

    50% {
        opacity: 1;
        transform: scale(1.02);
    }
}

@keyframes pulse {

    0%,
    100% {
        box-shadow: inset 0 0 20px 0px rgba(255, 255, 255, 0);
    }

    50% {
        box-shadow: inset 0 0 50px 10px rgba(255, 255, 255, 0.05);
    }
}

.breathing-effect #app {
    animation: breath 8s ease-in-out infinite;
}

.pulse-effect {
    animation: pulse 1s ease-in-out infinite;
}

#app {
    width: 100%;
    height: 100%;
    max-width: 1200px;
    position: relative;
    display: flex;
    flex-direction: column;
}

.screen {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.5s ease;
    padding: 2rem;
}

.screen.active {
    opacity: 1;
    pointer-events: all;
    z-index: 10;
}

.hidden {
    display: none !important;
}

/* Typography */
h1 {
    font-size: 2.5rem;
    font-weight: 300;
    letter-spacing: -0.05em;
    margin-bottom: 0.5rem;
    text-align: center;
}

.subtitle {
    font-size: 1rem;
    color: var(--dim-text);
    text-align: center;
    margin-bottom: 3rem;
}

/* Level Grid */
.level-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    width: 100%;
    max-width: 900px;
}

.level-card {
    background: transparent;
    border: 1px solid var(--border-color);
    padding: 2rem;
    text-align: left;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.level-card:hover {
    border-color: var(--accent-color);
    background: rgba(255, 255, 255, 0.05);
}

.level-number {
    font-size: 0.8rem;
    color: var(--dim-text);
    font-weight: 600;
}

.level-title {
    font-size: 1.5rem;
    font-weight: 400;
}

.level-desc {
    font-size: 0.9rem;
    color: var(--dim-text);
    line-height: 1.4;
}

/* Footer & Icons */
footer {
    position: absolute;
    bottom: 2rem;
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

.credits {
    text-align: center;
    font-size: 0.8rem;
    color: var(--dim-text);
    margin-bottom: 0.5rem;
}

.credits a {
    color: var(--dim-text);
    text-decoration: none;
    border-bottom: 1px dotted var(--dim-text);
    transition: color 0.3s;
}

.credits a:hover {
    color: var(--text-color);
}

.icon-btn {
    background: none;
    border: none;
    color: var(--text-color);
    cursor: pointer;
    padding: 0.5rem;
    opacity: 0.6;
    transition: opacity 0.3s;
}

.icon-btn:hover {
    opacity: 1;
}

.top-right {
    position: absolute;
    top: 2rem;
    right: 2rem;
    z-index: 20;
}

.top-left {
    position: absolute;
    top: 2rem;
    left: 2rem;
    z-index: 20;
}

/* Session Screen */
.session-content {
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 3rem;
    width: 90%;
    max-width: 800px;
}

.instruction-display {
    font-size: clamp(1rem, 2.5vw, 1.5rem);
    line-height: 1.6;
    color: var(--dim-text);
    min-height: 100px;
    max-width: 800px;
    /* Prevent layout shift */
}

.timer-display {
    font-size: 6rem;
    font-weight: 200;
    font-variant-numeric: tabular-nums;
    letter-spacing: -2px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

#overtime-indicator {
    font-size: 1.5rem;
    color: var(--dim-text);
    margin-top: -10px;
}

.controls {
    display: flex;
    gap: 1rem;
}

.control-btn {
    background: transparent;
    border: 1px solid var(--text-color);
    color: var(--text-color);
    padding: 0.8rem 2rem;
    font-size: 1rem;
    cursor: pointer;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    transition: all 0.2s ease;
}

.control-btn:hover {
    background: var(--text-color);
    color: var(--bg-color);
}

/* Overlays */
.overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.9);
    backdrop-filter: blur(5px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 50;
}

.overlay-content,
.settings-modal {
    background: #111;
    border: 1px solid var(--border-color);
    padding: 2rem;
    width: 90%;
    max-width: 400px;
    text-align: center;
}

.stat-item {
    display: flex;
    justify-content: space-between;
    margin: 1rem 0;
    border-bottom: 1px solid #222;
    padding-bottom: 0.5rem;
}

.close-overlay-btn {
    margin-top: 1.5rem;
    background: transparent;
    border: 1px solid var(--dim-text);
    color: var(--dim-text);
    padding: 0.5rem 1.5rem;
    cursor: pointer;
}

.close-overlay-btn:hover {
    border-color: var(--text-color);
    color: var(--text-color);
}

/* Settings */
.settings-modal h2 {
    margin-bottom: 1.5rem;
}

.settings-modal label {
    display: block;
    margin-bottom: 1rem;
    text-align: left;
    color: var(--dim-text);
}

.settings-modal input[type="number"] {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 0.5rem;
    width: 100%;
    margin-top: 0.5rem;
}

.toggle-label {
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
}