:root {
    --primary: #ffffff;
    --accent: #5865F2;
    --accent-glow: rgba(88, 101, 242, 0.4);
    --glass-bg: rgba(255, 255, 255, 0.08);
    --glass-border: rgba(255, 255, 255, 0.12);
    --glass-blur: blur(25px);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Space Grotesk", sans-serif;
    -webkit-font-smoothing: antialiased;
}

body {
    background-color: #000;
    height: 100vh;
    overflow: hidden;
    color: var(--primary);
}

body::before {
    content: "";
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(
        to bottom,
        rgba(0, 0, 0, 0.4),
        rgba(0, 0, 0, 0.8)
    ), var(--bg-image) no-repeat center center fixed;
    background-size: cover;
    z-index: -1;
    transition: opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

body.changing-background::before {
    opacity: 0;
}

/* Header & Info */
.header {
    position: absolute;
    top: 40px;
    left: 50px;
    font-size: 52px;
    font-family: "Cedarville Cursive", cursive;
    opacity: 0.9;
    text-shadow: 0 4px 20px rgba(0, 0, 0, 0.5);
    z-index: 10;
}

.session-info {
    position: absolute;
    top: 55px;
    right: 80px;
    text-align: right;
    z-index: 10;
}

.session-label {
    display: block;
    font-size: 12px;
    text-transform: uppercase;
    letter-spacing: 3px;
    opacity: 0.5;
    margin-bottom: 4px;
}

.session-type {
    font-size: 18px;
    font-weight: 500;
    letter-spacing: 1px;
}

/* Main Container */
.container {
    height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.main-display {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 50px;
    animation: fadeIn 1.2s ease-out;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Mode Selector */
.mode-selector {
    display: flex;
    gap: 8px;
    background: var(--glass-bg);
    padding: 6px;
    border-radius: 40px;
    backdrop-filter: var(--glass-blur);
    border: 1px solid var(--glass-border);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
}

.mode-btn {
    background: none;
    border: none;
    color: var(--primary);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    opacity: 0.5;
    padding: 12px 24px;
    border-radius: 30px;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    letter-spacing: 1px;
}

.mode-btn:hover {
    opacity: 0.8;
}

.mode-btn.active {
    opacity: 1;
    background-color: var(--accent);
    box-shadow: 0 4px 15px var(--accent-glow);
}

/* Timer */
.timer-display {
    font-size: 200px;
    font-weight: 700;
    line-height: 1;
    letter-spacing: -8px;
    color: var(--primary);
    text-shadow: 0 10px 60px rgba(0, 0, 0, 0.3);
    font-variant-numeric: tabular-nums;
    transition: transform 0.3s ease;
}

.timer-display:hover {
    transform: scale(1.02);
}

/* Controls */
.controls {
    display: flex;
    align-items: center;
    gap: 20px;
}

.start-btn {
    background-color: var(--primary);
    color: #000;
    border: none;
    padding: 18px 60px;
    font-size: 16px;
    font-weight: 800;
    border-radius: 40px;
    cursor: pointer;
    transition: all 0.3s ease;
    letter-spacing: 2px;
    box-shadow: 0 10px 30px rgba(255, 255, 255, 0.2);
}

.start-btn:hover {
    transform: translateY(-4px);
    box-shadow: 0 15px 40px rgba(255, 255, 255, 0.3);
}

.start-btn:active {
    transform: translateY(-1px);
}

.reset-btn {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    cursor: pointer;
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    transition: all 0.3s ease;
    backdrop-filter: var(--glass-blur);
}

.reset-btn:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: rotate(-180deg);
}

.reset-icon {
    width: 20px;
    height: 20px;
    filter: invert(1);
    opacity: 0.8;
}

/* Audio Player Overlay */
.audio-player {
    position: fixed;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
    background: var(--glass-bg);
    padding: 12px 24px;
    border-radius: 50px;
    backdrop-filter: var(--glass-blur);
    border: 1px solid var(--glass-border);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.4);
    transition: all 0.3s ease;
}

.audio-controls {
    display: flex;
    align-items: center;
    gap: 15px;
}

.play-btn, .mute-btn, .next-btn {
    background: none;
    border: none;
    color: white;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 18px;
    opacity: 0.6;
    transition: all 0.2s ease;
}

.play-btn:hover, .mute-btn:hover, .next-btn:hover {
    opacity: 1;
    transform: scale(1.1);
}

.visualizer {
    display: flex;
    align-items: flex-end;
    gap: 4px;
    height: 20px;
}

.visualizer-bar {
    width: 3px;
    background: var(--accent);
    border-radius: 3px;
    transition: height 0.1s ease;
}

.volume-slider {
    width: 80px;
    appearance: none;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 10px;
    height: 4px;
    outline: none;
}

.volume-slider::-webkit-slider-thumb {
    appearance: none;
    width: 12px;
    height: 12px;
    background: white;
    border-radius: 50%;
    cursor: pointer;
}

/* Utilities */
.bg-switcher {
    position: fixed;
    top: 40px;
    right: 30px;
    z-index: 100;
}

.bg-switch-btn {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    color: white;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 18px;
    backdrop-filter: var(--glass-blur);
    transition: all 0.3s ease;
}

.bg-switch-btn:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: translateY(-2px);
}

.scratchpad-toggle {
    position: fixed;
    bottom: 40px;
    right: 40px;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    color: white;
    width: 56px;
    height: 56px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 20px;
    backdrop-filter: var(--glass-blur);
    transition: all 0.3s ease;
    z-index: 100;
}

.scratchpad-toggle:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: scale(1.05);
}

.scratchpad-container {
    position: fixed;
    top: 40px;
    right: -400px;
    width: 360px;
    height: calc(100vh - 80px);
    background: rgba(10, 10, 10, 0.6);
    backdrop-filter: blur(40px);
    border: 1px solid var(--glass-border);
    border-radius: 30px;
    z-index: 99;
    display: flex;
    flex-direction: column;
    transition: all 0.6s cubic-bezier(0.16, 1, 0.3, 1);
    box-shadow: -20px 0 50px rgba(0, 0, 0, 0.5);
}

.scratchpad-container.active {
    right: 40px;
}

.scratchpad-header {
    padding: 25px 30px;
    border-bottom: 1px solid var(--glass-border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 18px;
    font-weight: 700;
    letter-spacing: 1px;
}

.scratchpad-close {
    background: none;
    border: none;
    color: white;
    font-size: 28px;
    cursor: pointer;
    opacity: 0.4;
}

.scratchpad-content {
    flex: 1;
    background: none;
    border: none;
    padding: 30px;
    color: rgba(255, 255, 255, 0.8);
    font-size: 17px;
    resize: none;
    outline: none;
    line-height: 1.7;
    font-weight: 300;
}

/* Mobile Adjustments */
@media (max-width: 768px) {
    .header { font-size: 38px; left: 25px; top: 25px; }
    .session-info { right: 25px; top: 35px; }
    .timer-display { font-size: 120px; letter-spacing: -4px; }
    .start-btn { padding: 15px 40px; }
    .scratchpad-container { width: 90%; right: -100%; }
    .scratchpad-container.active { right: 5%; }
}

@media (max-width: 480px) {
    .header { display: none; }
    .session-info { 
        position: relative; 
        top: 0; 
        right: 0; 
        text-align: center; 
        margin-bottom: -20px;
    }
    .timer-display { 
        font-size: 84px; 
        letter-spacing: -2px; 
    }
    .mode-selector {
        flex-direction: column;
        padding: 10px;
        border-radius: 20px;
        width: 100%;
        max-width: 200px;
    }
    .mode-btn {
        padding: 8px 16px;
    }
    .start-btn {
        padding: 15px 30px;
        width: 100%;
    }
    .audio-player {
        width: 90%;
        bottom: 20px;
    }
    .scratchpad-toggle {
        bottom: 20px;
        right: 20px;
        width: 48px;
        height: 48px;
    }
}