:root {
    --bg-dark: #0f172a;
    --bg-gradient: linear-gradient(135deg, #0f172a 0%, #1e1b4b 100%);
    --card-bg: rgba(255, 255, 255, 0.03);
    --card-border: rgba(255, 255, 255, 0.08);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    
    --work-color: #f43f5e;
    --work-color-glow: rgba(244, 63, 94, 0.4);
    --break-color: #10b981;
    --break-color-glow: rgba(16, 185, 129, 0.4);
    
    --primary-color: var(--work-color);
    --primary-glow: var(--work-color-glow);
    
    --font-main: 'Inter', sans-serif;
    --font-display: 'Outfit', sans-serif;
}

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

body {
    background: var(--bg-gradient);
    color: var(--text-primary);
    font-family: var(--font-main);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
    overflow-x: hidden;
}

/* Background Animated Orbs */
body::before, body::after {
    content: '';
    position: fixed;
    border-radius: 50%;
    filter: blur(100px);
    z-index: -1;
    animation: float 20s infinite ease-in-out alternate;
}

body::before {
    width: 40vw;
    height: 40vw;
    background: var(--primary-glow);
    top: -10vw;
    left: -10vw;
}

body::after {
    width: 30vw;
    height: 30vw;
    background: rgba(99, 102, 241, 0.2);
    bottom: -5vw;
    right: -10vw;
    animation-delay: -10s;
}

@keyframes float {
    0% { transform: translate(0, 0) scale(1); }
    100% { transform: translate(5vw, 5vw) scale(1.1); }
}

.app-container {
    width: 100%;
    max-width: 480px;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

header {
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

.back-btn {
    position: absolute;
    left: 0;
    display: flex;
    align-items: center;
    gap: 0.4rem;
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    padding: 0.5rem 0.9rem;
    border-radius: 99px;
    border: 1px solid var(--card-border);
    background: rgba(255, 255, 255, 0.04);
    backdrop-filter: blur(8px);
    transition: all 0.25s ease;
    white-space: nowrap;
}

.back-btn:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.2);
    transform: translateX(-2px);
}

.back-btn .back-arrow {
    display: inline-block;
    transition: transform 0.25s ease;
    font-size: 1rem;
    line-height: 1;
}

.back-btn:hover .back-arrow {
    transform: translateX(-3px);
}

header h1 {
    font-family: var(--font-display);
    font-size: 2.5rem;
    font-weight: 800;
    text-align: center;
    letter-spacing: -0.02em;
    background: linear-gradient(to right, #fff, #a5b4fc);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.timer-card, .settings-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-radius: 24px;
    padding: 2.5rem;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    display: flex;
    flex-direction: column;
    align-items: center;
}

/* Mode Selector */
.mode-selector {
    display: flex;
    background: rgba(0, 0, 0, 0.2);
    border-radius: 99px;
    padding: 0.3rem;
    margin-bottom: 2rem;
    width: 100%;
    position: relative;
}

.mode-btn {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 99px;
    cursor: pointer;
    transition: all 0.3s ease;
    z-index: 1;
}

.mode-btn.active {
    color: #fff;
    background: var(--primary-color);
    box-shadow: 0 4px 15px var(--primary-glow);
}

.mode-btn:not(.active):hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.05);
}

/* Timer Display */
.timer-display-container {
    position: relative;
    width: 300px;
    height: 300px;
    display: flex;
    justify-content: center;
    align-items: center;
    margin-bottom: 2.5rem;
}

.progress-ring {
    position: absolute;
    top: 0;
    left: 0;
    transform: rotate(-90deg);
}

.progress-ring__circle {
    stroke-dasharray: 879; /* 2 * pi * 140 */
    stroke-dashoffset: 0;
    transition: stroke-dashoffset 0.1s linear, stroke 0.5s ease;
    stroke-linecap: round;
}

.time-display {
    font-family: var(--font-display);
    font-size: 5.5rem;
    font-weight: 700;
    letter-spacing: -0.04em;
    color: var(--text-primary);
    text-shadow: 0 0 20px rgba(255, 255, 255, 0.2);
    z-index: 1;
    font-variant-numeric: tabular-nums;
}

/* Controls */
.controls {
    display: flex;
    gap: 1rem;
    width: 100%;
}

.control-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    border: none;
    padding: 1rem 1.5rem;
    font-size: 1.1rem;
    font-weight: 600;
    border-radius: 16px;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.control-btn:active {
    transform: scale(0.95);
}

.control-btn.primary {
    flex: 2;
    background: var(--primary-color);
    color: #fff;
    box-shadow: 0 8px 25px var(--primary-glow);
    transition: background 0.5s ease, box-shadow 0.5s ease, transform 0.2s ease;
}

.control-btn.primary:hover {
    filter: brightness(1.1);
    box-shadow: 0 10px 30px var(--primary-glow);
}

.control-btn.secondary {
    flex: 1;
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
    border: 1px solid var(--card-border);
}

.control-btn.secondary:hover {
    background: rgba(255, 255, 255, 0.1);
}

/* Settings */
.settings-card {
    padding: 1.5rem 2.5rem;
}

.settings-card h2 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    width: 100%;
    color: var(--text-secondary);
}

.setting-group {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    margin-bottom: 1rem;
}

.setting-group:last-child {
    margin-bottom: 0;
}

.setting-group label {
    font-weight: 500;
    color: var(--text-primary);
}

.setting-group input {
    background: rgba(0, 0, 0, 0.2);
    border: 1px solid var(--card-border);
    color: #fff;
    font-family: var(--font-main);
    font-size: 1rem;
    padding: 0.5rem;
    border-radius: 8px;
    width: 80px;
    text-align: center;
    outline: none;
    transition: border-color 0.3s ease;
}

.setting-group input:focus {
    border-color: var(--primary-color);
}

/* Hide number input spinners */
input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}
input[type="number"] {
    -moz-appearance: textfield;
}

/* Transition for switching modes */
body.mode-work {
    --primary-color: var(--work-color);
    --primary-glow: var(--work-color-glow);
}

body.mode-break {
    --primary-color: var(--break-color);
    --primary-glow: var(--break-color-glow);
}

/* Alarm Overlay */
.hidden {
    display: none !important;
}

.alarm-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(15, 23, 42, 0.9);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    z-index: 100;
    display: flex;
    justify-content: center;
    align-items: center;
}

.alarm-modal {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 24px;
    padding: 3rem;
    text-align: center;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    animation: pulse 2s infinite;
}

.alarm-modal h2 {
    font-family: var(--font-display);
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.alarm-modal p {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

@keyframes pulse {
    0% { transform: scale(1); box-shadow: 0 0 20px var(--primary-glow); }
    50% { transform: scale(1.05); box-shadow: 0 0 40px var(--primary-glow); }
    100% { transform: scale(1); box-shadow: 0 0 20px var(--primary-glow); }
}