/* RESET & BASE STYLES  */
*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Light Mode Colors */
    --primary-color: #3B82F6;
    --success-color: #10B981;
    --danger-color: #EF4444;
    --warning-color: #F59E0B;
    --bg-color: #F3F4F6;
    --card-bg: #FFFFFF;
    --text-primary: #1F2937;
    --text-secondary: #6B7280;
    --border-color: #E5E7EB;
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* Transitions */
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Dark Mode Variables */
body.dark-mode {
    --bg-color: #111827;
    --card-bg: #1F2937;
    --text-primary: #F9FAFB;
    --text-secondary: #D1D5DB;
    --border-color: #374151;
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md);
    color: var(--text-primary);
    transition: var(--transition);
}

body.dark-mode {
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
}

/* CONTAINER  */
.container{
    width: 100%;
    max-width: 600px;
    animation: fadeIn 0.6s ease;
}

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

/* HEADER */

header{
    text-align: center;
    margin-bottom: var(--spacing-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: #fff;
}

header h1{
    font-size: 2rem;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.header-controls{
    display: flex;
    gap: var(--spacing-sm);
}

.icon-btn{
    background: rgba(255, 255, 255, 0.2);
    border: none;
    color: #fff;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1rem;
}

.icon-btn:hover{
    background: rgba(255, 255, 255, 0.3);
    transform: scale(1.1);
}

/* TABS NAVIGATION  */

.tabs {
    display: flex;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-md);
}

.tab-btn{
    flex: 1;
    padding: var(--spacing-sm) var(--spacing-md);
    background: rgba(255, 255, 255, 0.2);
    border: none;
    color: #fff;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.95rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
}

.tab-btn:hover{
    background: rgba(255, 255, 255, 0.3);
}

.tab-btn.active{
    background: #fff;
    color: var(--primary-color);
    box-shadow: var(--shadow);
}

/* CARD */

.card{
    background: var(--card-bg);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow);
    transition: var(--transition);
}

/* MODE CONTENT  */
.mode-content{
    display: none;
    animation: slideIn 0.4s ease;
}

.mode-content.active{
    display: block;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* CLOCK MODE */
.date-display{
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: var(--spacing-md);
    font-weight: 500;
}

.time-display{
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.2rem;
    font-size: 4rem;
    font-weight: 700;
    color: var(--text-primary);
    font-family: 'Courier New', Courier, monospace;
    margin: var(--spacing-lg) 0; 
}

.separator{
    animation: blink 1s infinite;
}

@keyframes blink {
    0%, 49%{
        opacity:1;
    }
    50%, 100%{
        opacity: 0.3;
    }
}

.ampm{
    font-size: 2rem;
    color: var(--text-secondary);
    margin-left: var(--spacing-sm);
}


.timezone-info{
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* STOPWATCH MODE  */
.stopwatch-display{
    text-align: center;
    padding: var(--spacing-lg) 0;
}


.time-large{
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--text-primary);
    font-family:'Courier New', monospace;
    display: flex;
    justify-content: center;
    align-items: baseline;
    gap: 0.2rem;
}

.milliseconds{
    font-size: 2rem;
    color: var(--text-secondary);
}

/* CONTROLS  */
.controls{
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-lg);
    flex-wrap: wrap;
}

.btn{
    flex: 1;
    min-width: 100px;
    padding: var(--spacing-sm) var(--spacing-md);
    border: none;
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
}

.btn:disabled{
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-success{
    background: var(--success-color);
    color: #fff;
}

.btn-success:hover:not(:disabled){
    background: #059669;
    transform: translateY(-2px);
}

.btn-danger{
    background: var(--danger-color);
    color: #fff;
}

.btn-danger:hover:not(:disabled) {
    background: #DC2626;
    transform: translateY(-2px);
}

.btn-primary {
    background: var(--primary-color);
    color: white;
}

.btn-primary:hover:not(:disabled) {
    background: #2563EB;
    transform: translateY(-2px);
}

.btn-secondary {
    background: var(--text-secondary);
    color: white;
}

.btn-secondary:hover:not(:disabled) {
    background: #4B5563;
    transform: translateY(-2px);
}

.btn-warning {
    background: var(--warning-color);
    color: white;
}

.btn-warning:hover:not(:disabled) {
    background: #D97706;
    transform: translateY(-2px);
}

/* LAPS  */
.laps-container{
    margin-top: var(--spacing-lg);
    padding-top: var(--spacing-lg);
    border-top: 2px solid var(--border-color);
}

.laps-title{
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
    font-size: 1.2rem;
}

.laps-list{
    max-height: 200px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.lap-item{
    display: flex;
    justify-content: space-between;
    padding: var(--spacing-sm);
    background: var(--bg-color);
    border-radius: var(--radius-md);
    border-left: 4px solid var(--primary-color);
    animation: slideIn 0.3s ease;
}

.lap-number{
    font-weight: 600;
    color: var(--text-primary);
}

.lap-time{
    font-family: 'Courier New', monospace;
    color: var(--text-secondary);
}

.empty-message{
    text-align: center;
    color: var(--text-secondary);
    padding: var(--spacing-lg);
    font-style: italic;
}

/* TIMER MODE */

.timer-input{
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    margin-bottom: var(--spacing-lg);
}

.input-group{
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
}

.input-group label{
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-weight: 600;
}

.input-group input{
    width: 80px;
    padding: var(--spacing-sm);
    font-size: 1.5rem;
    text-align: center;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-color);
    color: var(--text-primary);
    font-weight: 700;
    transition: var(--transition);
}

.input-group input:focus{
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.timer-display{
    text-align: center;
    padding: var(--spacing-lg) 0;
}

.progress-ring{
    position: relative;
    display: inline-block;
    margin-top: var(--spacing-lg);
}

.progress-ring-circle{
    transform: rotate(-90deg);
    transform-origin: 50% 50%;
    transition: stroke-dashoffset 0.5s ease;
    stroke-dasharray: 565.48;
    stroke-dashoffset: 565.48;
}

.progress-text{
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
}

/* FOOTER  */

footer{
    text-align: center;
    margin-top: var(--spacing-lg);
    color: #fff;
    font-size: 0.9rem;
}

footer a{
    color: #fff;
    text-decoration: none;
    font-weight: 600;
    border-bottom: 2px solid #fff;
}

footer a:hover{
    opacity: 0.8;
}

.shortcuts{
    margin-top: var(--spacing-sm);
    font-size: 0.8rem;
    opacity: 0.9;
}

/* RESPONSIVE DESIGN  */

@media (max-width: 640px) {
    header h1 {
        font-size: 1.5rem;
    }

    .tabs {
        flex-direction: column;
    }

    .time-display {
        font-size: 3rem;
    }

    .time-large {
        font-size: 2.5rem;
    }

    .controls {
        flex-direction: column;
    }

    .btn {
        width: 100%;
    }

    .timer-input {
        flex-direction: column;
        gap: var(--spacing-sm);
    }

    .card {
        padding: var(--spacing-md);
    }
}

@media (max-width: 480px) {
    .time-display {
        font-size: 2.5rem;
    }

    .ampm {
        font-size: 1.5rem;
    }

    .time-large {
        font-size: 2rem;
    }
}