:root {
    --bg-color: #0f172a; /* Slate 900 */
    --text-color: #f8fafc; /* Slate 50 */
    --secondary-text: #94a3b8; /* Slate 400 */
    --accent-color: #3b82f6; /* Blue 500 */
    --accent-hover: #2563eb; /* Blue 600 */
    --error-color: #ef4444; /* Red 500 */
    --input-bg: #1e293b; /* Slate 800 */
    --input-border: #334155; /* Slate 700 */
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    overflow-x: hidden;
}

.main-content {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100%;
}


.container {
    text-align: center;
    width: 100%;
    max-width: 600px;
    padding: 2rem;
}

/* Typography elements */
.app-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    letter-spacing: -0.05em;
}

.description {
    color: var(--secondary-text);
    margin-bottom: 2rem;
    font-size: 1rem;
}

/* Helper Class */
.hidden {
    display: none !important;
}

/* Input Section Styles */
.setup-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    animation: fadeIn 0.5s ease-out;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    width: 100%;
    max-width: 320px;
}

.datetime-input {
    background-color: var(--input-bg);
    border: 1px solid var(--input-border);
    color: var(--text-color);
    padding: 0.75rem 1rem;
    border-radius: 0.5rem;
    font-family: inherit;
    font-size: 1.1rem;
    outline: none;
    transition: border-color 0.2s;
}

.datetime-input:focus {
    border-color: var(--accent-color);
}

/* Force dark theme for datetime picker in webkit */
::-webkit-calendar-picker-indicator {
    filter: invert(1);
}

.start-btn {
    background-color: var(--accent-color);
    color: white;
    border: none;
    padding: 0.75rem 2rem;
    border-radius: 0.5rem;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s, transform 0.1s;
}

.start-btn:hover {
    background-color: var(--accent-hover);
}

.start-btn:active {
    transform: scale(0.98);
}

.error-message {
    color: var(--error-color);
    margin-top: 1rem;
    font-size: 0.9rem;
    font-weight: 500;
    animation: shake 0.4s cubic-bezier(.36,.07,.19,.97) both;
}

/* Timer Section Styles */
.timer-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    animation: fadeIn 0.5s ease-out;
}

.countdown-display {
    font-family: 'Roboto Mono', monospace;
    font-size: clamp(4rem, 15vw, 12rem);
    font-weight: 700;
    line-height: 1;
    letter-spacing: -0.05em;
    text-shadow: 0 0 20px rgba(255, 255, 255, 0.1);
}

.completion-message {
    font-size: 2rem;
    font-weight: 600;
    margin-top: 2rem;
    color: var(--accent-color);
    animation: fadeInUp 0.8s ease-out;
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

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

@keyframes shake {
    10%, 90% { transform: translate3d(-1px, 0, 0); }
    20%, 80% { transform: translate3d(2px, 0, 0); }
    30%, 50%, 70% { transform: translate3d(-4px, 0, 0); }
    40%, 60% { transform: translate3d(4px, 0, 0); }
}

/* Footer */
.footer {
    text-align: center;
    padding: 1.5rem;
    font-size: 0.85rem;
    color: var(--secondary-text);
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin-bottom: 0.5rem;
    flex-wrap: wrap;
}

.footer-links a, .text-content a {
    color: var(--secondary-text);
    text-decoration: none;
    transition: color 0.2s;
}

.text-content a {
    color: var(--accent-color);
}

.footer-links a:hover, .text-content a:hover {
    color: var(--text-color);
}

.copyright {
    margin-top: 0.5rem;
    opacity: 0.7;
}

/* Text Pages (About, Privacy, Contact) */
.page-container {
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
    padding: 3rem 2rem;
}

.page-header {
    margin-bottom: 2.5rem;
    text-align: center;
}

.page-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    letter-spacing: -0.02em;
}

.text-content {
    line-height: 1.8;
    color: var(--text-color);
}

.text-content h2 {
    font-size: 1.5rem;
    margin-top: 2.5rem;
    margin-bottom: 1rem;
    color: var(--text-color);
    border-bottom: 1px solid var(--input-border);
    padding-bottom: 0.5rem;
}

.text-content p {
    margin-bottom: 1.25rem;
    color: var(--secondary-text);
}

.text-content ul {
    margin-bottom: 1.5rem;
    padding-left: 1.5rem;
    color: var(--secondary-text);
}

.text-content li {
    margin-bottom: 0.5rem;
}

.back-link {
    display: inline-block;
    margin-bottom: 2rem;
    color: var(--accent-color) !important;
    text-decoration: none;
    font-weight: 500;
    transition: opacity 0.2s;
}

.back-link:hover {
    opacity: 0.8;
    color: var(--accent-color);
}